Texture Changes and Plant Cell Wall Degrading Enzymes Producing Microorganism Diversity in Different Varieties of Cowpea during Fermentation

Four different varieties of cowpea were studied as the research object, and the changes of microbial flora and texture properties were explored. The main typical species of plant cell wall degrading enzymes (PCWDEs) caused by different varieties of fermented cowpea soft rot were analyzed. The textures of fermented cowpea were determined by texture analyzer. The PCWDEs producing agents were separated by differential plates and identified through the 16S/18S rDNA sequencing. The results showed that cowpea A presented the best texture quality during the whole fermenting process. The hardness, springness and chewiness of cowpea B, cowpea C, cowpea D were destroyed faster than cowpea A in fermentation process, especially cowpea B. Cell wall degrading enzymes (PCWDEs) producing isolates were selected. The results presented that the fermented cowpea B harbored the most numbers and varieties of PCWDEs producing microorganisms, which belonged to Enterobacter, Citrobacter, Pseudomonas, Staphylococcus, Myroides, Pantoea and Klebsiella. The PCWDEs microorganisms in fermented cowpea A, cowpea C and cowpea D were less than cowpea B. Only Raoultella ornithinolytica presented in cowpea D. Lactobacillus plantarum producing protease and Wickerhamomyces anomalus producing amylase were found in four fermented cowpeas. The present study showed that the texture and microbial changes during the fermentation in different fermented cowpeas presented respective specificities. The soft rot of fermented cowpeas was related to the number and variety of PCWDEs producing agents in the later fermented process.