Sinki: A traditional lactic acid fermented radish tap root product.

Sinki, a non-salted fermented radish tap root product, is traditionally consumed as a base for soup and as a pickle in some north-eastern states of India, in Nepal and a few places of Bhutan. A total of 453 strains of lactic acid bacteria were isolated from 40 samples of sinki. They belonged to either Lactobacillus plantarum or Lactobacillus brevis. In the substrate, in addition to these two, Lactobacillus fermentum was present. Sinki was dominated by L. plantarum followed by L. brevis, with their prevalence in 100% of the samples. In order to study the changes in proximate and microbial composition accompanying fermentation, the process conditions for the production of sinki were optimized. Glass jar as a fermentation container and 12 days' fermentation at 30°C were found optimum. During fermentation under optimized conditions, the pH of the fermenting mass dropped from 6.7 to 3.3. This was due to an increase in titratable acidity from 0.04 to 1.28%. The fermentation was initiated by hetero-fermentative L. fermentum, followed by another heterofermentative L. brevis, and finally succeeded by homofermentative L. plantarum.