Abstract As the demand for probiotic foods continues to increase and lactose intolerance is common, it is necessary to develop a range of non-milk probiotic beverages. The purpose of this study was to evaluate the preparation process of fermented probiotic beverages using various vegetables as raw materials, and to evaluate the chemical and organoleptic properties of the mixed fermented vegetable juices. The mixed fermented vegetable juice was a beverage obtained by mixing the vegetable juice (purple cabbage, tomato and carrot) fermented by Lactobacillus plantarum and the yam juice fermented by the yeast in an appropriate ratio. During lactobacillus fermentation (48 hours at 30 °C), the cell count of Lactobacillus plantarum increased from 7.49 ± 0.21 log CFU/mL to 9.13 ± 0.19 log CFU/mL (p < 0.05), the glucose decreased from 8.924 g/L to 5.528 g/L, and the pH decreased from 5.03 to 3.62. Oxidation activity slightly decreased. The lactic acid and titratable acid/total acid content increased, and the trend of change was similar. During the yeast fermentation (28 °C, 24h), the glucose was almost depleted and ethanol was accumulated. GC-MS analysis showed that microbial fermentation had a significant effect on volatile components. The sensory evaluation results showed that the proper mixing of fermented vegetable juice and fermented yam juice had a significant increase in taste, odor and overall acceptance of the product. The mixed fermented vegetable juice has the potential to adapt to the consumer groups and has in-depth research value.

Background: The effect of diverse oxygen transfer coefficient on the L-erythrulose production from meso-erythritol by a newly isolated strain, Gluconobacter kondonii CGMCC8391 was investigated. In order to elucidate the effects of volumetric mass transfer coefficient (K La) on the fermentations, baffled and unbaffled flask cultures, and fed-batch cultures were developed in present work. Results: With the increase of the K La value in the fed-batch culture, L-erythrulose concentration, productivity and yield were significantly improved, while cell growth was not the best in the high K La. Thus, a two-stage oxygen supply control strategy was proposed, aimed at achieving high concentration and high productivity of L-erythrulose. During the first 12 h, Klawas controlled at 40.28 h-1 to obtain high value for cell growth, subsequently K La was controlled at 86.31 h-1 to allow for high L-erythrulose accumulation. Conclusions: Under optimal conditions, the L-erythrulose concentration, productivity, yield and DCW reached 207.9 ± 7.78 g/L, 6.50 g/L/h, 0.94 g/g, 2.68 ± 0.17 g/L, respectively. At the end of fermentation, the L-erythrulose concentration and productivity were higher than those in the previous similar reports.

Abstract The principal objective of this study was to evaluate the kinetics of dihydroxyacetone production by Gluconobacter frateurii CGMCC 5397 under different oxygen volumetric mass transfer coefficient (kLa) conditions in submerged bioreactors using biodiesel-derived crude glycerol as the carbon source. kLa is a key fermentation parameter for the production of dihydroxyacetone. Cultivations were conducted in baffled- and unbaffled-flask cultures (the kLa values were 24.32 h−1 and 52.05 h−1, respectively) and fed-batch cultures (the kLa values were held at 18.21 h−1, 46.03 h−1, and 82.14 h−1) to achieve high dihydroxyacetone concentration and productivity. The results showed that a high kLa could dramatically increase dihydroxyacetone concentrations and productivities. The baffled-flask culture (with a kLa of 52.05 h−1) favored glycerol utilization and dihydroxyacetone production, and a dihydroxyacetone concentration as high as 131.16 g/L was achieved. When the kLa was set to 82.14 h−1 in the fed-batch culture, the dihydroxyacetone concentration, productivity and yield were 175.44 g/L, 7.96 g/L/h and 0.89 g/g, respectively, all of which were significantly higher than those in previous studies and will benefit dihydroxyacetone industrial production.