Effect of Heat-Moisture Treatment on the Structure and Digestibility of Sweet Potato Starch.

The objective of this study was to investigate the effect of temperature changes during heat-moisture treatment (HMT) on the appearance, structure and digestibility of sweet potato starch (SPS). The results showed that after HMT, there were depressions, cavities and fragments on the surface of SPS particles. The polarized crosses of SPS were irregular and partially blurred. The relative crystallinity and short-range order of SPS decreased, while rearrangement and reorientation of the starch molecules occurred and the thermal stability increased. The resistant starch content of SPS reached the highest (24.77%) after 4 h treatment at 110 °C and 25% moisture. The obtained results can provide a reference for the modification of SPS.

RS5 Produced More Butyric Acid through Regulating the Microbial Community of Human Gut Microbiota.

The objective of this research was to compare the in vitro fermentability of three resistant starches (RS2, RS3, and RS5). Structural analyses showed that there were small changes in the long- and short-range ordered structure of three RSs after fermentation by human gut microbiota. The fermentation of RSs by gut microbiota produced large amounts of short-chain fatty acids, with RS5 producing more butyric acid and RS3 producing more lactic acid. RS3 and RS5 decreased the pH of the fermentation culture to a greater extent compared with RS2. Moreover, RS5 increased significantly the relative abundance of Bifidobacterium, Dialister, Collinsella, Romboutsia, and Megamonas. The results suggested that the form of RS was the main factor affecting the physiological function of RS and that RS5, as a recently recognized form of resistant starch, could be a better functional ingredient to improve health compared with RS2 and RS3.

Correlation Analysis of Intestinal Redox State with the Gut Microbiota Reveals the Positive Intervention of Tea Polyphenols on Hyperlipidemia in High Fat Diet Fed Mice.

Tea polyphenols (TP) possess the ability to regulate dyslipidemia and gut microbiota dysbiosis. However, the underlying mechanism is still elusive. The present study explored the intervention of TP on high fat diet induced metabolic disorders, gut microbiota dysbiosis in mice, and the underlying intestinal mechanism. As a result, TP significantly ameliorated hyperlipidemia, improved the expression levels of hepatic lipid metabolism genes, and modulated gut microbiota. The underlying mechanism was supposed to rely on the maintaining of intestinal redox state by TP. Intestinal redox related indicators were significantly correlated with the distribution of gut microbiota. An unidentified genus of Lachnospiraceae, Bacteroides, Alistipes, and Faecalibaculum were identified as the biomarkers for intestinal redox state. Importantly, different dosages of TP modulated intestinal redox state and gut microbiota in varied patterns, and an overdose intake attenuated the beneficial effects on gut health. Our findings offered novel insights into the mechanism of TP on intestinal homeostasis.

Structural Changes of Starch-Lipid Complexes during Postprocessing and Their Effect on In Vitro Enzymatic Digestibility.

The effects of cooking and storage on the structure and in vitro enzymatic digestibility of complexes formed between fatty acids and debranched high-amylose starch (DHA7-FA) were investigated for the first time. Cooking greatly decreased the crystallinities of DHA7-lauric acid (LA) and DHA7-myristic acid (MA) complexes but had little effect on the crystallinities of DHA7-palmitic acid (PA) and DHA7-stearic acid (SA) complexes. Cooking increased the enthalpy-change (Δ H) values and short-range molecular orders of DHA7-FA complexes. Cooking decreased the in vitro enzymatic digestibility of DHA7-FA complexes, with the extent of the effect decreasing with increasing fatty acid chain length. Holding the samples at 4 °C for 24 h after cooking did not greatly affect the long- and short-range molecular orders nor the in vitro enzymatic digestibility of DHA7-FA complexes. From this study, we conclude that cooking disrupted the long-range crystalline structures of DHA7-LA and DHA7-MA complexes but enhanced the short-range molecular orders of all of the DHA7-FA complexes. The latter effect accounted mainly for the reduced in vitro enzymatic digestibility of DHA7-FA complexes.

[Condition optimization for degradation of chlorophenols using laccase from Amillariella mellea].

Crude laccase extracted from the Amillariella mellea fermentation broth was directly used to catalyze the degradation of 2,4-chlorophenol (2,4-DCP) and 2-chlorophenol (2-CP). The effects of reaction time, pH, temperature, chlorophenol concentration, and laccase dosage on the removal efficiency of chlorophenols were investigated. Optimal catalytic conditions for the degradation of chlorophenols were obtained and the degradation kinetics were analyzed. The results indicated that the crude laccase from Amillariella mellea was able to effectively degrade 2,4-DCP and 2-CP, with higher catalytic ability towards 2,4-DCP degradation. For 2,4-DCP degradation, the optimal temperature was 40 degrees C, the optimal substrate concentration was 75 mg x L(-1), the optimal enzyme dosage was 0. 1 U x mL(-1), and the optimal pH was 6.5. Under these conditions, the maximum degradation rate of 2,4-DCP reached > 97% after 10 h. For 2-DCP degradation, the optimal temperature was 50 degrees C, the optimal substrate concentration was 100 mg x L(-1), the optimal enzyme dosage was 0.1 U x mL(-1), and the optimal pH was 6. Under these conditions, the maximum degradation rate of 2-CP was over 93% after 10 h. The reaction process of laccase-catalyzed 2,4-DCP and 2-CP degradation obeyed the first-order kinetics equation. The laccase from Amillariella mellea was able to effectively degrade chlorophenols, indicating its potential application value in phenolic pollutant control and environmental protection.

[Optimization on decoloration conditions of anthraquinone dyes by laccase from Amillariella mellea].

Laccase extracted from the Amillariella mellea fermentation catalytic decolored on two common anthraquinone dyes: Reactive Brilliant Blue KN-R and Reactive Brilliant Blue X-BR which is broadly used in the printing and dyeing industry and obtained the optimal catalytic decolorizing conditions. The results showed that optimum temperature of Reactive Brilliant Blue KN-R decolorization was 30 degrees C, the optimum dye concentrations was 80 mg x L(-1), the optimum enzyme dosage was 0.25 U x mL(-1), and the optimum pH was 5. Under this optimal conditions, the maximum decolorization rate of Reactive Brilliant Blue KN-R was over 90%. The optimum temperature Reactive Brilliant Blue X-BR decolorization was 30 degrees C, the optimum dye concentrations was 50 mg x L(-1), the optimum enzyme dosage was 0.5 U x mL(-1), and the optimum was pH 4. Under the optimal conditions, the maximum decolorization rate of Reactive Brilliant Blue X-BR was over 70%. The decolorization on the two common industrial dyes by crude enzyme from Amillariella mellea fermentation obtained a good results. The results indicated that the decoloration on anthraquinone dyes by laccase from Amillariella mellea has a potential value in the printing and dyeing industry.