Wheat Protein Hydrolysates Improving the Stability of Purple Sweet Potato Anthocyanins under Neutral pH after Commercial Sterilization at 121 °C.

Anthocyanins are prone to degradation and color fading after sterilization. This work examined the potential of wheat protein hydrolysates (WPHs, 40 g/L) in improving the stability of purple sweet potato anthocyanins (PSPAs) under a pH of 6.8 after sterilization at 121 °C followed by storage. Results showed that WPHs increased the thermal degradation half-life of PSPAs 1.65 times after sterilization. Compared to PSPAs alone, after being stored at 37 °C and 45 °C for 7 days, the retention concentration of PSPAs with WPHs was 5.4 and 32.2 times higher, and the color change of PSPAs with WPHs decreased from 6.19 and 10.46 to 0.29 and 0.77, respectively. AFM data, fluorescence and UV spectrograms indicated the formation of complexes between PSPAs and WPHs by hydrophobic attraction confirmed by zeta-potential data. PSPAs with WPHs had stable particle size and zeta potential, which may also significantly increase the concentrations after digestion and antioxidant power of PSPAs. This work indicated that the assembled PSPAs composite structure by WPHs significantly reduced the degradation of PSPAs at a pH of 6.8 after sterilization at 121 °C followed by long-term storage.

The effects of wheat cultivar, flour particle size and bran content on the rheology and microstructure of dough and the texture of whole wheat breads and noodles.

The rheological properties and microstructure of doughs, and the texture properties of whole wheat breads and noodles were investigated. The gluten strength of doughs were discriminated due to wheat cultivar. Reduced flour particle size led to the doughs with a stronger gluten strength (i.e., smaller C2), lower degree of starch retrogradation (i.e., smaller C5), and longer relaxation time (i.e., larger n values). Firmer crumb of breads were prepared by flours with smaller particle size. With increased bran content, the gluten strength of dough weakened (i.e., increased C2), the development and relaxation time of dough and the degree of starch retrogradation decreased (i.e., decreased C1 time, n values and C5), the dough structure became more porous, and the product texture appeared to be firmer. As such, outcomes from this research will provide a practical guidance for the bakery industry to improve the consumer acceptability of whole wheat products.

Low concentrations of Al(III) accelerate the formation of biofilm: Multiple effects of hormesis and flocculation.

Residual Al(III) (at low concentration) is common in water treatment plants (WTPs) and is associated with bacteria. We hypothesize that Al(III) accelerate biofouling due to its hydrolysis and hormesis characteristics, as compared with other cations. To verify this, we elaborated the roles of Al(III) at low concentrations on the biofilm formation. Al(III) hormesis (<2.0mg/L) stimulated bacteria growth increased by ~3.7 times, and extracellular polymeric substances production also enhanced. Al(III) flocculation resulted in the suspended cells precipitation instantly, for Al(III) dosages of 0.6 and 2.0mg/L and the concentration of Al(III) decreased by 0.07 and 0.14mg/L, respectively. Al(III) poisoned the bridged bacterial cells and decreased their ATP by 22.36% and 55.91%, respectively. Al(III) formed polymer presented strong affinity with bacterial outer membrane, and this damaged the bacterial outer membrane. This caused proteins to leak at the combined point. Al-polymer bound to NH2 and/or NH on the leaked protein, contributed to biofilm formation. Biofilm maturity was aided by polysaccharides, which shielded Al(III) toxicity for the formed biofilm. Thus, the biofilm exhibited a distinguished double-layer microstructure, principally with proteins and inactivated cells at the bottom, polysaccharides and activated cells at the top. Thus, hormesis and flocculation caused by low concentration Al(III) mutually promoted each other, and together accelerated biofilm formation.