research article quality parameters of six cultivars of

Hindawi Publishing CorporationInternational Journal of Food ScienceVolume 2013 Article ID 419535 8 pageshttpdxdoiorg1011552013419535

Research ArticleQuality Parameters of Six Cultivars of Blueberry UsingComputer Vision

Silvia Matiacevich1 Daniela Celis Cofreacute1 Patricia Silva1

Javier Enrione2 and Fernando Osorio1

1 Departamento de Ciencia y Tecnologıa de los Alimentos Facultad Tecnologica Universidad de Santiago de ChileAvenida Libertador Bernardo OrsquoHiggins No 3363 Estacion Central 9170022 Santiago Chile

2 Departamento de Nutricion y Dietetica Facultad de Medicina Universidad de los Andes San Carlos de Apoquindo 2200Las Condes 7620001 Santiago Chile

Correspondence should be addressed to Silvia Matiacevich silviamatiacevichusachcl

Received 29 November 2012 Revised 5 March 2013 Accepted 19 March 2013

Academic Editor Carl J Schaschke

Copyright copy 2013 Silvia Matiacevich et al This is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work is properlycited

Background Blueberries are considered an important source of health benefits This work studied six blueberry cultivars ldquoDukerdquoldquoBrigittardquo ldquoElliottrdquo ldquoCenturionrdquo ldquoStarrdquo and ldquoJewelrdquo measuring quality parameters such as ∘Brix pHmoisture content using standardtechniques and shape color and fungal presence obtained by computer vision The storage conditions were time (0ndash21 days)temperature (4 and 15∘C) and relative humidity (75 and 90) Results Significant differences (119875 lt 005) were detected betweenfresh cultivars in pH ∘Brix shape and color However the main parameters which changed depending on storage conditionsincreasing at higher temperature were color (from blue to red) and fungal presence (from 0 to 15) both detected using computervision which is important to determine a shelf life of 14 days for all cultivars Similar behavior during storage was obtained for allcultivars Conclusion Computer vision proved to be a reliable and simple method to objectively determine blueberry decay duringstorage that can be used as an alternative approach to currently used subjective measurements

1 Introduction

Blueberries have an increasing demand for popular con-sumption because of their nutraceutical properties [1 2]including their high content of phenolic compounds with awide spectrum of biochemical activities such as antioxidantantimutagenic cardiovascular protection antidiabetic visionimprovement properties and carcinogenesis inhibition [3]

Blueberries are little blue fruits of the genus Vacciniumthat have short shelf life It has been stated that underrefrigeration temperatures (0∘C) the shelf life of blueberriesis about 14ndash20 days [4 5] The main quality indicators ofthe fruit are appearance (color size and shape) firmness ortexture flavor (soluble solids and pH) and nutritive value [6]The color ranges from light blue to deep black blue dependingon the cultivar and the presence of an epicuticular wax whichgives its attractive appearance [4] Color changes during

storagemay have a profound effect on consumer acceptability[7]

Consumers demand high quality fruits which are depen-dent on harvestmethods cultivar characteristics postharvesthandling and storage temperatures [1] Computer vision(CV) is a nondestructive technology used for acquiring andanalyzing digital images to obtain information of heteroge-neous products It has been regarded as a valuable tool whichhelps to improve the automatic assessment of food quality [89] CV has been recently used in the food industry for qualityand color evaluation detection of defects grading and sort-ing of fruits and vegetables among other applications [7ndash11]

The objectives of this work were to study importantquality factors of six different blueberry cultivars harvested inChile under different storage conditions and to compare thesecultivars as part of a comprehensive study of blueberry con-servation including the innovative technology of computer

2 International Journal of Food Science

0 1 2 3

Figure 1 Fruit dehydration degree visually observed following the norms for quality of fresh blueberries from Chilean Blueberry Committee(CBBC 2011)

Figure 2 Computer vision system Elements distribution in thedigital image acquisition

vision which was applied in this research as a preliminarystudy to determine blueberry decay objectively instead ofmeasuring it subjectively as is done nowadays

2 Materials and Methods

21 Plant Material This study was conducted during the2009-2010 harvest season All cultivars were donated bythe Chilean Association of Exporters (ASOEX-Chile) Threeblueberry cultivars (ldquoBrigittardquo ldquoElliottrdquo and ldquoDukerdquo) fromSouthern Highbush variety (Vaccinium darrowii) two cul-tivars (ldquoJewelrdquo and ldquoStarrdquo) from Northern Highbush vari-ety (Vaccinium corymbosum) and the cultivar ldquoCentu-rionrdquo from Rabbiteye variety (Vaccinium virgatum) wereused All cultivars were hand-harvested at full maturityfrom commercial plantations located in the central valleyof the Metropolitan Region in Chile (Curacavı HortifrutSA) during mid-December (ldquoDukerdquo and ldquoJewelrdquo) January(ldquoBrigittardquo) mid-February (ldquoElliottrdquo and ldquoCenturionrdquo) andmid-March (ldquoStarrdquo) and transported to the laboratory onthe same day High quality blueberries (119899 = 50) at eachstorage condition were obtained by random (119899 = 10 ofeach clamshell) from 12 clamshells of approximately 125mgeach presorted by hand discarding the excessively small softvisually damaged nonblue fruits and those with the presenceof pedicel and floral remains as sample set for all experiments

22 Storage Conditions Blueberries (119899 = 50 at each con-dition) were stored at 4 and 15∘C and equilibrated underdifferent relative humidities (RH) using saturated solutionsof NaCl (75 RH) and KCl (90 RH) [12] during differentstorage times (0 7 14 and 21 days)

23 Fruit Quality Indicators

231 pH and Total Soluble Solids Content Blueberry juicewas preparedfrom 5 blueberries randomly selected (in trip-licate) at each storage time The pH was measured with a pHmeter (Jenway UK) using a liquid electrode (Jenway 924-001model 3505) calibrated according toOMA 1975 Total solublesolids concentration was determined by placing a drop of thisblueberry juice (1mL) on a calibrated portable refractometer(0ndash32 ∘Brix RHB-32ATC)Themean and standard deviationof three replicates were recorded and expressed as ∘Brix

232 Fruit Size and Form The equatorial and polar diameterof each blueberry was measured with a digital caliper (BullTools USA) and the roundness index (RI) was determinedfrom (1) Mean and standard deviation of all blueberries(119899 = 50) measured at each storage condition were reportedThese parameters were also obtained from image analysiscorrelating linearly with experimental data (1198772 = 0998)

RI = polar diameterequatorial diameter

(1)

233Water Content and Fruit-Dehydrated Percentage Watercontent was gravimetrically determined using an analyticalbalance (Mettler Toledo Switzerland) Twelve blueberries (intriplicate) were dried for 24 h in an oven (Wiseven Korea) at105∘C until constant weight Water content was expressed aswet basis percentage (g water100 g wet sample)

Dehydrated fruit percentage was evaluated visually usingthe photographies obtained by computer vision taking intoaccount the different degrees of fruit dehydration (Figure 1)following the norms for quality of fresh blueberries fromChilean Blueberry Committee [13] Fruits with dehydrationdegree of 2 or 3 were counted as dehydrated fruit

24 Image Analysis

241 Color Digital images of each blueberry (of two oppo-site sides) were taken at each storage time in order to obtainthe surface color of the fruit using a computer vision system(Figure 2) which consisted of a black box with four 18Wnatural light tubes (D65 Philips) and a digital camera (Canon10MP PowerShot G4) placed in a vertical position 225 cmfrom the samples (camera lens angle and lights at 45∘) [9]All images were obtained under the same conditions thecamera was remotely controlled by ZoomBrowser software(v60 Canon) Surface color data were measured in the CIEL

International Journal of Food Science 3

1

2

3

4

0 7 14 21 28

pH

Storage time (days)

BrigittaElliott

CenturionStar

Duke

(a)

0

4

8

12

16

0 7 14 21 28Storage time (days)

BrigittaElliott

CenturionStar

Duke

∘Br

ix(b)

Figure 3 pH and ∘Brix variations of different cultivars for different storage times at 4∘C and 90 RH

Table 1 Quality parameter differences between fresh cultivars

Cultivar pH ∘Brix RI1 Water content( wb)2 Llowast3

ldquoDukerdquo 374 plusmn 011(a) 1033 plusmn 031(a) 073 plusmn 001(a) 8650 plusmn 052(a) 6496 plusmn 282(a)

ldquoBrigittardquo 357 plusmn 017(ac) 1270 plusmn 053(ab) 074 plusmn 001(a) 8759 plusmn 072(a) 7149 plusmn 197(a)

ldquoElliottrdquo 294 plusmn 006(b) 1320 plusmn 010(b) 072 plusmn 001(a) 8346 plusmn 079(b) 7285 plusmn 520(a)

ldquoCenturionrdquo 341 plusmn 002(c) 1393 plusmn 150(b) 095 plusmn 003(b) 8236 plusmn 083(b) 7185 plusmn 194(a)

ldquoStarrdquo 303 plusmn 006(b) 1293 plusmn 011(b) 078 plusmn 001(c) 8397 plusmn 051(b) 7178 plusmn 300(a)

ldquoJewelrdquo 350 plusmn 010(c) 1190 plusmn 038(a) 082 plusmn 002(d) 7986 plusmn 085(c) 7220 plusmn 250(a)

Different superscript letters for the same column indicate values to be significantly different (P lt 005)1RI roundness index (1)2 wb means wet basis percentage3Llowast color parameter of lightness

Table 2 Percentages () of dehydrated fruits take into accountvisually surface dehydration at different storage conditions oftemperature (∘C) and relative humidity (RH) after 21 days of storage

Cultivar 4∘C75RH

4∘C90RH

15∘C75RH

15∘C90RH

ldquoDukerdquo 12 107 21 19ldquoBrigittardquo 5 27 351 333ldquoElliottrdquo 201 155 357 354ldquoCenturionrdquo 20 187 402 396ldquoStarrdquo 37 36 381 38ldquoJewelrdquo 155 125 381 375

lowast

119886lowast

119887lowast space and image analysis was performedwith the Balu

Toolbox in Matlab software (v7) [8] The camera parametersandBalu softwarewere calibrated using 30-color charts with aMinolta colorimeterTherefore 119871lowast119886lowast119887lowast values obtained fromimage analysis were equal to the values from the colorimeter

Color variation CIEDE2000 or Δ11986400 is regarded as

the best uniform color difference model coinciding withsubjective visual perception which can reflect the colordifference between two images The color variation (Δ119864

00

(2)) during storage time was determined using the formulaswhich include the concepts of chroma (119862lowast (3)) and hue (ℎ1015840(4)) for119871lowast119886lowast119887lowast values [14]The color grade differences (Δ119864

00)

between two samples (1 2) were determined as follows theperception of color differences was taken as imperceptibleif Δ11986400lt 15 noticeable if Δ119864

00lt 3 and appreciable if

Δ11986400lt 6 [15]

Δ11986400= radic(

Δ1198711015840

119870119871119878119871

)

2

+ (Δ1198621015840

119870119862119878119862

)

2

+ (Δ1198671015840

119870119867119878119867

)

2

+ 119877119879(Δ1198621015840

119870119862119878119862

)(Δ1198671015840

119870119867119878119867

) (2)


119862lowast

119894119886119887

= radic(119886lowast

119894

)2

+ (119887lowast

119894

)2

119894 = 1 2 (3)

ℎ1015840

119894

= tanminus1 (119887lowast

119894

1198861015840

119894

) 119894 = 1 2 (4)

where

1198861015840

119894

= (1 + 119866) 119886lowast

119894

119894 = 1 2

119866 = 05(1 minus radic119862lowast

119886119887

2

119862lowast

119886119887

7

+ 257

)

119862lowast

119886119887

=

(119862lowast

1119886119887

+ 119862lowast

2119886119887

)

2

1198621015840

119894


119894

)2

+ (119887lowast

119894

)2

119894 = 1 2

9987791198711015840

= 119871lowast

2

minus 119871lowast

1

9987791198621015840

= 119862lowast

2

minus 119862lowast

1

998779ℎ1015840

= ℎ1015840

2

minus ℎ1015840

1

9987791198671015840

= 2radic1198621015840

1

1198621015840

2

sin(Δℎ1015840

2)

1198711015840 =(119871lowast

1

+ 119871lowast

2

)

2

1198621015840 =

(1198621015840

1

+ 1198621015840

2

)

2

ℎ1015840 =

(ℎ1015840

1

+ ℎ1015840

2

)

2

119878119871= 1 +

0015(1198711015840 minus 50)2

radic20 + (1198711015840 minus 50)2

119878119862= 1 + 00451198621015840

119878119867= 1 + 00151198621015840119879

119879 = 1 minus 017 cos (ℎ1015840 minus 30) + 024 cos (2ℎ1015840)

+ 032 cos (3ℎ1015840 + 6) minus 020 cos (4ℎ1015840 minus 63)

119877119879=minus sin (2Δ120579)119877119862

998779120579 = 30 exp

minus[

[

(ℎ1015840 minus 275∘

)

25

]

]

2

119877119862= 2radic

11986210158407

(11986210158407

+ 257

)

119870119871= 119870ℎ= 119870119862= 1

(5)

(see [16])

242 Fungal Presence Fungal presence percentage wasobtained by image analysis by computer vision taking as pos-itive blueberry when fungal filaments were visually observedaccording to (6)

Fungal presence = No of positive blueberriesNo of total blueberries

times 100

(6)

In order to validate the fungal presence percentagevisually observed by image analysis fungal filaments fromfruits were extracted by immersion of fruits in 5mL ofdistilled water for 1min with manual agitation Turbidity ofextracted aqueous samples was measured by absorbance at720 nm A linear correlation of fungal presence on fruits thatmeasured both turbidity and image analysis (1198772 = 0995) wasobtained Pearson correlation coefficient was 099 indicatinga good positive correlation between the values reported byabsorbance and image analysis using (6) [7]

25 Statistical Analysis Statistical analysis was made byanalysis of variance (ANOVA) and Tukeyrsquos posthoctestconsidering significant differences if 119875 le 005 Pearsonrsquoscorrelation coefficient (119875) was also calculated

3 Results and Discussions

In first place a characterization of quality indicators of sixcultivars was determined at initial time (fresh blueberries) toobtain possible differences among cultivars Then a charac-terization of each quality indicator was made during storagetime under different storage conditions in order to obtain theshelf life and the behaviour of blueberries under the studiedstorage conditions

31 pH and ∘Brix All evaluated cultivars were from the samefield conditions (Summer 2009-2010) in order to avoid theinfluence of growing conditions such as soil pH and waterthat could affect the pH of the fruits [17] The pH and ∘Brixobtained from each fresh cultivar are shown in Table 1

The initial pH (fresh fruits) founded in ldquoDukerdquo (pH =

374 plusmn 011) was higher than other blueberry cultivars whilethe lowest value was obtained for ldquoElliottrdquo (pH = 29 plusmn 006)The reason for these differences would be the citric acidconcentration present in each cultivar which also depends


on genetic differences [17] The pH values obtained for allthe cultivars were in the range of 275ndash381 in agreementwith previous literature reports for other different blueberrycultivars [18]

The highest ∘Brix values were found in ldquoCenturionrdquo( ∘Brix = 139plusmn05) and ldquoElliottrdquo ( ∘Brix = 135plusmn05) and thelowest value was found for ldquoJewelrdquo ( ∘Brix = 119plusmn04)Theseresults are in agreement with the expected range of 112ndash143∘Brix reported for other blueberry cultivars [18 19]

Although pH and ∘Brix values were different amongcultivars of fresh fruits these values remained constant withrespect to the initial values (119875 gt 005) during the storagetime regardless of storage conditions (Figure 3) It has beenreported that the increasing pH in the fruit is due tomaturingtime on the plant and also to dehydration during postharveststorage [1 20]Therefore the constant values of pH and ∘Brixduring postharvest storage obtained in this study could bean indicative that no significant dehydration occurred duringevaluated storage conditions

32 Fruit Size and Shape The equatorial diameter androundness index (RI (1)) of each fresh cultivar are shownin Table 1 All the cultivars presented an equatorial diametergreater than 1 cm which is required to satisfy Chilean exportspecifications Therefore these blueberries were not consid-ered as low calibre [13] However the percentage variationof the equatorial diameter of all the cultivars (50ndash60) washigher than 3 which is established for export standards

The roundness index (RI) indicated that ldquoCenturionrdquo hada significant RI difference (119875 lt 005) compared to the othercultivars presenting a more spherical shape (095 plusmn 003)while ldquoElliottrdquo presented the smallest RI (072 plusmn 001)

After harvest fruit size could be altered by both watercontent which is kept within in the cell by osmotic forcesand degradation of peptic substances which weakens thecell walls Consequently the fruits cannot retain their shapeand integrity [21] However under the two storage conditionsstudied (75 and 95 RH 4 and 15∘C) no significant differ-ences (119875 gt 005) in both round index (RI) and equatorialdiameter were found among the different cultivars (Figure 4)These results indicated that neither significant dehydrationnor pectin degradation occurred during storage time underboth storage conditions studied

33 Water Content and Dehydrated Fruits Thewater contentof each fresh cultivar is shown in Table 1The cultivar with thehighest water content value was ldquoBrigittardquo (875 plusmn 07wb)and the lowest water content value was obtained for ldquoJewelrdquo(799 plusmn 08wb)

At the storage conditions no significant differences (119875 gt005) were found in water content in each cultivar during thewhole storage period which indicates that the blueberriesdid not undergo significant dehydration (119875 gt 005) duringstorage under the controlled temperature and humidity

The percentage of fruits with presence of surface dehy-dration at final storage time (21 days) calculated using imageanalysis following dehydration degree of Chilean BlueberryCommittee [13] is presented in Table 2 The results showed

0

02

04

06

08

1

12

0 7 14 21 28

Roun

dnes

s ind

ex

Storage time (days)

BrigittaElliott

CenturionStar

Duke

Figure 4 Roundness index (RI) of different cultivars over time at4∘C and 90 RH

0

1

2

3

4

5

6


JewelBrigittaElliott

CenturionStar

Duke

Δ11986400

Figure 5 Color change (Δ11986400

) of different cultivars over storagetime at 4∘C and 90 RH

that although water content values are constant amongstorage time for all cultivars the percentage of fruits withsurface dehydration degree higher than 2 on all evaluatedcultivars increased with high temperature and low relativehumidity as expected

Therefore the results showed that the quality parametersof pH ∘Brix shape roundness index and water content offresh blueberries are different among the evaluated six culti-vars hand-harvested inChile However the storage behaviourwas similar between them independently of temperatureand humidity conditions indicating that in the selectedstorage conditions no significant differences (119875 gt 005) wereobtained during storage time Regarding these importantquality parameters which remained constant during storagetime could not indicate deteriorative changes on the evalu-ated storage conditions However a surface dehydration of


0

4

8

12

16

20

0 7 14 21 28

Frui

ts w

ith fu

ngal

pre

senc

e (

)

Storage time (days)

BrigittaElliott

CenturionStar

Duke

4∘C- 90 RH

(a)

0

4

8

12

16

20

0 7 14 21 28

Frui

ts w

ith fu

ngal

pre

senc

e (

)

Storage time (days)

15∘C-90 RH

BrigittaElliott

CenturionStar

Duke

(b)

Figure 6 Percentage of fruits with fungal presence (6) in six blueberry cultivars stored under different storage conditions (4 and 15∘C and90 RH)

80

75

70

65

60

55

500 7 14 21

Ligh

tnes

s (119871lowast

)

Storage time (days)

4∘C-75 RH4∘C-90 RH

15∘C-75 RH

15∘C-90 RH

Figure 7 Total lightness (119871lowast) of ldquoBrigittardquo at different temperatures(∘C) and relative humidities (RH) of storage conditions Similarbehavior was observed for other cultivars

cuticle of fruits was detected visually using image analysisThis is an important approach to define a damage patternwith different quality degree levels which can be designed byautomatic classification algorithms to be implemented in theindustry reducing overall batch rejections for the market

34 Color The use of image analysis using computer visionallowed differentiating the blueberry color of different culti-vars at various storage times

The lightness (119871lowast value) of the blueberry surface showedsignificant differences (119875 lt 005) in the initial colorof fresh ldquoDukerdquo cultivar compared to the other cultivarsamong which no significant differences (119875 gt 005) werefound (Table 1) This 119871lowast value for ldquoDukerdquo could not beassociated with a lower presence of epicuticular wax on thisfruitrsquos surface because the percentage of epicuticular wax(30 plusmn 5) was similar among the cultivars as expected[7] Similar results (28 plusmn 8) were found by Matiacevichet al [7] comparing ldquoDukerdquo ldquoJewelrdquo and ldquoElliottrdquo culti-vars

Color change during storage observed as Δ11986400

(2)showed that the behaviour of each cultivar does not differsignificantly (119875 gt 005) as a function of storage time at 4∘Cand 90RH (Figure 5) At 7 days of storage the color changesare imperceptible for all cultivars However appreciable colordifferences (Δ119864

00gt 3) were obtained for ldquoJewelrdquo ldquoElliottrdquo

ldquoStarrdquo and ldquoBrigittardquo at final storage time of 21 days OnlyldquoDukerdquo retained a noticeable range of color change value atthe end of the storage period

The observed behaviour in Figure 5 was similar to thosefruits under the other storage conditions indicating thatthe color variation was mainly due to differences amongcultivars andnot to storage temperature and relative humidityconditionsThe color change was appreciable from the initialblue to a red color which was observed by changes in both119886lowast and 119887lowast values indicating senescence of the fruit The 119886lowast

values for all fresh blueberries analysed in this study wereobtained in the range from minus5 to 5 and 119887lowast values from minus10 to5 as in agreement with those found for the same cultivars [7]However these values increased during storage time showinga range for 119886lowast of 0ndash12 and for 119887lowast from minus2 to 6 As a function


of storage time the color change occurred in more than 90of the blueberries for all cultivars except for ldquoCenturionrdquowhere the color change occurred in around of 75 of thefruits

These results showed the importance of color fruit as anindicative of deterioration of blueberry quality which wasdetermined using image analysis

35 Fungal Presence As expected fungal presence obtainedthrough image analysis by computer vision using (6) wasaffected significantly (119875 lt 005) by storage conditionstemperature and time Figure 5 shows that fruits with fungalpresence increased with increasing storage temperature andtime for all cultivars analyzed showing a lower growth kineticat 4∘C (2) than at 15∘C (up to 14) at both RHs after 21 days

It is important to note that the behavior under eachstorage condition was different for all cultivars whereldquoJewelrdquo was more susceptible to fungal growth emphasiz-ing that the development of Botrytis in blueberries couldbe due to the presence of fungi in the fruit in the ini-tial phase of the study as natural inoculums and it wasnot exposed intentionally or inoculated during its storageTherefore the differences between cultivars may mainlybe due to differences of initial inoculums obtained in thefield and not to different genomic susceptibility betweencultivars

The color parameter lightness (119871lowast) increased duringstorage time (Figure 7) This increase was related to fungalpresence in all cultivars which was attributed to Botrytiscinerea identified taxonomically [22] Pearson correlationcoefficient between lightness and fungal presence was higherthan 09 for all cultivars indicating that total lightnessincreased principally due the characteristic white-gray colorof Botrytis filaments [22]

Therefore the results showed that color changes outsidethe initial color range of each cultivar are an important qualityfactor to define another damage pattern which could bemeasured by image analysis and therefore is possible fordesigned automatic algorithms using computer vision

36 Shelf Life The shelf life of blueberries is based mainly onvisual choice by consumers during its consumption wherethe conditions that may change during storage time are themost important ones to be taken into account Therefore thefactors considered on determination of shelf-life in this studywere fungal presence and color change

Since the determination of shelf-life is a subjective param-eter its determination was based on the occurrence of someof the following conditions (i) color change from blue to redin more than 45 of the samples andor (ii) fungal presencehigher than 2 due to the only presence of fungal filamentsis unacceptable by the consumers [7]

According to information delivered by blueberry produc-ers and used in this research the shelf-life of different culti-vars at 90 RH and 0ndash4∘C is 20 days However experimentaldata indicated that shelf life was 14 days for all cultivarsprincipally due to fungal presence higher than 2 as shownin Figure 6

4 Conclusions

Quality parameters (pH ∘Brix shape water content andcolor) were different among fresh cultivars as expecteddue principally to genetic differences between them andthese values did not changed during the evaluated storageconditions Other parameters depended on storage condi-tions as expected such as color changes from blue to redby time in all conditions surface dehydration and fungalpresence which both increased principally with temperatureand time However fungal presence was considered the mostimportant quality parameter to determine a shelf-life due toits unacceptability by consumers

Despite the differences on temperature and humidity ofthe storage conditions the shelf life (taking into accountmore than 2 of fruits with presence of fungal filaments)was calculated as 14 days for all cultivars independently of thestorage conditions

Moreover the innovative technology of computer visionapplied in this research was a useful tool to determineblueberry decay such as color surface dehydration andfungal presence in an objectivemanner instead of measuringit subjectively as is done nowadays

Practical applications of the results obtained in this studyare related to the knowledge of the important quality factorsfrom six different blueberry cultivars harvested in Chileunder different storage conditions as part of a comprehensivestudy of blueberry conservation Computer vision couldbe used as an approach to obtain damage patterns thatdefine different quality levels of blueberries This technologyallows designing automatic classification algorithms to beimplemented in the industry based on its simplicity allowingalso the analysis of heterogeneous materials such as freshfruits

Disclosure

This paper has not been published elsewhere and has not beensubmitted for publication elsewhere

Acknowledgments

The authors gratefully acknowledge the financial support ofProject Innova Chile-Corfo CT11 PUT-20 and CONICYTby Project PBCT-PSD-62 and FONDECYT Project Grants11100209 and 1110607

References

[1] V Chiabrando G Giacalone and L Rolle ldquoMechanicalbehaviour and quality traits of highbush blueberry duringpostharvest storagerdquo Journal of the Science of Food and Agricul-ture vol 89 no 6 pp 989ndash992 2009

[2] N Sinelli A Spinardi VDi Egidio IMignani andECasiraghildquoEvaluation of quality and nutraceutical content of blueberries(Vaccinium corymbosum L) by near and mid-infrared spec-troscopyrdquo Postharvest Biology and Technology vol 50 no 1 pp31ndash36 2008


[3] G Antonio F Faria C Takeiti and K Park ldquoRheologicalbehovior of blueberryrdquo Ciencia y Tecnologıa de Alimentos vol29 pp 732ndash737 2009

[4] M C Nunes J P Emon and J K Brecht ldquoQuality curves forHighbush blueberries as a function of the storage temperaturerdquoinProceedings of the 9thNorth American Blueberry Research andExtension Workers Conference and In Small Fruits Review pp423ndash438 Food Product press Haworth Press 2004

[5] A Yommi and C Godoy ldquoArandanos fisiologıa y tecnologıasde postcosechardquo 2002 httpanteriorintagovarfurl=httpanteriorintagobarbalcarceinfodocumentosagricposcofruyhortarandanohtm

[6] C Duarte M Guerra P Daniel A L Camelo and A YommildquoQuality changes of highbush blueberries fruit stored in CAwith different CO

2

levelsrdquo Journal of Food Science vol 74 no4 pp S154ndashS159 2009

[7] S Matiacevich P Silva F Osorio and J Enrione ldquoEvaluation ofblueberry color during storage using image analysisrdquo in Colorin Food Technological and Psychophysical Aspects J L Caivanoand M P Buera Eds pp 211ndash218 CRC Publisher 2011

[8] D Mery J J Chanona-Perez A Soto et al ldquoQuality classifi-cation of corn tortillas using computer visionrdquo Journal of FoodEngineering vol 101 pp 357ndash364 2010

[9] F Pedreschi J Leon D Mery and P Moyano ldquoDevelopment ofa computer vision system to measure the color of potato chipsrdquoFood Research International vol 39 no 10 pp 1092ndash1098 2006

[10] S Gunasekaran and K Ding ldquoUsing computer vision for foodquality evaluationrdquo Food Technology vol 48 no 6 pp 151ndash1541994

[11] V Leemans H Magein and M F Destain ldquoDefects segmen-tation on ldquoGolden Deliciousrdquo apples by using colour machinevisionrdquo Computers and Electronics in Agriculture vol 20 no 2pp 117ndash130 1998

[12] L Greenspan ldquoHumidity fixed points of binary saturatedaqueous solutionsrdquo Journal of Research of the National Bureauof Standards vol 81 no 1 pp 89ndash96 1977

[13] Chilean Blueberry Comittee ldquoNorma de calidad arandanofresco de exportacionrdquo pp 1ndash9 2011

[14] G Sharma W Wu and E N Dalal ldquoThe CIEDE2000 color-difference formula implementation notes supplementary testdata and mathematical observationsrdquo Color Research andApplication vol 30 no 1 pp 21ndash30 2005

[15] Y Yang J Ming and N Yu ldquoColor image quality assessmentbased on CIEDE2000rdquo Advances in Multimedia vol 2012Article ID 273723 6 pages 2012

[16] M R Luo G Cui and B Rigg ldquoThe development of the CIE2000 colour-difference formula CIEDE2000rdquo Color Researchand Application vol 26 no 5 pp 340ndash350 2001

[17] J M Molina D Calvo J J Medina C Barrau and F RomeroldquoFruit quality parameters of some southern highbush blueber-ries (Vaccinium xcorymbosum L) grown in Andalusia (Spain)rdquoSpanish Journal of Agricultural Research vol 6 no 4 pp 671ndash676 2008

[18] J Duan R Wu B C Strik and Y Zhao ldquoEffect of ediblecoatings on the quality of fresh blueberries (Duke and Elliott)under commercial storage conditionsrdquo Postharvest Biology andTechnology vol 59 no 1 pp 71ndash79 2011

[19] W Kalt and J EMcDonald ldquoChemical composition of lowbushblueberry cultivarsrdquo Journal of the American Society for Horti-cultural Science vol 121 no 1 pp 142ndash146 1996

[20] CGodoy ldquoConservacion de dos variedades de arandano alto encondiciones de frıo convencionalrdquo Revista Facultad de CienciasAgrarias de UNCuyo vol 36 pp 53ndash61 2004

[21] V Graciela Echeverrıa V Juan Canumir and G HumbertoSerri ldquoPostharvest behavior of highbush blueberry fruits cvOrsquoNeal cultivated with different organic fertilization treat-mentsrdquo Chilean Journal of Agricultural Research vol 69 no 3pp 391ndash399 2009

[22] S Mirzaei E M Goltapeh andM Shams-bakhsh ldquoTaxonomi-cal studies on the genus Botrytis in Iranrdquo Journal of AgriculturalTechnology vol 3 pp 65ndash76 2007

Submit your manuscripts athttpwwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Anatomy Research International

PeptidesInternational Journal of


Hindawi Publishing Corporation httpwwwhindawicom

International Journal of

Volume 2014

Zoology


Molecular Biology International

GenomicsInternational Journal of


The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014


BioinformaticsAdvances in

Marine BiologyJournal of



Signal TransductionJournal of


BioMed Research International

Evolutionary BiologyInternational Journal of



Biochemistry Research International

ArchaeaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014


Genetics Research International


Advances in

Virolog y

Hindawi Publishing Corporationhttpwwwhindawicom

Nucleic AcidsJournal of

Volume 2014

Stem CellsInternational



Enzyme Research



Microbiology


0 1 2 3

Figure 1 Fruit dehydration degree visually observed following the norms for quality of fresh blueberries from Chilean Blueberry Committee(CBBC 2011)

Figure 2 Computer vision system Elements distribution in thedigital image acquisition

vision which was applied in this research as a preliminarystudy to determine blueberry decay objectively instead ofmeasuring it subjectively as is done nowadays

2 Materials and Methods

21 Plant Material This study was conducted during the2009-2010 harvest season All cultivars were donated bythe Chilean Association of Exporters (ASOEX-Chile) Threeblueberry cultivars (ldquoBrigittardquo ldquoElliottrdquo and ldquoDukerdquo) fromSouthern Highbush variety (Vaccinium darrowii) two cul-tivars (ldquoJewelrdquo and ldquoStarrdquo) from Northern Highbush vari-ety (Vaccinium corymbosum) and the cultivar ldquoCentu-rionrdquo from Rabbiteye variety (Vaccinium virgatum) wereused All cultivars were hand-harvested at full maturityfrom commercial plantations located in the central valleyof the Metropolitan Region in Chile (Curacavı HortifrutSA) during mid-December (ldquoDukerdquo and ldquoJewelrdquo) January(ldquoBrigittardquo) mid-February (ldquoElliottrdquo and ldquoCenturionrdquo) andmid-March (ldquoStarrdquo) and transported to the laboratory onthe same day High quality blueberries (119899 = 50) at eachstorage condition were obtained by random (119899 = 10 ofeach clamshell) from 12 clamshells of approximately 125mgeach presorted by hand discarding the excessively small softvisually damaged nonblue fruits and those with the presenceof pedicel and floral remains as sample set for all experiments

22 Storage Conditions Blueberries (119899 = 50 at each con-dition) were stored at 4 and 15∘C and equilibrated underdifferent relative humidities (RH) using saturated solutionsof NaCl (75 RH) and KCl (90 RH) [12] during differentstorage times (0 7 14 and 21 days)

23 Fruit Quality Indicators

231 pH and Total Soluble Solids Content Blueberry juicewas preparedfrom 5 blueberries randomly selected (in trip-licate) at each storage time The pH was measured with a pHmeter (Jenway UK) using a liquid electrode (Jenway 924-001model 3505) calibrated according toOMA 1975 Total solublesolids concentration was determined by placing a drop of thisblueberry juice (1mL) on a calibrated portable refractometer(0ndash32 ∘Brix RHB-32ATC)Themean and standard deviationof three replicates were recorded and expressed as ∘Brix

232 Fruit Size and Form The equatorial and polar diameterof each blueberry was measured with a digital caliper (BullTools USA) and the roundness index (RI) was determinedfrom (1) Mean and standard deviation of all blueberries(119899 = 50) measured at each storage condition were reportedThese parameters were also obtained from image analysiscorrelating linearly with experimental data (1198772 = 0998)

RI = polar diameterequatorial diameter

(1)

233Water Content and Fruit-Dehydrated Percentage Watercontent was gravimetrically determined using an analyticalbalance (Mettler Toledo Switzerland) Twelve blueberries (intriplicate) were dried for 24 h in an oven (Wiseven Korea) at105∘C until constant weight Water content was expressed aswet basis percentage (g water100 g wet sample)

Dehydrated fruit percentage was evaluated visually usingthe photographies obtained by computer vision taking intoaccount the different degrees of fruit dehydration (Figure 1)following the norms for quality of fresh blueberries fromChilean Blueberry Committee [13] Fruits with dehydrationdegree of 2 or 3 were counted as dehydrated fruit

24 Image Analysis

241 Color Digital images of each blueberry (of two oppo-site sides) were taken at each storage time in order to obtainthe surface color of the fruit using a computer vision system(Figure 2) which consisted of a black box with four 18Wnatural light tubes (D65 Philips) and a digital camera (Canon10MP PowerShot G4) placed in a vertical position 225 cmfrom the samples (camera lens angle and lights at 45∘) [9]All images were obtained under the same conditions thecamera was remotely controlled by ZoomBrowser software(v60 Canon) Surface color data were measured in the CIEL


1

2

3

4

0 7 14 21 28

pH

Storage time (days)

BrigittaElliott

CenturionStar

Duke

(a)

0

4

8

12

16


BrigittaElliott

CenturionStar

Duke

∘Br

ix(b)












Cultivar 4∘C75RH

4∘C90RH

15∘C75RH

15∘C90RH


lowast

119886lowast





00


00)



Δ11986400lt 6 [15]

Δ11986400= radic(

Δ1198711015840

119870119871119878119871

)

2

+ (Δ1198621015840

119870119862119878119862

)

2

+ (Δ1198671015840

119870119867119878119867

)

2

+ 119877119879(Δ1198621015840

119870119862119878119862

)(Δ1198671015840

119870119867119878119867

) (2)


119862lowast

119894119886119887


119894

)2

+ (119887lowast

119894

)2

119894 = 1 2 (3)

ℎ1015840

119894


119894

1198861015840

119894

) 119894 = 1 2 (4)

where

1198861015840

119894

= (1 + 119866) 119886lowast

119894

119894 = 1 2


119886119887

2

119862lowast

119886119887

7

+ 257

)

119862lowast

119886119887

=

(119862lowast

1119886119887

+ 119862lowast

2119886119887

)

2

1198621015840

119894


119894

)2

+ (119887lowast

119894

)2

119894 = 1 2

9987791198711015840

= 119871lowast

2

minus 119871lowast

1

9987791198621015840

= 119862lowast

2

minus 119862lowast

1

998779ℎ1015840

= ℎ1015840

2

minus ℎ1015840

1

9987791198671015840

= 2radic1198621015840

1

1198621015840

2

sin(Δℎ1015840

2)

1198711015840 =(119871lowast

1

+ 119871lowast

2

)

2

1198621015840 =

(1198621015840

1

+ 1198621015840

2

)

2

ℎ1015840 =

(ℎ1015840

1

+ ℎ1015840

2

)

2

119878119871= 1 +

0015(1198711015840 minus 50)2

radic20 + (1198711015840 minus 50)2

119878119862= 1 + 00451198621015840

119878119867= 1 + 00151198621015840119879



119877119879=minus sin (2Δ120579)119877119862

998779120579 = 30 exp

minus[

[

(ℎ1015840 minus 275∘

)

25

]

]

2

119877119862= 2radic

11986210158407

(11986210158407

+ 257

)

119870119871= 119870ℎ= 119870119862= 1

(5)

(see [16])



times 100

(6)


















0

02

04

06

08

1

12

0 7 14 21 28

Roun

dnes

s ind

ex

Storage time (days)

BrigittaElliott

CenturionStar

Duke


0

1

2

3

4

5

6



CenturionStar

Duke

Δ11986400






0

4

8

12

16

20

0 7 14 21 28

Frui

ts w

ith fu

ngal

pre

senc

e (

)

Storage time (days)

BrigittaElliott

CenturionStar

Duke

4∘C- 90 RH

(a)

0

4

8

12

16

20

0 7 14 21 28

Frui

ts w

ith fu

ngal

pre

senc

e (

)

Storage time (days)

15∘C-90 RH

BrigittaElliott

CenturionStar

Duke

(b)


80

75

70

65

60

55

500 7 14 21

Ligh

tnes

s (119871lowast

)

Storage time (days)

4∘C-75 RH4∘C-90 RH

15∘C-75 RH

15∘C-90 RH





















4 Conclusions





Disclosure


Acknowledgments


References








2

























Volume 2014

Zoology






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology


1

2

3

4

0 7 14 21 28

pH

Storage time (days)

BrigittaElliott

CenturionStar

Duke

(a)

0

4

8

12

16


BrigittaElliott

CenturionStar

Duke

∘Br

ix(b)












Cultivar 4∘C75RH

4∘C90RH

15∘C75RH

15∘C90RH


lowast

119886lowast





00


00)



Δ11986400lt 6 [15]

Δ11986400= radic(

Δ1198711015840

119870119871119878119871

)

2

+ (Δ1198621015840

119870119862119878119862

)

2

+ (Δ1198671015840

119870119867119878119867

)

2

+ 119877119879(Δ1198621015840

119870119862119878119862

)(Δ1198671015840

119870119867119878119867

) (2)


119862lowast

119894119886119887


119894

)2

+ (119887lowast

119894

)2

119894 = 1 2 (3)

ℎ1015840

119894


119894

1198861015840

119894

) 119894 = 1 2 (4)

where

1198861015840

119894

= (1 + 119866) 119886lowast

119894

119894 = 1 2


119886119887

2

119862lowast

119886119887

7

+ 257

)

119862lowast

119886119887

=

(119862lowast

1119886119887

+ 119862lowast

2119886119887

)

2

1198621015840

119894


119894

)2

+ (119887lowast

119894

)2

119894 = 1 2

9987791198711015840

= 119871lowast

2

minus 119871lowast

1

9987791198621015840

= 119862lowast

2

minus 119862lowast

1

998779ℎ1015840

= ℎ1015840

2

minus ℎ1015840

1

9987791198671015840

= 2radic1198621015840

1

1198621015840

2

sin(Δℎ1015840

2)

1198711015840 =(119871lowast

1

+ 119871lowast

2

)

2

1198621015840 =

(1198621015840

1

+ 1198621015840

2

)

2

ℎ1015840 =

(ℎ1015840

1

+ ℎ1015840

2

)

2

119878119871= 1 +

0015(1198711015840 minus 50)2

radic20 + (1198711015840 minus 50)2

119878119862= 1 + 00451198621015840

119878119867= 1 + 00151198621015840119879



119877119879=minus sin (2Δ120579)119877119862

998779120579 = 30 exp

minus[

[

(ℎ1015840 minus 275∘

)

25

]

]

2

119877119862= 2radic

11986210158407

(11986210158407

+ 257

)

119870119871= 119870ℎ= 119870119862= 1

(5)

(see [16])



times 100

(6)


















0

02

04

06

08

1

12

0 7 14 21 28

Roun

dnes

s ind

ex

Storage time (days)

BrigittaElliott

CenturionStar

Duke


0

1

2

3

4

5

6



CenturionStar

Duke

Δ11986400






0

4

8

12

16

20

0 7 14 21 28

Frui

ts w

ith fu

ngal

pre

senc

e (

)

Storage time (days)

BrigittaElliott

CenturionStar

Duke

4∘C- 90 RH

(a)

0

4

8

12

16

20

0 7 14 21 28

Frui

ts w

ith fu

ngal

pre

senc

e (

)

Storage time (days)

15∘C-90 RH

BrigittaElliott

CenturionStar

Duke

(b)


80

75

70

65

60

55

500 7 14 21

Ligh

tnes

s (119871lowast

)

Storage time (days)

4∘C-75 RH4∘C-90 RH

15∘C-75 RH

15∘C-90 RH





















4 Conclusions





Disclosure


Acknowledgments


References








2

























Volume 2014

Zoology






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology


119862lowast

119894119886119887


119894

)2

+ (119887lowast

119894

)2

119894 = 1 2 (3)

ℎ1015840

119894


119894

1198861015840

119894

) 119894 = 1 2 (4)

where

1198861015840

119894

= (1 + 119866) 119886lowast

119894

119894 = 1 2


119886119887

2

119862lowast

119886119887

7

+ 257

)

119862lowast

119886119887

=

(119862lowast

1119886119887

+ 119862lowast

2119886119887

)

2

1198621015840

119894


119894

)2

+ (119887lowast

119894

)2

119894 = 1 2

9987791198711015840

= 119871lowast

2

minus 119871lowast

1

9987791198621015840

= 119862lowast

2

minus 119862lowast

1

998779ℎ1015840

= ℎ1015840

2

minus ℎ1015840

1

9987791198671015840

= 2radic1198621015840

1

1198621015840

2

sin(Δℎ1015840

2)

1198711015840 =(119871lowast

1

+ 119871lowast

2

)

2

1198621015840 =

(1198621015840

1

+ 1198621015840

2

)

2

ℎ1015840 =

(ℎ1015840

1

+ ℎ1015840

2

)

2

119878119871= 1 +

0015(1198711015840 minus 50)2

radic20 + (1198711015840 minus 50)2

119878119862= 1 + 00451198621015840

119878119867= 1 + 00151198621015840119879



119877119879=minus sin (2Δ120579)119877119862

998779120579 = 30 exp

minus[

[

(ℎ1015840 minus 275∘

)

25

]

]

2

119877119862= 2radic

11986210158407

(11986210158407

+ 257

)

119870119871= 119870ℎ= 119870119862= 1

(5)

(see [16])



times 100

(6)


















0

02

04

06

08

1

12

0 7 14 21 28

Roun

dnes

s ind

ex

Storage time (days)

BrigittaElliott

CenturionStar

Duke


0

1

2

3

4

5

6



CenturionStar

Duke

Δ11986400






0

4

8

12

16

20

0 7 14 21 28

Frui

ts w

ith fu

ngal

pre

senc

e (

)

Storage time (days)

BrigittaElliott

CenturionStar

Duke

4∘C- 90 RH

(a)

0

4

8

12

16

20

0 7 14 21 28

Frui

ts w

ith fu

ngal

pre

senc

e (

)

Storage time (days)

15∘C-90 RH

BrigittaElliott

CenturionStar

Duke

(b)


80

75

70

65

60

55

500 7 14 21

Ligh

tnes

s (119871lowast

)

Storage time (days)

4∘C-75 RH4∘C-90 RH

15∘C-75 RH

15∘C-90 RH





















4 Conclusions





Disclosure


Acknowledgments


References








2

























Volume 2014

Zoology






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology











0

02

04

06

08

1

12

0 7 14 21 28

Roun

dnes

s ind

ex

Storage time (days)

BrigittaElliott

CenturionStar

Duke


0

1

2

3

4

5

6



CenturionStar

Duke

Δ11986400






0

4

8

12

16

20

0 7 14 21 28

Frui

ts w

ith fu

ngal

pre

senc

e (

)

Storage time (days)

BrigittaElliott

CenturionStar

Duke

4∘C- 90 RH

(a)

0

4

8

12

16

20

0 7 14 21 28

Frui

ts w

ith fu

ngal

pre

senc

e (

)

Storage time (days)

15∘C-90 RH

BrigittaElliott

CenturionStar

Duke

(b)


80

75

70

65

60

55

500 7 14 21

Ligh

tnes

s (119871lowast

)

Storage time (days)

4∘C-75 RH4∘C-90 RH

15∘C-75 RH

15∘C-90 RH





















4 Conclusions





Disclosure


Acknowledgments


References








2

























Volume 2014

Zoology






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology


0

4

8

12

16

20

0 7 14 21 28

Frui

ts w

ith fu

ngal

pre

senc

e (

)

Storage time (days)

BrigittaElliott

CenturionStar

Duke

4∘C- 90 RH

(a)

0

4

8

12

16

20

0 7 14 21 28

Frui

ts w

ith fu

ngal

pre

senc

e (

)

Storage time (days)

15∘C-90 RH

BrigittaElliott

CenturionStar

Duke

(b)


80

75

70

65

60

55

500 7 14 21

Ligh

tnes

s (119871lowast

)

Storage time (days)

4∘C-75 RH4∘C-90 RH

15∘C-75 RH

15∘C-90 RH





















4 Conclusions





Disclosure


Acknowledgments


References








2

























Volume 2014

Zoology






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology











4 Conclusions





Disclosure


Acknowledgments


References








2

























Volume 2014

Zoology






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology






2

























Volume 2014

Zoology






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology








Volume 2014

Zoology






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology

research article quality parameters of six cultivars of

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