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The stabilisation treatments of rice bran were performed using microwave heating (100% power, 1–2 min) and dry heating (120°C, 10–20 min), respectively, and then protein was prepared by alkaline extraction (pH 9.5) and acid precipitation (pH 4.5). Stabilisation treatments resulted in a decrease in the protein yield, but an increase in the pro­tein purity. Heat-stabilisation was effective in inhibiting the rancidity of rice bran, and microwave heating was more effective than dry heating. The functional properties of proteins such as the emulsifying properties and oil holding capacity were improved with the stabilised rice bran, while the foaming properties, water holding capacity and nitrogen solubility of protein were slightly impaired. By comparison, dry heating treatment at 120°C for 20 min was effective and suitable for the stabilisation of rice bran for long term storage, as well as improving some functional properties of rice bran proteins. These results could provide basic information for industrial preparation of rice bran protein and its application in various food formulas.

In this study, rice bran protein was prepared by ultrasound-assisted extraction, and its physicochemical and emulsifying properties were also evaluated. Results demonstrated that a significant increase in protein yield was observed when ultrasound-assisted method was employed for extracting protein. Noticeably, obtained rice bran protein possessed excellent physicochemical properties, such as oil absorption capacity, protein solubility and foaming property. More hydrophobic groups were exposed in the process of ultrasound-assisted extraction, which led to the increase of surface hydrophobicity. More importantly, the ultrasound-assisted extraction could improve emulsifying properties of rice bran protein, and the emulsions prepared using protein samples exhibited the great stability. Besides, it was also found that emulsifying properties of protein samples presented a decrease trend with increasing ultrasound power and time. All in all, ultrasound-assisted extraction is a suitable alternative process for preparing rice bran protein.

Yeast flocculation is an important property for the brewing industry as well as for ethanol fermentation to facilitate biomass recovery by sedimentation from the fermentation broth, which is cost-effective. In this study, a new flocculating gene FLO10  spsc of 4,221 bp homologous to FLO10 was identified in the industrial flocculating yeast SPSC01. Sequence analysis indicated that the N- and C-terminus of the deduced protein of this new FLO gene are 99 % identical to that of FLO10, but more intragenic repeats are included. The study on the function of FLO10  spsc by its integrative expression in the non-flocculating industrial yeast indicated severe inhibition in the flocculation of the transformant by mannose and maltose, moderate inhibition by sucrose and glucose and no inhibition by xylose and galactose, and thus the NewFlo type was established. Meanwhile, the flocculation of the transformant was stable when the temperature was below 50 °C and the pH was in the range of 4.0–6.0. Furthermore, the medium containing 250 g/l glucose was completely fermented within 48 h by the transformant, with about 110 g/l ethanol and 5.5 g(DCW)/l biomass produced, and no significant difference in ethanol fermentation performance was observed compared to its wide-type strain. Therefore, the FLO gene and corresponding transformation strategy provide a platform for engineering yeast strains with the flocculation phenotype to facilitate biomass recovery.

Ultrasonic, homogenization and microwave were used to assist alkali extraction of rice bran protein, respectively, and the characterizations of rice bran protein were also evaluated. The results of this study showed that the highest extraction yield of protein reached 57.89 % by using ultrasonic-assisted alkali method (U-AM), while only it was 43.74 % by microwave-assisted alkali method (M-AM). Both U-AM and homogenization-assisted alkali methods (H-AM) could effectively improve some properties of proteins such as oil absorption capacity, emulsion stability and foaming capacity, and the effects of ultrasonic were better than those of homogenization. However, protein solubility, water absorption capacity, emulsifying activity and foaming stability were subject to different degrees of impairments by using various physical technique-assisted alkali methods (AMs). Moreover, physical processing also has exhibited appreciable influence on sulfhydryl and disulfide bond contents. Taking all these factors into consideration, ultrasonic-assisted alkali method was a potential method for the extraction of rice bran protein.

The self-flocculation of yeast cells presents advantages for continuous ethanol fermentation such as their self-immobilization within fermenters for high density to improve ethanol productivity and cost-effective biomass recovery by gravity sedimentation. We sequenced and analyzed the genome of the self-flocculating Saccharomyces cerevisiae SPSC01 for the industrial production of fuel ethanol.