Glucose adsorption and α-amylase activity inhibition mechanism of insoluble dietary fiber: Comparison of structural and microrheological properties of three different modified coconut residue fibers

Agrocybe cylindracea Dietary Fiber Modification: Sodium Hydroxide Treatment Outperforms High-Temperature, Cellulase, and Lactobacillus Fermentation

Agrocybe cylindracea dietary fiber (ADF) contains 95% water-insoluble dietary fiber, resulting in poor application performance. To address this issue, ADF was modified by four methods (cellulase, sodium hydroxide, high-temperature, and Lactobacillus fermentation) in this paper. By comparing the physicochemical properties, microstructures, monosaccharide compositions, and functional characteristics (antioxidant and α-glucosidase inhibitory activities in vitro) of all modified ADF samples, the optimal modification method was selected. Results showed that sodium hydroxide treatment was deemed the most effective modification method for ADF, as alkali-treated ADF (ADF-A) revealed a higher oil-holding capacity (2.02 g/g), swelling capacity (8.38 mL/g), cholesterol adsorption (6.79 mg/g), and α-glucosidase inhibitory activity (more than 70% at 0.4-0.6 mg/mL) than the other modified samples. The looser microstructure in ADF-A might be attributed to molecular rearrangement and spatial structure disruption, which resulted in smaller molecular sizes and decreased viscosity, hence improving ADF's physicochemical and functional qualities. All these findings indicate the greater application potential of modified ADF products in food and weight-loss industries, providing a comprehensive reference for the industrial application of ADF.

Physicochemical properties and in vitro digestion behavior of emulsion micro-gels stabilized by κ-carrageenan and whey protein: Effects of sodium alginate addition

Emulsion micro-gels exhibit significant potential as functional ingredients for modifying food texture, replacing saturated fats, or serving as templates for the controlled release of bioactive compounds. Structural design principles are being applied more frequently to develop innovative emulsion micro-gels. In this paper, whey protein concentrate (WPC), κ-carrageenan and sodium alginate (SA) were utilized for preparing emulsion micro-gels. To reveal the regulation mechanism of the structural and physicochemical properties of emulsion micro-gels on lipid digestion, the influence of SA additions on the structural, physicochemical properties and in vitro digestion behavior of κ-carrageenan/WPC-based emulsion micro-gel were explored. The FTIR results suggest that the emulsion micro-gels are formed through non-covalent interactions. With the increase of SA addition (from 0.7 g/100 mL to 1.0 g/100 mL), the decreased mean droplet size, the increased hardness, elasticity indexes, and water holding capacity, the reduced the related peak times all indicated that the emulsion micro-gels exhibit enhanced rheological, stability, and mechanical properties. It can be concluded from the microstructure, particle size distribution of the emulsion micro-gels during simulated digestion and free fatty acid release that both κ-carrageenan/WPC-based emulsion micro-gel and κ-carrageenan/WPC/SA-based emulsion micro-gel can inhibit lipid digestion due to the ability to maintain structural stability and hindering the penetration of bile salts and lipase through the hydrogel networks. And the ability is regulated by the binding properties the gel matrix and oil droplets, which determine the structure and physicochemical properties of emulsion micro-gels. The research suggested that the structure of emulsion micro-gels can be modified to produce various lipid digestion profiles. It may be significant for certain practical application in the design of low-fat food and controlled release of bioactive agents.

Improvement of soluble dietary fiber quality in Tremella fuciformis stem by steam explosion technology: An evaluation of structure and function

Edible fungi by-products are rich in dietary fiber (DF). In this study, we used steam explosion (SE) to modify Tremella fuciformis (T. fuciformis) stem DF. The SE conditions were optimized using response surface methodology (RSM), and the soluble dietary fiber (SDF) extraction rate increased 1.42-fold (from 23.33 ± 0.42 % to 33.21 ± 0.28 %) under optimized conditions. SE destroyed the dense structure of SDF, which improved the specific surface area and thermal stability. Furthermore, the structural changes induced by SE resulted in improved functional properties, and SDF had better hydration properties (water holding capacity, oil holding capacity, and swelling capacity increased by 1.23, 1.59, and 1.24 times, respectively) and hypoglycemic capacity (glucose adsorption capacity increased 1.84-fold at 100 mmol/L glucose). Therefore, SE is an excellent modification method for improving quality of edible fungi processing by-products SDF.

Self-assembly of coconut residue fiber with chitosan: Effect of three pre-treatments on the self-assembly process and bile salt adsorption

Self-assembly with chitosan is a promising method for improving bile salt (BS) adsorption by coconut residue fiber (CRF). To study the self-assembly process, three pre-treatments were performed and investigated using microrheological analysis. The effects of the pretreatments on the self-assembly of CRF and the BS adsorption were evaluated. During self-assembly, CRFs underwent Brownian-like motion, and the addition of chitosan facilitated the formation of inter-particle interactions between CRFs in the system. These interactions were small in extent, large in number, and slow to state change, in addition to relatively high strength and longer maintenance, all of which contributed to the binding to BS. The conventional pretreatments failed to effectively improve the BS adsorption of the self-assembled CRFs and weakened the inter-particle interactions in the system. These results suggest that chitosan assists in the adsorption of self-assembled CRF to BS through a combination of H-bonds and other weak intermolecular forces.

Different influences of dietary fiber from various sources on the in vitro digestibility of casein as uncovered by the study of protein-dietary fiber interactions

How different dietary fibers including pectin, cellulose and lignin affect casein digestibility was studied using in vitro static protocols. Peptides' profile, free amino acids (AAs) content, casein-DF interactions and their influences on enzymatic activities of proteolytic enzymes were studied using combined techniques. Under gastric and intestinal digestive conditions, while pectin could reduce casein digestibility (with an averaged decrease of 12.15% and 7.83, respectively) through both depletion flocculation and hydrogen-binding interactions, lignin inhibited the digestion of casein straightly through reducing the enzymatic activity of proteolytic enzymes, thereby altering the production of free AAs. Although cellulose showed the least detrimental effects, it still significantly reduced the content of Thr, Glu, Val, Leu, Phe, Lys, and no Arg was released. Deeper insight into casein-DF interactions and their influences on casein digestibility improves the development of more effective forms of DF for improving AA homeostasis in individuals.

Lowering glycemic levels via gastrointestinal tract factors: the roles of dietary fiber, polyphenols, and their combination

Dietary fiber (DF) and polyphenols (DP) are typical blood sugar-lowering components, and both play distinct yet interconnected roles in exerting their blood sugar-lowering effects. We comprehensively summarized the single and combined effects of DF and DP on blood glucose homeostasis through regulating the relevant factors in the upper gastrointestinal tract (UGT) and lower gastrointestinal tract (LGT). In the UGT, DF slowed down glucose metabolism by enhancing digesta viscosity and hindering enzyme-substrate interaction. DP primarily targeted enzymes and substrates. When combined, DP enhanced the adsorption capacity of DF for glucose. DF weakened DP's inhibitory effect on enzymes. Both DF and DP disrupted glucose intestinal uptake via physical or genomic modulation, but the co-consumption of DF and DP demonstrated a lower inhibitory effect on glucose uptake than DP alone. In the LGT, DF and DP showed synergistic or antagonistic effects on gut microbiota. Remarkably, whole foods exhibited potent prebiotic effects due to their compound-rich matrix, potentially enhancing glucose homeostasis and expanding dietary options for glucose regulation research.