Rapid Integrated Total Dietary Fiber Assay Kit

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Rapid Integrated Total Dietary Fiber Assay Kit K-RINTDF Scheme
Reference code: K-RINTDF
SKU: 700004335

100 assays per kit

Content: 100 assays per kit
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/HPLC
Signal Response: Increase
Limit of Detection: 0.5 g/100 g
Total Assay Time: ~ 3 h work (over 1-2 days)
Application examples: Food ingredients, food products and other materials.
Method recognition: AACC Method 32-60.01, AOAC Method 2022.01, AOAC Method 2017.16, ICC Standard Method No. 185 and CODEX Method Type I

The Rapid Integrated Total Dietary Fiber Assay Kit method is validated under collaborative study (AACC Method 32-60.01, AOAC Method 2022.01, AOAC Method 2017.16, ICC Standard No. 185) and is recognized as a Type I Method by CODEX Alimentarius. The K-RINTDF method is the recommended one for the measurement of total dietary fiber in all foods that may or may not contain resistant starch. This method is updated to be more consistent with in vivo conditions in the human small intestine, i.e. a 4 h incubation time. Under these conditions more accurate measurement of resistant starch is obtained, including phosphate cross-liked starch (RS4). Use of higher enzyme concentrations ensures that resistant maltodextrins produced from non-resistant starch under the incubation conditions of the Integrated Total Dietary Fiber procedure (AOAC Methods 2009.01 and 2011.25) are no longer produced.

In this improved, rapid method, the incubation time with PAA + AMG is reduced to 4 h and the levels of both PAA and AMG are increased to ensure that resistant starch levels obtained with a set of control samples are consistent with ileostomy data. Under these conditions, the DF values obtained for most samples are the same as those obtained with AOAC Methods 2009.01 and 2011.25.

The dietary fiber fractions that are measured with this method are:

1. High Molecular Weight Dietary Fiber (HMWDF) including Insoluble Dietary Fiber (IDF) and High Molecular Weight Soluble Dietary Fiber (SDFP; soluble dietary fiber which is precipitated in the presence of 78% aqueous ethanol), and

2. Low Molecular Weight Soluble Dietary Fiber (SDFS; water soluble dietary fiber that is soluble in the presence of 78% aqueous ethanol).

Alternatively, IDF, SDFP and SDFS can be measured separately.

The enzymes used in this method are high purity and effectively devoid of contaminating enzymes active on other dietary fiber components such as β-glucan, pectin and arabinoxylan. They are supplied as freeze-dried powders; allowing the use of glycerol as an internal standard in the method.

See our full range of dietary fiber assay kits.

* See McCleary, B. V., Sloane, N & Draga, A. (2015). Determination of total dietary fibre and available carbohydrates: a rapid integrated procedure that simulates in vivo digestion. Starch/Starke, 66, 1-24.
Scheme-K-RINTDF RINTDF Megazyme
Validation of Methods
  • More rapid measurement - incubation time with PAA + AMG reduced to 4 h in comparison with AOAC 2009.01 (increased levels of enzyme employed) 
  • DF values for most samples are very similar to those obtained with AOAC Method 2009.01 
  • Rapid Integrated Total Dietary Fiber method removes all of the limitations that have been identified with AOAC Method 2009.01* 
  • All reagents stable for > 2 years after preparation 
  • The method is consistent with the CODEX Alimentarius definition of dietary fiber 
  • Mega-Calc™ software tool is available from our website for hassle-free raw data processing 
  • Very competitive price (cost per test)
Certificate of Analysis
Safety Data Sheet
FAQs Assay Protocol Data Calculator
Megazyme publication

Measurement of available carbohydrates, digestible, and resistant starch in food ingredients and products.

McCleary, B. V., McLoughlin, C., Charmier, L. M. J. & McGeough, P. (2019). Cereal Chemistry, 97(1), 114-137.

Background and objectives: The importance of selectively measuring available and unavailable carbohydrates in the human diet has been recognized for over 100 years. The levels of available carbohydrates in diets can be directly linked to major diseases of the Western world, namely Type II diabetes and obesity. Methodology for measurement of total carbohydrates by difference was introduced in the 1880s, and this forms the basis of carbohydrate determination in the United States. In the United Kingdom, a method to directly measure available carbohydrates was introduced in the 1920s to assist diabetic patients with food selection. The aim of the current work was to develop simple, specific, and reliable methods for available carbohydrates and digestible starch (and resistant starch). The major component of available carbohydrates in most foods is digestible starch. Findings: Simple methods for the measurement of rapidly digested starch, slowly digested starch, total digestible starch, resistant starch, and available carbohydrates have been developed, and the digestibility of phosphate cross‐linked starch has been studied in detail. The resistant starch procedure developed is an update of current procedures and incorporates incubation conditions with pancreatic α‐amylase (PAA) and amyloglucosidase (AMG) that parallel those used AOAC Method 2017.16 for total dietary fiber. Available carbohydrates are measured as glucose, fructose, and galactose, following complete and selective hydrolysis of digestible starch, maltodextrins, maltose, sucrose, and lactose to glucose, fructose, and galactose. Sucrose is hydrolyzed with a specific sucrase enzyme that has no action on fructo‐oligosaccharides (FOS). Conclusions: The currently described “available carbohydrates” method together with the total dietary fiber method (AOAC Method 2017.16) allows the measurement of all carbohydrates in food products, including digestible starch. Significance and novelty: This paper describes a simple and specific method for measurement of available carbohydrates in cereal, food, and feed products. This is the first method that provides the correct measurement of digestible starch and sucrose in the presence of FOS. Such methodology is essential for accurate labeling of food products, allowing consumers to make informed decisions in food selection.

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Megazyme publication

Definition and Analysis of Dietary Fiber in Grain Products.

McCleary, B. V., Cox, J, Ivory, R. & Delaney, E. (2019). “Cereal Grain-based Functional Foods", (Trust Beta and Mary Ellen Camire), CPI Group (UK) Ltd, pp. 103-126.

This chapter discusses the evolution of the definition of dietary fiber and the methodology to service this definition. Cereals are an important source of fiber in the human diet and therefore accurate analyses of the compounds that make up this dietary component are needed. The need to quantify the amount of carbohydrate that affects blood glucose levels led to methods to measure “available” carbohydrates and the recognition of the presence of “unavailable” carbohydrates, although no physiological role was assigned for this latter material. The term dietary fiber was introduced in 1953 and a physiological definition was introduced in 1976. A concerted effort was made to develop a method to service this definition through research. The outcome was the Prosky method (AOAC Method 985.29), which was accepted in 1985 as the gold standard method for the measurement of dietary fiber. As our understanding of the physiological importance of dietary fiber has advanced, it was realized that carbohydrates other than those measured by AOAC Method 985.29, namely resistant starch and non-digestible oligosaccharides, should also be included in the definition and measured and a new definition for dietary fiber was released by Codex Alimentarius. This definition includes resistant starch and the option to include non-digestible oligosaccharides. An integrated total dietary fiber (INTDF) method was developed in 2007 (AOAC Methods 2009.01 and 2011.25) and in 2015 was updated as a rapid integrated total dietary fiber method.

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Megazyme publication

Evolution of a Definition for Dietary Fiber and Methodology to Service this Definition.

McCleary, B. V. & Cox, J. (2017). Luminacoids Research, 21(2), 9-21.

The definition of dietary fiber has been evolving over the past 70 years. The changing definitions reflect our better understanding of the types and physiological functions of dietary fiber. Initial definitions focused on “the remnants of the plant cell walls which are not hydrolyzed by the digestive enzymes of man” and appropriate analytical methods were developed and implemented. More recently, the role of resistant starch and non-digestible oligosaccharides (NDO) as dietary fiber components has been recognized. Incorporation of these has required the development of a host of other methodologies to measure specific dietary fiber components such as fructo-oligosaccharides, galacto-oligosaccharides, resistant maltodextrins, resistant starch and others. Having these specific methods is useful for product manufacturers, but not necessarily for regulators because some of the specific component may also be partially measured by the “gold standard” fiber method, the Prosky method (AOAC Method 985.29). It is thus not possible to simply sum the various specific components with the value obtained with AOAC Method 985.29, as this will lead to “double counting” and thus overestimation of fiber content. To resolve this problem, and allow measurement of all dietary fiber components, an integrated method for measurement of total dietary fiber (AOAC Method 2009.01/AACCI method 32-45.01) was developed and adopted. Evaluation of this method over the past 8 years identified some aspects of the method that could be improved. Modifications have been made and incorporated into a Rapid Integrated Total Dietary Fiber (RINTDF) method, and this method has been subjected to interlaboratory evaluation under the auspices of ICC International and AACC International.

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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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Effect of extrusion processing parameters on structure, texture and dietary fibre composition of directly expanded wholegrain oat-based matrices.

Nikinmaa, M., Zehnder-Wyss, O., Nyström, L. & Sozer, N. (2023). LWT, 114972.

Oat flour mixed with 30 g/100 g rice flour was extruded with a twin-screw extruder using a central composite orthogonal design. Temperatures (120°C,140°C, 160°C) and moisture (14.5 g/100 g, 17.7 g/100 g, 20.6 g/100 g) were adjusted during extrusion, while screw speed was kept constant (400 rpm). Extrudates were analysed for structure (expansion, density, microstructure), texture (hardness), β-glucan (molecular weight and extractability), as well as fibre content. Expansion varied between 250 and 329%, density between 165 and 457 kg/m3 and hardness between 27 and 64 N. The response surface model showed that more expanded, less dense and less hard extrudates were achieved at low moisture, while high temperature resulted in lower density and hardness. Significant differences in β-glucan extractability were observed depending on extrusion conditions, with values ranging between 0.64 and 1.31 g/100 g. β-glucan extractability correlated with positively with porosity, and negatively with moisture content during extrusion, cell wall thickness and density. The results indicate that conditions that produce a more porous, crispier structure, also increases β-glucan extractability.

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Associating Compositional, Nutritional and Techno-Functional Characteristics of Faba Bean (Vicia faba L.) Protein Isolates and Their Production Side-Streams with Potential Food Applications.

Krause, M., Sørensen, J. C., Petersen, I. L., Duque-Estrada, P., Cappello, C., Tlais, A. Z. A., Di Cagno, R., Ispiryan, L., Sahin, A. W., Arendt, E. K. & Zannini, E. (2023). Foods, 12(5), 919.

Faba beans (Vicia faba L.) show exciting prospects as a sustainable source of protein and fibre, with the potential to transition to a more sustainable food production. This study reveals the compositional, nutritional and techno-functional characteristics of two protein isolates from faba beans (Vicia faba L.), a high-starch fraction and a high-fibre side-stream. During the analysis of those four ingredients, particular attention was paid to the isolates’ protein profile and the side-streams’ carbohydrate composition. The isoelectric precipitated protein isolate 1 showed a protein content of 72.64 ± 0.31% DM. It exhibited low solubility but superior digestibility and high foam stability. High foaming capacity and low protein digestibility were observed for protein isolate 2, with a protein content of 71.37 ± 0.93% DM. This fraction was highly soluble and consisted primarily of low molecular weight proteins. The high-starch fraction contained 83.87 ± 3.07% DM starch, of which about 66% was resistant starch. Over 65% of the high-fibre fraction was insoluble dietary fibre. The findings of this study provide a detailed understanding of different production fractions of faba beans, which is of great value for future product development.

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Dietary Fibers-Classification, Properties, Analysis and Function: A Review.

Ibrahim, O. & Menkovska, M. (2022). Advances in Bioscience and Biotechnology, 13(12), 527-544.

Dietary Fiber (DF) is a plant bioactive compound, mainly a mixture of complex organic soluble and non-soluble polysaccharides that is non-digestible and less hydrophobic. This dietary fiber is one of nutritional supplements that demonstrated to have impact on human and animal health. Chemical structures, sources, classification, methods of analysis and therapeutic functions of DF are under investigation by researchers for diseases prevention and enhancing immune response. Dietary Fiber (DF) is diverse organic chemicals with higher molecular weight (HMW) over 10 DP and lower molecular weight of lower under 10 DP and can be classified generally by their solubility, viscosity, and fermentability. Dietary fiber is non-digestible by enteric enzymes and passes through small intestine into the colon intake where is fermented by enteric microbial biomass into beneficial metabolites and short chains fatty acids. Other health benefits from the acceptable daily intake such as adsorption of bile salts, polyphenols, and minerals. In addition to, influence gastrointestinal tract physiology where it has high water holding capacity and viscosity resulted in feeling satiety, alternate digestive enzymes activity, improved gastric emptying, and increase healthy microbial biomass in the colon.

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Extrusion processing modifications of a dog kibble at large scale alter levels of starch available to animal enzymatic digestion.

Corsato Alvarenga, I., Keller, L. C., Waldy, C. & Aldrich, C. G. (2021). Foods, 10(11), 2526.

The objective of the present work was to produce dog foods from a single recipe at three levels of resistant starch (RS). The low (LS), medium (MS), and high shear (HS) foods were produced on a single-screw extruder at target screw speeds of 250, 375 and 460 rpm, respectively, and with increasing in-barrel moisture as shear decreased. Post-production, kibble measurements and starch analyses were conducted. Kibble parameters were compared by ANOVA with significance noted at p < 0.05 with a single degree of freedom orthogonal contrasts for extrusion outputs, starch analyses, and viscosity (RVA). The MS and LS kibbles exiting the extruder were denser and less expanded (p < 0.05) than the HS treatment. Resistant starch, starch cook, and raw:cooked starch RVA AUC increased linearly as shear decreased. These results confirmed that lower mechanical energy processes led to decreased starch gelatinization and greater retention of in vitro RS.

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Application of heat moisture treatment in wheat pasta production.

Iuga, M. & Mironeasa, S. (2021). Food Control, 128, 108176.

Heat moisture treatment (HMT) is an accessible starch and flour physical modification that could enhance the physico-chemical characteristics of products. In this study, the influence of HMT conditions (temperature, time, moisture) on wheat flour, dough and pasta properties were investigated trough Response Surface Methodology (RSM) and an advanced characterization of the optimal sample was performed. The optimal treatment conditions were 85.30°C for 1 h at 26.80% moisture. Higher resistant starch and fibers content and dough complex modulus values were obtained for the optimal sample compared to the control. HMT determined a decrease of pasta chewiness, while cooking loss and dough cohesiveness were kept within acceptable limits. Starch and protein secondary structures were changed after HMT, confirming molecules reorganizations and proteins denaturation of wheat flour during treatment. After HMT, pores and chains were observed on some starch grains. The obtained results underlined the suitability of HMT for wheat pasta production.

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Effect of soybean processing on cell wall porosity and protein digestibility.

Zahir, M., Fogliano, V. & Capuano, E. (2020). Food & Function, 11(1), 285-296.

Apart from the presence of antinutritional factors, digestibility of soybean proteins is limited in intact cells by cell wall permeability to proteolitic enzymes. Food processing may modulate cell wall permeability and hence the accessibility of protease enzymes to intracellular proteins. In this study, soybeans were processed in various ways, e.g. cooking applied alone or with either germination or fermentation processes, and the modification in cell wall permeability was investigated using confocal microscopy to visualize the penetration of FITC-dextran probes into isolated cells/cell clusters. Diffusion of fluorescently labelled trypsin into cells and cell clusters was also monitored. Microscopy observations showed that fermentation and germination as well as proteolitic enzymes increase the permeability of boiled soybean cotyledon cells. The diffusion of trypsin into all the isolated cells was observed at an early stage of simulated in vitro digestion, whereas diffusion into cell clusters was delayed due to a bigger size and limited permeability of cell clusters. A modest, although significant, increase in protein digestibility was observed when boiling was combined with fermentation or germination likely due to pre-digestion of storage proteins and inactivation of trypsin inhibitors. This study highlights the positive role of fermentation and germination in improving protein digestibility in soybeans but overall suggests that cell wall permeability to trypsin plays a minor role in the extent of protein digestion of intact soybean cells.

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Effect of drying and extrusion processing on physical and nutritional characteristics of bilberry press cake extrudates.

Höglund, E., Eliasson, L., Oliveira, G., Almli, V. L., Sozer, N. & Alminger, M. (2018).

LWT, In Press.Mild drying and extrusion processing of side streams from berry juice production can enable retention of valuable compounds in the food chain and reduce waste production. The aim of this study was to evaluate the applicability of using hot air (HA) and microwave assisted hot air (MWHA) drying combined with extrusion for conversion of bilberry press cake into value-added extruded food products. Bilberry press cake was dried at 40°C by HA and MWHA drying to a moisture content of 17 g/100 g. A twin screw extruder (average feed rate 72 g/min, temperature profile 135-128-89-69°C) was used to extrude products containing organic wholegrain rye flour and 10% or 25% dried bilberry press cake powder. A consumer panel (n = 15) evaluated four extrudates on hedonic and Just-About-Right (JAR) scales, with a main focus on texture properties. The results indicate that different drying techniques implied a difference in processing time (40% reduction with MWHA drying). However, the retention of total phenolics and physical characteristics of extruded snacks containing bilberry powders were independent of drying techniques. In sum, powder of bilberry press cake can be incorporated in cereal based extruded snacks with enhanced phenolic content and potential for palatable sensory properties.

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Safety Information
Symbol : GHS05, GHS08
Signal Word : Danger
Hazard Statements : H318, H334
Precautionary Statements : P261, P280, P284, P304+P340, P305+P351+P338, P310, P342+P311, P501
Safety Data Sheet
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