Abstract:

The effect of four different fermentation methods, i.e., spontaneous fermentation, spontaneous mixed fermentation,
inoculated fermentation, and inoculated mixed fermentation on physicochemical and microbiological characteristics of
pickled Chinese yam was studied. Sensory quality of final pickles was also evaluated. Results showed that the periods of
spontaneous fermentation and inoculated fermentation were 11 and 14 days, respectively. Compared with spontaneous
fermentation, pickle from inoculated fermentation showed lower pH and nitrite content, reduced number of aerobic bacteria
and coliform, and decreased hardness and sensory evaluation scores. Contrarily, total acid content and the number of lactic
acid bacteria were increased. Pickle from mixed fermentation obtained good sensory evaluation, and its pH value was 3.0
and total acid content 8.01 mg/kg. Nitrite content, the numbers of lactic acid bacteria, aerobic bacteria and coliform, hardness
and sensory evaluation score were 1.4 mg/kg, 7.33 (lg(CFU/mL)), 3.2 (lg(CFU/mL)), 15 MPN/100 g, 2 975.00 g and 89.10,
respectively in spontaneously mixed fermented pickle, while those were 1.2 mg/kg, 9.04 (lg(CFU/mL)), 2.1 (lg(CFU/mL)),
6 MPN/100 g, 2 765.00 g, and 86.26 in inoculated mixed fermented pickle, respectively. Therefore, inoculated fermentation
can be considered as a promising fermentation method for Chinese yam pickle.

Key words: pickled Chinese yam, fermentation methods, physicochemical characteristics, microorganism, sensory quality