No abstract

The aim of this study was to assess the potential impact of 10 exogenous strains on acid production of maize resistant starch (RS) and xylo‐oligosaccharides (XOS) during in vitro fermentation and on anti‐colon cancer activities of fermentation products. Maize RS and XOS were fermented in vitro by the fecal extract from healthy adults in the absence and presence of one exogenous strain culture. Fermentation products were measured for their acetate, propionate, butyrate, and lactate contents, and growth inhibition on human colon carcinoma (HCT‐116) cells. These strains in general conferred fermentation products with increased acetate, propionate, and butyrate contents, enhanced lactate conversion, and different growth inhibition on HCT‐116 cells. Correlation analysis results demonstrated that butyrate and lactate contents of fermentation products made respective positive and negative contribution to the measured growth inhibition (p < 0.05); however, acetate and propionate contents made an insignificant contribution to the measured growth inhibition (p > 0.05). These results were mostly consistent with those from confirmation trials using standard acid solutions for the cells. It is highlighted that these strains had beneficial intervention in colonic fermentation of maize RS and XOS and anti‐cancer activities of fermentation products, rendering lower lactate and higher butyrate contents and especially higher anti‐colon cancer activities.

Inulin was fermented by adult faecal microbiota and 10 exogenous strains for 24 or 48 h. The contents of acetate, propionate, butyrate and lactate were quantified in the fermented products, and the growth-inhibitory and apoptosis-inducing effects on a human colon cell line (HCT-116 cells) were assessed. Most of these strains increased contents of acetate, propionate and butyrate, and promoted lactate conversion. Correlation analysis suggested that butyrate and lactate in the fermentation products were positively and negatively correlated with the measured inhibition ratios (p < .05). The results were mostly consistent with the verification trial results using standard acid solutions. The fermentation products could cause apoptosis via inducing DNA fragmentation and increasing total apoptotic populations in the treated cells. Moreover, the fermentation products with higher growth-inhibitory activities demonstrated the increased apoptosis-inducing properties. In conclusion, these strains could cooperate with adult faecal microbiota to confer inulin fermentation products with higher anti-colon cancer activity.

Huigan is an important sensory attribute which is commonly used as a quality indicator evaluation of tea products. Previous studies showed a strong correlation between the lubrication behavior of saliva-tea compound mixture and the sensory perception of Huigan from trained panelists. This work was further designed to investigate how the effect of tea consumption on the rate of saliva secretion and its functional properties including total protein content of saliva (TPC), salivary α-amylase (AMY) and lipase activity (LP). A quartz crystal microbalance with dissipation monitoring (QCM-D) was applied to reveal the adsorption behavior of human whole saliva and how the salivary film is affected by the presence of tea compounds. Results showed a significant positive correlation among TPC, LP and Huigan intensity for subjects who are Huigan-sensitive. Compared to the desorption of salivary film, the desorption of saliva-EC/EGC (epicatechin/epigallocatechin) mixture from the gold surface by QCM-D observation showed a significant effect on Huigan intensity in sensitive group when comparing to the salivary layer (blank).