Comparative Investigation of Combined Metabolomics-Flavoromics during the Ripening of Mango (Mangifera indica L.) cv. 'Nam Dok Mai Si Thong' and 'Nam Dok Mai No. 4'.

A metabolomics-flavoromics approach was conducted to assess the micromolecules of 'Nam Dok Mai Si Thong' and 'Nam Dok Mai No. 4' mango cultivars from two seasons. During ripening, FAMEs, FFAs, fatty alcohols, sterols, and organic acids were dominant at 0-2 days, whereas amino acids, sugars, and volatile organic compounds, including esters, alcohols, ketones, aldehydes, and terpenes, were at higher levels at 4-8 days. Nine metabolites (palmitic/linoleic/linolenic/citric/malic acids, ß-sitosterol, sucrose, glycine, and leucine) and two volatile organic compounds (ethyl octanoate/decanoate) were related to ripening-associated changes within eight days. During ripening, sucrose at 6-8 days, citric/malic acid at 0-2 days, glycine and leucine at 4 days, and ethyl octanoate and ethyl decanoate at 8 days could be used as quality biomarkers for Nam Dok Mai Si Thong; palmitic/linoleic/linolenic acids at 0 days and ß-sitosterol at 0-4 days could be used as quality biomarkers for Nam Dok Mai No. 4.

Reducing chicken nugget oil content with fortified defatted rice bran in batter.

Defatted rice bran (DRB) is a by-product in the rice bran oil industry generated in large quantities. Unfortunately, DRB, is underutilized and often discarded despite containing valuable proteins, minerals, dietary fiber, and bioactive phytochemicals. This study examined the effects of four DRB substitution levels (0, 10, 15 and 20% of mixed flour in batter and pre-dust) on fried chicken nugget properties. Increasing DRB substitutions increased both batter viscosity and pickup (%) resulting in thicker nugget crusts. The 15 and 20% DRB substitutions significantly decreased both the crispness and lightness of battered fried chicken nuggets. Furthermore, oil content decreased significantly while moisture and fiber content increased in DRB batter-coated chicken nuggets compared to the control without DRB. In conclusion, 15% or less DRB substitution in batter reduces fried chicken nugget oil content while maintaining product quality and healthfulness.

Oligosaccharides Preparation from Rice Bran Arabinoxylan by Two Different Commercial Endoxylanase Enzymes.

Xylooligosaccharides (XOS) and arabinoxylooligosaccharides (AXOS), potential prebiotics, can be produced from rice bran arabinoxylan (RBAX) using commercial endoxylanase enzymes. However, differences in rice bran cultivars and endoxylanase enzyme types may affect extracted oligosaccharides (OS) yields. This study investigated extracted OS structures derived from three different RBAX using two commercial endoxylanase enzymes. RBAX extracted from commercially defatted rice bran (CDRB) yielded the greatest OS amount (456.69 mg/g RBAX), followed by that of the San-Pah-Tawng1 (SPT1) cultivar (231.7 mg/g RBAX), and lastly, the Chai-Nat1 (CN1) cultivar (172.57 mg/g RBAX), as evidenced via Ultraflo L enzyme hydrolysis. Ultraflo Max enzyme hydrolysis produced a similar trend, however, OS amounts from all RBAX sources were remarkably lower (83.39 mg/g RBAX extracted from CDRB, 27.05 mg/g RBAX from SPT1 cultivar, and 21.53 mg/g RBAX from CN1 cultivar). Interestingly, 32-α-L-Araf-(1-4)-ß-D-xylobiose (A3X) was the primary AXOS product in all RBAX hydrolysates prepared by Ultraflo Max. RBAX extracted from CDRB solubilized by Ultraflo L (45.67% weight of RBAX) had higher OS yields than that obtained via Ultraflo Max (8.3% weight of RBAX). Ultraflo L was therefore a suitable commercial enzyme for short-chain OS conversion from RBAX.

Physical Inaccessibility of a Resistant Starch Shifts Mouse Gut Microbiota to Butyrogenic Firmicutes.

SCOPE: Resistant starch (RS) is utilized by Gram-negative Bacteroidetes through a starch utilization system (Sus), which requires physical attachment of the bacteria to the substrate. Gram-positive Firmicutes, which include butyrate producers, utilize RS by other mechanisms, such as amylosomes and secreted amylases/glucoamylases. It has been previously shown that fabricated RS [alginate-based starch-entrapped microspheres (SM)] increases butyrate in in vitro human fecal fermentation and was slow fermenting. It has been hypothesized that in vivo SM would disfavor Bacteroidetes and promote Firmicutes, leading to an increase in butyrate production. METHODS AND RESULTS: A C57BL/6J mouse model is used to test type 2 RS (RS2, raw potato) and SM for SCFAs and fecal microbial community structure. Feeding SM for 2 weeks results in 2.4 times higher mol% butyrate in the mouse distal gut than RS2. SM reduces relative abundance of Bacteroidetes and increases Firmicutes in fecal samples at the end of the 2-week feeding. This phylum-level taxonomic shift is not observed in animals fed RS2. CONCLUSION: Through an approach to understand bacterial requirements related to starch utilization, a designed fiber type favors butyrogenic Firmicutes bacteria and provides higher mol% butyrate in the distal gut with potential benefit as an anti-inflammatory agent and to improve gut barrier function.

Elevated propionate and butyrate in fecal ferments of hydrolysates generated by oxalic acid treatment of corn bran arabinoxylan.

Previous work in our laboratory showed that alkali-solubilized corn arabinoxylan (CAX) has a slow initial, but later complete, in vitro human fecal fermentation. CAX and a moderately high molecular weight hydrolysate (CH) were propiogenic, and produced low levels of butyrate. Here, we show that oxalic acid-generated hydrolysates from CAX, which include a large xylooligosaccharide, and free arabinose fractions, increased short chain fatty acid (SCFA) production, which included relatively high levels of both propionate and butyrate, an unusual SCFA combination. Hydrolytic degradation of CAX by acid hydrolysis (0.05 M oxalic acid at 100 °C for 2 h) and subsequent graded ethanol precipitations were used to obtain mixtures with different molecular weight ranges. Ethanol-precipitated fractions (F 0-65%, F 65-75%, F 75-85%) were mostly lower than 100 kDa and F > 85% was composed of monosaccharides and oligosaccharides of DP 2-8. Oxalic acid treatment caused the removal of all single arabinose unit branch chains and some di/trisaccharide branch chains, producing lightly substituted xylan backbone fragments, most of which were in the oligosaccharide (DP < 10) size range. In vitro human fecal fermentation analyses showed all oxalic acid-hydrolysate fractions were slower fermenting than fructooligosaccharides (FOS), but produced similar or higher amounts of total SCFAs. Butyrate production in two hydrolyzate fractions was double that of CH, while propionate levels remained relatively high.

Small differences in amylopectin fine structure may explain large functional differences of starch.

Four amylose-free waxy rice starches were found to give rise to gels with clearly different morphology after storage for seven days at 4°C. The thermal and rheological properties of these gels were also different. This was remarkable in light of the subtle differences in the molecular structure of the amylopectin in the samples. Addition of iodine to the amylopectin samples suggested that not only external chains, but also the internal chains of amylopectin, could form helical inclusion complexes. It is suggested that these internal helical segments participate in the retrogradation of amylopectin, thereby stabilising the gels through double helical structures with external chains of adjacent molecules. Albeit few in number, such interactions appear to have important influences on starch functional properties.

Structural features of soluble cereal arabinoxylan fibers associated with a slow rate of in vitro fermentation by human fecal microbiota.

Most soluble dietary fibers ferment rapidly in the proximal colon, potentially causing discomfort and poor tolerability. Alkali-extracted arabinoxylan isolates from corn, wheat, rice and sorghum brans were prepared, through hydrolysis (except sorghum) and ethanol fractionation, to have a broad range of initial fermentation rates, and their linkage patterns were determined to understand structural aspects related to slow fermentation rate. They were all highly branched polymers with degree of substitution greater than 64%. There was no relationship of molecular mass, arabinose:xylose ratio, or degree of substitution to fermentation rate patterns. Slow fermenting wheat and corn arabinoxylans had much higher amount of terminal xylose in branches than fast fermenting rice and sorghum arabinoxylans. The slowest fermenting wheat arabinoxylan additionally contained a complex trisaccharide side chain with two arabinoses linked at the O-2 and O-3 positions of an arabinose that is O-2 linked to the xylan backbone. Structural features were proposed for tolerable slowly fermentable arabinoxylan with possible beneficial fermentation function into the distal colon.

Heat and pH stability of alkali-extractable corn arabinoxylan and its xylanase-hydrolyzate and their viscosity behavior.

UNLABELLED: In in vitro batch fermentations, both alkali-extractable corn arabinoxylan (CAX) and its xylanase-hydrolyzate (CH) were utilized by human fecal microbiota and produced similar short chain fatty acid (SCFA) contents and desirable long fermentation profiles with low initial gas production. Fortification of these arabinoxylans into processed foods would contribute desirable dietary fiber benefits to humans. Heat and pH stability, as well as viscosity behavior of CAX and CH were investigated. Size exclusion chromatography was used to analyze the molecular size distribution after treatment at different pH's and heating temperatures for different time periods. Treated under boiling and pressure cooking conditions at pH 3, CAX was degraded to a smaller molecular size, whereas the molecular size of the CH showed only a minor decrease. CAX and CH were mostly stable at neutral pH, except when CAX was treated under pressure for 60 min that slightly lowered molecular size. At 37 °C, neither CAX nor CH was adversely affected by treatment at low or neutral pH. The viscosities of solutions containing 5% and 10% of CAX were 48.7 and 637.0 mPa.s, respectively that were higher than those of solutions containing 5% and 10% of its hydrolyzate at shear rate 1 s⁻¹. The CAX solutions showed Newtonian flow behavior, whereas shear-thinning behavior was observed in CH solutions. In conclusion, the hydrolyzate of CAX has potential to be used in high fiber drinks due to its favorable fermentation properties, higher pH and heat stability, lower and shear-thinning viscosity, and lighter color than the native CAX. PRACTICAL APPLICATION: Arabinoxylan extracted by an alkali from corn bran is a soluble fiber with a desirable low initial and extended fermentation property. Corn arabinoxylan hydrolyzate using an endoxylanase was much more stable at different levels of acidity and heat than the native arabinoxylan, and showed lower solution viscosity and shear-thinning property that indicates its potential as an alternative functional dietary fiber for the beverage industry.

In vitro batch fecal fermentation comparison of gas and short-chain fatty acid production using "slowly fermentable" dietary fibers.

UNLABELLED: 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 ß-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 ß-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.