Microbial succession and anthocyanin concentration during sorghum fermentation

Abstract

Among the cereals, sorghum is notable for its high phytochemicals contents. The levels of these phytochemicals are, however, affected by processing methods, such as fermentation. This study evaluated the microbial succession and anthocyanins concentration during red sorghum grains fermentation. Sorghum grains were spontaneously fermented for five days in a solid-state, during which samples were collected daily for microbial and anthocyanins analyses. Isolation and identification of the bacterial isolates were conducted using standard methods, and anthocyanins concentration was determined using a spectrophotometer. Five different bacterial species, including Enterobacter sp., Lactobacillus sp., Pediococcus sp., Cronobacter sp., and Pantoea sp., were isolated and identified, during the five days of spontaneous fermentation. The anthocyanins level of the fermented grains peaked (0.45 mg/g) on the fifth day. The predominant microorganisms (Pantoea dispersa LMG 2603 and Cronobacter sakazakii NBRC 102,416) isolated on the fifth day were later used as starter cultures for the fermentation of a fresh batch of sorghum grains for another five days, during which the anthocyanins level increased to 0.82 mg/g on the fifth day. Molecular identification revealed that Pantoea dispersa LMG 2603 was capable of increasing anthocyanins content, suggesting that it can be used as a starter culture for the fermentation of sorghum to yield a higher anthocyanins content.