Fermentation characteristics of tofu with kimchi seasoning

Characterization of Volatile Compounds by SPME-GC-MS During the Ripening of Kedong Sufu, a Typical Chinese Traditional Bacteria-Fermented Soybean Product

The purpose of the present study was to evaluate the volatile profile of Kedong sufu, which is a typical bacteria-fermented soybean product in China, using solid phase microextraction coupled to gas chromatography and mass spectrometry and to reveal the evolution and diversity of flavor substances for this specialty. A total of 75 compounds were identified, including 35 esters, 4 alcohols, 4 phenols, 4 aldehydes, 7 acids, 10 ketones, and 11 other compounds from sufu samples during ripening. Some volatile compounds increased with ripening time, especially hexadecenoic acid ethyl ester, methoxy acetic acid pentyl ester, benzene propanoic acid ethyl ester, ethyl 9-hexadecenoate, ethyl oleate, ethanol, 3-methyl-1-butanol, 5-methoxy-1-pentanol, and eugenol; these compounds enriched the flavors and provided the typical savory taste of Kedong sufu. PRACTICAL APPLICATION: This research elucidated the formation of flavor substances in sufu. For traditional fermented foods, this study provides a scientific basis for promoting the generation of typical flavor substances and for the precise determination of maturity time.

Antioxidant effects of kimchi supplemented with black raspberry during fermentation protect against liver cirrhosis-induced oxidative stress in rats

BACKGROUND/OBJECTIVES

Oxidative stress is a major effector of various diseases; accordingly, antioxidants are frequently ingested in order to prevent or alleviate disease symptoms. Kimchi contains various natural antioxidants, and it is known that the functional activity varies depending on the ingredients and fermentation state. Black raspberries (BR) contain various bioactive compounds with antioxidant effects. This study investigated the antioxidant and liver-protection effects of kimchi supplemented with black raspberry juice powder (BJP).

MATERIALS/METHODS

BJP-added kimchi (BAK; at 0.5%, 1%, and 2% concentrations of BJP) and control (without BJP) were prepared and fermented at 4℃ for 4 weeks. Changes in the antioxidant effects of BAK during fermentation were investigated. In addition, the protective activity of BAK against oxidative stress was investigated in a liver cirrhosis-induced animal model in vivo.

RESULTS

BAK groups showed the acidity and pH of optimally ripened (OR) kimchi at 2 weeks of fermentation along with the highest lactic acid bacterial counts. Additionally, BAK groups displayed a higher content of phenolic compounds and elevated antioxidant activities relative to the control, with the highest antioxidant effect observed at 2 weeks of fermentation of OR 1% BAK. After feeding the OR 1% BAK to thioacetamide-induced liver cirrhosis rats, we observed decreased glutamate oxaloacetate transaminase and glutamate pyruvate transaminase activities and elevated superoxide dismutase activity.

CONCLUSIONS

These findings showed that the antioxidant effects of OR BAK and feeding of OR 1% BAK resulted in liver-protective effects against oxidative stress.