Optimization of fermentation process for maximized isothiocyanate content in kohlrabi pickle

Abstract

Fermented kohlrabi, known as Mounji achar, is an indigenous fermented food product of the Himalayan region of J&K, India. The present study explored the influence of three fermentation parameters-temperature, time, and salt concentration on the formation of health-promoting compounds, isothiocyanates (ITC). Box Behnken design was used to optimize the traditional fermentation process. The second-order polynomial model exhibited a strong correlation with the experimental data, effectively predicting responses in terms of total ITC content (R² = 0.98, p < 0.0001), pH (R² = 0.98, p < 0.0001), and titratable acidity (R² = 0.96, p = 0.0002). The optimal conditions identified for maximizing isothiocyanate formation were a fermentation temperature of 29.83 °C, a fermentation time of 180.66 h, and a salt concentration of 2.48 %. Furthermore, HPLC was used to quantify two isothiocyanate molecules, erucin and phenethyl isothiocyanate, individually. Moreover, the optimized Mounji Achar presented a viable Lactic Acid Bacteria (LAB) population. 16 s rDNA sequencing revealed a diverse microbial community, including Lactiplantibacillus, Limosilactobacillus, and Bacillus species. This study sheds light on the potential for optimizing fermentation conditions to enhance total isothiocyanate content and the development of a product with a beneficial microbial profile, contributing to its nutritional and potential probiotic value.