|Content:||100 assays / 200 assays|
|Storage Temperature:|| Short term stability: 2-8oC, |
Long term stability: See individual component labels
|Stability:||> 2 years under recommended storage conditions|
|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.
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.
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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.Hide Abstract
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.Hide Abstract
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.Hide Abstract
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.Hide Abstract
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.Hide Abstract
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.Hide Abstract
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.Hide Abstract
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.Hide Abstract
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.Hide Abstract
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.Hide Abstract
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).Hide Abstract
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.Hide Abstract
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.Hide Abstract
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.Hide Abstract
Ultrasound-assisted cellulase pretreatment and cooking with enzymatic hydrolysates enhance the freeze-thaw stability of brown rice.
Lu, S., Mu, Y., Xu, M., Wen, Y., Li, H., Wang, J. & Sun, B. (2022). LWT, 114390.
Brown rice (BR) is rich in nutrients and becoming a good source for convenience rice development. However, the bran layer of BR and freeze-thawing in food supply chains affects the rice texture and limits the palatability. This study aims to apply the preprocessing method of ultrasound-assisted cellulase (UAC) that has been demonstrated to improve the textural attributes of BR, and further make use of the enzymatic hydrolysates for rice cooking, to stabilize the texture against freeze-thawing. BR with cellulase pretreatment and addition of the enzymatic hydrolysates during cooking exhibited stable hardness and stickiness over five freeze-thaw cycles as compared to the rice cooked with water or the diluted hydrolysates. As observed by scanning electron microscopy and low-field nuclear magnetic resonance, BR cooked with the hydrolysates displayed more homogenous microstructure and the reduced water mobility against freeze-thawing, revealing that sugar and proteins in the hydrolysates contributed to promote the water holding capacity of cooked rice. Moreover, BR cooked with the hydrolysates exhibit noted advantages in fiber (0.23 g/kg) and proteins (0.19 g/kg) content. The combination of UAC pretreatment and cooking with the enzymatic hydrolysates provides a promising processing method for convenience brown rice with improved freeze-thaw stability and nutritional quality.Hide Abstract
Composition of Polysaccharides in Hull-Less Barley Sourdough Bread and Their Impact on Physical Properties of Bread.
Reidzane, S., Gramatina, I., Galoburda, R., Komasilovs, V., Zacepins, A., Bljahhina, A., Kince T., Traksmaa, A. & Klava, D. (2022). Foods, 12(1), 155.
The complex of polysaccharides of the grain transforms during processing and modifies the physical and chemical characteristics of bread. The aim of the research was to characterize the changes of glucans, mannans and fructans in hull-less barley and wholegrain wheat breads fermented with spontaneous hull-less barley sourdough, germinated hull-less barley sourdough and yeast, as well as to analyze the impact of polysaccharides on the physical parameters of bread. By using the barley sourdoughs for wholegrain wheat bread dough fermentation, the specific volume and porosity was reduced; the hardness was not significantly increased, but the content of β-glucans was doubled. Principal component analysis indicates a higher content of β-glucans and a lower content of starch, total glucans, fructans and mannans for hull-less barley breads, but wholegrain wheat breads fermented with sourdoughs have a higher amount of starch, total glucans, fructans and mannans, and a lower content of β-glucans. The composition of polysaccharides was affected by the type of flour and fermentation method used.Hide Abstract
Upcycling Rocha do Oeste Pear Pomace as a Sustainable Food Ingredient: Composition, Rheological Behavior and Microstructure Alone and Combined with Yeast Protein Extract.
Fernandes, A., Simões, S., Ferreira, I. M., Alegria, M. J., Mateus, N., Raymundo, A. & de Freitas, V. (2022). Molecules, 28(1), 179.
This work explores the potential of Rocha do Oeste pear pomace to be used as a sustainable and healthy food ingredient. Moreover, the enrichment with yeast protein extract (YPE) may be useful to design innovative food products. The main goals of this study were to assess pear pomace concerning: (i) chemical composition and antioxidant capacity; (ii) rheology, texture, and microstructure characterization (alone or enriched with YPE), before and after heating. The results showed that pear pomace was a rich source of dietary fibers (74.5% DW), with phenolic compounds (3.9 mg chlorogenic acid equivalents/g dry weight), also presenting antiradical activity (3.90 μmol Trolox equivalents/g DW). Pear pomace showed a shear thinning behavior and a typical soft-gel behavior, which was not affected by YPE enrichment, thus suggesting that YPE did not affect pear pomace technological properties. Thermal treatment also did not alter pear pomace rheological properties. YPE addition induced a decrease in the apparent viscosity and a destabilizing effect, compared to the samples that were subjected to thermal processing. These results highlight the importance of pear pomace and the use of YPE for protein enrichment, opening new opportunities for their exploitation.Hide Abstract
Effect of High-Pressure and Thermal Pasteurization on Microbial and Physico-Chemical Properties of Opuntia ficus-indica Juices.
Ferreira, R. M., Amaral, R. A., Silva, A., Cardoso, S. M. & Saraiva, J. A. (2022). Beverages, 8(4), 84.
Opuntia fruits are recognized for their richness in nutrients and in bioactive compounds, being also highly appreciated by consumers as a juice. Nevertheless, without further processing, prickly pear juices have a short shelf-life, hampering their commercial use. In this work, thermal (TP) and high-pressure (HPP) pasteurization were applied to juices from Opuntia ficus-indica cultivars ‘Rossa’, ‘Gialla’, and ‘Bianca’ to understand the impact of those methods on the microbial safety, physico-chemical properties, and the nutritional content of the samples, over storage at 4°C. In general, thermal pasteurization at 71.1°C for 30 s increased the shelf-life by 22 days, and high-pressure pasteurization at 500 MPa for 10 min increased the shelf-life by 52 days with regard to microbial growth as well as maintenance of physical-chemical characteristics. The application of these two pasteurization methods delayed changes in the physico-chemical characteristics of the juices, with a more pronounced effect on the titratable acidity, °Brix and browning. For the same periods of time, the application of pasteurization methods decreased the variation in these quality parameters by around 75%. Similarly, these methods were shown to have the same effect on the polyphenolic concentration as well as the antioxidant activity of the juices. In particular, HPP was more efficient in preventing a decrease in °Brix and increase in titratable acidity, which normally negatively affect the flavor of the juices.Hide Abstract
Popped rice with distinct nutraceutical properties.
Itagi, H., Sartagoda, K. J. D., Pratap, V., Roy, P., Tiozon, R. N., Regina, A. & Sreenivasulu, N. (2023). LWT, 173, 114346.
Iron-pan roasting is a common processing technique used in India to produce value-added popped rice. For the first time, traditional landrace genotypes black rice (Chak-hao), red (CRVR 68), Kalanamak, and a high-yielding variety Samba Mahsuri (SM) were extensively examined for the effects of the popping process on their physical and biochemical properties. SM had the highest volume increase and popping percentage, both of which are consumer-preferred attributes for popped products. The Fe content was significantly increased by popping in all genotypes. The Mg content of de-husked Red and Chak-hao did not substantially differ from that of its popped forms. Total starch decreased in popped red and Chak-hao, owing to amylose/amylopectin leaching from the grains. Popped landrace accessions retained most bioactives (~70%, oryzanol, 14-28% total phenolic content, 48-65% total flavonoid content, and 38% total anthocyanin content) and antioxidant potency, especially in pigmented rice. Interestingly, the popped rice retained total dietary fibre across all genotypes. This work demonstrated that pigmented rice landraces can be transformed into nutraceutically-rich and wholesome, ready-to-eat popped rice product that is consumed as a primary product or as an ingredient to novel functional foods that could optimize human health.Hide Abstract
Use of response surface methodology to investigate the effect of sodium chloride substitution with Salicornia ramosissima powder in common wheat dough and bread.
Toumi, O., Conte, P., da Silva, A. M. G. M., Barroca, M. J. & Fadda, C. (2022). Journal of Functional Foods, 99, 105349.
Sodium chloride is known to influence several technological and sensory characteristics of bread. The high dietary daily intake of sodium, however, raises concern because of serious health implications. In this study, response surface methodology was used to optimize the extent of sodium chloride reduction (0.6-1.2-1.8%) and its replacement with Salicornia ramosissima powder (0-50-100%) to achieve the best low-sodium wheat bread, while meeting dough quality standards. Mixing, viscoelastic, extensional, and fermentation properties of doughs, as well as specific volume, textural, and color features of breads were evaluated as response variables. After applying optimization criteria via desirability function, results evidenced that using 1.8% salt with a substitution ratio of 65.24% is the best combination to obtain both doughs with longer development times, high stability, better viscoelastic properties and similar fermentation capacity, and breads with higher specific volumes, softer and less chewy crumbs, but higher green tones, than those containing only sodium chloride.Hide Abstract