FOOD COMPOSITION DATA, FROM THE LAB TO THE LABEL: CODEX ALIMENTARIUS RECOMMENDATIONS FOR THE ANALYSIS OF DIETARY FIBRE IN FOOD ESTE (HH) VORSTER, CENTRE OF EXCELLENCE, FACULTY OF HEALTH SCIENCES CAPE TOWN, 9 NOVEMBER 2011
AGENDA 1. Dietary fibre (Definition and importance ) 2. Codex Alimentarius, CCNFSDU & CCMAS 3. Codex methods for dietary fibre analysis 4. Implications: some problems with methodolgy and recommendations
DIETARY FIBRE
CODEX DEFINITION OF DIETARY FIBRE 4 November 2008, 30 th session of CCNFSDU Dietary fibre means carbohydrate polymers with ten or more monomeric units, which are not hydrolysed by endogenous enzymes in small intestine of human beings and belong to following categories: Edible carbohydrate polymers naturally occurring in food as consumed Carbohydrate polymers which have been obtained from raw material in food by physical, enzymatic, or chemical means and which have been shown to have physiological effect of benefit to health by generally accepted scientific evidence to competent authorities Synthetic carbohydrate polymers, which have been shown to have physiological effect of benefit to health by generally accepted evidence to competent authorities * A footnote was added to the definition to allow national authorities to include nondigestible oligosaccharides (degree of polymerisation 3-9)
DF DEFINITION: Footnotes Modified in 2010 (ALINORM 10/33/26, 10/33/REP) When derived from a plant origin, dietary fibre may include fractions of lignin and/or other compounds associated with polysaccharides in the plant cell walls. These compounds also may be measured by certain analytical method(s) for dietary fibre. However, such compounds are not included in the definition of dietary fibre if extracted and re-introduced into a food. Decision on whether to include carbohydrates of 3 to 9 monomeric units should be left up to national authorities.
WHY IS LABELLING FOR PRECISE/CORRECT AMOUNTS** OF DIETARY FIBRE IMPORTANT? In the mind of consumers: DIETARY FIBRE AND HIGH FIBRE DIETS ARE ASSOCIATED WITH HEALTH Indirectly, the labeling of fibre = health claim ** Measured according to the CODEX definition
THE FIBRE STORY 1. Early observations by British missionary doctors in Africa of the low prevalence of chronic Western diseases (NCDs) in Africa; 2. Discussions with Alec Walker in South Africa; 3. Realisation it may be because of roughage in the traditional African diet; 4. Roughage became dietary fibre; (early definitions) 5. Extractions of fibre components; 6. Clinical and epidemiological studies to assess physiological and metabolic effects of fibre components 7. Development of methods of analysis followed
SOME PHYSIOLOGICAL EFFECTS AND HEALTH BENEFITS OF DIETARY FIBRE Mouthfeel properties Chewing of food Slower eating Lower energy density Fullness ; volume Slower absorption of CHO Binding of bile acids/salts; changed fat absorption Physical and other effects on absorption? Fermentation in large gut: SCFAs Volume effects, transit times Increased satiety Limited energy intake Weight control Decreased risk of obesity, Blood glucose control, insulin sensitivity, MS, DM Lower blood lipids, risk CVD Calcium; Nutritional, health status? Variety of beneficial metabolic effects; immunomodulatory Protects against NCDs (epithelial cell health) Increase stool weight Prevents constipation Gut health; regular High fibre diets: associated with micronutrient density Improved nutritional status, lower risk of NCDs
WHY THE CONTROVERSY REGARDING DIETARY FIBRE DEFINITION AND METHODS OF ANALYSIS? Dietary fibre is an unfortunate term; it is an umbrella term for many chemical substances (compare with vitamins and minerals); But it is the term that consumers know Digestibility is a poorly defined physiological variable The original concept (definition) of dietary fibre, was based on physiological effects At present, the composition of food is measured by agreed chemical methods Long-term epidemiological and experimental evidence about health benefits of fibre derives from studies of diets based on whole grains, fruit and vegetables (intrinsic carbohydrates of the plant cell wall)
WHY EXCLUDE WATER SOLUBLE OLIGOSACCHARIDES IN DEFINITION OF DIETARY FIBRE? These are non-digestible oligosaccharides with a degree of polymerisation between 3 and 9 Water soluble: can be added to water and juices as a source of fibre (this is not in the public interest) There is some experimental evidence of health benefits but more research is needed to convince competent authorities of health benefit (Long-term, prospective epidemiological and clinical studies)
CODEX ALIMENTARIUS
CODEX ALIMENTARIUS: DEFINITION The Codex Alimentarius is a collection of internationally adopted food standards and related texts** presented in a uniform manner... In order to: protect consumer health ensure fair practices in food trade ensure international harmonisation and facilitate trade ** Codes of practice, guidelines, other recommendations
CODEX ALIMENTARIUS COMMISSION UNITED NATIONS ORGANIZATIONS Food and Agriculture World Health Organization Organization (FAO) (WHO) FOOD STANDARDS PROGRAMME To implement To implement CODEX ALIMENTARIUS COMISSION Codex Committee on Nutrition and foods for Special Dietary Uses(CCNFSDU) Codex Committee on Methods of Analysis and Sampling (CCMAS)
CODEX COMMITTEES The Codex Commission may establish subsidiary bodies for the accomplishment of its work, such as Codex Committees and Coordinating Committees (Rule XI of XVI Rules of Procedures) Codex Committees prepare draft standards for submission to the Commission, intended for: worldwide use, and/or a given region, and/or a group of countries specifically enumerated by the Commission
PURPOSE OF THE CODEX ALIMENTARIUS CODEX implements the FAO/WHO food Standards Programme in order to: Protect health of consumers Ensure fair practices in food trade Coordinate food standards work of Governments and NGOs, prioritize and publish standards in Codex Alimentarius and amend as appropriate in light on developments (See Statutes of the Codex Alimentarius Commission)
SCOPE OF CODEX ALIMENTARIUS (CA) 1. The CA includes standards for all the principle foods: processed, semi-processed or raw, for distribution to the consumer. 2. Materials for further processing into foods should be included to the extent necessary to achieve the purpose of the CA as defined. 3. The CA includes provisions for: food hygiene, food additives, contaminants, labelling and presentation methods of analysis and sampling, residues of pesticides and veterinary drugs, import and export inspection and certification
THE NATURE OF CODEX STANDARDS 1. CA standards and related texts are NOT a substitute, nor alternative to national legislation; 2. They contain requirements for food aimed at ensuring for the consumer a safe, wholesome food product free from adulteration, correctly labelled and presented. A Codex standard for any food or foods should be drawn up in accordance with the format of the Codex Commodity Standards and should contain, as appropriate, the sections listed therein.
REVISION OF CODEX STANDARDS 1. Codex Standards should reflect current scientific knowledge and information. 2. When required, they shall be revised or removed according to specific procedures. 3. Each member of the Codex Alimentarius Commission is responsible to identify and present new information to the relevant committee
THE 8 STEP CODEX DECISION PROCESS Step 1: Approves a new standard for debate Step 2: New standard is drafted Step 3: Circulated to member governments for comment Step 4: Comments incorporated into the draft standard Step 5: The Executive Committee adopts the draft standard Step 6: Draft text is circulated for another round of comment Step 7: Amendments are made and the proposed standard is referred to the Commission for adoption Step 8: A last opportunity to debate the proposed standard Source:http://www.foodsafetycentre.com.au/fsh/fshbull37a.htm
CODEX METHODS OF ANALYSIS Section VI of Codex Alimentarius Commission procedural manual: PRINCIPLES FOR THE ESTABLISHMENT OF CODEX METHODS OF ANALYSIS Different types (classes) of methods defined
CODEX METHODS OF ANALYSIS The purpose of the methods are primarily intended as international methods for verification of provisions in Codex Standards. They should be used for reference, in calibration of methods in use, or introduced for routine examination and control processes
Defining methods TYPE I METHODS A method which determines a value that can only be arrived at in terms of the method per se and serves by definition as the only method for establishing the accepted value of the item measured
Reference methods TYPE II METHODS A Type II Method is the one designated Reference Method where type I methods do not apply. It should be selected from Type III methods. It should be recommended for use in cases of dispute and for calibration purposes.
Alternative approved methods TYPE III METHODS A Type III Method is one which meets the criteria required by the Codex Committee on Methods of Analysis and sampling for methods that may be used for control, inspection or regulatory purposes.
TYPE IV METHODS Tentative method A Type IV Method is a method that has been used traditionally or else has been recently introduced but for which the criteria required for acceptance by the Codex Committee on Methods of Analysis and sampling have not yet been determined
GENERAL CRITERIA FOR THE SELECTION OF METHODS OF ANALYSIS Official methods of analysis elaborated by international organizations occupying themselves with a food or group of foods should be preferred; Preference to methods that are established re specificity, accuracy, precision, repeatability, reproducibility, limit of detection, sensitivity, practicability & applicability under normal laboratory conditions, as well as other criteria as required; All proposed methods of analysis must have direct pertinence to the Codex Standard to which they are directed. Methods of analysis which are applicable uniformly to various groups of commodities should be given preference over methods that apply only to individual commodities.
CODEX METHODS FOR DIETARY FIBRE (32 nd session of CCNFSDU in Santiago, Chile, 1-5 November 2010)
THE MAJOR ISSUES REGARDING A METHOD TO MEASURE DIETARY FIBRE 1. Industry wants a simple, single method that is do-able and inexpensive, giving maximum, values (Fibre = health message: it is good for you!) 2. Food Composition data: a reliable method that measures dietary fibre in food for calculating nutrient composition of diets 3. Governments: labelling legislation 4. There IS NO SINGLE METHOD: Therefore Codex has a menu of methods
THE PROCESS CCNFSDU compiled a menu (list) of methods in 2010 (Santiago, Chile) The Codex Alimentarius Commission referred this list to CCMAS CCMAS amended this list and made some recommendations for use at their 32 nd Session on 7-11 March 2011 in Budapest, Hungary, inter alia establishing an electronic working group to develop a decision tree
GROUPS OF CCNFSDU AGREED METHODS 1. Type I: General methods that do not measure the lower molecular fraction (i.e. monomeric units < = 9) 2. Type I: General methods that measure both the higher (monomeric units > = 9) and the lower molecular weight fraction (monomeric units < = 9) 3. Type I: Methods that measure individual specific components (monomeric units: the whole range for each type of components is covered) 4. Type IV: Other methods that have not been subjected to interlaboratory evaluation under AOAC international guidelines (Type IV methods)
TYPE I METHODS (Group 1) Standard: All foods Provisions: method applicable for determining dietary fibres that do not include the lower molecular weight fraction Method: AOAC 985.29 and AACC Intl 32-05.01 (1991, 1999) Principle: Enzymatic gravimetric
TYPE I METHODS (Group 1) Standard: All foods Provisions: method applicable for determining dietary fibres that do not include the lower molecular weight fraction and also includes determination for soluble and insoluble fibres Method: AOAC 991.43, AACC Intl 32-07.01 (1991, 1999), and NMKL 129 (2003) Principle: Enzymatic gravimetric
TYPE I METHODS (Group 1) Standard: All foods Provisions: method applicable for determining dietary fibres that do not include the lower molecular weight fraction, in foods and food products containing more than 10% dietary fibres and less than 2% starch (e.g. fruits) Method: AOAC 993.21 Principle: Non-enzymatic gravimetric
TYPE I METHODS (Group 1) Standard: All foods Provisions: method applicable for determining dietary fibres that do not include the lower molecular weight fraction. Provide sugar residue composition of dietary polysaccharides, as well as content of Klason lignin Method: AOAC 994.13, AACC Intl 32-25.01 (1994, 1999), and NMKL 162 (1998) Principle: Enzymatic chemical
TYPE I METHODS (Group 2) Standard: All foods Provisions: method applicable for determining dietary fibres of higher and lower molecular weight, in food where resistant starches are not present Method: AOAC 2001.03, AACC Intl 32-41.01 (2002) Principle: Enzymatic gravimetric and Liquid Chromatography (LC)
TYPE I METHODS (Group 2) Standard: All foods Provisions: method applicable for determining dietary fibres of higher and lower molecular weight. The method is applicable in food that may, or may not, contain resistant starches. Method: AOAC 2009.01, AACC Intl 32-45.01 (2009) Principle: Enzymatic gravimetric and High Pressure Liquid Chromatography (HPLC) method.
TYPE I METHODS (Group 3) Standard: All foods Provisions and method: 1. Insoluble dietary fibres in food and food products (AACC Intl 32-20.01 (1982,1999); AOAC 991.42 (specific for insoluble fibre) 2. Soluble dietary fibres in food and food products (AOAC 993.19) 3. (1-3)(1-4) Beta-D-Glucans (AOAC 995.16; AACC Intl 32-23.01 (1995,1999)) 4. Fructans (oligofructoses, inulin, hydrolysed inulin, polyfructoses, fructooligosaccharides) applicable to added fructans (AOAC 997.08, AACC Intl 32-32.01 (2001)) 5. Fructans (as above but not applicable to highly depolymerised fructans (AOAC 999.03, AACC Intl 32-32.01 (2001)) 6. Polydextrose (AOAC 2000.11, AACC Intl 32-28.01 (2001)) 7. Trans-galacto-oligosaccharides (AOAC 2001.02, AACC Intl 32-33.01 (20010)) 8. Resistant starch (recommended for RS 3) AAOAC 2002.02; AACC Intl 32-40.01 (2002))
Standard: All foods TYPE IV METHODS Provisions and methods: 1. Insoluble glucans and mannans of yeast cell wall only (Eurasyp, Chemical, HPAEC-PAD) 2. Fructo-oligosaccharides (monomeric units <5) (Quarne et al. HPAEC-PAD) 3.Non-starch polysaccharides (Englyst et al. GLC)
Summary slide of some DF methods Method Principle What does it measure? AOAC 985.29 Enzymatic gravimetric for total DF (soluble plus insoluble,) Cellulose, beta glucan, galactomannan, arabinoxylans and varying amounts of the polymers mentioned in 2009.01; (DP > 3) AOAC 991.43 Enzymatic gravimetric As above, soluble and insoluble DF AOAC 993.21 Non-enzymatic gravimetric As above for foods with > 10% DF and < 2% starch (e.g. fruits) AOAC 994.13 Enzymatic chemical Includes Klason lignin (Maillard reaction products) AOAC 2001.03 AOAC 2009.01 Enzymatic gravimetric and Liquid Chromatography Enzymatic gravimetric and High-performance Liquid Chromatography (HPLC) Total DF, similar to AOAC 985.29 plus resistant maltodextrins (DP > 3) Total DF: cellulose, beta-glucan, galactomannan, arabinoxylan, pectin, arabinogalactin, polydextrose, fibersol 2, galacto-oligosaccharides, raffinose / stachyose, fructans (inulin, FOS), resistant starch (DP > 3)
SOME METHODS IN MORE DETAIL
FLOW CHART OF AOAC 2009.01/AACC 32-45.01 METHOD 1. Double sample 2. Incubate with pancreatic alpha amylase and amyloglucosidase for 16 hours at 37 degrees C (nonresistant starch is hydrolyzed to maltose and glucose) 3. Adjust ph to 8.2 and inactivate by heating to 100 degrees for 20 min and cool 4. Incubate for 30 min at 60 degrees with protease to digest proteins 5. Adjust ph to 4.3
FLOW CHART (CONTINUED) 6. Proceed to Total DF or Soluble and Insoluble DF 7. HMWDF is measured by adding ethanol, capturing insoluble and precipitable soluble DF 8. Wash with ethanol and acetone, dry, weigh 9. Analyse one sample for protein and the other for ash Non-precipitable DF in the filtrate is recovered by concentrating, desalting through ion exchange resins, concentrating and quantifying by LC
ADVANTAGES AND DISADVANTAGES OF OAC 2009.01 METHOD 1. ApproachES the wish for a single method for total dietary fibre 2. Empirical method that does not comply to fibre definition, especially because it also includes oligosaccharides with DP 3-9 and some other non-cell wall substances; 3. Therefore, it measures substances that are not associated with the established health benefits of high fibre intake
NSP METHOD (Englyst et al) NSP = Polysaccharides that do not have alpha 1-4 glucosidic linkages (as starch has); NSP isolated by dispersion and enzymatic hydrolysis of starch, which is then removed along with sugars by precipitating in 80% ethanol. NSP constituent sugars then individually determined by chromatography, colometric assays, etc. Does not measure DP 3-9 Also excludes some of the other oligosaccharides
OLIGOSACCHARIDES 1. They are not part of the cell-wall substances and was not part of the original fibre concept 2. They have not be shown to be associated with the established health benefit of fibre (satiety, bowel habits, lipids etc.) 3. HOWEVER, they do have beneficial effects on large gut flora (probiotic), calcium absorption and possibly immune effects in small bowel 4. Eventually it would be better to label them separately
AMENDMENTS BY CCMAS (2011) In view of the overlaps, group 3 of Type I methods: soluble and insoluble dietary fibre moved to group 1; The method for fructans endorsed as Type III; The remaining methods in group 3 endorsed as Type II as they are rational methods; Retained the Type IV methods;
RECOMMENDATIONS OF CCMAS An electronic working group led by the UK will consider a decision tree to facilitate the selection by analysts of available methods for dietary fibre for consideration at next sesion; At present it is IMPORTANT for analysts to specify what method was used and for what purpose as this would be especially relevant for enforcement and trade purposes
IMPLICATIONS AND PROBLEMS
1. JHC, HE, KE (2010): PROBLEM NO 1 The main limitation of applying the empirical enzymatic-gravimetric AOAC methods is that they do not provide any information on what has been measured and therefore it is not possible to authenticate whether what has been measured conforms with the definition 2. CCMAS: Most of the methods are empirical and some may be overlapping
JHC, HE, KE (2010) PROBLEM NO 2 In principle there should be only one Type 1 method. It is of concern that having Type 1 methods will result in a continuation of the approach where what is recovered by a method is in essence defined as dietary fibre, rather than the more progressive approach of evaluating methods of analysis on the basis that they recover materials included in the definition. It would also be unusual to have Type 1 methods where rational methods providing direct chemical determinations are available.
PROBLEM 3 Some countries wish to include non-digestible carbohydrates of DP 3-9 in their definition of fibre. This makes the designation of a single Type 1 method for the whole world untenable, because there are effectively two definitions of dietary fibre. It does not pose a problem for Type III and IV methods
KE (2010): PROBLEM 4 Combining results from chemical methods with those from enzymatic gravimetric methods may in some cases be inappropriate due to double accounting of some fractions. It is therefore preferable to combine values from chemical methods, as their high degree of specificity makes double accounting less likely
KE (2010): PROBLEM 5 The present type 1 enzymatic gravimetric methods include some poorly defined non-carbohydrate material naturally occurring in plant foods, or added from other sources or produced during food processing (e.g. Maillard reaction products).
RECOMMENDATIONS
RECOMMENDATION 1 KE (2010): All methods in the current Codex Alimentarius list should have remained Type IV methods. The aim would be to select chemical methods that could be established as Type III and Type II Codex methods, which would then have precedence for enforcement purposes.
RECOMMENDATION 2 What should be measured to enforce the definition of dietary fibre? 1. Polysaccharides of the plant cell wall (NSP) and Resistant Starch 3 (retrograded RS) 2. Other Resistant starch (in a few products) 3. Resistant oligosaccharides: Other naturally occurring NSP such as higher molecular weight fructans (inulins), plant gums and mucilages Note: methods should be required to measure these and only these
THE WAY FORWARD FOR RSA 1. Use a menu of reliable chemical methods of which results are combined (2011 CCMAS) 2. For labelling and enforcement purposes, when extracted or synthetic materials have been added to food products, confirm their presence by chemical methods that provide sufficient information so that their identity and hence conformity with the Codex definition of dietary fibre (associated with a beneficial physiological effect) can be assessed 3. Use CCMAS EWG decision tree (2012) 4. Specify the method used, for what purpose (CCMAS 2011)