joint symposium on food science and technology · joint symposium on food science and technology...

Joint Symposium on Food Science and

Technology

Food Science and Technology

Programme, NUS

and

Food Quality and Design Group,

WUR

29th October 2014

Programme Schedule and

Abstracts Book

Joint Symposium on Food Science and Technology between NUS and WUR 29 October 2014, National University of Singapore

pg. 1

Table of contents

Programme outline pg. 3

Presentation 1: Volatile organic compounds synthetized by specific spoilage organisms as spoilage indicators of raw salmon fillets

pg. 5

Presentation 2: Detection of chemical adulterations in spices pg. 6

Presentation 3: Chemical and volatile composition of lychee wines fermented with three non-Saccharomyces yeast strains

pg. 7

Presentation 4: Processing of several tropical fruits: Understanding the effect on the sensory properties, texture and nutritional composition

pg. 8

Presentation 5: Influence of fatty acid composition and stereochemistry of triacylglycerols on physical properties of milk fat

pg. 9

Presentation 6: Frozen bread dough: Mathematical modelling and controller design pg. 10

Presentation 7: Bioactive properties of red sorghum bio-colorant and their derivatives pg. 11

Presentation 8: Organopolysulfides with potential H2S-releasing activity from shallot (Allium cepa L. Aggregatum Group) and stinky beans (Parkia speciosa)

pg. 12

Poster 1: Application of novel ingredients and technologies to nutritional powders - Effects on its physicochemical properties

pg. 14

Poster 2: Effect of intensely heated milk proteins on the development of immune tolerance to milk allergens

pg. 16

Poster 3: Authentication of edible bird’s nest using GC/MS pg. 17

Poster 4: Shortening the dry period of the dairy cow – influence on milk composition and quality

pg. 18

Poster 5: The impact of structural modifications of dracoflavan B on their alpha-amylase inhibition activity

pg. 19

Poster 6: Proteomic study of the dynamics in immune proteins between human milk and bovine milk

pg. 20

Poster 7: Characterization of starch hydrolysis inhibitors in Lepisanthes alata pg. 21

Poster 8: Stability of health-promoting compounds in Colombian Cape gooseberry (Physalis peruviana L.) and its products from a supply chain perspective

pg. 22

Poster 9: Effects of salt and sugar addition on the properties of fish gelatin by nanostructural and physicochemical analyses

pg. 23

Poster 10: Extraction and characterization of proteins from five insect species pg. 24

Poster 11: Antibacterial effect of LEDs on Salmonella spp. in orange juice – Influence of temperature and irradiance

pg. 26

Poster 12: Novel processing technologies and novel protein foods pg. 27

Poster 13: Effects of high-intensity 405 nm light emitting diode on inactivation of Gram-negative foodborne pathogens

pg. 28

Poster 14: Production and valorisation of high quality proteins from insects pg. 30


pg. 2

Poster 15: Temperature adaptation alters Salmonella Enteritidis heat/acid resistance, membrane lipid composition and stress/virulence related gene expression

pg. 31

Poster 16: Interplay of consumer psychology, product properties and sensory perception on the consumer acceptance of insects as food

pg. 32

Poster 17: Optimization of real-time PCR method combined with immunomagnetic separation for detecting healthy and heat-injured Salmonella Typhimurium on raw duck wings

pg. 34

Poster 18: Dynamic texture perception and food oral breakdown pg. 35

Poster 19: Masticatory effort and bolus formation during oral processing of bread in relation to its physicochemical properties

pg. 37

Poster 20: Oral coatings, tastant migration and perception pg. 38


pg. 3

Programme

09:30 – 10:10 Opening address and overview of NUS FST/Food Quality and Design Group

Dr HUANG Dejian Associate Professor, Acting Programme Director, Food Science and Technology Programme, NUS

Dr Vincenzo FOGLIANO Professor, Chair, Food Quality and Design Group, WUR

10:10 – 10:30 Coffee break, get-to-know-each other session Presentation session 1

10:30 – 10:50 Volatile organic compounds synthetized by specific spoilage organisms as spoilage indicators of raw salmon fillets

Dr Marta MIKŠ-KRAJNIK Visiting research fellow, NUS

10:50 – 11:10 Detection of chemical adulterations in spices

Miss Isabelle SILVIS Postgraduate student, WUR

11:10 – 11:30 Chemical and volatile composition of lychee wines fermented with three non-Saccharomyces yeast strains

Miss CHEN Dai Postgraduate student, NUS

11:30 – 11:50 Processing of several tropical fruits: Understanding the effect on the sensory properties, texture and nutritional composition

Miss Ita SULISTYAWATI Postgraduate student, WUR

11:50 – 13:30 Lunch break and poster viewing

13:30 – 14:00 Laboratory visit

Presentation session 2

14:00 – 14:20 Influence of fatty acid composition and stereochemistry of triacylglycerols on physical properties of milk fat

Miss Daylan A. TZOMPA SOSA Post-doctoral fellow, WUR

14:20 – 14:40 Frozen bread dough: Mathematical modelling and controller design

Mr Turkay KONDACKI Postgraduate student, NUS


pg. 4

14:40 – 15:00 Bioactive properties of red sorghum bio-colorant and their derivatives

Mr Folachodé AKOGOU Postgraduate student, WUR

15:00 – 15:20 Organopolysulfides with potential H2S-releasing activity from shallot (Allium cepa L. Aggregatum Group) and stinky beans (Parkia speciosa)

Mr Restituto T. TOCMO Postgraduate student, NUS

15:20 – 16:00 Tea break and poster viewing

Presentation session 3

16:00 – 17:30 Food and nutrition: Perspectives from the government, industry, and academia

Ms Sharon SIA Senior Executive, Health Promotion Board

Dr Marjolijn BRAGT Manager, FrieslandCampina Institute International

Dr Jeya HENRY Professor, Director, Clinical Nutrition Research Centre, Singapore Institute of Clinical Sciences, A*STAR

17:30 – 18:00 Closing ceremony and remarks

Dr HUANG Dejian Associate Professor, Acting Programme Director, Food Science and Technology Programme, NUS

Dr Vincenzo FOGLIANO Professor, Chair, Food Quality and Design Group, WUR


pg. 5

Volatile organic compounds synthetized by specific spoilage organisms as spoilage indicators of raw salmon fillets

Marta MIKŠ-KRAJNIK1,2, YOON Yong-Jin3, and YUK Hyun-Gyun1,4,*

1 Food Science and Technology Programme, c/o Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore

2 Chair of Industrial and Food Microbiology, Faculty of Food Science, University of Warmia and Mazury in Olsztyn, Plac Cieszyński 1, 10-726 Olsztyn, Poland

3 Division of Engineering Mechanics, School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore

4 National University of Singapore (Suzhou) Research Institute, No. 377 Linquan Street, Suzhou Industrial Park, Suzhou, Jiangsu, China 215123

* Corresponding author: [email protected]

Abstract

Specific spoilage organisms (SSOs) are the major cause of spoilage of perishable food, like raw

salmon. As the effect of their metabolic activity, volatile organic compounds (VOCs) are synthetized,

causing off-odours. This study aimed to identify unique VOCs as possible spoilage indicators of raw

salmon spoilage stored aerobically under different temperature conditions and to characterize SSOs

growth dynamics. The growth of total viable count (TVC) and seven SSOs namely: psychrotrophs,

Pseudomonas spp., coliforms, lactic acid bacteria (LAB), Brochothrix thermosphacta, H2S producing

bacteria and yeasts and moulds were investigated at 4, 10 and 21 °C. The VOCs were determined by

HS-SPME-GC-MS. The maximum growth rates (µmax), shelf lives, spoilage (S) and maximum (M)

values for TVC and SSOs were calculated with the modified Gompertz model. In spoiled salmon, the

major SSOs characterized by the highest µmax, S and M values were psychrotrophs, probably

represented by Pseudomonas spp. The estimated microbial shelf lives (TVC) of salmon were 3.02,

1.82 and 0.60 days at 4, 10 and 21 °C, respectively. Significant correlations were observed between

TVC/SSOs and VOCs for trimethylamine, ethanol, 3-methyl-1-butanol, acetoin, acetic acid and 2,3-

butanediol in all conditions. The selected VOCs might be used as promising spoilage indicators for

raw salmon.

About the speaker

Dr Marta Mikš-Krajnik obtained her PhD degree in 2011 from Faculty of Food

Science, University of Warmia and Mazury in Olsztyn (Poland), where subsequently

she worked as Assistant Professor. Currently, she is a Visiting Research Fellow

under the supervision of Assistant Professor Yuk Hyun-Gyun in FST programme

(NUS). Her previous research focused on physiological state and metabolism of

lactic and propionic acid bacteria as well as the detection of starter cultures with 16/23S rRNA

oligonucleotide probes.


pg. 6

Detection of chemical adulterations in spices

Isabelle SILVIS1,2, and Saskia VAN RUTH*

1 Food Quality & Design Group, Wageningen University & Research Centre, 6700 AA Wageningen, the Netherlands

2 RIKILT, 6708 WB WAGENINGEN, the Netherlands


Abstract

Foods scandals, recently reported in the media as the addition of melamine in infant formula and the

substitution of beef with horsemeat, made consumers more aware of the vulnerability of food in the

links of the processing chain. Especially condiments as spices are susceptible to fraud as there origin

is often hard to trace. Examples of currently used methods in the detection of adulterations are

targeted DNA based techniques as PCR. With this method it is possible to find, what you are looking

for. If you are looking for the DNA of horsemeat, this technique will tell you whether it is absent or

present, but not in which quantity. PCR is time consuming and highly trained personnel are required.

Therefore, due to these drawbacks the advantages of untargeted methods are investigated and their

suitability in producing a comprehensive overview of the chemical content of a food matrix. Major

challenge is to determine if a combination of the detection of volatiles and non-volatiles combined

with multivariate data analysis works in obtaining a chemical fingerprint of the food matrix. The

chemical composition of adulterated material shall be distinctive after multivariate data analysis from

the authentic samples. Challenge is to determine how these untargeted methods can be implemented

in industry to reduce the tension for people in the food chain to commit food fraud. The methods that

we use now are the Proton Transfer Mass Spectrometry and the Direct Infusion Mass Spectrometry.

About the speaker

Miss Isabelle Silvis began her bachelor in Food Technology in Wageningen in

2007. As she was interested in different cultures and countries, she continued with

the European Master in Food studies that allowed her to study food related courses

in three other European countries and to taste their authentic flavours. Currently,

she is in the second year of her PhD, working on the authenticity of herbs and

spices.


pg. 7

Chemical and volatile composition of lychee wines fermented with three non-Saccharomyces yeast strains

CHEN Dai1, YAP Zhi Yin1, and LIU Shao-Quan1,2,*

1 Food Science and Technology Programme, Department of Chemistry, National University of Singapore, Science Drive 3, Singapore 117543

2 National University of Singapore (Suzhou) Research Institute, No. 377 Linquan Street, Suzhou Industrial Park, Suzhou, Jiangsu, China 215123


Abstract

This study was conducted to examine the effects of three non-Saccharomyces yeasts (Williopsis

saturnus var.saturnus NCYC 22, Torulaspora delbrueckii PRELUDE and Kluyveromyces lactis KL

71) on non-volatile and volatile composition of lychee wine. Growth of the non-Saccharomyces

yeasts was significantly different in the lychee fermentations. Additionally, the utilization of sugars

and the production of volatile compounds such as ethanol, esters and the retention of some juice

volatiles such as terpene compounds differed significantly among the fermentations by different yeast

strains. T. delbrueckii PRELUDE was shown to have the best ability to grow, utilize sugars and

produce ethanol (around 8 %), as well as to generate fruity ethyl esters (ethyl octanoate and decanoate)

and to retain main terpene compounds (cis-rose oxide and linalool). The lychee wine fermented with

T. delbrueckii PRELUDE was the most preferred among the treatments, which could be selected as a

desirable non-Saccharomyces yeast strain for lychee wine fermentation.

About the speaker

Miss Chen Dai is currently a PhD candidate at the Food Science and Technology

Programme at the National University of Singapore, under the supervision of

Associate Professor Liu Shao-Quan. She obtained her Bachelor of Engineering in

Viticulture and Enology Engineering, and Master of Engineering in Food

Biotechnology degrees from the College of Food Science & Nutritional Engineering

at China Agricultural University. Her current research is focusing on the chemical and volatile

composition of lychee wines produced by fermentation.


pg. 8

Processing of several tropical fruits: Understanding the effect on the sensory properties, texture and nutritional composition

Ita SULISTYAWATI1,2, Matthijs DEKKER, Ruud VERKERK, and Vincenzo FOGLIANO* 1 Food Quality & Design Group, Wageningen University & Research Centre, 6700 AA Wageningen, The

Netherlands 2 Indonesia Directorate General of Higher Education (DGHE/DIKTI)


Abstract

The world production of tropical fruit variety from the most to less dominant are mango, pineapple,

papaya and avocado, respectively. Among the minor tropical fruits of global production, guava poses

the largest contribution, followed by lychees, longan, durian, rambutan and passion fruit. From

various processed fruit products existing, dried/dehydrated fruits are attaining substantial attention,

and recently the availability of those fruits products in the market has increased considerably. Dried

fruit is higher in energy per serving than fresh, canned, frozen fruit and most fruit juices, so it makes

them a good source of dietary fibre and most of them contain vitamins (especially vitamin A) and

phytochemicals. Meanwhile, it is well known that drying, and indeed other thermal and even non-

thermal processing, leads to a number of changes of the fruit material, include physical, chemical

and/or biochemical changes.

Aims

- investigate the effects of processing (especially osmotic dehydration and drying techniques)

of several tropical fruits (i.e. pineapple, mango, papaya, guava) on the microstructural

changes, β-carotene and antioxidant activity

- study the effect of matrix modification (i.e. calcium salts addition) on the osmotic dehydrated

and dried fruits in terms of the microstructural changes, β-carotene, antioxidant activity and

sensory perception

- understand the role of residual enzymes in the quality of dried fruits during storage

- study the key quality features of dried fruits valued by consumers

About the speaker

Miss Ita Sulistyawati graduated with a MSc in Urban Environmental

Management, from Wageningen University, The Netherlands. She is a lecturer at

Food Technology Department of Soegijapranata Catholic University in Indonesia.

Currently she is a first year PhD fellow at Food Quality and Design group of

Wageningen University, The Netherlands. Her interest include food quality, food

sensory and food safety.


pg. 9

Influence of fatty acid composition and stereochemistry of triacylglycerols on physical properties of milk fat

Daylan A. TZOMPA SOSA1,2, George VAN AKEN, Hein VAN VALENBERG, Henk BOVENHUIS, Toon VAN HOOIJDONK*


2 CONACYT (Consejo Nacional de Ciencia y Tecnología)


Abstract

Selective breeding and feeding make a significant contribution to changes in the fatty acid and

triacylglycerol profile of bovine’s milk fat that in turn affect the thermal behaviour (polymorphic

transitions and melting behaviour) of milk fat. Modification in the fatty acid and triacylglycerol

profile will probably lead to a rearrangement of the TAG molecule, which will also influence the

physical properties of milk fat. A deep understanding of the thermal behaviour of milk fat is of

importance for rich fat products, and for industrial purposes such as for milk fat fractionation. Milk fat

with different physical profiles and various stereochemistry structures are desirable for the dairy

industry in order to develop functional products. These different profiles could be obtained in a

natural way by selective breeding and feeding.

Milk fat with different genetic profiles were submitted to thermal behaviour analysis (DSC) and to

fatty acid (GC-FID) and triacylglycerol profiling (GC-FID and HPLC-ELSD). The structure analysis

of milk fat triacylglycerols was determined with a regiospecific approach. This research will try to

establish the influence of genetics, fatty acid and triglyceride profile on the physical properties of

bovine milk fat. With this knowledge, bovine MF could be modified for different needs.

Aims

Understand the relation between fatty acid and triacylglycerol profile on the thermal behaviour of milk fat.

Study milk fat triacylglycerol structure and its relation with fatty acid profile and DGAT1 genotype.

Increase the knowledge on milk fat thermal behaviour.

About the speaker

Miss Daylan Tzompa is currently a post-doc at the Dairy Science Group of

Wageningen University. She works on physical and chemical properties of lipids

from various sources. Her main work is on the effect of DGAT1 on the physical and

chemical properties of bovine milk fat triacylglycerols. She also has worked on the

effect of lipid extraction on insect lipids. Daylan is Mexican and likes dancing,

climbing and swimming.


pg. 10

Frozen bread dough: Mathematical modelling and controller design

Turkay KONDACKI and ZHOU Weibiao *

Food Science and Technology Programme, c/o Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543


Abstract

It is essential to understand and quantify the mechanisms of heat transfer between the food and the

heat transfer medium during freezing. Freezing process for bread dough shows non-linear dynamics

during phase change stage. Hence, mathematical modelling of freezing may improve the

understanding of the freezing process and help to overcome the issues of dough quality during

freezing.

This research was aimed to develop mathematical models of freezing process for bread dough. A

two dimensional hemispherical model has been used to represent the shape of bread dough. The heat

transfer model produced a good agreement with the experimental data, resulting in a high coefficient

of determination (R2) and a low root mean square error (RMSE). It has been confirmed that the model

has a good performance and can be used to predict temperature profiles in the dough during freezing

process. Therefore, a controller design becomes valuable to enhance the quality of frozen dough.

A closed loop control system has been designed in Labview for a blast freezer. Effects of the

freezing process on baked bread quality have been investigated employing a PI-Controller design

which is mostly known as a classical control technique in food industry. It has been concluded that

PI-controlled freezing process showed improved quality characteristics compared to conventional

freezing methods.

About the speaker

Mr Turkay Kondakci is a PhD student working with Professor Zhou Weibiao. He

received his Bachelor’s degree from Department of Food Engineering in Istanbul

Technical University, Turkey. He then pursued his postgraduate studies in the NUS-

FST programme after he was awarded the A*STAR-SINGA scholarship. His

research work focuses on functional foods, modelling, baking process, freezing

process and advanced process control.


pg. 11

Bioactive properties of red sorghum bio-colorant and their derivatives

Folachodé AKOGOU1,2,3，Polycarpe KAYODÉ，Heidy DEN BESTEN，Anita

LINNEMANN，and Vincenzo FOGLIANO* 1 Food Quality & Design Group, Wageningen University & Research Centre, 6700 AA Wageningen, The

Netherlands 2 Laboratory of Valorization and Quality Management of Food Bio-Ingredients (LaBio), DNSA/FSA

Université d’Abomey-Calavi, Benin 3 Laboratory of Food Microbiology (WUR)，Wageningen University & Research Centre, 6700 AA Wageningen,

The Netherlands * Corresponding author: [email protected]

Abstract

Dye sorghum leaf sheaths are is a good source of 3-deoxyanthocyanins. In addition, the stability of

dimeric 3-deoxyanthocyanins in acid and neutral conditions increased the interest of 3-

doexyanthocyanin for food industry. In West Africa, sorghum colorant has been used in food and in

blood related ailments. In Benin, the water extract of the pigment is intensively applied in foods as

colorant and as preservative agent. Our objectives are to provide qualitative and quantitative data on

the extraction methods of the colorant, its applications on foods, the consumption of dyed foods in

Benin and the consumer’s perception on dyed foods. Cool alkaline extraction is the most efficient

method traditionally used to extract anthocyanins. Nevertheless, 82.6% of anthocyanin is non-

extracted using traditional methods. Sorghum colorants are applied in fermented (koko) and non-

fermented foods (wagashi). Koko is a fermented maize-based infant porridge dyed to treat related

blood ailment. Wagashi, soft West African is dye for aesthetic reason and for preservative purpose.

The application of sorghum colorants in infant fermented food like koko and on wagashi raise the

interest for the accessibility of minerals in infant foods like koko, the effect sorghum colorant might

have on the growth of lactic bacteria and its role on the wagashi preservation The perspectives are

then structured on two main points: the effect of sorghum colorant on microorganism growth and the

mineral accessibility in dyed foods.

.

About the speaker

Mr Folachodé Akogou started his university studies at the University of Abomey-

Calavi in Benin where he got an Engineer degree in Nutrition and Food Science at the

Faculty of Agronomic Sciences in 2009. He is currently doing a PhD study on the

bioactive properties of sorghum biocolorant at Wagenigen University, The

Netherlands.


pg. 12

Organopolysulfides with potential H2S-releasing activity from shallot (Allium cepa L. Aggregatum Group) and stinky beans (Parkia speciosa)

Restituto TOCMO, LIANG Dong, WANG Chenhui, and HUANG Dejian*



Abstract

Organosulfur-rich foods have been highly regarded for their broad spectrum of benefits in

disease prevention, particularly in promoting cardiovascular health. The discovery of

hydrogen sulfide (H2S) as an important endogenous signaling molecule has provided a new

avenue of research on organosulfur-rich foods as potential dietary sources of H2S donors. The

purported health benefits of dietary organosulfides via their H2S releasing activity, however,

remains an underexplored area of research and poses a considerable amount of challenge.

One of the complexities is brought about by the labile nature of organosulfur compounds,

which readily undergo chemical transformations under various processing conditions. In this

study, we characterized the organopolysulfide compositions of two tropical vegetables,

shallot and stinky beans, and investigated the effects of extraction methods, pH, and different

processing conditions on their organopolysulfide profiles. Lipophilic extracts and essential

oils were obtained by solvent extraction (SE) and hydrodistillation (DI), respectively, and

analyzed by GC and GC-MS/FID. Various sulfur-containing compounds, including disulfides,

trisulfides, and cyclic organosulfides were identified in shallot, whereas, nine cyclic

organopolysulfides with three to five tethering sulfur atoms in their chemical structures were

detected in stinky beans. We found significant differences in the quantitative and qualitative

profiles of organosulfur compounds as affected by the oil isolation methods (SE vs DI), pHs,

and processing conditions. The application of heat (cooking), autoclaving, and freeze-drying

significantly altered the concentrations of organic polysulfides as compared to those of

untreated samples. These results provide information on the effects of several factors that are

relevant for optimizing extraction and isolation of organopolysulfides from dietary sources.

We tested the H2S releasing activity of stinky bean oil in Mcf-7 cells using an H2S

fluorescent probe and preliminary results indicate that stinky bean oil has high H2S releasing

activity. Since processing conditions can greatly alter the polysulfide profiles in foods, an

H2S releasing activity guided optimization of processing conditions would lead to optimal


pg. 13

effectiveness of supplements or functional foods based on Alliums and stinky beans for their

cardiovascular health promoting functions.

Fig. 1. Dietary organopolysulfides as potential H2S donors.

About the speaker

Mr Resty Tocmo obtained an MSc in Food Science from Cornell University (2012).

Currently, he is a PhD student in the lab of Assoc. Professor Dejian Huang of the

NUS FST Programme. His research work focuses on the characterization, isolation,

and purification of organopolysulfides from organosulfide-rich dietary sources for

their H2S releasing activity.


pg. 14

Application of novel ingredients and technologies to nutritional powders - Effects on its physicochemical properties

THAM Wei Yi Tammie and Zhou Weibiao*



Abstract

Nutritional powders are specially designed products that contain essential ingredients to fulfil

nutritional requirements or act as supplements. Due to its complexity, conventional processing affects

its physicochemical properties and functionality. This paper aims to review the use of various novel

ingredients and emerging technologies in nutritional powders and their effects on its physicochemical

properties.

Several novel ingredients that are safe, nutritive and aid physicochemical stability are trehalose, n-

ocetenylsuccinate-derivatized starch (n-OSA) and inulin. For example, trehalose has unique

physicochemical properties such as high glass transition temperature (Tg), ability to retain glassy state

at high temperature, low hygroscopic profile and stability in the presence of other components.

Microcapsules with trehalose stored under low relative humidity had decreased lipid oxidation due to

its binding affinity to dienes while retaining its glassy state. Low viscosity n-OSA starch is

amphiphilic and it stabilized microencapsulated hydrophobic components and reduced the

coalescence of oil droplets under moderate spray-drying conditions. Besides improving gut microflora,

inulin that have high molecular weight could aid both processing and storage stability.

The application of novel processing technologies such as microencapsulation, extrusion

porosification and protein conjugation can be used independently or in combination with these novel

ingredients to enhance stability during processing and improve its functional properties.

Microencapsulation using ingredients such as trehalose and n-OSA starch, prevented oxidative

deterioration and enabled developments in controlled-release mechanisms. Extrusion porosification of

milk protein concentrate had high dispersibility index which enhanced its rehydration behaviour due

to casein micelle dissociation prior to drying. Protein conjugation of various milk proteins and

polysaccharidesimproved heat stability and protein solubility at the isoelectric pH during processing.

Further research is required to understand the physicochemical properties, overall stability,

component interactions, safety and nutrition of the finished product after introducing both novel

ingredients and processing technologies. In addition, industrial application must be practical and

economical in order to implement these improvements in nutritional powders.


pg. 15

About the author

Miss Tammie Tham graduated with a B. Sc in Food Science and Technology from

the University of New South Wales (UNSW), Australia. She is an FST PhD student

under the EDB IPP Scholarship. Her PhD work focuses on the physicochemical

characteristics of infant nutritional formula.


pg. 16

Effect of intensely heated milk proteins on the development of immune tolerance to milk allergens

LIU Fahui1,2, Kasper HETTINGA, Harry WICHERS, and Tiny VAN BOEKEL*


2 Food Bio-Based research, 6708 WB WAGENINGEN, The Netherlands


Abstract

Food allergy is an adverse health effect arising from a specific immune response. Cow’s milk is one

of the leading causes of food allergy especially in infants. Previous studies have estimated the

prevalence of hypersensitivity to cow’s milk from 0.6% to 2.5%. However, most studies have shown

the prognosis of developing immune tolerance to cow’s milk to be good, with the majority

outgrowing their allergy by the age of 3 years. It was reported that intensely heated (baked) milk

products contribute to the development of immune tolerance to cow’s milk allergens.

This work focuses on the mechanism of this observation and the possible compounds that may

contribute to the induction of immune tolerance. The chemical and physical properties of the heated

proteins, such as the secondary structures, available amino acids, particle size, antigenicity and the

like, were studied in this work. The amount of furosine was also measured by HPLC to reflect the

level of Maillard reaction. Then all the heated and unheated proteins were digested and absorbed in

vitro. All samples are resistant to gastric digestion, but not to the duodenal digestion. After that, the

antigenicity of the digesta was measured.

We find that the destruction of protein conformational structures resulted in the decrease of the

antigenicity of milk whey proteins. In addition, aggregates were formed during heat treatment, the

particle size of the aggregates was related to the change of antigenicity. These aggregates result from

aggregation of proteins or Maillard reaction may be the important compounds responsible for the

induction of immune tolerance.

About the author

Mr Liu Fahui comes from China and is working as a PhD student at the Dairy

Science Group of Wageningen University. The research topic is the introduction of

immune tolerance to cow’s milk allergens. He got the Master degree from

Nanchang University, China. Fahui likes computer graphics, guitar and basketball.


pg. 17

Authentication of edible bird’s nest using GC/MS

CHUA Yong Guan Peter1, LEONG Lai Peng2, Bosco Chen BLOODWORTH3, and Sam LI Fong Yau1,*

1 Department of Chemistry, National University of Singapore 2 Food Science and Technology Programme, Department of Chemistry, National University of Singapore,

Science Drive 3, Singapore 117543 3 Food Laboratory, Centre of Analytical Sciences, Health Sciences Authority


Abstract

An approach was developed and validated for the authentication of edible bird’s nest (EBN) using

gas chromatography coupled with mass spectrometer (GC/MS) and multivariate analysis. The

approach comprises of qualitative and quantitative discrimination of EBN and spiked samples. The

detectable spiking level for qualitative discrimination was as low as 0.5 % of the sample. Meanwhile,

in quantitative discrimination the approach was able to achieve an accurate detectable as low as 1 %.

The success of qualitative and quantitative discrimination of EBN and a low level of spiked samples

illustrate the feasibility of employing one analytical method for the authentication of EBN.

About the presenter

Mr Chua Yong Guan is currently a research assistant at the National University of Singapore. His

research interests include food characterisation, and toxins in food and water. His research work on

edible bird’s nest has been published in several international conferences and also in international

journals.


pg. 18

Shortening the dry period of the dairy cow – influence on milk composition and quality

Reuben DE VRIES1,2, Kasper HETTINGA, and Toon VAN HOOIJDONK*

1 Food Quality & Design Group, Wageningen University & Research Centre, 6700 AA Wageningen, The Netherlands

2 Swedish University for Agricultural Sciences (SLU) Uppsala, Sweden


Abstract

Dairy cows are commonly subjected to a dry period–a period without milking the cow- of

approximately 8 weeks between two lactations. This has been done since the beginning of the 20th

century, because of the high milk production at beginning of the next lactation. This high production

results in a negative energy balance (NEB) at the beginning of lactation, since the sudden increase in

production is not compensated by feed intake. This NEB is related to a decreased health status, and

can result in metabolic, immunity and fertility problems. When a shorter or no dry period is applied, a

lower peak production and a better energy balance of the cow are obtained.

Milk samples of three different cow breeds are analysed in this study. Cows are subjected to a

normal, a shortened or no dry period. Samples are taken both before and after calving at several time

points. Protein profiles, mainly caseins, are analysed with capillary zone electrophoresis and high

performance liquid chromatography. These techniques allow quantification all caseins, including

levels of phosphorlylation and glycosylation, and thus indicate processability of milk. Proteomic

analyses are done with LC-MS/MS technology, which is able to identify >250 proteins in milk,

including important immune proteins for the offspring. Increased knowledge of milk composition

when shortening the dry period is needed with regard to processability of milk as well as cow and calf

health. This study has the aim to study milk composition and quality of cows with a shortened or no

dry period, with focus on:

- The profile of highly abundant proteins in milk - The proteome of colostrum and milk - Processing quality of the milk

About the author

Mr Reuben de Vries’s education traject was completed in his home country the

Netherlands, finishing as an MSc in Food Technology at Wageningen UR in 2012

with specialisation Dairy Science and Technology. After graduation he started his

PhD, entitled 'Shortening the dry period of the dairy cow - influence on milk

composition and quality'. This is a joint project of Wageningen UR and the Swedish

University of Agricultural Sciences (SLU) in Uppsala. Besides working he spend his time with

cycling, running and playing badminton.


pg. 19

The impact of structural modifications of dracoflavan B on their alpha-amylase inhibition activity

TOH Zhi Siang, LU Yuyun, and HUANG Dejian*

Food Science and Technology Programme, Department of Chemistry, National University of Singapore, Science Drive 3, Singapore 117543


Abstract

Type II diabetes is an escalating problem worldwide where the number of cases can rise up to 552

million by the year 2030. Effective hyperglycaemia control can be achieved via the retardation of

starch digestive enzymes like α-amylase which have been targeted by many anti-diabetic drugs. In

this research, the A and B type dracoflavan B inhibition against pancreatic α-amylase were

investigated. Additionally, a series of chemical modifications such as esterification, sulphation and

demethylation were performed on dracoflavan B to probe its structural activity relationship (SAR)

towards α-amylase inhibition. Both the A and B type dracoflavan B strongly suppressed the

hydrolysis of starch by α-amylase with IC50 values of 23.2 and 27.6 µM respectively. Comparatively,

the A type dracoflavan B is only 16% more potent than their B type diastereomer. This result

highlighted that there is no stereospecific requirement for dracoflavan B to inhibit α-amylase.

Conversely, SAR studies demonstrated that the hydroxyl and methoxy groups of dracoflavan B are

essential for its α-amylase retardation. The turbidity assay results on starch digestion revealed that

esterification, sulphation and demethylation on these functional groups led to loss of α-amylase

inhibition. The SAR finding provides an important direction for future dracoflavan B modifications to

enhance its α-amylase inhibition.

About the presenter

Mr Toh Zhi Siang is currently a PhD student at the Food Science and Technology

Programme at the National University of Singapore. He graduated from Nanyang

Technological University with a B. Sc. in chemistry and biological chemistry. He is

currently working on inhibition of starch hydrolysis using derivatives of dracoflavan

B, under the supervision of Associate Professor Huang Dejian.


pg. 20

Proteomic study of the dynamics in immune proteins between human milk and bovine milk

Lina ZHANG1,2 , Kasper HETTINGA, and Toon VAN HOOIJDONK*


2 Bio-chemistry Group, Wageningen University & Research Centre, 6700 ET Wageningen


Abstract

Milk is the most important food for the growth and development of the neonate because of its

unique nutrient composition combined with the presence of many bioactive proteins. One of the most

interesting components, the immune proteins, plays a pivotal role in protecting the gut mucosa against

pathogens and achieving many beneficial outcomes for the immunity status of the neonate. The two

main functions of immune proteins are protecting the mammary gland against mastitis and providing

the neonate with an immunological defence against pathogen. Milk composition is not constant due to

many factors, such as, health status, lactation stage, individual differences and species differences.

Some, mainly qualprtive, studies have already been done to describe the high abundant immune

proteins in both human and bovine milk, but the knowledge on dynamics of the low abundant immune

proteins is still very limited.

The objective of this project is to study the extent and causes of variation in immune proteins from

both human and bovine milk using an advanced proteomics techniques, filter aided sample

preparation and dimethyl labelling combined with LC-MS/MS. The researches will be carried out in

four parts as shown follows: 1. The influence of healthy status on the bovine milk proteome,

especially on immune proteome; 2. The milk proteome of human and bovine milk over lactation; 3.

The differences in the milk proteome between individual mothers and between individual cows; 4.

The differences between human and bovine milk proteome. Detailed determination of the dynamics in

immune proteins in human and bovine milk not only help in understanding the role of immune

proteins for cow and human healthy but also contribute to our knowledge on the differences in the

needs of calves and babies. The comprehensive understanding in the dynamic of bovine and human

milk proteome may therefore provide guidance on how to develop infant formulas more similar in

protein composition to human milk.

About the author

Miss Lina Zhang comes from China. She studied on Food Science and Technology

during her Bachelor and agricultural products processing and preservation

engineering during der Master in China Agricultural University. Now, she is doing

PhD in Wageningen University. Her research topic is about the dynamic of immune

proteins in both human milk and bovine milk.


pg. 21

Characterization of starch hydrolysis inhibitors in Lepisanthes alata

ZHANG Yan, Adeline WONG Ik Chian, and HUANG Dejian*



Abstract

Type-II diabetes is a chronic disease with gradual deterioration in glucose metabolism. Postprandial

hyperglycemia is a concern in the management of type-II diabetes. Inhibition of α-amylase is

postulated to be a preventive treatment among the available antidiabetic therapeutic methods. After

screening around 350 natural plants from Singapore Botanical Gardens as starch hydrolase inhibitors,

we discovered a promising edible plant named Lepisanthes alata (Sapindaceae Family) with

extremely high α-amylase inhibition. The leaves of Lepisanthes alata show higher α-amylase

inhibitory activity (IC50 = 0.007±0.001 mg/ml; equals to 1643.939 μmol acarbose equivalent/g) than

that of the barks (IC50 = 0.012±0.001 mg/ml; equals to 863.934 μmol acarbose equivalent/g). Defat

leaves with hexane before extraction of leaves with a mixture of acetone, ethanol, H2O, and acetic

acid (40.0:40.0:19.9:0.1, v/v). Evaporation of the supernatant centrifuged from mixture resulted in

solid extracts. Fractionation of crude extracts was carried out by a solid-liquid extraction method,

which is to wash crude extracts by ethyl acetate, chloroform, n-Butanol, and H2O in sequence.

Chloroform fraction and aqueous fraction show relatively high α-amylase inhibitory activity, which

have IC50 values of 0.025±0.002 mg/ml and 0.0024 mg/ml, respectively. The structural information

of the active compounds are further elucidated by LCMSn approach.

About the presenter

Miss Zhang Yan completed her Bachelor’s degree and Master’s degree in

Northeast Agricultural University and her majors are Food Science and Engineering,

and Cereals, Oil and Vegetable Protein Engineering, respectively. Currently, she is a

PhD student under Associate Professor Huang Dejian in FST, and she focuses on

isolation and characterization of bioactive compounds from leaves of Lepisanthes

alata and analysis of its starch hydrolase inhibitory activity.


pg. 22

Stability of health-promoting compounds in Colombian Cape gooseberry (Physalis peruviana L.) and its products from a supply chain perspective

Mary Luz OLIVARES TENORIO1,2, and Anita LINNEMANN*


2 Uniagraria (Fundación Universitaria Agraria de Colombia)


Abstract

Cape gooseberries are fruits of the plant Physalis peruviana L. that belongs to the Solanaceae family

and contains health-promoting compounds. The small yellow to orange fruits have cherry tomato-like

appearance and sour-sweet flavour. They also have a juicy pulp that contains many kernels. Currently,

Cape gooseberry gains popularity at European markets due to its attractive appearance and is

appreciated for decoration in high cuisine. Main current producer is Colombia, followed by South

Africa. Research indicates that the gooseberry could become a fruit of particular interest to the food

industry given its contents of b-carotene, vitamin C, flavonoids and for its antioxidant activity. This

study aims to determine the thermal stability of these compounds.

About the presenter

Ms Mary Luz is from Colombia. She obtained her bachelor in food engineering

at the Fundación Universitaria Agraria de Colombia in 1998. She has worked in

food industry, especially in the sector of food services in the area of food quality

and food safety. In 2006, she received her Msc in Food Quality Management at

Wageningen University in The Netherlands, which she followed thanks to a

fellowship granted by NUFFIC. Since 2007, she has been working at Fundación Universitaria de

Colombia, her alma máter, as lecturer and now she is the director of the program of food engineering,

already for 5 years. In 2012, she was granted by NUFFIC again with a fellowship to pursuit PhD

program in the group of food quality and design at Wageningen University. Her graduation date is

expected in 2016. She is very social persona, likes to go out, read, listen to music and go to movies.

She has a lovely son whose name is Tomas.


pg. 23

Effects of salt and sugar addition on the properties of fish gelatin by nanostructural and physicochemical analyses

SOW Li Cheng and YANG Hongshun*

1 Food Science and Technology Programme, Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543


Abstract

Application of fish gelatin as a food component in replace of mammalian sources has attracted

attentions recently. However, physicochemical properties of fish gelatin might be affected by other

food components thus affecting its application. To determine whether and how sugar and salt

components in food affect the physicochemical properties of fish gelatin, nanostructure of tilapia fish

gelatin was studied by atomic force microscopy (AFM) with the secondary structure investigated by

Fourier transform infrared (FTIR) spectroscopy. The results indicated that 1.5% NaCl addition led to

a loss in molecular order in secondary structure which was accompanied with reducted gel strength;

however, addition of 1.5 % sucrose did not affect physicochemical and structural properties of fish

gelatin. Fish gelatin possessed heterogeneous nanostructure including spherical aggregates, ring like

structure, short and long rods as well as continuous fibre network. Incorporation of NaCl with fish

gelatin increased diameter of spherical aggregates to more than two folds of control. These data

suggest that addition of sodium chloride reduced gel strength through inducing large nano-aggregates,

which could be at improper alignment that prevented the formation of a rigid gel. Interestingly, the

fish skin gelatin studied here showed good storage stability over 30 days of storage at 4°C. Sodium

chloride affects fish gelatin’s nanostructure and physicochemical properties more than sucrose at the

same concentration.

About the presenter

Miss Sow Li Cheng graduated with a BSc with Honours from the National University

of Singapore, Food Science and Technology programme. She is currently a first year

PhD student doing her PhD under Assistant Professor Yang Hongshun. One special

area of interest of her work under Assistant Professor Yang Hongshun is to apply

atomic force microscopy to study the nanostructure of food. Her previous work

during her honours project was to study the impact of salt and sugar on the nanostructure of fish

gelatin. Her current on-going work is to develop a nanoemulsion based food coating for seafood

products to extend their shelf life.


pg. 24

Extraction and characterization of proteins from five insect species

YI Liya, Catriona LAKEMOND, and Tiny VAN BOEKEL*

Food Quality & Design Group, Wageningen University & Research Centre, 6700 AA Wageningen, the Netherlands


Abstract

Insects are now seriously considered as an alternative and additional source of protein in developed

countries in view of an increasing world population and the environmental problems caused by

conventional cattle.

In many countries of South America and Africa, edible insects are habitually used as animal protein

food for human consumption. However, people in the western world on average have a strong bias

against insects as food, which will hamper them to eat insects, especially when the insects are offered

in a recognizable form (including egg, larvae, pupae or adult). However, it is also possible to extract

proteins from insects for further use in food products. In view of consumer acceptance, this is

particularly relevant for countries with no habit of consuming insects, such as Europe and North

America.

Very little information from a food science point of view is available on characteristics and

functionality of extracted insect proteins. The aim of this study is to extract proteins from insects,

namely the Yellow mealworm (Tenebrio molitor), the Super mealworm (Zophobas morio), the Lesser

mealworm (Alphitobius diaperinus), crickets (Acheta domesticus) and cockroach (Blaptica dubia), in

order to characterize the obtained protein fractions and to establish their functional properties.

During the extraction procedure, firstly, fresh insects were frozen by liquid nitrogen. After adding

demineralized water and blending, the insect suspension obtained was sieved and a suspension and a

residue were collected. After centrifugation, three fractions were obtained from the filtrate:

supernatant, pellet, and fat. The supernatant and pellet fractions are characterized in terms of protein

content (Dumas analysis), molecular weight (SDS-PAGE), and functionality (foam & gel formation).

Furthermore, amino acid compositions of five insect species are also determined by using reversed

phase C18 HPLC.

It was found that crude protein content of five insect species studied ranged from 19 - 22 %.

Essential amino acid levels in all insect species were comparable with soybean proteins, but lower

than for casein. After aqueous extraction, next to a fat fraction, supernatant, pellet, and residue

fractions contained 17 – 23 %, 33 – 39 %, 31 – 47 % of total protein, respectively. The storage

modulus G' is a measure for the elastic energy stored reversibly in a gel during deformation, and

characterizes its stiffness. At 3 % (w/v), supernatant fractions did not form stable foams and gels at

pH 3, 5, 7, and 10, except for gelation for A. domesticus at pH 7. At 30 % w/v, gels at pH 7 and pH

10 were formed, but not at pH 3 and pH 5.


pg. 25

In conclusion, the insect species studied have potential to be used in foods due to: 1) absolute

protein levels; 2) protein quality; 3) ability of forming gels.

About the presenter

Miss Yi Liya is currently finishing her PhD at Food Quality & Design group of

Wageningen University. Her PhD project is on extraction, purification and

characterization of protein and lipid fractions from selected insect species. She

obtained her BSc & MSc degree, and worked as a PhD all in Wageningen

University (2005-2014). She likes playing badminton and basketball. She plays

piano for more than ten years.


pg. 26

Antibacterial effect of LEDs on Salmonella spp. in orange juice – Influence of temperature and irradiance

Vinayak S. GHATE, YUK Hyun-Gyun*, and ZHOU Weibiao



Abstract

LEDs have emerged as a novel means for ensuring food safety. They work on the principle of

photodynamic inactivation, bringing about bacterial death through the cytotoxic effect of reactive

oxygen species. Fruit juices, which are sold from dispensers in food courts are prone to post-

processing contamination either as a result of contaminated equipment or poor hygiene of food

handlers. Hence, their safety is of paramount importance. In this study, the antibacterial effect of 460

nm LEDs was studied on Salmonella spp. was studied at three temperatures (4, 12 and 20 °C and

three irradiances (92, 148 and 255 mW/cm2). The total dosage incident on the cultures was 4500 J. It

was observed that the temperature as well as the irradiance influenced the inactivation of the

pathogens. A lower temperature resulted in a higher inactivation. A similar trend was observed with

the irradiance. The colour of the orange juice samples during the illumination was monitored using a

Hunter colorimeter and certain changes in the colour were observed and quantified. Different

mathematical models such as the linear model, the Weibull model and the reparameterized Gompertz

model were also evaluated for their fit to the inactivation curves. Finally, a secondary model was

developed which related the influence of temperature and irradiance on the antibacterial effect of the

LEDs.

About the presenter

Mr Vinayak S. Ghate is a PhD student at the National University of Singapore. He

completed his B. tech. in Food Engineering & technology from the Institute of

Chemical Technology, Mumbai in 2011. He will be graduating next year.


pg. 27

Novel processing technologies and novel protein foods

Geraldine RUIZ1, Marcel MINOR, Markus STIEGER, and Tiny VAN BOEKEL*


2 Food Bio-based Reseach, Wageningen University & Research Centre, 6700 AA Wageningen, the Netherlands


Abstract

The global population is rising, so is the demand for protein foods. Traditional protein-rich products,

like meat and dairy are not very sustainable and not always healthy, and protein-enriched products

used in sports nutrition are not very appealing and targeted at too small population groups. This is

why, more recently, tasty and healthy protein-enriched products for the mass population have been

developed and the market for this is booming. Such protein-enriched products need to be processed in

a way to be safe to consume. Traditionally, this can be done by thermal treatments. However, as it is

known from other foods, those treatments may negatively affect food quality parameters such as

nutritional and sensory properties. This is why much research has gone into novel processing

technologies that use no or low heat to reduce the impact on food quality while achieving the same

food safety and shelf-life as traditional thermal treatments. One of these novel technologies is high

pressure processing.

The aim of this study is to evaluate the effects of high pressure and heat processing on quality

properties of protein-rich food systems using different protein sources.

The effects of high pressure and heat processing on quality attributes of liquid and possibly semi-

solid food model systems containing protein and sugar will be investigated and causes on a molecular

and microscopic level will be searched for. The quality attributes examined include viscosity, colour

(browning), acidity, protein digestibility and, possibly, overall sensorial quality.

About the presenter

Miss Geraldine Ruiz is a PhD employed by the Food & Biobased Research, a

business affiliated to Wageningen University and Research. She works on the

impact of high pressure processing on protein properties and on quinoa protein

extraction and characterisation (two separate projects). She is German, studied in

France, Scotland and the Netherlands in the Medical, Biological and Food

Sciences and has completed internships in hospitals and in the food industry. She enjoys cooking,

eating, sporting, socialising and exploring new cultures.


pg. 28

Effects of high-intensity 405 nm light emitting diode on inactivation of Gram-negative foodborne pathogens

KIM Min-Jeong1, Marta MIKŠ-KRAJNIK1,2, Amit KUMAR1, and YUK Hyun-Gyun1 *

1 Food Science and Technology Programme, c/o Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543

2 Chair of Industrial and Food Microbiology, Faculty of Food Science, University of Warmia and Mazury in Olsztyn, Plac Cieszyński 1, 10-726 Olsztyn, Poland


Abstract

A light emitting diode (LED) has recently received increased attention due to its antibacterial effect.

Some researchers have reported that 405 nm LED had bactericidal effect, demonstrating the potential

of novel food preservation technology. However, little information is available on its effectiveness on

foodborne pathogens and its antibacterial mechanism. The aim of this study was to investigate the

antimicrobial effect of LED on the selected Gram-negative foodborne pathogens and to elucidate its

antibacterial mechanism by determining bacterial membrane damage.

Escherichia coli O157:H7, Salmonella Typhimuirum, and Shigella sonnei were treated with 405 nm

LED. A 10 ml volume of bacterial suspension (about 108 CFU ml-1) was exposed to 1,067 J cm-2 of

LED at 4°C. The irradiance was 35±5 mW cm-2. The percent of sublethal injuries were determined

by plating tryptic soy agar (TSA) and TSA including 2-3% NaCl and 1% bile salts as selective agents,

respectively. A Live/Dead® Cell Viability assay was used to examine the membrane damage using

fluorescence microscopy. E. coli O157:H7, S. Typhimuirum, and S. sonnei were inactivated by 1.0-,

2.0-, and 0.8-log CFU ml-1, respectively, at 1,067 J cm-2. Regardless of bacterial strain and selective

agent, longer exposure time resulted in an increase in the injury percent, indicating that LED-treated

cells became more susceptible to NaCl and bile acid than untreated control cells. A Live/Dead® Cell

Viability assay also clearly showed that LED-treated cells underwent loss of the physical integrity of

the membrane, whereas untreated cells were intact.

These results indicate that 405 nm LED might be effective to inactivate the selected Gram-negative

foodborne pathogens in foods, exhibiting the potential of novel food preservation technology. In

addition, this study suggests that the antibacterial effect of the LED would be due to the membrane

damage.


pg. 29

About the presenter

Miss Kim Min-Jeong is currently a PhD candidate at the Food Science and Technology Programme

at the National University of Singapore. She graduated from Kyungnam University

(Republic of Korea) with a Bachelor of Applied Science and Master of Applied

Science in Food Science and Technoogy. She started her PhD studies in 2012,

working on food microbiology and safety, with a focus on inactivating foodborne

pathogens with light emmiting diode (LED), under the supervision of Assistant

Professor Yuk Hyun-Gyun.


pg. 30

Production and valorisation of high quality proteins from insects

Renske JANSSEN1 2, Jean-Paul VINCKEN, Catriona LAKEMOND, Vincenzo FOGLIANO, and Tiny VAN BOEKEL*


2 Food Chemistry Group, Wageningen University & Research Centre, 6700 AA Wageningen, the Netherlands


Abstract

There is a growing demand for proteins to feed the increasing world population. It is estimated that

the world population in 2050 will be around 9 billion and that 70% more food is necessary. An

alternative protein source can be insects, since the nutritional value is comparable to conventional

meat, and its production is more sustainable. Although 80% of the world population consumes insects

already occasionally, consumers in most Western countries appear to dislike such protein sources.

This might change when insect protein is added as a food ingredient, so that the insect is not

recognisable as such.

To use the insect proteins as a food ingredient, it is necessary to maintain their techno-functional

properties. For this, protein extraction from the whole insect under mild extraction conditions is

essential to preserve the characteristics of the native protein. Preliminary experiments have shown that

substantial enzymatic browning occurred during grinding of insects. Enzymatic browning is caused by

oxidation of phenolic compounds and subsequent condensation. This enzymatic reaction is catalysed

by polyphenol oxidase (PPO), which can be activated in insects as a defence reaction during

wounding and it plays a role in the exoskeleton formation. The browning can influence the techno-

functional properties, like solubility and digestibility. So efficient inhibition is necessary in order to

prevent this.

The objective of this research is to extract and characterize the water-soluble proteins efficiently

from insects, while preventing browning. This will be done by developing an efficient protein

extraction method to obtain the soluble proteins. Different methods will be investigated for the

inhibition of enzymatic browning.

About the presenter

Miss Renske Janssen was born in Rotterdam, the Netherlands. She did her

bachelor and master in Food Technology at the Wageningen University with

specialization in ingredient functionality. For her Masters, she did an internship at

Nestlé research centre in Lausanne, Switzerland. Her thesis was performed in the

laboratory of Food Chemistry on the inhibitory effect of plant extracts on

polyphenol oxidase from mushroom and potato. She is now a PhD student at Food Quality and Design

and Food Chemistry on the extraction of proteins from insects and prevention of enzymatic browning.


pg. 31

Temperature adaptation alters Salmonella Enteritidis heat/acid resistance, membrane lipid composition and stress/virulence related gene expression

YANG Yishan1, KHOO Wei Jie1, ZHENG Qianwang1, CHUNG Hyun-Jung2, and YUK Hyun-Gyun1,*

1 Food Science & Technology Programme, Department of Chemistry, National University of Singapore, Singapore

2 Department of Food & Nutrition, Inha University, Incheon, Republic of Korea


Abstract

The influence of growth temperature (10-42°C) on the survival of Salmonella Enteritidis during

heat treatment (54-60°C) and in simulated gastric fluid (pH = 2.0), on the membrane lipid

composition, as well as on stress-/virulence-related gene expression was studied. The results showed

that cells incubated at 37°C had the greatest acid resistance; while cells incubated at higher

temperature exhibited increased heat resistance. A decrease in the ratio of unsaturated to saturated

fatty acids (USFA/SFA) was observed as the growth temperature increased. Compared to the control

cells grown at 37°C, the expression of rpoS was 16.5- and 14.4-fold higher in cells cultivated at 10

and 25°C, respectively; while the expression of rpoH was 2.9-fold higher in those cultivated at 42°C.

The increased expression of rpoH and the decreased USFA/SFA correlated with the greater heat

resistance of bacteria grown at 42°C; while the decreased expression of rpoS at 42°C might contribute

to the decreased acid resistance. Virulence related genes-spvR, hilA, avrA-were induced in cells

cultivated at 42°C, except sefA which was induced in the control cells. This study indicates that

environmental temperature may affect the virulence potential of S. Enteritidis, thus temperature

should be well controlled during food storage.

About the presenter

Ms Yang Yishan is a PhD student under supervision of Dr. Yuk Hyun-Gyun. She

received her B.Sc and M.Eng degree from Department of Food Science and

Technology in Huazhong Agricultural University, China. Her research work focuses

on the responses of Salmonella Enteritidis under various adverse stress conditions.


pg. 32

Interplay of consumer psychology, product properties and sensory perception on the consumer acceptance of insects as food

Grace TAN Hui Shan1, 2, Catriona LAKEMOND, Markus STIEGER, Arnout FISCHER, and Hans VAN TRIJP*


2 Marketing & Consumer Behavior, Human Nutrition (Sensory Science), 6700 AA Wageningen, the Netherlands


Abstract

Eating is a frequent activity that is strongly motivated by pleasure, and hence dilemmas often arise

in food choice decisions where the immediate pleasure of consuming a food could conflict with the

longer term rewards of healthy and sustainable eating. Currently, there is great interest in the West

regarding the potential of insects as a source of sustainably produced protein-rich foods. Efforts to

promote the consumption of insects in the West have largely focussed on the environmental and

nutritional advantages over traditional meat sources, but despite strong public interest, the arguments

presented are insufficient to convert consumers who are unaccustomed to eating insects. This is

largely due to the unfamiliarity of insects as food but also the familiarity with them as pests and

disease that result in the elicitation of disgust at the prospect of consumption. In contrast, in insect-

eating cultures, consumers eat insects for the pleasure of taste and are specific in their preferences for

the various species, preparation methods and eating contexts.

The basis of acceptance and rejection of insects as food was explored in a cross-cultural focus group

study with consumers in Thailand, where insects are part of the cuisine, and in The Netherlands,

where insects are generally not considered food. It was found that while extrinsic factors such as

healthiness and sustainability arouse interest, they do not overcome the psychological barriers to

consuming inappropriate and unfamiliar foods. Prior exposure with food items leads to preferences

and expectations towards what is appropriate and tasty. Prior experience also influenced whether

evaluations were based on actual tasting experiences or on insect- and appearance-related associations,

which tended to be very negative. In addition, items that are normally perceived to be tasty could be

rejected if the combination is not considered appropriate. The outcomes of this study showed that the

basis of perception and evaluation of insects as food are very different depending on the degree of

prior experience and cultural background, and demonstrated that the promotion of insects should not

solely focus on communicating the benefits of consumption but should pay due attention to creating

products that suit consumer expectations in their own cultural context.


pg. 33

About the presenter

Miss Grace Tan Hui Shan is a 3rd year PhD student in the sensory and consumer

sciences. She works on understanding the cultural and psychological mechanisms

underlying the acceptance and rejection of insects as food, and how the successful

use of product design could help to overcome the barriers towards new foods. She is

originally from Singapore and did her Bachelors in Food Science and Technology at

the National University of Singapore, and a double masters in Nutrition and Health at Wageningen

University and Food Technology at the University of Copenhagen, where she specialized in sensory

science and eating behaviours. She loves to explore food cultures and to experience tastes from

around the world.


pg. 34

Optimization of real-time PCR method combined with immunomagnetic separation for detecting healthy and heat-injured Salmonella

Typhimurium on raw duck wings

ZHENG Qianwang1, YANG Yishan1, KIM Min-Jeong1, Marta Mikš-Krajnik1,2, and YUK Hyun-Gyun 1,3,*

1 Food Science & Technology Programme, Department of Chemistry, National University of Singapore, Singapore

2Chair of Industrial and Food Microbiology, Faculty of Food Science, University of Warmia and Mazury in Olsztyn, Plac Cieszyński 1, 10-726 Olsztyn, Poland

3National University of Singapore (Suzhou) Research Institute, No. 377 Linquan Street, Suzhou Industrial Park, Suzhou, Jiangsu, China 215123


Abstract

This study investigated a rapid detection method combining real-time PCR and immunomagnetic

separation (PCR-IMS) to determine healthy and heat-injured Salmonella Typhimurium on duck.

IMS was optimized on Salmonella cells with different reaction and separation times. Three Taqman

primers (Sal, invA and ttr) were evaluated to optimize the PCR protocol. The optimized PCR-IMS

was compared with ISO and PCR method by analyzing raw duck wings with healthy and heat-injured

Salmonella cells at low innoculum levels, followed by validating with naturally contaminated samples.

Under optimal IMS conditions (30 min reaction and 3 min separation), 85 and 64 % of Salmonella

were captured from pure culture and food suspensions. Sal showed lower LOD (103 CFU/mL) and

higher PCR efficiency (94.1%) than invA and ttr, therefore Sal was chosen for further experiments.

The optimized PCR-IMS method was significantly better to detect healthy Salmonella after 7-h

enrichment than PCR method alone, however there was no significant difference between two

methods with longer enrichment time (14 h). The diagnostic accuracy of PCR-IMS was shown to be

97.5% through the validation study.

The optimized PCR-IMS method could provide a sensitive and rapid detection for Salmonella.

However, a longer enrichment time should be needed for reliable detection of heat-injured cells.

About the presenter

Ms Zheng Qianwang received her bachelor in the Department of Biological

Science, Sun Yat-Sen University (Guangdong, China) in 2011. She started her PhD

in Food Science and Technology in NUS in the same year. Currently, she is under

the supervision of Assistant Professor Yuk Hyun-Gyun, and mainly focus on

foodborne pathogen rapid detection.


pg. 35

Dynamic texture perception and food oral breakdown

Marine DEVEZEAUX DE LAVARGNE1 2, Markus STIEGER, and Tiny VAN BOEKEL*


2 Top Institute Food and Nutrition, Human Nutrition (Sensory Science) (WUR)


Abstract

Texture perception depends on oral processing as the food structure is constantly modified during

eating until it forms a ready to swallow paste called food bolus. In order to obtain a full understanding

of texture perception, food structure, food breakdown in mouth, eating behaviour and physiology

must be controlled and/or measured in parallel.

Texture perception in mouth depends on the food structure and its contact with the oral cavity. Food

structure can be controlled in order to obtain desired sensory textures, however this structures are

modified during oral processing and are hardly correlated with perception of chew down texture

attributes. The main phenomenon occurring during oral processing are the decrease in structure of the

food by comminution during chewing and the increase in lubrication by salivation. In order to

understand the changes in food texture, the properties of the forming bolus can be analysed. A wide

range of analyses on spit out bolus exist in literature from measuring particle size to saliva content.

Due to the complexity of food structures, a wholesome understanding is difficult to obtain and model

foods such as gels are usually designed in investigating texture perception. Mixed gels containing

several gelling agents can be used to control structural and microstructural aspects of the food.

Emulsion filled gels can be used to investigate perception of fat related attributes. In this PhD,

emulsion filled gels with varying fracture properties were designed, breakdown and bolus properties

were analysed on spit out bolus and linked to dynamic texture perception. Measuring the temporal

aspect of sensory texture can be done with the separation between first bite, chew down and after-feel

texture attribute in a quantitative descriptive analysis (QDA). More dynamic methods such as

sequential profiling and temporal dominance of sensations (TDS) have recently been developed. In

this work, several methods were used separate or in combination to obtain a wholesome sensory

profile of foods.

In this PhD work, food gel structure impact on breakdown was investigated, moreover the

properties of the food bolus were linked to dynamic texture perception. It was shown that some bolus

properties explain the perception of chew down texture attributes such as graininess or melting.

Creaminess is a multimodal sensory attribute depending on several bolus properties. Other work on

inter-individual differences on texture perception showed that eating speed influenced perception of

texture attributes perceived towards the end of mastication.


pg. 36

About the presenter

Miss Marine Devezeaux de Lavargne is a 4th year PhD student in the FQD

department and as part of the sensory group of the Human Nutrition department of

Wageningen UR. Her PhD combines the fields of food structuring, sensory science

and human physiology. She studied Food Science Engineering in France in

AgroParisTech where she finalized her studies by a double-degree with Wageningen

University. She enjoys travelling and trying all sorts of new foods.


pg. 37

Masticatory effort and bolus formation during oral processing of bread in relation to its physicochemical properties

GAO Jing, Jocelyn WONG Xue Yan, and ZHOU Weibiao*

Food Science and Technology Programme, Department of Chemistry, National University of Singapore, Science Drive 3, Singapore 117543


Abstract

Food structure is dramatically modified when it undergoes oral processing. The breakdown of food

structure and formation of bolus are determined both by intrinsic food properties and extrinsic

individual physiological differences. This study aimed to investigate the role of physicochemical

properties of bread on its disintegration and human masticatory behavior during oral processing.

Three types of bread, i.e. baked white bread, steamed bread, and French baguette, with distinct crumb

grain feature were evaluated. Single human panelist masticated the bread freely until ready to swallow

and then spat out the bolus. Collected bolus was analyzed for its density, saliva impregnation and

particle size distribution. Muscle activity of the evaluator’s muscles (i.e. masseters and anterior

temporalis) was monitored using surface electromyography (SEMG). Results showed that the total

chewing duration was significantly shorter and the number of chewing cycles was significantly lesser

for the steamed bread compared to the baked bread and the baguette. The baguette exhibited the

largest SEMG amplitude and muscle work per chew, followed by the baked bread and the steamed

bread. These results suggested that the steamed bread required the least amount of chewing effort to

form a safe-to-swallow bolus, followed by the baked bread and the baguette. Results from bolus

characterization showed that baguette bolus had the greatest amount of saliva impregnation whereas

steamed bread bolus had the largest median particle size, indicating a different level of lubrication and

mechanical breakdown of the three types of bread. Specific volume of bread was found to be

significantly correlated with chewing cycle, saliva impregnation level, and median particle size. Our

study demonstrated that bread with different physicochemical properties required a different level of

oral processing, leading to different levels of disintegration and lubrication after chewing which may

have a profound impact on its subsequent digestion in stomach and small intestine.

About the presenter

Ms Gao Jing is currently a PhD student at the Food Science and Technology

Programme in the National University of Singapore. She obtained her Bachelor of

Applied Science (with Honours) degree from the same programme in 2012. She

started her postgraduate study early 2013 under the supervision of Professor Zhou

Weibiao, working on the study of bread structure and its digestion.


pg. 38

Oral coatings, tastant migration and perception

Sara Marina RODRIGUES CAMACHO1 2, Markus STIEGER, and Kees DE GRAAF*


2 Top Institute Food and Nutrition, Human Nutrition (Sensory Science) (WUR)


Abstract

Oral coatings are residues remaining on oral surfaces after the consumption of foods and beverages.

Oral coatings have been shown to influence taste and aroma perception. Madrigal-Galan and

Heymann observed a decrease in intensity of several wine sensory attributes, such as astringency, bell

pepper, and oak flavour, when the wine was evaluated after eating cheeses. It was hypothesized that

the decrease in intensity might be caused by an oral coating of fat in the oral cavity, formed by the

cheese. Furthermore, de Wijk suggested that fat containing oral coatings lubricate the movement of

the food bolus on the oral tissue leading to lower intensities of perceived dryness and roughness and

higher intensities of creaminess of custards2. Although the influence of oral coatings on sensory

perception has been studied by several authors, there is only very little information available on the

composition and structure of oral coatings.

The aim of this project was to investigate the physical and sensory properties of coatings on the

tongue formed by oil/water (o/w) emulsions as a model system for beverages. In vivo fluorescence

measurements were used to quantify the fraction of oil (moil/Atongue) deposited on the tongue in

relation to dynamic sensory perception. In vivo fluorescence method provides a direct measure of oral

coatings deposition, without damaging any of its components and gives a spatial.

Different o/w emulsions were prepared to investigate the influence of several factors (e.g. oil

content, protein type and content) on the deposition and clearance of oral coatings. Curcumin was

added as a hydrophobic fluorescent marker to all the samples. Twenty subjects processed orally each

sample for 30s, in triplicate. The fluorescence intensity of the oral coating was measured at eight time

points, in the front and back part of the tongue. Simultaneously, subjects rated the perceived intensity

of coating related attributes.

For every sample, the oil fraction was significantly higher on the back part of the tongue than on the

front part. The oil fraction initially deposited on the tongue was affected by the oil composition of the

o/w emulsion. The type and amount of protein used in the emulsions had a significant effect on the

deposition and clearance of the coating. This project unravels new insights in the oral processing of

emulsions, and demonstrates the potential of in vivo fluorescence to study food behaviour in mouth.


pg. 39

About the presenter

Miss Sara Rodrigues Camacho is a PhD student on a project financed by TI Food

and Nutrition, and is working within the Divisions of Food Quality and Design and

Human Nutrition (Sensory Science Group) of Wageningen University, the

Netherlands. Sara was born in a small island called Madeira, in Portugal, known as

the “Pearl of the Atlantic”. She made her bachelor and master on Biological

Engineering in the Technical University of Lisbon, Portugal. Sara really enjoys to explore new places,

meet new people and loves animals.

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