Effects of Different Fermentation Methods on the Quality and Flavor of Pickled Cowpeas

To enhance the quality of pickled cowpeas, the natural wet fermentation and pure-bred wet fermentation were used to ferment cowpeas in this research, and the fresh cowpea from Liuzhou, Guangxi as raw materials. To explore the effects of natural wet fermentation and wet fermentation with an inoculum of 0.04 g/kg of Lactobacillus plantarum on the quality of pickled cowpeas, the pH, total acid, amino acid nitrogen, reducing sugar, total sugar and nitrite content were determined during the curing process of different methods, and the texture analysis of fermented cowpeas was detected. The sensory score and gas chromatography-mass spectrometry (GC-MS) was used to assess the flavor components of pickled cowpeas. The results indicated that the pH, total acid, amino acid nitrogen and nitrite content of pure-bred wet pickled cowpeas were lower than those of natural wet fermentation during the fermentation process. The consumption rate of reducing sugar and total sugar was higher than that of natural wet fermentation. After fermentation, the hardness, crispness and sensory scores of pure-bred wet fermented cowpeas were higher than those of natural wet pickled cowpeas. The volatile flavors in pickled cowpeas with different fermentation methods were similar, and the content of esters, acids, and alcohols was higher. Compared with natural wet fermentation, the pure-bred wet fermentation shortened the fermentation cycle of cowpeas, and the content of nitrous acid was significantly reduced which was 0.035 mg/kg at minimum. The pure-bred fermented cowpeas maintained the similar flavor with naturally fermented cowpeas. This research would provide a certain reference value for the quality optimization and flavor composition analysis of pickled cowpeas.