Oxidative stress leads to various diseases, including diabetes, cardiovascular diseases, neurodegenerative diseases, and even cancer. The dietary flavonol glycoside, hyperoside (quercetin-3-O-galactoside), exerts health benefits by preventing oxidative damage. To further understand its antioxidative defence mechanisms, we systemically investigated the regulation of hyperoside on oxidative damage induced by hydrogen peroxide, carbon tetrachloride, and cadmium in Saccharomyces cerevisiae. Hyperoside significantly increased cell viability, decreased lipid peroxidation, and lowered intracellular reactive oxygen species (ROS) levels in the wild-type strain (WT) and mutants gtt1∆ and gtt2∆. However, the strain with ctt1∆ showed variable cell viability and intracellular ROS-scavenging ability in response to the hyperoside treatment upon the stimulation of H2O2 and CCl4. In addition, hyperoside did not confer viability tolerance or intercellular ROS in CdSO4-induced stress to strains of sod1∆ and gsh1∆. The results suggest that the antioxidative reactions of hyperoside in S. cerevisiae depend on the intercellular ROS detoxification system.

Increasing glycerol production in low-temperature wine fermentation is of concern for winemakers to improve the quality of wines. The objective of this study was to investigate the effect of 10 different Saccharomyces cerevisiae on the kinetics of production of glycerol, ethanol and the activities of glycerol-3phosphate dehydrogenase (GPD) and alcohol dehydrogenase (ADH) in low-temperature fermentation. Ethanol production was influenced by temperature, and it was slightly higher at 13°C than at 25°C. Glycerol yields were significantly affected by both temperature and strains. More glycerol was produced at 25°C than at 13°C because the activity of GPD was higher at 25°C than at 13°C. Glycerol production of the different yeast strains was up to 3.19 and 3.18 g L À1 at 25 and 13°C, respectively. Therefore, isolating the yeast strains with high glycerol production and adaptation to low-temperature fermentation is still the best method in winemaking.Yeast strains affect glycerol production Y.-T. Gao et al.Significant difference in glycerol production with same yeast strain at different temperatures P < 0.001. *** Significant difference in ethanol production with same yeast strain at different temperatures P < 0.05.

In this paper, ultrasonic cellulase extraction (UCE) was applied to extract polyphenols from passion fruit. The extraction conditions for total phenol content (TPC) and antioxidant activity were optimized using response surface methodology (RSM) coupled with a Box-Behnken design (BBD). The results showed that the liquid-to-solid ratio (X2) was the most significant single factor and had a positive effect on all responses. The ANOVA analysis indicated quadratic models fitted well as TPC with R2 = 0.903, DPPH scavenging activity with R2 = 0.979, and ABTS scavenging activity with R2 = 0.981. The optimal extraction parameters of passion fruit were as follows: pH value of 5 at 30 °C for extraction temperature, 50:1 (w/v) liquid-to-solid ratio with extraction time for 47 min, the experimental values were found matched with those predicted. Infrared spectroscopy suggested that the extract contained the structure of polyphenols. Furthermore, three main polyphenols were identified and quantified by HPLC. The results showed the content of phenolic compounds and antioxidant activity of the optimized UCE were 1.5~2 times higher than that determined by the single extraction method and the Soxhlet extraction method, which indicates UCE is a competitive and effective extraction technique for natural passion fruit polyphenols.

This is the first study on the effect of carbonic maceration on the quality (color, aroma profile and sensory properties) of Muscat Hamburg, contrasting two winemaking procedures used in Tianjin (classical white and red-winemaking techniques). The values of C* (psychometric chroma), a* (measure of redness) and b* (measure of yellowness) were significantly higher (p < 0.01) in the carbonic macerated wine than in red wine. However, there were no visual differences in color, and classical red wine and carbonic macerated wine had similar h (hue angle) values and located in the red region. Thirty-two aromatic compounds were identified and quantified in Muscat Hamburg wines. The content of volatile compounds (6384.97 μg/L) was significantly higher (p < 0.001) in the carbonic macerated Muscat Hamburg wine than in the other kinds of wine. This result led to the carbonic macerated wine having the highest odor activity values (OAVs) and sensory evaluation scores (86.8 points), which correlates with an “excellent” sensory perception. This study demonstrated that carbonic maceration significantly improved the quality of Muscat Hamburg wine based on volatile analysis and sensory evaluation compared with other conventional methods. Therefore, carbonic maceration could be well suited for making Muscat Hamburg wine.