Ochratoxin A (OTA) is a potential human carcinogen that poses a significant concern in food safety and public health. OTA has been found in a wide variety of agricultural commodities, including cereal grains. This study investigated the reduction of OTA during the preparation of rice- and oat-based porridge by a simulated indirect steam process. The effects of sodium bicarbonate (NaHCO3) and fructose on the reduction of OTA were also investigated. During the processing, OTA in rice- and oat-porridge was decreased by 59% and 14%, respectively, from initial OTA artificially added at 20 μg/kg (dry weight basis). When 0.5% and 1% of sodium bicarbonate were added to rice porridge, increased reduction of OTA was observed as 78% and 68%, respectively. The same amounts of added sodium bicarbonate also further reduced OTA in oat porridge to 58% and 72%, respectively. In addition, increased reduction of OTA in the presence of fructose was observed. A combination of the two, i.e., 0.5% sodium bicarbonate and 0.5% fructose, resulted in a 79% and 67% reduction in rice porridge and oat porridge, respectively. These results indicate that indirect steaming may effectively reduce OTA in preparation of porridge-type products, particularly when sodium bicarbonate and/or fructose are added.

Ochratoxin A (OTA) is a mycotoxin that is potentially carcinogenic to humans. Although its mechanism remains unclear, oxidative stress has been recognized as a plausible cause for the potent renal carcinogenicity observed in experimental animals. The effect of OTA on oxidative stress parameters in two cell lines of LLC-PK1 and HK-2 derived from the kidneys of pig and human, respectively, were investigated and compared. We found that the cytotoxicity of OTA on LLC-PK1 and HK-2 cells was dose- and time-dependent in both cell lines. Furthermore, increased intracellular reactive oxygen species (ROS) induced by OTA in both cell lines were observed in a time-dependent manner. Glutathione (GSH) was depleted by OTA at >48 h in HK-2 but not in LLC-PK1 cells. While the mRNA levels of glucose-6-phosphate dehydrogenase (G6PD) and glutathione peroxidase 1 (GPX1) in LLC-PK1 were down-regulated by 0.67- and 0.66-fold, respectively, those of catalase (CAT), glutathione reductase (GSR), and superoxide dismutase 1 (SOD) in HK-2 were up-regulated by 2.20-, 2.24-, and 2.75-fold, respectively, after 72 h exposure to OTA. Based on these results, we conclude that HK-2 cells are more sensitive to OTA-mediated toxicity than LLC-PK1, and OTA can cause a significant oxidative stress in HK-2 as indicated by changes in the parameter evaluated.

Spent coffee grounds (SCG) are inexpensive materials that have been used as a source of antioxidants and polysaccharides with immunostimulatory activity. In this study, we performed a microbial fermentation of SCG using Cordyceps sinensis and investigated the radical scavenging and immunostimulatory activity of fermented SCG. SCG fermentation using C. sinensis was performed at 25 °C for 8 d. The polyphenol content of the fermented SCG increased from 1022.4 to 1562.0 μg/mL. The glucosamine content of the mycelia also continuously increased during fermentation. The main polyphenol compounds of fermented SCG were chlorogenic acid and p-coumaric acid, which were increased by fermentation. Fermented SCG also showed significantly higher content of chlorogenic acid isomers than unfermented SCG. The fermented SCG exhibited significantly higher 2,2-diphenyl-2-picrylhydrazyl hydrate (half maximal inhibitory concentration: IC50, 0.37 mg/mL) and 2,2-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) (IC50, 0.93 mg/mL) radical scavenging activities than those of the control (0.54 mg/mL and 1.20 mg/mL, respectively; p < 0.05). The fermented SCG stimulated macrophages and promoted the production of various immunostimulatory cytokines (IL-12, IL-6, and TNF-α) compared to control; therefore, microbial fermentation of SCG using C. sinensis is an effective means of generating antioxidant and immunostimulatory materials.