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ABSTRACT: The propensity for xylanase to convert insoluble to soluble arabinoxylan is an important parameter in many applications. Current
methods for determining xylanase activity on insoluble substrates are nonspecific or utilize artificial substrates which may
provide much different results from native substrates. Therefore, a new method for the determination of xylanase activity
on insoluble substrates was developed. This method involved incubation of the enzyme with a material containing insoluble
arabinoxylan. Arabinoxylan released by the enzyme was quantified as total pentose sugars colorimetrically by reaction with
phloroglucinol upon heating in acetic–hydrochloric acid. Absorbance was determined at 552nm, and interfering hexoses were
accounted for by subtracting the absorbance at 510nm. Because the method measured total pentose sugars released by the enzyme,
(arabino)xylanase activity, rather than xylanase activity, was recommended for expressing results. The method was tested using
two xylanases and six insoluble arabinoxylan-containing substrates. Sodium acetate and sodium citrate buffers (50mM) were
suitable for the reaction; sodium phosphate buffer substantially interfered with quantification of reaction products by reducing
color development. The enzymic release of soluble arabinoxylan was linear for at least 5min under all reaction conditions
tested. Contaminating amylase and cellulase activity did not influence the results, despite the presence of starch and cellulose
in many substrate sources. Relative standard deviations were <5% between reactions assayed on different days. Activity on
substrates from different botanical origin differed by up to 100-fold, emphasizing the need for the use of application-specific
substrates to obtain accurate estimations of enzyme activity.
KeywordsBread–Enzyme–Pentosan–Wheat–Arabinoxylan
Food Analytical Methods 05/2012; 4(1):66-72. · 1.94 Impact Factor
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ABSTRACT: The purpose of this research was to develop a simple method for measuring lipase activity as an indicator of wheat and wheat
bran storage quality. This simplified method does not require the separation or purification of lipase. Optimal conditions
for lipase activity measurements were determined by varying the substrate (olive oil) and water concentrations, temperature,
and incubation time. Following incubation, FFA were quantified spectrophtometrically using a copper soap assay, and lipase
activity was expressed as units/gram (U/g), where 1 U was defined as the microequivalents of oleic acid liberated per hour.
The method was tested on one commercial and four pure wheat cultivars. The lipase activity was also correlated with the development
of FFA during actual storage of heat-treated commercial bran. Lipase activity in wheat bran ranged from 2.17 to 9.42 U/g,
and in whole kernel wheat from 1.05 to 3.54 U/g. Optimal olive oil and water concentrations were 0.4 to 0.8 mL and 0.15 to
0.20 mL per g of defatted sample, respectively. Optimal incubation temperature was 40°C, and incubation times of up to 8 h
were linear. Lipase activity was highly correlated with the buildup of FFA in stored wheat bran (R
2=0.97).
Journal of Oil & Fat Industries 04/2012; 83(5):415-419. · 1.77 Impact Factor
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ABSTRACT: Sustained colonic fermentation supplies beneficial fermentative by-products to the distal colon, which is particularly prone to intestinal ailments. Blunted/delayed initial fermentation may also lead to less bloating. Previously, we reported that starch-entrapped alginate-based microspheres act as a slowly fermenting dietary fiber. This material was used in the present study to provide a benchmark to compare to other "slowly fermentable" fibers. Dietary fibers with previous reports of slow fermentation, namely, long-chain inulin, psyllium, alkali-soluble corn bran arabinoxylan, and long-chain β-glucan, as well as starch-entrapped microspheres were subjected to in vitro upper gastrointestinal digestion and human fecal fermentation and measured over 48 h for pH, gas, and short-chain fatty acids (SCFA). The resistant fraction of cooked and cooled potato starch was used as another form of fermentable starch and fructooligosaccharides (FOS) served as a fast fermenting control. Corn bran arabinoxylan and long-chain β-glucan initially appeared slower fermenting with comparatively low gas and SCFA production, but later fermented rapidly with little remaining in the final half of the fermentation period. Long-chain inulin and psyllium had slow and moderate, but incomplete, fermentation. The resistant fraction of cooked and cooled potato starch fermented rapidly and appeared similar to FOS. In conclusion, compared to the benchmark slowly fermentable starch-entrapped microspheres, a number of the purported slowly fermentable fibers fermented fairly rapidly overall and, of this group, only the starch-entrapped microspheres appreciably fermented in the second half of the fermentation period. PRACTICAL APPLICATION: Consumption of dietary fibers, particularly commercial prebiotics, leads to uncomfortable feelings of bloating and flatulence due to their rapid degradation in our large intestine. This article employs claimed potential slowly fermenting fibers and compares their fermentation rates with a benchmark slow fermenting fiber that we fabricated in an in vitro simulation of the human digestive system. Results show a variety of fermentation profiles only some of which have slow and extended rate of fermentation.
Journal of Food Science 06/2011; 76(5):H137-42. · 1.66 Impact Factor
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03/2011: pages 185 - 221; , ISBN: 9780470958186
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ABSTRACT: Two-stage hydrothermal processing was employed to obtain feruloylated arabinoxylooligosaccharides (AXOS) from wheat bran. First, wheat bran in water (10% w/w solids) was heated to 130 degrees C, releasing 36.3% of total solids, 70.3% of starch, and 6.06% of pentose sugars. Wheat bran was then heated to 170-220 degrees C. Heating to 200 and 210 degrees C released the most AXOS (70% of the insoluble arabinoxylan) and esterified ferulate (30% of the initial ferulic acid). Treatment of 200 degrees C retained a higher proportion of high molecular weight (>1,338) compounds than 210 degrees C and was the preferred treatment temperature because autohydrolysate liquors contained lower concentrations of many contaminants. Purification of this autohydrolysate liquor with ethyl acetate extraction, vacuum concentration, and ion exchange resulted in a product containing 32.0% AXOS and 4.77% esterified ferulate, accompanied by 36.0% other oligosaccharides and free sugars, with an antioxidant activity of 29.7 micromol Trolox equivalents/g dry matter.
Journal of Agricultural and Food Chemistry 05/2010; 58(10):6427-32. · 2.82 Impact Factor
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ABSTRACT: The milling of corn for the production of food constituents results in a number of low-value co-products. Two of the major co-products produced by this operation are corn bran and corn fiber, which currently have low commercial value. This review focuses on current and prospective research surrounding the utilization of corn fiber and corn bran in the production of potentially higher-value food components. Corn bran and corn fiber contain potentially useful components that may be harvested through physical, chemical or enzymatic means for the production of food ingredients or additives, including corn fiber oil, corn fiber gum, cellulosic fiber gels, xylo-oligosaccharides and ferulic acid. Components of corn bran and corn fiber may also be converted to food chemicals such as vanillin and xylitol. Commercialization of processes for the isolation or production of food products from corn bran or corn fiber has been met with numerous technical challenges, therefore further research that improves the production of these components from corn bran or corn fiber is needed.
Journal of the Science of Food and Agriculture 04/2010; 90(6):915-24. · 1.44 Impact Factor
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ABSTRACT: The purpose of this research was to test the hypothesis that starch-entrapped microspheres would produce favourable fermentation profiles and microbial shifts during in vitro fermentation with the faecal microbiota from patients with inflammatory bowel disease (IBD). In vitro fermentation was carried out using a validated, dynamic, computer-controlled model of the human colon (Toegepast Natuurwetenschappelijk Onderzoek gastro-intestinal model-2) after inoculation with pooled faeces from healthy individuals, patients with inactive IBD (Crohn's disease (CD)) or patients with active IBD (ulcerative colitis (UC)). Starch-entrapped microspheres fermented more slowly and produced more butyrate than fructo-oligosaccharides (FOS) when fermented with the faecal microbiota from patients with active UC. When fermented with the microbiota from patients with inactive CD, starch-entrapped microspheres also fermented more slowly but produced similar amounts of butyrate compared with FOS. Starch-entrapped microspheres showed a greater ability to maintain a low pH during simulated-distal colon conditions compared with FOS. After fermentation with the microbiota from inactive CD patients, starch-entrapped microspheres resulted in lower concentrations of some potentially harmful gut bacteria, included in Bacteroides, Enterococcus, Fusobacterium and Veillonella, compared with FOS. These findings suggest that slow fermenting starch-entrapped microspheres may induce a favourable colonic environment in patients with IBD through high butyrate production, maintenance of low pH in the distal colon and inhibition of the growth of potentially harmful bacteria.
The British journal of nutrition 12/2009; 103(10):1514-24. · 3.45 Impact Factor
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ABSTRACT: Human fecal fermentation profiles of maize, rice, and wheat bran and their dietary fiber fractions released by alkaline-hydrogen peroxide treatment (principally arabinoxylan) were obtained with the aim of identifying and characterizing fractions associated with high production of short chain fatty acids and a linear fermentation profile for possible application as a slowly fermentable dietary fiber. The alkali-soluble fraction from maize bran resulted in the highest short chain fatty acid production among all samples tested, and was linear over the 24 h fermentation period. Size-exclusion chromatography and (1)H NMR suggested that higher molecular weight and uniquely substituted arabinose side chains may contribute to these properties. Monosaccharide disappearance data suggest that maize and rice bran arabinoxylans are fermented by a debranching mechanism, while wheat bran arabinoxylans likely contain large unsubstituted xylose regions that are fermented preferentially, followed by poor fermentation of the remaining, highly branched oligosaccharides.
Journal of Agricultural and Food Chemistry 12/2009; 58(1):493-9. · 2.82 Impact Factor
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ABSTRACT: Previous research has revealed that waxy corn starch which has been entrapped in a matrix of electrostatically cross-linked alginate, shows a slow digestion rate such that much of the starch may reach the colon; thus making this a new type of resistant starch. The purpose of this research was to test the fermentative properties of starch-entrapped microspheres using a batch fecal fermentation method. Fermentation of starch-entrapped microspheres showed significantly lower rates of gas production compared to waxy corn starch, and showed significant increases in total SCFAs during the latter stages of fermentation (24-48 h), whereas waxy corn starch did not. Cooking the starch-entrapped microspheres increased the amount of SCFAs and the molar fraction of butyrate produced during fermentation. Bacterial fingerprinting revealed that uncooked starch-entrapped microspheres have a unique effect on the microbiota that is different from waxy corn starch alone, but cooking causes a shift toward a pattern more closely resembling that of the starch. Starch-entrapped microspheres may deliver slowly fermentable carbohydrate to the colon, with the ability to influence the microbiota. Further human studies are required to determine whether these characteristics occur in vivo.
Molecular Nutrition & Food Research 11/2008; 53 Suppl 1:S121-30. · 4.30 Impact Factor
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ABSTRACT: The benefits of dietary fiber on inflammatory bowel disease may be related to the fermentative production of butyrate in the colon, which appears to decrease the inflammatory response. The benefits of dietary fiber against colon cancer may be related to both fermentative and non-fermentative processes, although poorly fermentable fibers appear more influential. Dietary fiber fermentation profiles are important in determining optimal fibers for colonic health, and may be a function of structure, processing conditions, and other food components. A greater understanding of the relationships between fermentation rate and dietary fiber structure would allow for development of dietary fibers for optimum colonic health.
Nutrition Reviews 03/2007; 65(2):51-62. · 4.47 Impact Factor
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ABSTRACT: The benefits of dietary fiber on inflammatory bowel disease may be related to the fermentative production of butyrate in the colon, which appears to decrease the inflammatory response. The benefits of dietary fiber against colon cancer may be related to both fermentative and non-fermentative processes, although poorly fermentable fibers appear more influential. Dietary fiber fermentation profiles are important in determining optimal fibers for colonic health, and may be a function of structure, processing conditions, and other food components. A greater understanding of the relationships between fermentation rate and dietary fiber structure would allow for development of dietary fibers for optimum colonic health.
Nutrition Reviews 01/2007; 65(2):51 - 62. · 4.47 Impact Factor
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ABSTRACT: Maize bran was treated with microwave irradiation (160–200 °C for 2–20 min) to release feruloylated arabinoxylo-oligosaccharides (AXOS). Lower temperatures and shorter treatment times were consistent with low AXOS yields, while higher temperatures and longer reaction times also resulted in low yields, which were contaminated with increasing levels of monosaccharides, free ferulic acid, and furfural. Maximum release of AXOS, accompanied by low production of monosaccharides, free ferulic acid, and furfural, occurred with treatment at 180 °C for 10 min or 200 °C for 2 min. Under these conditions, about 50% of the initial arabinoxylan content could be released as AXOS, containing a wide variety of molecular weights. AXOS were highly feruloylated, containing 6.62 and 8.00 g of esterified ferulate/100 g of AXOS. These feruloylated AXOS may provide health benefits, including prebiotic effects and prevention of detrimental oxidation reactions. The evaluation of these benefits will be the subject of future research.
Food Chemistry.
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ABSTRACT: The purpose of this study was to extract phenolic compounds and antioxidant activity from buckwheat with water, 50% aqueous ethanol, or 100% ethanol using microwave irradiation or a water bath for 15min at various temperatures (23-150°C). Phenolic content of extracts increased with increasing temperature. In general, phenolic contents in microwave irradiated extracts were higher than those heated with a water bath. The highest phenolic content, 18.5±0.2mg/g buckwheat, was observed in the extract that was microwave irradiated in 50% aqueous ethanol at 150°C. The highest antioxidant activities, 5.61±0.04-5.73±0.00μmol Trolox equivalents/g buckwheat, were found in the 100% ethanol extracts obtained at 100 and 150°C, independent of heat source. These results indicate that microwave irradiation can be used to obtain buckwheat extracts with higher phenolic content and similar antioxidant activity as extracts heated in a water bath.
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Devin J Rose
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ABSTRACT: Dietary fiber refers to a broad class of nutrients that have differing physiological effects; the ideal dietary fiber is likely to: (1) have a low, steady rate of gas production to minimize bloating; (2) produce high levels of short chain fatty acids to prevent the growth of pathogenic bacteria and reduce inflammation; (3) ferment slowly to deliver beneficial fermentation products to all regions of the colon and prevent the production of putrefactive metabolites (e.g., ammonia, phenol); and (4) promote the maintenance of a healthy colonic microbiota by selectively stimulating the growth of beneficial bacteria or preventing the growth of undesirable bacteria. We have undertaken 3 research projects to identify such dietary fibers. First, the fermentation profiles of various dietary fiber fractions from corn, rice, and wheat bran were determined using an in vitro method. An alkali-soluble fraction from corn bran, consisting mainly of arabinoxylans, fermented slowly and produced the highest level of short chain fatty acids. Monosaccharide disappearance data suggested that corn and rice bran arabinoxylans ferment by a debranching mechanism, while wheat bran arabinoxylans contain large unsubstituted xylose regions that are utilized by bacteria first, before fermenting the more difficult to digest highly branched regions. In the second study, starch-entrapped microspheres, composites of starch and alginate, showed potential as a novel source of dietary fiber with slow fermentation characteristics, high butyrate production, and the ability to change the microbiota pattern during in vitro fermentation. The final study compared the fermentation profiles of fecal microbiota obtained from people with inflammatory bowel disease to that of healthy individuals after exposure to starch-entrapped microspheres, waxy corn starch, or fructooligosaccharides. Starch-entrapped microspheres produced more total short chain fatty acids and were more butyrogenic than fructooligosaccharides. Starch-entrapped microspheres were also superior to fructooligosaccharides with respect to preventing the growth of putative undesirable bacteria in inflammatory bowel disease.
ETD Collection for Purdue University.
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ABSTRACT: The purpose of this study was to determine the efficacy of extracting phenolic compounds with antioxidant activity from distillers' dried grains with solubles (DDGS) with water, 50% aqueous ethanol, and absolute ethanol, using microwave irradiation or a water bath at various temperatures. DDGS was extracted for 15 min with each solvent while heating at 23, 50, 100, and 150°C by microwave irradiation or in a water bath at 23, 50, and 100°C. Phenolic content of extracts increased with increasing temperature to a maximum of 12.02 mg/g in DDGS extracts that were microwave irradiated in water or with 50% aqueous ethanol at 150°C. Antioxidant activity range was 1.49–6.53 μmol of Trolox equivalents/g of DDGS. Highest antioxidant activities were obtained from 50% aqueous ethanol extracts at all temperatures, and water extracts that were heated at 100 and 150°C. These data indicate that DDGS extracts with high phenolic content and antioxidant activity can be obtained from DDGS, particularly with the use of water or 50% ethanol and high temperature (100 or 150°C). This may be valuable to ethanol manufacturers, livestock producers, and food and nutraceutical companies.
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ABSTRACT: Samples of hard red wheat packaged for long-term storage, ranging in age from 0 to 32 y, were obtained from donors in residential households. All samples had been stored under nonabusive conditions (7% to 10% moisture, 13 to 27 °C). Selected quality parameters of the wheat (moisture, thiamin, free fatty acids, flour extraction rate, bread loaf volume, and bread firmness) and sensory properties of bread made from the stored wheat (aroma, appearance, texture, flavor, overall liking, acceptance for use as part of the regular diet, and acceptance for use in emergency situations) were evaluated. Free fatty acids increased significantly from 0.897 to 11.8 μmol/g, and flour extraction rate decreased significantly from 76.5% to 69.9% over time. None of the other quality parameters measured (moisture, thiamin, bread loaf volume, and bread firmness) were significantly correlated with wheat storage time. Panelists who frequently or occasionally consume whole wheat bread rated all breads made from the stored wheat with hedonic scores (9-point scale) of at least 6.4 (like slightly to moderately). Consumer ratings of bread texture, flavor, and overall acceptability were negatively correlated with storage time (P < 0.001); however, at least 70% of panelists indicated that they would consume the bread as part of their regular diet even after 32 y of wheat storage, while over 97% would do so in an emergency. These data indicate that wheat maintains nutritional quality and makes acceptable bread when stored up to 32 y at 13 to 27 °C and 7% to 10% moisture. Practical Application: Wheat stored for the purposes of disaster relief has the potential of being stored for extremely long periods of time, which may result in undesirable changes in milling and baking quality. Therefore, we tested wheat that had been stored under residential conditions for up to 32 y to determine its functional quality and consumer acceptability. Our results indicate that wheat of low moisture (7% to 10%) packaged in sealed cans and stored for up to 32 y at or below typical room temperature retains quality and can be made into bread that is well accepted by consumers. Thus, whole wheat has good long-term storage stability and can be recommended for emergency food supplies.
Journal of Food Science 76(1):S8-S13. · 1.66 Impact Factor
