2011-07-1_adulteration food chem uni lecture_bra cm
TRANSCRIPT
8/3/2019 2011-07-1_Adulteration Food Chem Uni Lecture_BRA Cm
http://slidepdf.com/reader/full/2011-07-1adulteration-food-chem-uni-lecturebra-cm 1/16
1
Markus Lipp, Ph.D.Director, Food Ingredient Standards
US Pharmacopeia, Rockville, [email protected]
Food Quality, Safety, and the role ofthe Compendial Standards
Ice Breaker: Hypothetical scenario
• You are the chief chemist in charge of QA/QCand scientific affairs for a bread company
• Reports from customer hotline
– Nausea and vomiting after wheat breadconsumption
– Ammonia odor
• Determined that wheat flour used in yourproduct is likely the issue
Wheat flour certificate of analysis
DESCRIPTION OFGOODS:
WHEAT FLOUR
PACKING: PACKED IN 25KGBAGS
ORIGIN: USA
TEST SPEC RESULTMoisture NMT 14.0% 7.5%
Ash ( On drybasis)
NMT 2.0% 0.89%
Protein (On dry
basis N x 5.7):
NLT 9.0% 9.1%
Vomitoxin NMT 1 ppm < 18.5 ppb
Vomitoxin (Deoxynivalenol)?
Result:
< LOD (18.5 ppb)
ELISA
8/3/2019 2011-07-1_Adulteration Food Chem Uni Lecture_BRA Cm
http://slidepdf.com/reader/full/2011-07-1adulteration-food-chem-uni-lecturebra-cm 2/16
2
What is happening here?
Test WG:Why?
9.0%
Control flour 9.0% 9.0%
Test flour 9.0% 8.0 %
Wheat flour specsfor protein content
NIR spectral analysis of wheat flour
Courtesy of K. Norris, 2009
Wavelength used for
protein measurement
due to N-H vibrations
(2180 nm = 4587 cm–1)
Hold that thought!
• Understand:
– The role of food chemistry and compendialstandards in food quality and food safety for foodingredients and additives
– The importance of methods of analysis andreference standards for food ingredient analysis
• Apply knowledge:
– As future food science professionals
Lecture objectives
8/3/2019 2011-07-1_Adulteration Food Chem Uni Lecture_BRA Cm
http://slidepdf.com/reader/full/2011-07-1adulteration-food-chem-uni-lecturebra-cm 3/16
3
Food quality, safety, and chemistry
Food Quality Food Safety
– Physical hazards
– Microbiological hazards
– Chemical hazards
Organoleptic
properties
Toxicological
properties
Food quality, safety, and chemistry
• Is the quality of an incoming ingredient goodenough for its intended use – “food-grade” ?
• How do you know that is safe (toxicologically)unless you know something about itscomposition (chemical)?
• If the ingredient is safe, how do you know thatthe material you purchased is chemically thesame as the material used to carry out the
safety evaluation?
Food quality, safety, and chemistry
• How do you know if the ingredient has anunacceptable level of a contaminant(unintentional impurity inherent to raw
material or formed during processing)? – Examples: Metal impurities, organic
solvents
Certificate of analysis (CoA)
• From buyer: Procurement specifications
• From seller: Certificate of analysis
• What test methods were used? Are themethods reliable? Validated?
• What reference standards were used?Are the standards reliable?
8/3/2019 2011-07-1_Adulteration Food Chem Uni Lecture_BRA Cm
http://slidepdf.com/reader/full/2011-07-1adulteration-food-chem-uni-lecturebra-cm 4/16
4
Certificate of analysis (CoA) How to measure is important
• Analyzing for the same constituentor property using different methodscan yield different results
Examples to demonstrate importance of…
• Method validation: assessingperformance characteristics for analyticalmethods
– Specificity/Selectivity: Ability to distinguishanalyte from other similar components inmatrix
– Accuracy: Closeness to true value
– Limit of detection: Lowest amount ofanalyte that can be detected
– 5 other parameters
• Reference standards
Example 1: Measuring water content (specificity)
• Water content measurement
– Same sample analyzed for water content by “Losson Drying” and “Karl Fisher” methods
– Data: 0.088% vs 0.068%, respectively
• Loss on drying• Principle: Evaporation of volatile compounds
• Only water evaporating?
• LOD results 30% higher than KF, why?
• Results highly dependent upon conditions used
• Karl Fisher• Principle: Reduction of iodine by SO2 in the presence
of H2O, titration
8/3/2019 2011-07-1_Adulteration Food Chem Uni Lecture_BRA Cm
http://slidepdf.com/reader/full/2011-07-1adulteration-food-chem-uni-lecturebra-cm 5/16
5
Example 1: Measuring water content (specificity)
• Why is water important?
– Water activity <-> foodsafety/quality
– Diluting a product with water is aneasy way to economicallyadulterate the product
• Methodology, Pre-1996 (FCC IV) – Hydrogen sulfide method (colormetric test)
• Metallic impurities colored as sulfides
• Visual comparison with known leadstandards
• ISSUES: – Not sensitive enough to work with limits below
10 ppm
– Not very accurate (next slide)
– Not very selective
Example 2: Measuring Pb
Example 2: Measuring Pb impurities (accuracy)
0
20
40
60
80
100
120
Pb As Se Sn Sb Cd Pd Pt Ag Bi Mo Ru In Hg
Elements
A v e r a g e % R e c o v e r i e s
USP Results
ICP-MS Results
Hydrogen Sulfide
Method Results
Lewen, N. et al J. Pharm. & Biomed. Anal. 35 (2004) 739-752
Example 3: Measuring metal impurities (limit
of detection)
• Specification requires “less than 5 ppm lead”
• CoA result: ND
• What does this mean?
– Less than the limit of detection of the method
• What if limit of detection for method is greaterthan 5 ppm?
– Actual concentration could be more than 5 ppm!
8/3/2019 2011-07-1_Adulteration Food Chem Uni Lecture_BRA Cm
http://slidepdf.com/reader/full/2011-07-1adulteration-food-chem-uni-lecturebra-cm 6/16
6
Example 4: Reference standards:
the phoenician balance Example 4: Reference standards
• 1) Qualitative reference standard
– To substantiate the identity/ authenticity of an ingredient you cancompare to an authentic referencestandard
• 2) Quantitative reference standards
– Chemical “yard stick”
Qualitative reference standards
IR spectrum from authentic
glycerin
IR spectrum from test sample
(diethylene glycol)
Quantitative reference standards
HPLC chromatogram from stevia extract
Rebaudioside A
•How to determineconcentration?
Need an external
reference
standard!
8/3/2019 2011-07-1_Adulteration Food Chem Uni Lecture_BRA Cm
http://slidepdf.com/reader/full/2011-07-1adulteration-food-chem-uni-lecturebra-cm 7/16
7
Standardization challenge!• Who sets the minimum standard?
– Who determines what minimum qualityspecifications (purity, impurities) are appropriate forfood ingredients?
– How do you ensure they are set in an objective andfair manner?
• How do you ensure that everyone’ s analyticalresults are comparable?
– Who sets the methods? Who validates testprocedures?
– How do you ensure that everyone is using thesame reference standards?
Food ingredients compendial
standards• What is a compendium?
– Wikipedia: “A compendium is a concise, yetcomprehensive compilation of a body ofknowledge”
• In the case of food ingredient standards,a compilation of chemical test methodsand specifications to establish quality andthus safety of individual ingredients.
– Comprehensive analysis of ingredients
(Identity, Purity, Impurities)
• Is this lot of material what the food ingredientseller claims it to be? How do you test for this?
– IDENTITY
• How pure is it? What purity is acceptable for
“food-grade” ? How do you test for this? – PURITY
• What kind of impurities does it contain? Whichones are important and what levels areacceptable? How do you test for these?
– IMPURITIES
Food ingredients compendial
standards Examples• The Food Chemicals Codex (FCC )
• The United States Pharmacopeia
• The Joint FAO/WHO Expert Committee on FoodAdditives (JECFA’ s)
“Combined Compendium of Food AdditiveSpecifications”
• Codex Alimentarius
• Other compendia
8/3/2019 2011-07-1_Adulteration Food Chem Uni Lecture_BRA Cm
http://slidepdf.com/reader/full/2011-07-1adulteration-food-chem-uni-lecturebra-cm 8/16
8
What is the Food Chemicals Codex (FCC )?
• FCC is a compendium that establishes
internationally recognized scientific standards
to promote uniformity of quality and added
assurance of safety for food ingredients.
• FCC standards set using an objective, science
evidence–based, transparent process
• Food Quality↔ Safety
– How do you know it is safe if you don’t know whatit is? (identity and purity)
• Methods and limits for contaminants (inherentor process related impurites)
• First line of defense against economicadulteration
• Validated methods
• Developed by independent, volunteer scientificexperts through a transparent process
The need for FCC ?
What do FCC standards look like?
• Monographs
• Specifications for identity
(authenticity), purity and impurities
• Supporting test procedures and
reference standards
8/3/2019 2011-07-1_Adulteration Food Chem Uni Lecture_BRA Cm
http://slidepdf.com/reader/full/2011-07-1adulteration-food-chem-uni-lecturebra-cm 9/16
9
Scientific utility of FCC
• Students
– Source, method of manufacturer, physicochemical
characteristics, CAS, INS, FEMA, and function(s) of
food ingredients
– Methods of analysis
• Validated analytical methods for specific food
ingredients
• Validated analytical methods in Appendices
– Potential impurities and contaminants in food
ingredients
– Validated analytical methods
Scientific utility of FCC
• Industry / Regulatory
– Use FCC specifications, supporting test procedures,
and associated reference materials to establish the
food-grade quality and safety of their ingredients,
and thus a stronger marketing presence
– Ensure that food ingredient in commerce is
equivalent to that which was toxicologically evaluated
– Aid to effective self-regulation by industry
• Specifications often referenced in agreements for sale
and receipt of food ingredients
– Source of food ingredient GMPs
The future of food chemistry to support compendial
testing standards
• Economically motivated adulteration
• Authentication and characterization of
botanically derived, complex mixture food
ingredients
• Nanotechnology
• Functional foods and nutraceuticals
• Green technology and sustainability
Definition of Economically Motivated Adulteration
“The fraudulent addition of non-authentic
substances or removal or replacement of
authentic substances without the purchaser’s
knowledge for economic gain of the seller”
Also known as: “Food Fraud”, “Food Counterfeiting”, “Intentional
Adulteration”
8/3/2019 2011-07-1_Adulteration Food Chem Uni Lecture_BRA Cm
http://slidepdf.com/reader/full/2011-07-1adulteration-food-chem-uni-lecturebra-cm 10/16
10
Recipe for EMA
• Rising raw material prices
• Complex supply chains
• Complex and variable
compositions
• Sophisticated fraudsters
• Lack of tools to prevent
• Accepting culture
Significant
Fraud
opportunity
Sophisticated Fraudsters and Creative Fraud
Fraudster “designs”adulterant to evade existingQA system
QA system reacts bydeveloping new tests
Public health threat of EMA
• Food safety assumes a known composition
• Next adulterant is unknown
Food safety
collapses to a
singularity
The fraudster’s ethics &
knowledge define food
safety throughout the
whole supply chain
Reducing the Risk of EMA: Multi-Pronged Approach
Testing Supply Chain
Management
• Know your suppliers, andtheir supply chains
• Supplier qualifications and
audits
• QA systems
• GMPs
• HACCP
• “Anchors” food safetysystems in reality by
guaranteeing ingredient
authenticity
• Quality systems built on
this assumption
8/3/2019 2011-07-1_Adulteration Food Chem Uni Lecture_BRA Cm
http://slidepdf.com/reader/full/2011-07-1adulteration-food-chem-uni-lecturebra-cm 11/16
11
(1) Test for the absence of a known
adulterant
Two Analytical Approaches To Verify Ingredient Integrity
Disadvantages:
– Known does not guarantee detection
2007 melamine in wheat gluten & 2008
melamine in milk
– Cannot feasibly test for all known adulterants
– Cannot detect unknown adulterants
(2) Test for what is supposed to be there
(compendial approach)
– Detect EMA by:
• Decrease in puritytest result
• Abnormal identity test result
Two Analytical Approaches To Verify Ingredient Integrity
Advantage:
– Can detect both known and unknown
adulterants when present at EMA levels
State of Compendial Testing Standards
• Identification Tests
– Virtually non-existent for many widely used complex food
ingredients (e.g. wheat gluten, whey)
– Many outdated non-specific wet-chemistry tests that are
not sufficient to detect and deter EMA• Flame tests, solubility tests
• Assay (Purity) Tests
– Many outdated non-specific wet-chemistry tests that are
not sufficient to detect and deter EMA
• Indirect purity methods (Kjeldahl for total protein)
• Titrimetric methods
• The technology exists, but…
• R&D is necessary to adapt it into viable
compendial tools to detect and deter EMA
Moving Testing Technology into the 21st Century
8/3/2019 2011-07-1_Adulteration Food Chem Uni Lecture_BRA Cm
http://slidepdf.com/reader/full/2011-07-1adulteration-food-chem-uni-lecturebra-cm 12/16
12
Opportunities to Advance Compendial Testing Standards
• Higher selectivity, instrumental methods
– Identification Tests
• Non-targeted analysis using IR, Raman, or NMR + chemometrics
• Semi-targeted (chemical fingerprinting) using LC-UV/Vis, GC-FID,
LC-HRMS, GC-MS, CE + chemometrics
• Isotope ratio fingerprinting: IRMS, SNIF-NMR
• Other: PCR; DSC; Rheological Methods; Microscopy
– Assay (Purity Tests)
• Instrument LC or GC methods
Back to wheat flour!
What Actually Happened?
• 1980’ s: Urea added to wheat to artificiallyincrease the nitrogen content -> apparentincrease in protein
• Where? – Minnesota, USA
Folkenberg J, Nelson R, Snider S. 1990. Spiked wheat - Schuler Grain Co. uses additive to artificially boost the protein
content of its wheat. FDA Consumer 24 (Dec.)
Why urea?
• Classic case of economically motivatedadulteration: “The fraudulent addition of non-authentic substances or removal or replacement ofauthentic substances for economic gain without the
knowledge of the purchaser.”
• Urea falsely measured as protein by twointernationally recognized protein assays
– Nitrogen-based and NIR total protein
8/3/2019 2011-07-1_Adulteration Food Chem Uni Lecture_BRA Cm
http://slidepdf.com/reader/full/2011-07-1adulteration-food-chem-uni-lecturebra-cm 13/16
13
Economics*
Wheat commodity pricing based on protein content
Premium wheat (12% P) = $13.12 / bushel
Regular wheat (11.5% P) = $12.12 / bushel
Recipe for “Fake Premium Wheat” with 0.06% urea:
100 lbs regular wheat (11.5% P) + 1 lb water + 3 ouncesurea
Cost of “Fake Premium Wheat” = $12.02 / Bushel
Profit = $1.10/bushel = $880 / truckload
*DeVries, 2009. www.usp.org/goto/proteins
Chemistry
• 46.7% nitrogen
• Kjeldahl response = Protein
• Dumas (combustion) response = Protein
• NIR response = Protein – WHY????
Chemistry of NIR
Absorption bands are weak overtones orcombinations of fundamental stretchingvibrational bands that occur in the mid-infraredregion
Chemistry of NIR
• NIR Diffuse-reflectance used for grain proteinanalysis, calibrated against Kjeldahl/Dumas
– NIR does not sense nitrogen, but rather
overtones of NH vibrations of the amino acids tosense protein
– Bands at 2055, 2100, and2180 nm arecommonly used for protein
– Urea has absorption bands at2197 and 2162 nmcorresponding to NH vibrations
McDonald CE, Bruns . 1988. Cereal Food World 33(4):367-9.
8/3/2019 2011-07-1_Adulteration Food Chem Uni Lecture_BRA Cm
http://slidepdf.com/reader/full/2011-07-1adulteration-food-chem-uni-lecturebra-cm 14/16
14
NIR spectral analysis of wheat flour
Courtesy of K. Norris, 2009
Wavelength used for
protein measurement
due to N-H vibrations
(2180 nm = 4587 cm–1)
NIR spectrum of urea
Courtesy of K. Norris, 2009
Wavelength used for
protein measurement
due to N-H vibrations
(2180 nm = 4587 cm–1)
Courtesy of K. Norris, 2011
Importance to food chemistry?
• Incidents such as urea and melamine
adulteration have underscored the
importance of having reliable routine QA
methods that measure with a high degree
of selectivity/specificity
• Ensuring the safety of the food supply
8/3/2019 2011-07-1_Adulteration Food Chem Uni Lecture_BRA Cm
http://slidepdf.com/reader/full/2011-07-1adulteration-food-chem-uni-lecturebra-cm 15/16
15
Moving forward for food protein analysis
• Authentication methods to detect
abnormalities/aberrations resulting
from significant level of adulteration
• New quantitative methods capable of
selectively and precisely determining
total protein contents
– To replace total nitrogen (Kjeldahl and
Dumas) approaches
58
Deliberately adulterated milk by FTIR and PCA
-0.5 -0.4 -0.3 -0.2 -0.1 0 0.1 0.2 0.3 0.4
-0.1
-0.05
0
0.05
0.1
0.15
Score PC2
S c o r e
P C 5
Melamine+water
Cyanuric acid
Urea Melamine
Ammonium sulphate
• Normal milk• Adulterated milk
*Juan Romero, Wisconsin Dairy Center
Conclusions• Specifications play an important role in the quality
and safety of food ingredients
• The method of analysis and reference standard
used to assess conformance to a specification can
influence the outcome
• FCC is a source of minimum quality specifications
for the identity, purity, and impurities of food
ingredients along with supporting validated test
procedures
• FCC standards benefit industry, regulators, and
consumers, and promote the quality and safety of
food ingredients
Conclusions• There are many critical needs in the area of
compendial testing standards that will rely on
advances in food chemistry
• There are many “at-risk” ingredients that will
require substantial efforts to establish reliablestandards to prevent food fraud
• Food and agricultural science should be driving
these multi-disciplinary research efforts