Effects of rice bran rancidity on the release of phenolics and antioxidative properties of rice bran dietary fiber in vitro gastrointestinal digestion products

Machine learning-enhanced modeling and characterization for optimizing dietary Fiber production from Highland barley bran

This study investigated the modification of highland barley bran through co-fermentation of Lactobacillus bulgaricus and Kluyveromyces marxianus, and developed a dynamic prediction model for DF content under these co-fermentation conditions using machine learning algorithms. The results showed that the XGBoost algorithm could predict changes in the DF component content (R2 = 0.9553(SDF/IDF), RMSE = 0.0464.) and identify optimal fermentation conditions. Under these optimal conditions, both strains exhibited synergistic effects, where the lactic acid produced by Lactobacillus bulgaricus and β-glucosidase produced by Kluyveromyces marxianus may facilitate IDF decomposition and conversion, resulting in a maximum SDF/IDF ratio of 0.6911. This led to a 27.65 % reduction in IDF content and a 19.11 % increase in SDF content. Moreover, the physicochemical and functional properties of DF were enhanced after co-fermentation. The structure of DF became looser and more porous, its thermal stability improved, and its water-holding, oil-holding, and swelling capacities increased by 53.54 %, 16.11 %, and 44.96 %, respectively, compared with the unfermented counterpart; in terms of adsorption characteristics, its glucose, cholesterol and nitrite adsorption capacities were also significantly improved. According to in vitro gastrointestinal simulated digestion, digestion would have a great impact on the fermented DF, which showed good antioxidant properties during the intestinal digestion stage.

The synergistic effects of rice bran rancidity and dephenolization on digestive properties of rice bran protein

Both rice bran (RB) rancidity and dephenolization could affect the structural characteristics and phenolics composition of rice bran protein (RBP), thereby affecting RBP digestibility. The synergistic effects of RB rancidity and dephenolization on RBP digestibility were investigated. Excessive RB rancidity (RB stored for 10 d) and non-dephenolization reduced RBP digestibility, while moderate RB rancidity (RB stored for 1 d) combined with dephenolization improved RBP digestibility to a maximum of 74.19%. Dephenolization reduced the antioxidant capacities of RBP digestive products. The digestibility of non-dephenolized RBP (NDRBP) was significantly (P < 0.05) related with its carbonyl content, surface hydrophobicity, and ζ-potential. The digestibility of dephenolized RBP (DRBP) was significantly related with its β-sheet structure content, surface hydrophobicity, ζ-potential, and average particle size. Overall, moderate RB rancidity combined with dephenolization enhanced RBP digestibility by reducing the non-competitive inhibition of endogenous phenolics on protease and regulating the spatial structural characteristics of RBP.

Impact of particle size on the functionality of corn-derived dietary fiber-phenolic acid complexes

Milling and sieving were applied to modify corn-derived cell wall dietary fiber-phenolic acid complexes (CWDFPC) to enhance their functionality and gut fermentability. The physicochemical properties of three modified CWDFPCs (CWDFPC-M1, CWDFPC-M2, and CWDFPC-M3) were characterized, showing changes in particle size (430-73.55 μm) and bulk density (0.29-0.57 g/mL). Sieving altered the composition, with CWDFPC-M1 and CWDFPC-M3 exhibiting higher bound phenolic contents than CWDFPC-M2. Increased water holding capacity indicated improved functionalities. Modified CWDFPCs exhibited a 4-fold increase in glucose adsorption capacity, higher phenolic acid release during gastrointestinal digestion in vitro, and a greater proportion of short-chain fatty acids in fecal fermentation in vitro. Hemicellulose from CWDFPC-M3 was primarily composed of →4)-β-Xylp-(1→ and →3)-β-Xylp-(1→, and →3,4)-β-Xylp-(1→, with branches possibly including →5)-α-Araf-(1→ and →3)-α-Araf-(1→ units. These modifications highlight the potential of milling and sieving to convert CWDFPCs into valuable functional food ingredients.