The effects of vegetable pickling conditions on the dynamics of microbiota and metabolites

Abstract

Background Salting is a traditional procedure for producing pickled vegetables. Salting can be used as a pretreatment, for safe lactic acid fermentation and for salt stock preparation. This study aimed to provide valuable knowledge to improve pickle production by investigating the dynamics of microbiota and metabolites during the pretreatment and salt stock preparation processes, which have previously been overlooked. The differences in these process conditions would be expected to change the microbiota and consequently influence the content of metabolites in pickles. Methods Samples, collected from eight commercial pickle manufacturers in Japan, consisted of the initial raw materials, pickled vegetables and used brine. The microbiota were analyzed by 16S rRNA sequencing and the metabolites quantified by liquid chromatograph-mass spectrometry. Statistical analyses helped to identify any significant differences between samples from the initial raw materials, pretreatment process and salt stock preparation process groups. Results Under pretreatment conditions, aerobic and facultative anaerobic bacteria were predominant, including Vibrio, a potentially undesirable genus for pickle production. Under salt stock preparation conditions, the presence of halophilic bacteria, Halanaerobium, suggested their involvement in the increase in pyruvate derivatives such as branched-chain amino acids (BCAA). PICRUSt analysis indicated that the enhanced production of BCAA in salt stock was caused not by quantitative but by qualitative differences in the biosynthetic pathway of BCAA in the microbiota. Conclusion The differences in the microbiota between pretreatment and previously studied lactic acid fermentation processes emphasized the importance of anaerobic conditions and low pH under moderate salinity conditions for assuring safe pickle production. The results from the salt stock preparation process suggested that the Halanaerobium present may provide a key enzyme in the BCAA biosynthetic pathway which prefers NADH as a coenzyme. This feature can enhance BCAA production under anaerobic conditions where NADH is in excess. The effects shown in this study will be important for adjusting pickling conditions by changing the abundance of bacteria to improve the quality of pickled vegetables.

Pengaruh Penambahan Cabai ( Capsicum annum ) Dan Gula Terhadap Total Bakteri Asam Laktat (BAL) Dari Sauerkraut

“…However, if the salt level is too high it can have a bad impact on health, such as increasing the risk of heart disease and hypertension (Singh et al, 2017). Only a limited number of LAB genera can grow in high salinity conditions, thereby suppressing the dominance of LAB in the salt stock preparation process (Sawada et al, 2021). Fermentation time can also influence the presence of LAB.…”

Improvement of physicochemical properties and flavour of pickled radish through the use of a direct‐vat set starter consisting of Lactiplantibacillus plantarum and Leuconostoc mesenteroides

“…The pickling process follows a simple procedure: fresh vegetables are washed, dehydrated and immersed in brine before being placed in closed containers for anaerobic fermentation (Sawada et al, 2021). Conversely, this conventional approach might bring challenges such as unregulated product quality and an extended fermentation duration.…”

“…The utilisation of pickling and fermentation techniques presents a promising approach to preserving excess radish while simultaneously augmenting its nutritional value and conferring specific probiotic effects, such as antibacterial, hypolipidemic, antioxidant and cholesterol‐lowering properties (Hu et al ., 2022). The pickling process follows a simple procedure: fresh vegetables are washed, dehydrated and immersed in brine before being placed in closed containers for anaerobic fermentation (Sawada et al ., 2021). Conversely, this conventional approach might bring challenges such as unregulated product quality and an extended fermentation duration.…”