3-Methylthio-1-propanol (3-Met) is widely used as a flavoring substance and an essential aroma ingredient in many foods. Producing 3-Met by microbial transformation is green and eco-friendly. In the present study, one strain, YHM-G, which produced a high level of 3-Met, was isolated from the Baijiu-producing environment. Strain YHM-G was identified as Hyphopichia burtonii according to its morphological properties, physiological and biochemical characteristics, and ribosomal large subunit 26S rRNA gene D1/D2 domain sequence analysis. The optimal conditions for 3-Met production by YHM-G were obtained by single factor design, Plackett–Burman design, steepest ascent path design and response surface methodology as follows: 42.7 g/L glucose, pH 6, 0.9 g/L yeast extract, 6 g/L L-methionine (L-Met), culture temperature 28 °C, shaking speed 210 rpm, loading volume 50 mL/250 mL, inoculum size 0.5% (v/v), culturing period 48 h and 2.5 g/L Tween-80. Under these optimal conditions, the 3-Met production by strain YHM-G was 3.16 g/L, a value 88.1% higher than that before optimization. Strain YHM-G can also produce a variety of flavor compounds that are important for many foods. This strain thus has the potential to increase the abundance of 3-Met in some fermented foods and enhance their aroma profiles.

Polysaccharides extracted from Agrocybe aegerita (AAPS) have various physiological effects. In this study, we used the naturally aging Drosophila melanogaster and D-galactose-induced aging mice as animal models to study the anti-aging effects of AAPS via the alleviation of oxidative stress and regulation of gut microbiota. Results showed that AAPS could significantly prolong lifespan and alleviate oxidative stress induced by H2O2 of Drosophila melanogaster. In addition, AAPS significantly increased the activities of antioxidant enzymes in Drosophila melanogaster and mice, and reduced the content of MDA. Furthermore, AAPS reshaped the disordered intestinal flora, increased the abundance ratio of Firmicutes to Bacteroidetes, and increased the abundance of beneficial bacteria Lactobacillus. Our results demonstrated that AAPS had good antioxidant and potential anti-aging effects in vivo.

The production of xylooligosaccharides (XOS) from Jiuzao was studied using a two-stage process based on autohydrolysis pretreatment followed by enzymatic hydrolysis. Jiuzao was autohydrolyzed under conditions where temperature, time, particle size, and solid-liquid ratio were varied experimentally. Optimal XOS production was obtained from Jiuzao with a >20 mesh particle size treated at 181.5 °C for 20 min with a 1:13.6 solid-liquid ratio. Subsequently, optimal enzymatic hydrolysis conditions for xylanase XynAR were identified as 60 °C, pH 5, and xylanase XynAR loading of 15 U/mL. Using these conditions, a yield of 34.2% XOS was obtained from Jiuzao within 2 h. The process developed in the present study could enable effective and ecofriendly industrial production of XOS from Jiuzao.

Saccharomyces cerevisiae is indispensable in the production of Baijiu. This yeast not only produces ethanol, but also produces many flavorsubstances that impart unique quality characteristics to Baijiu. Ethyl caproate (EC) is the main flavor substance of strong-flavor Baijiu(SFB). S. cerevisiae that can produce a high yield of EC is critical for SFB production. In the present study, S. cerevisiae isolate YF1914produced an EC content of 1.27 mg/L, which was greater than that produced by other test isolates obtained from several Baijiu brewingenvironments. Through single factor experiments, the influence of various factors on EC production by YF1914 was measured. Eightvariables were tested using a Plackett-Burman design, and ethanol content, induction time, caproic acid content, initial pH, and temperaturesignificantly affected EC production. Further studies were done using the steepest ascent path and response surface methodology (RSM)designs to identify optimized fermentation conditions for EC production. The optimum conditions were found to be: sorghum hydrolysatemedium (SHM) with a sugar content of 12 Brix and an initial pH of 5.0, inoculum size 5% (v/v), incubation at 28 °C with shaking at180 rpm for 32 h, addition of 10% (v/v) ethanol and 0.046% (v/v) caproic acid at 32 h, then static culture at 24 °C for 32 h. Theoptimized conditions produced an EC content of 21.98 mg/L or 17.3 times greater than the content obtained using initial conditions. Thus,a selected S. cerevisiae isolate with high EC yield was obtained, which can potentially improve SFB quality by increasing EC content.Keywords: ethyl caproate; optimization; Saccharomyces cerevisiae; strong-flavor Baijiu

Corn cobs were fermented with Aspergillus niger to produce the high-quality soluble dietary fiber (SDF) with excellent food safety. In this work, the fermentation process was optimized by single-factor test and response surface methodology (RSM) to determine the fermentation conditions (material-liquid ratio 1:30, inoculum concentration 11%, temperature 32 ℃, time 6 d, shaking speed 200 r/min), the SDF yield of corn cob increased from 2.34–11.92% and SDF/TDF reached 19.08%, achieving the requirements of high-quality dietary fiber (SDF/TDF was more than 10%). SEM and FTIR analysis revealed that the fermentation effectively degraded part of cellulose and hemicellulose, resulting in the formation of a loose and porous structure. After fermentation the water swelling capacity, water-holding capacity, and oil-holding capacity of the corn cob SDF were obviously improved and the adsorption capacity of glucose, cholesterol, and nitrite ions all increased by more than 20%. Moreover, the total phenolic content increased by 20.96%, which correlated with the higher antioxidant activity of SDF. Overall, the fermentation of corn cobs by Aspergillus niger improved the yield and functional properties of its DF.