Total Dietary Fiber Assay Kit

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Total Dietary Fiber Assay Kit K-TDFR Scheme
   
Reference code: K-TDFR-200A
SKU: 700004347

Content:

200 assays

Content: 100 assays / 200 assays
Shipping Temperature: Ambient
Storage Temperature: Short term stability: 2-8oC,
Long term stability: See individual component labels
Stability: > 2 years under recommended storage conditions
Analyte: Dietary Fiber
Assay Format: Enzymatic
Detection Method: Gravimetric
Signal Response: Increase
Limit of Detection: 0.5 g/100 g
Total Assay Time: ~ 100 min
Application examples: Food ingredients, food products and other materials.
Method recognition: AACC Method 32-05.01, AACC Method 32-06.01, AACC Method 32-07.01, AACC Method 32-21.01, AOAC Method 985.29, AOAC Method 991.42, AOAC Method 991.43, AOAC Method 993.19, CODEX Method Type I and GB Standard 5009.88-2014

The Total Dietary Fiber Assay Kit for the analysis of Total, Soluble and Insoluble Dietary Fiber according to AOAC and AACC approved methods.

View Dietary Fiber Measurement Guide - Which Method for which sample?

Dietary fiber can generally be described as the carbohydrate content of food that is not digested in the human small intestine. It passes into the large intestine where it is partially or fully fermented. These characteristics of dietary fiber are associated with its numerous well documented health benefits.

Dietary Fiber is a mixture of complex organic substances, including hydrophilic compounds, such as soluble and insoluble polysaccharides and non-digestable oligosaccharides, as well as a range of non-swellable, more or less hydrophobic, compounds such as cutins, suberins and lignins. The procedures for the determination and analysis of total dietary fiber as outlined in our assay protocol are based on the methods of Lee et al.1 and Prosky et al.2,3 (AOAC 991.43, AOAC 985.29, AACC 32-07.01 and AACC 32-05.01). However, the enzymes in the Megazyme Total Dietary Fiber Kit can also be used in other dietary fiber analytical methods such as AACC Method 32-21.01 and AACC Method 32-06.01.

1. Association of Official Analytical Chemists. (1985). Official Methods of Analysis, 14th ed., 1st suppl. Secs. 43, A14-43, A20, p.399.
2. Association of Official Analytical Chemists. (1986). Changes in methods. J. Assoc. Off. Anal. Chem., 69, 370.
3. Association of Official Analytical Chemists. (1987). Changes in methods. J. Assoc. Off. Anal. Chem., 70, 393.

See General Referee Reports: Journal of AOAC INTERNATIONAL, Vol. 81, No. 1, 1998. 

Two separate methods are described in the associated assay protocol:

METHOD 1: DETERMINATION OF TOTAL, SOLUBLE AND INSOLUBLE DIETARY FIBER
Based on AOAC Method 991.43 “Total, Soluble, and Insoluble Dietary Fiber in Foods” (First Action 1991) and AACC Method 32-07.01 “Determination of Soluble, Insoluble, and Total Dietary Fiber in Foods and Food Products” (Final Approval 10-16-91).

METHOD 2: DETERMINATION OF TOTAL DIETARY FIBER
Based on AACC method 32-05.01 and AOAC Method 985.29.

Note that a letter of endorsement from the original method developer, Dr. Leon Prosky, is included in the Documents Tab.

Scheme-K-TDFR-200A TDFR Megazyme

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Validation of Methods
Advantages
  • Very competitive price (cost per test)   
  • All reagents stable for > 2 years 
  • High purity / standardised enzymes employed 
  • Mega-Calc™ software tool is available from our website for hassle-free raw data processing 
  • Simple format
Documents
Certificate of Analysis
Safety Data Sheet
FAQs Assay Protocol Data Calculator Letter of Endorsement
Publications
Megazyme publication
Determination of total dietary fibre and available carbohydrates: A rapid integrated procedure that simulates in vivo digestion.

McCleary, B. V., Sloane, N. & Draga, A. (2015). Starch/Stärke, 67(9-10), 860–883.

The new definition of dietary fibre introduced by Codex Alimentarius in 2008 includes resistant starch and the option to include non-digestible oligosaccharides. Implementation of this definition required new methodology. An integrated total dietary fibre method was evaluated and accepted by AOAC International and AACC International (AOAC Methods 2009.01 and 2011.25; AACC Method 32–45.01 and 32–50.01, and recently adopted by Codex Alimentarius as a Type I Method. However, in application of the method to a diverse range of food samples and particularly food ingredients, some limitations have been identified. One of the ongoing criticisms of this method was that the time of incubation with pancreatic α-amylase/amyloglucosidase mixture was 16 h, whereas the time for food to transit through the human small intestine was likely to be approximately 4 h. In the current work, we use an incubation time of 4 h, and have evaluated incubation conditions that yield resistant starch and dietary values in line with ileostomy results within this time frame. Problems associated with production, hydrolysis and chromatography of various oligosaccharides have been addressed resulting in a more rapid procedure that is directly applicable to all foods and food ingredients currently available.

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Megazyme publication

Modification to AOAC Official Methods 2009.01 and 2011.25 to allow for minor overestimation of low molecular weight soluble dietary fiber in samples containing starch.

McCleary, B. V. (2014). Journal of AOAC International, 97(3), 896-901.

AOAC Official Methods 2009.01 and 2011.25 have been modified to allow removal of resistant maltodextrins produced on hydrolysis of various starches by the combination of pancreatic α-amylase and amyloglucosidase (AMG) used in these assay procedures. The major resistant maltodextrin, 63,65-di-α-D-glucosyl maltopentaose, is highly resistant to hydrolysis by microbial α-glucosidases, isoamylase, pullulanase, pancreatic, bacterial and fungal α-amylase and AMG. However, this oligosaccharide is hydrolyzed by the mucosal α-glucosidase complex of the pig small intestine (which is similar to the human small intestine), and thus must be removed in the analytical procedure. Hydrolysis of these oligosaccharides has been by incubation with a high concentration of a purified AMG at 60°C. This incubation results in no hydrolysis or loss of other resistant oligosaccharides such as FOS, GOS, XOS, resistant maltodextrins (e.g., Fibersol 2) or polydextrose. The effect of this additional incubation with AMG on the measured level of low molecular weight soluble dietary fiber (SDFS) and of total dietary fiber in a broad range of samples is reported. Results from this study demonstrate that the proposed modification can be used with confidence in the measurement of dietary fiber.

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Megazyme publication

Measurement of total dietary fiber using AOAC method 2009.01 (AACC International approved method 32-45.01): Evaluation and updates.

McCleary, B. V., Sloane, N., Draga, A. & Lazewska, I. (2013). Cereal Chemistry, 90(4), 396-414.

The Codex Committee on Methods of Analysis and Sampling recently recommended 14 methods for measurement of dietary fiber, eight of these being type I methods. Of these type I methods, AACC International Approved Method 32-45.01 (AOAC method 2009.01) is the only procedure that measures all of the dietary fiber components as defined by Codex Alimentarius. Other methods such as the Prosky method (AACCI Approved Method 32-05.01) give similar analytical data for the high-molecular-weight dietary fiber contents of food and vegetable products low in resistant starch. In the current work, AACCI Approved Method 32-45.01 has been modified to allow accurate measurement of samples high in particular fructooligosaccharides: for example, fructotriose, which, in the HPLC system used, chromatographs at the same point as disaccharides, meaning that it is currently not included in the measurement. Incubation of the resistant oligosaccharides fraction with sucrase/β-galactosidase removes disaccharides that interfere with the quantitation of this fraction. The dietary fiber value for resistant starch type 4 (RS4), varies significantly with different analytical methods, with much lower values being obtained with AACCI Approved Method 32-45.01 than with 32-05.01. This difference results from the greater susceptibility of RS4 to hydrolysis by pancreatic α-amylase than by bacterial α-amylase, and also a greater susceptibility to hydrolysis at lower temperatures. On hydrolysis of samples high in starch in the assay format of AACCI Approved Method 32-45.01 (AOAC method 2009.01), resistant maltodextrins are produced. The major component is a heptasaccharide that is highly resistant to hydrolysis by most of the starch-degrading enzymes studied. However, it is hydrolyzed by the maltase/amyloglucosidase/isomaltase enzyme complex present in the brush border lining of the small intestine. As a consequence, AOAC methods 2009.01 and 2011.25 (AACCI Approved Methods 32-45.01 and 32-50.01, respectively) must be updated to include an additional incubation with amyloglucosidase to remove these oligosaccharides.

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Megazyme publication

Determination of insoluble, soluble, and total dietary fiber (codex definition) by enzymatic-gravimetric method and liquid chromatography: Collaborative Study.

McCleary, B. V., DeVries, J. W., Rader, J. I., Cohen, G., Prosky, P., Mugford, D. C., Champ, M. & Okuma, K. (2012). Journal of AOAC International, 95(3), 824-844.

A method for the determination of insoluble (IDF), soluble (SDF), and total dietary fiber (TDF), as defined by the CODEX Alimentarius, was validated in foods. Based upon the principles of AOAC Official MethodsSM 985.29, 991.43, 2001.03, and 2002.02, the method quantitates water-insoluble and water-soluble dietary fiber. This method extends the capabilities of the previously adopted AOAC Official Method 2009.01, Total Dietary Fiber in Foods, Enzymatic-Gravimetric-Liquid Chromatographic Method, applicable to plant material, foods, and food ingredients consistent with CODEX Definition 2009, including naturally occurring, isolated, modified, and synthetic polymers meeting that definition. The method was evaluated through an AOAC/AACC collaborative study. Twenty-two laboratories participated, with 19 laboratories returning valid assay data for 16 test portions (eight blind duplicates) consisting of samples with a range of traditional dietary fiber, resistant starch, and nondigestible oligosaccharides. The dietary fiber content of the eight test pairs ranged from 10.45 to 29.90%. Digestion of samples under the conditions of AOAC 2002.02 followed by the isolation, fractionation, and gravimetric procedures of AOAC 985.29 (and its extensions 991.42 and 993.19) and 991.43 results in quantitation of IDF and soluble dietary fiber that precipitates (SDFP). The filtrate from the quantitation of water-alcohol-insoluble dietary fiber is concentrated, deionized, concentrated again, and analyzed by LC to determine the SDF that remains soluble (SDFS), i.e., all dietary fiber polymers of degree of polymerization = 3 and higher, consisting primarily, but not exclusively, of oligosaccharides. SDF is calculated as the sum of SDFP and SDFS. TDF is calculated as the sum of IDF and SDF. The within-laboratory variability, repeatability SD (Sr), for IDF ranged from 0.13 to 0.71, and the between-laboratory variability, reproducibility SD (sR), for IDF ranged from 0.42 to 2.24. The within-laboratory variability sr for SDF ranged from 0.28 to 1.03, and the between-laboratory variability sR for SDF ranged from 0.85 to 1.66. The within-laboratory variability sr for TDF ranged from 0.47 to 1.41, and the between-laboratory variability sR for TDF ranged from 0.95 to 3.14. This is comparable to other official and approved dietary fiber methods, and the method is recommended for adoption as Official First Action.

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Megazyme publication

Determination of total dietary fiber (CODEX definition) by enzymatic-gravimetric method and liquid chromatography: collaborative study.

McCleary, B. V., DeVries, J. W., Rader, J. I., Cohen, G., Prosky, L., Mugford, D. C., Champ, M. & Okuma, K. (2010). Journal of AOAC International, 93(1), 221-233.

A method for the determination of total dietary fiber (TDF), as defined by the CODEX Alimentarius, was validated in foods. Based upon the principles of AOAC Official MethodsSM 985.29, 991.43, 2001.03, and 2002.02, the method quantitates high- and low-molecular-weight dietary fiber (HMWDF and LMWDF, respectively). In 2007, McCleary described a method of extended enzymatic digestion at 37°C to simulate human intestinal digestion followed by gravimetric isolation and quantitation of HMWDF and the use of LC to quantitate low-molecular-weight soluble dietary fiber (LMWSDF). The method thus quantitates the complete range of dietary fiber components from resistant starch (by utilizing the digestion conditions of AOAC Method 2002.02) to digestion resistant oligosaccharides (by incorporating the deionization and LC procedures of AOAC Method 2001.03). The method was evaluated through an AOAC collaborative study. Eighteen laboratories participated with 16 laboratories returning valid assay data for 16 test portions (eight blind duplicates) consisting of samples with a range of traditional dietary fiber, resistant starch, and nondigestible oligosaccharides. The dietary fiber content of the eight test pairs ranged from 11.57 to 47.83. Digestion of samples under the conditions of AOAC Method 2002.02 followed by the isolation and gravimetric procedures of AOAC Methods 985.29 and 991.43 results in quantitation of HMWDF. The filtrate from the quantitation of HMWDF is concentrated, deionized, concentrated again, and analyzed by LC to determine the LMWSDF, i.e., all nondigestible oligosaccharides of degree of polymerization 3. TDF is calculated as the sum of HMWDF and LMWSDF. Repeatability standard deviations (Sr) ranged from 0.41 to 1.43, and reproducibility standard deviations (SR) ranged from 1.18 to 5.44. These results are comparable to other official dietary fiber methods, and the method is recommended for adoption as Official First Action.

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Megazyme publication
Development and evaluation of an integrated method for the measurement of total dietary fibre.

McCleary, B. V., Mills, C. & Draga, A. (2009). Quality Assurance and Safety of Crops & Foods, 1(4), 213–224.

An integrated total dietary fibre (TDF) method, consistent with the recently accepted CODEX definition of dietary fibre, has been developed. The CODEX Committee on Nutrition and Foods for Special Dietary Uses (CCNFSDU) has been deliberating for the past 8 years on a definition for dietary fibre that correctly reflects the current consensus thinking on what should be included in this definition. As this definition was evolving, it became evident to us that neither of the currently available methods for TDF (AOAC Official Methods 985.29 and 991.43), nor a combination of these and other methods, could meet these requirements. Consequently, we developed an integrated TDF procedure, based on the principals of AOAC Official Methods 2002.02, 991.43 and 2001.03, that is compliant with the new CODEX definition. This procedure quantitates high- and low-molecular weight dietary fibres as defined, giving an accurate estimate of resistant starch and non-digestible oligosaccharides also referred to as low-molecular weight soluble dietary fibre. In this paper, the method is discussed, modifications to the method to improve simplicity and reproducibility are described, and the results of the first rounds of interlaboratory evaluation are reported.

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Megazyme publication

An integrated procedure for the measurement of total dietary fibre (including resistant starch), non-digestible oligosaccharides and available carbohydrates.

McCleary, B. V. (2007). Analytical and Bioanalytical Chemistry, 389(1), 291-308.

A method is described for the measurement of dietary fibre, including resistant starch (RS), non-digestible oligosaccharides (NDO) and available carbohydrates. Basically, the sample is incubated with pancreatic α-amylase and amyloglucosidase under conditions very similar to those described in AOAC Official Method 2002.02 (RS). Reaction is terminated and high molecular weight resistant polysaccharides are precipitated from solution with alcohol and recovered by filtration. Recovery of RS (for most RS sources) is in line with published data from ileostomy studies. The aqueous ethanol extract is concentrated, desalted and analysed for NDO by high-performance liquid chromatography by a method similar to that described by Okuma (AOAC Method 2001.03), except that for logistical reasons, D-sorbitol is used as the internal standard in place of glycerol. Available carbohydrates, defined as D-glucose, D-fructose, sucrose, the D-glucose component of lactose, maltodextrins and non-resistant starch, are measured as D-glucose plus D-fructose in the sample after hydrolysis of oligosaccharides with a mixture of sucrase/maltase plus β-galactosidase.

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Megazyme publication

Measurement of novel dietary fibres.

McCleary, B. V. & Rossiter, P. (2004). Journal of AOAC International, 87(3), 707-717.

With the recognition that resistant starch (RS) and nondigestible oligosaccharides (NDO) act physiologically as dietary fiber (DF), a need has developed for specific and reliable assay procedures for these components. The ability of AOAC DF methods to accurately measure RS is dependent on the nature of the RS being analyzed. In general, NDO are not measured at all by AOAC DF Methods 985.29 or 991.43, the one exception being the high molecular weight fraction of fructo-oligosaccharides. Values obtained for RS, in general, are not in good agreement with values obtained by in vitro procedures that more closely imitate the in vivo situation in the human digestive tract. Consequently, specific methods for the accurate measurement of RS and NDO have been developed and validated through interlaboratory studies. In this paper, modifications to AOAC fructan Method 999.03 to allow accurate measurement of enzymically produced fructo-oligosaccharides are described. Suggested modifications to AOAC DF methods to ensure complete removal of fructan and RS, and to simplify pH adjustment before amyloglucosidase addition, are also described.

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Megazyme publication
Dietary fibre analysis.

McCleary, B. V. (2003). Proceedings of the Nutrition Society, 62, 3-9.

The 'gold standard' method for the measurement of total dietary fibre is that of the Association of Official Analytical Chemists (2000; method 985.29). This procedure has been modified to allow measurement of soluble and insoluble dietary fibre, and buffers employed have been improved. However, the recognition of the fact that non-digestible oligosaccharides and resistant starch also behave physiologically as dietary fibre has necessitated a re-examination of the definition of dietary fibre, and in turn, a re-evaluation of the dietary fibre methods of the Association of Official Analytical Chemists. With this realisation, the American Association of Cereal Chemists appointed a scientific review committee and charged it with the task of reviewing and, if necessary, updating the definition of dietary fibre. It organised various workshops and accepted comments from interested parties worldwide through an interactive website. More recently, the (US) Food and Nutrition Board of the Institute of Health, National Academy of Sciences, under the oversight of the Standing Committee on the Scientific Evaluation of Dietary Reference Intakes, assembled a panel to develop a proposed definition(s) of dietary fibre. Various elements of these definitions were in agreement, but not all. What was clear from both reviews is that there is an immediate need to re-evaluate the methods that are used for dietary fibre measurement and to make appropriate changes where required, and to find new methods to fill gaps. In this presentation, the 'state of the art' in measurement of total dietary fibre and dietary fibre components will be described and discussed, together with suggestions for future research.

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Megazyme publication

Two issues in dietary fiber measurement.

McCleary, B. V. (2001). Cereal Foods World, 46, 164-165.

Enzyme activity and purity of these topics, the easiest to deal with is the importance of enzyme purity and activity. As a scientist actively involved in polysaccharide research over the past 25 years, I have come to appreciate the importance of enzyme purity and specificity in polysaccharide modification and measurement (7). These factors translate directly to dietary fiber (DF) methodology, because the major components of DF are carbohydrate polymers and oligomers. The committee report published in the March issue of Cereal FOODS WORLD refers only to the methodology for measuring enzyme purity and activity (8) that led up the AOAC method 985.29 (2). In this work enzyme purity was gauged by the lack of hydrolysis (i.e., complete recovery) of a particular DF component (e.g. β-glucan, larch galactan or citrus pectin). Enzyme activity was measured by the ability to completely hydrolyze representative starch and protein (namely wheat starch and casein). These requirements and restrictions on enzyme purity and activity were adequate at the time the method was initially developed and served as a useful working guide. However, it was recognized that there was a need for more stringent quality definitions and assay procedures for enzymes used in DF measurements.

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Megazyme publication

Measurement of dietary fibre components: the importance of enzyme purity, activity and specificity.

McCleary, B. V. (2001), “Advanced Dietary Fibre Technology”, (B. V. McCleary and L. Prosky, Eds.), Blackwell Science, Oxford, U.K., pp. 89-105.

Interest in dietary fibre is undergoing a dramatic revival, thanks in part to the introduction of new carbohydrates as dietary fibre components. Much emphasis is being placed on determining how much fibre is present in a food. Linking a particular amount of fibre to a specific health benefit is now an important area of research. The term 'dietary fibre' first appeared in 1953, and referred to hemicelluloses, celluloses and lignin (Theandere/tf/.1995). Trowell (1974) recommended this term as a replacement for the no longer acceptable term 'crude fibre'. Burkitt (1995) has likened the interest in dietary fibre to the growth of a river from its first trickle to a mighty torrent He observes that dietary fibre 'was first viewed as merely the less digestible constituent of food which exerts a laxative action by irritating the gut', thus acquiring the designation 'roughage' - a term later replaced by 'crude fibre' and ultimately by 'dietary fibre'. Various definitions of dietary fibre have appeared over the years, partly due to the various concepts used in deriving the term (i.e. origin of material, resistance to digestion, fermentation in the colon, etc.), and partly to the difficulties associated with its measurement and labelling (Mongeau et al. 1999). The principal components of dietary fibre, as traditionally understood, are non-starch polysaccharides (which in plant fibre are principally hemicelluloses and celluloses), and the non-carbohydrate phenolic components, cutin, suberin and waxes, with which they are associated in nature. In 1976, the definition of dietary fibre was modified to include gums and some pectic substances, based on the resistance to digestion of these components in the upper intestinal tract. For the purposes of labelling, Englyst et al. (1987) proposed that dietary fibre be defined as 'non-starch polysaccharides (NSP) in the diet that are not digested by the endogenous secretions of the human digestive tract'. Methods were concurrently developed to specifically measure NSP (Englyst et al. 1994).

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Megazyme publication

Importance of enzyme purity and activity in the measurement of total dietary fibre and dietary fibre components.

McCleary, B. V. (2000). Journal of AOAC International, 83(4), 997-1005.

A study was made of the effect of the activity and purity of enzymes in the assay of total dietary fiber (AOAC Method 985.29) and specific dietary fiber components: resistant starch, fructan, and β-glucan. In the measurement of total dietary fiber content of resistant starch samples, the concentration of α-amylase is critical; however, variations in the level of amyloglucosidase have little effect. Contamination of amyloglucosidase preparations with cellulase can result in significant underestimation of dietary fiber values for samples containing β-glucan. Pure β-glucan and cellulase purified from Aspergillus niger amyloglucosidase preparations were used to determine acceptable critical levels of contamination. Sucrose, which interferes with the measurement of inulin and fructooligosaccharides in plant materials and food products, must be removed by hydrolysis of the sucrose to glucose and fructose with a specific enzyme (sucrase) followed by borohydride reduction of the free sugars. Unlike invertase, sucrase has no action on low degree of polymerization (DP) fructooligosaccharides, such as kestose or kestotetraose. Fructan is hydrolyzed to fructose and glucose by the combined action of highly purified exo- and endo-inulinases, and these sugars are measured by the p-hydroxybenzoic acid hydrazide reducing sugar method. Specific measurement of β-glucan in cereal flour and food extracts requires the use of highly purified endo-1,3:1,4 β-glucanase and A. niger β-glucosidase. β-glucosidase from almonds does not completely hydrolyze mixed linkage β-glucooligosaccharides from barley or oat β-glucan. Contamination of these enzymes with starch, maltosaccharide, or sucrose-hydrolyzing enzymes results in production of free glucose from a source other than β-glucan, and thus an overestimation of β-glucan content. The glucose oxidase and peroxidase used in the glucose determination reagent must be essentially devoid of catalase and α- and β-glucosidase.

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Megazyme publication

Measuring dietary fibre.

McCleary, B. V. (1999). The World of Ingredients, 50-53.

Interest in dietary fibre is undergoing a dramatic revival thanks in part to the introduction of new carbohydrates as dietary fibre components. Much emphasis is being placed on determining how much fibre is present in a food. Linking a particular amount of fibre to a specific health benefit is now an important area of research. Total Dietary Fibre. The term “dietary fibre” first appeared in 1953 and referred to hemicelluloses, celluloses and lignin (1). In 1974, Trowell (2) recommended this term as a replacement for the no longer acceptable term “crude fibre” Burkitt (3) has likened the interest in dietary fibre to the growth of a river from its first trickle to a mighty torrent. He observes that dietary fibre “was viewed as merely the less digestible constituent of food which exerts a laxative action by irritating the gut “thus acquiring the designation “roughage” a term which was later replaced by “crude fibre” and ultimately by “dietary fibre” Various definitions of dietary fibre have appeared over the years, partly due the various concepts used in deriving the term (i.e. origin of material, resistance to digestion, fermentation in the colon etc.), and partly to the difficulties associated with its measurement and labelling (4). The principle components of dietary fibre, as traditionally understood, are non-starch polysaccharides, which in plant fibre are principally hemicelluloses and celluloses, and the non-carbohydrate phenolic components, cutin, suberin and waxes with which they are associated in Nature.

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Megazyme publication

Enzyme purity and activity in fibre determinations.

McCleary, B. V. (1999). Cereal Foods World, 44(8), 590-596.

Dietary fiber is mainly composed of plant cell wall polysaccharides such as cellulose, hemicellulose, and pectic substances, but it also includes lignin and other minor components (1). Basically, it covers the polysaccharides that are not hydrolyzed by the endogenous secretions of the human digestive tract (2,3). This definition has served as the target for those developing analytical procedures for the measurement of dietary fiber for quality control and regulatory considerations (4). Most procedures for the measurement of total dietary fiber (TDF), or specific polysaccharide components, either involve some enzyme treatment steps or are mainly enzyme-based. In the development of TDF procedures such as the Prosky method (AOAC International 985.29, AACC 32—05) (5), the Uppsala method (AACC32-25) (6), and the Englyst method (7), the aim was to remove starch and protein through enzyme treatment, and to measure the residue as dietary fiber (after allowing for residual, undigested protein and ash). Dietary fiber was measured either gravimetrically or by chemical or instrumental procedures. Many of the enzyme treatment steps in each of the methods, particularly the prosky (5) and the Uppsala (6) methods are very similar. As a new range of carbohydrates is being introduced as potential dietary fiber components, the original assay procedures will need to be reexamined, and in some cases slightly modified, to ensure accurate and quantitative measurement of these components and of TDF. These “new” dietary fiber components include resistant nondigestible oligosaccharides; native and chemically modified polysaccharides of plant and algal origin (galactomannan, chemically modified celluloses, and agars and carrageenans); and resistant starch. To measure these components accurately, the purity, activity, and specificity of the enzymes employed will become much more important. A particular example of this is the mesurement of fructan. This carbohydrate consists of a fraction with a high degree of polymerization (DP) that is precipitated in the standard Prosky method (5,8) and a low DP fraction consequently is not measured (9). Resistant starch poses a particular problem. This component is only partially resistant to degradation by α-amylase, so the level of enzyme used and the incubation conditions (time and temperature) are critical.

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Publication

Effects of various processing methods on the dietary fiber and antioxidant properties of Bignay (Antidesma bunius L. Spreng) fruit.

Carbonera, A. F. A., Atienza, L. M., Estacio, M. A. C., Duque, S. M. M., Lizardo-Agustin, R. C. M., Flandez, L. E. L. & Castillo-Israel, K. A. T. (2023). Food Chemistry Advances, 3, 100561.

Bignay (Antidesma bunius L. Spreng) is an indigenous fruit in the Philippines known for its bioactive compounds and is commonly preserved by conventional freezing. Processing can be done to improve its storage condition and convert it into functional ingredients. This study aimed to determine the effect of freeze-drying, oven drying (50°C), spray drying, and juice concentrating on the dietary fiber composition, phenolic compounds, and antioxidant activity of Bignay. Results showed that oven drying increased the total dietary fiber of Bignay by 29% while freeze drying resulted to an increase in total phenolics, total flavonoids, and total anthocyanin by 69%, 55%, and 66%, respectively, with an increase in antioxidant activity in terms of DPPH, FRAP, and ABTS by 57%, 15% and 31%, respectively. Spray drying was found to be the most detrimental method while juice concentration gave little to no significant effects. Epicatechin, catechin, and gallic acid were the main phenolic compounds quantified in the processed Bignay. The study recommends that freeze-drying is the best method followed by oven drying, concentration, and spray drying.

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Comparative study of nutritional composition, antioxidant activity and functional properties of Cucumis melo and Citrullus lanatus seeds powder. 

Saeed, F., Afzaal, M., Niaz, B., Hussain, M., Rasheed, A., Raza, M. A., Umar, M., Khan, M. A., Suleria, H., Tufail, T. & Al Jbawi, E. (2024). Cogent Food & Agriculture, 10(1), 2293517.

The current research studied the nutritional and functional properties and antioxidant profile of Cucumis melo and Citrullus lanatus seeds. Results showed that the protein, fat, and fiber content of C. melo seed powder were significantly (p < 0.05) higher than C. lanatus. Furthermore, results of mineral profile showed that Citrullus lanatus seeds have 236.7 ± 4.4 mg/100 g potassium, 98.6 ± 0.3 mg/100 g sodium, 25.0 ± 0.03 mg/100 g magnesium, and 30.8 ± 0.04 mg/100 g calcium while Cucumis melo seeds showed 309.1 ± 5.3 mg/100 g potassium, 61.5 ± 0.2 mg/100 g sodium, 57.8 ± 0.15 mg/100 g magnesium, and 53.1 ± 0.07 mg/100 g calcium. Moreover, amino acids (valine (4.14), leucine (6.11), isoleucine (5.32), cysteine (1.43), lysine (2.93), glycine (6.23), alanine (3.24), and aspartic acid (6.87) of C. melo seeds were higher as compared to C. lanatus seeds. Total phenolic and total flavonoids contents of Cucumis melo were significantly (p < 0.05) higher than Citrullus lanatus. Results regarding the DPPH and FRAP of Cucumis melo were comparatively higher than Citrullus lanatus seeds powder due to higher phenolic contents. Further, water holding capacity of Cucumis melo seeds powder was 2.78 g H2O/g as compared to Cucumis melo (2.52 g H2O/g) and Cucumis melo seed powder showed a higher oil retention capacity 1.88 g oil/g as compared to Citrullus lanatus seeds powder 1.80 g oil/g. Conclusively, the outcome from comparative study presented C. melo as valuable and superior source of essential nutrients along with bioactive components which enhance their technological properties. Incorporation of C. melo and C. lanatus is highly recommended as a sustainable source of agro-industrial waste to achieve the nutritional and technological properties in the end product.

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Influence of malted buckwheat, foxtail and proso millet flour incorporation on the physicochemical, protein digestibility and antioxidant properties of gluten-free rice cookies.

Kumari, S., Singh, B. & Kaur, A. (2023). Food Chemistry Advances, 3, 100557.

The gluten-free cookies with improved nutritional value and health promoting qualities were prepared by substituting rice flour with malted buckwheat (BW), foxtail millet (FM) and proso millet (PM) flours at 15 % and 30 % levels. The characteristics of malted BW, FM and PM flours obtained after germination for 1–4 days (GD = 1–4) were first evaluated. The increment in germination days caused a significant improvement in protein content, total dietary fibre (TDF), oil absorption capacity, amylase and protease activity of malted BW, FM and PM flours. Incorporation of 30 % malted (GD=3 and 4) BW, FM and PM flours increased the G', G" and tan δ values of the cookies dough. The protein, ash, fat, TDF content and in vitro protein digestibility (IVPD) of cookies increased while glycaemic and starch hydrolysis index decreased by incorporating malted flours of all three grains. The incorporation of 30 % malted BW flour (GD = 3) increased IVPD, antioxidant capacity, protein, phenolics and flavonoids while incorporation of 30 % malted FM flour (GD = 4) proved useful in improving dietary fibres in gluten-free rice cookies. The 30 % malted BW and FM flour (GD = 3) can be incorporated in rice cookies for the improvement of nutritional and functional properties.

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Evaluation of the chemical composition and nutritional value of lettuce (Lactuca sativa L.) biofortified in hydroponics with iodine in the form of iodoquinolines. 

Dyląg, A., Smoleń, S. & Wisła-Świder, A. (2023). Frontiers in Plant Science, 14, 1288773.

Iodine deficiency in the diet creates the need to search for innovative, more sustainable and more effective strategies for enriching food with this microelement. The adopted research hypothesis assumed that the use of organic forms of iodine for supplementation of lettuce (Lactuca sativa L.), compared to mineral iodine, has a more favorable effect not only on the concentration of iodine, but also on the yield and the content of other chemical components determining its nutritional and health-promoting value. Lettuce was planted in a nutrient film technique (NFT) hydroponic study in a greenhouse. The following application of iodine compounds (all in 5 µM molar mass equivalents) were tested in the studies: control (without of iodine application); potassium iodate (positive iodine control), 8-hydroxy-7-iodo-5-quinolinesulfonic acid, 5-chloro-7-iodo-8-quinolinol, 5,7-diiodo-8-quinolinol and 4-hydroxy-8-iodo-3-quinolinecarboxylic acid. In this work, it was shown for the first time that iodoquinolines can be 1) a source of iodine for plants; 2) they have a biostimulating effect on their yielding and 3) they increase the resistance of crops to stress (due to a significant increase in the level of polyphenolic compounds). Lettuce with the addition of 8-hydroxy-7-iodo-5-quinolinesulfonic acid was characterized by the highest content of iodine, which was 221.7 times higher than in control plants. The weight gain of the whole plant was particularly visible in the case of lettuce enriched with 5-chloro-7-iodo-8-quinolinol and amounted to 26.48% compared to the control. Lettuce biofortified with iodine in the form of iodoquinolines can successfully become part of a sustainable diet based on plant products, which has a low impact on the environment and contributes to the long-term good health of an individual or community. Reducing iodine deficiency through the use of organoiodine compounds can help achieve the sustainability goal of eliminating hidden hunger, improving nutritional status and promoting sustainable agriculture.

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Comprehensive Physical and Chemical Characterization of Corncob and Nopal Fibers: Exploring Sustainable Alternatives for High-Value Applications. 

Bonifaz Delgado, L. V., de la Rosa Millán, J. & Guajardo Flores, D. (2023). ACS Food Science & Technology, 3(12), 2132-2143.

Corn and nopal residues are abundantly available renewable materials that have the potential to produce functional fibers, with applications in industries such as food, pharmaceuticals, and textiles. This study analyzes corncob and nopal pruning waste as potential sources of functional fibers. A comparison between the properties of raw and cooked corncob’s pith and woody ring, alongside nopal mucilage and cladode fiber, is carried out. The study examines various physicochemical properties through proximate analysis, functionality tests, phenolic determination, and enzyme inhibition tests. Results indicated that the cooking process resulted in an insoluble-fiber-rich material. Nopal-derived samples exhibited higher water solubility, while corn-derived samples showed greater water and oil absorption. Nopal-derived samples displayed total phenolic content between 9.3 and 14.4 mg gallic acid equivalent /g of dry basis sample (DB) and antioxidant activity varying from 4.2 to 5.8 μmol Trolox/g DB. Corncob-derived samples exhibited higher amounts of bound ferulic acid content, ranging from approximately 6.9 to 32.5 μg/mg DB. Nopal fiber and corn broth precipitate demonstrated remarkable enzyme inhibition activity, suggesting their potential applications in functional foods and dietary interventions. Overall, this research provides valuable insights into the physical and chemical properties of corn and nopal cladode fibers, shedding light on their potential utilization in food formulation design due to their properties and potential health benefits.

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Beneficial glycaemic effects of high-amylose barley bread compared to wheat bread in type 2 diabetes.

Bohl, M., Gregersen, S., Zhong, Y., Hebelstrup, K. H. & Hermansen, K. (2023). European Journal of Clinical Nutrition, 1-8.

Background: Cereals foods with a high content of dietary fibres or amylose have potential to lower postprandial glucose levels. Optimisation of cereal foods may improve management of type 2 diabetes (T2D). Methods: We investigated the impact on 4 h postprandial glucose responses given as incremental area under curve (iAUC) of bread made of either 50% RNAi-based (genetically modified) amylose-only barley flour (AmOn) (and 50% wheat flour), 50% hulless barley flour (and 50% wheat flour) or 75% hulless barley (and 25% wheat flour) in subjects with T2D compared with 100% wheat flour bread. Design: Twenty adults with T2D were randomly allocated to one of four breads at four separate visits. We measured fasting and 4 h postprandial responses of glucose, insulin, glucagon, triacylglycerol (TG), free fatty acids (FFA), glucagon-like peptide-1 (GLP-1) and gastric inhibitory polypeptide (GIP). Mixed model ANOVA was used to examine the differences. Results: Bread made from 50% AmOn lowered the 4 h postprandial glucose by 34%, 27%, 23% (P < 0.05) compared with 100% wheat, 50% or 75% hulless barley, respectively. Bread made from 75% hulless barley reduced the postprandial glucose response (iAUC) by 11% (P < 0.05) compared to 100% wheat bread. Postprandial insulin responses (iAUC) were reduced for 50% AmOn compared with 100% wheat and 50% hulless barley and for 75% hulless compared to 50% hulless barley bread (P < 0.05). 4 h postprandial glucagon (tAUC) did not differ between the four bread types (P > 0.05). Lower postprandial GIP (iAUC) was observed after all barley breads compared to 100% wheat (P < 0.05), whereas no difference was seen in postprandial GLP-1. Postprandial TG and FFA (tAUC) were difficult to judge due to differences in fasting values. Conclusions: Bread made by replacing wheat flour with either 50% high-amylose or 75% hulless barley flour lowered postprandial glucose responses compared to 100% wheat bread indicating a beneficial impact on glucose regulation in T2D subjects.

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