Abstract
Salt concentrations in brine and temperature are the major environmental factors that affect activity of microorganisms and, thus may affect formation of biogenic amines (BAs) during the fermentation process. A model system to ferment cucumbers with low salt (0.5%, 1.5% or 5.0% NaCl) at two temperatures (11 or 23 °C) was used to study the ability of indigenous microbiota to produce biogenic amines and metabolize amino acid precursors. Colony counts for presumptive Enterococcus and Enterobacteriaceae increased by 4 and up to 2 log of CFU∙mL−1, respectively, and remained viable for more than 10 days. 16S rRNA sequencing showed that Lactobacillus and Enterobacter were dominant in fermented cucumbers with 0.5% and 1.5% salt concentrations after storage. The initial content of BAs in raw material of 25.44 ± 4.03 mg∙kg−1 fluctuated throughout experiment, but after 6 months there were no significant differences between tested variants. The most abundant BA was putrescine, that reached a maximum concentration of 158.02 ± 25.11 mg∙kg−1. The Biogenic Amines Index (BAI) calculated for all samples was significantly below that needed to induce undesirable effects upon consumption. The highest value was calculated for the 23 °C/5.0% NaCl brine variant after 192 h of fermentation (223.93 ± 54.40). Results presented in this work indicate that possibilities to control spontaneous fermentation by changing salt concentration and temperature to inhibit the formation of BAs are very limited.
Highlights
Lactic acid fermentation is a traditional method of food preservation [1]
The initial heterofermentation stage is dominated by Leuconostoc (e.g., L. citreum, L. mesenteroides) and Weissella (e.g., W. koreensis) genera, whereas members of Lactobacillaceae family such as Lactiplantibacillus plantarum, Levilactobacillus brevis, Latilactobacillus curvatus, and Latilactobacillus sakei prevailed in the successive homofermentation stage [5,6,7]
Lactic Acid Bacteria (LAB) were cultured on MRS agar (Becton–Dickinson, Franklin Lakes, NJ, USA), Enterobacteriaceae on VRBD agar (MERCK, Darmstadt, Germany), fecal enterococci on Enterococcosel Agar (Graso, Starogard Gdanski, Poland), E. coli on CHROMagar ECC (Graso, Starogard Gdanski, Poland), Pseudomonas spp. on ChromAgar Pseudomonas (Graso, Starogard Gdanski, Poland), and fungi on YPG agar (MERCK, Darmstadt, Germany)
Summary
Lactic acid fermentation is a traditional method of food preservation [1]. If carried out properly, it may prolong the shelf life of perishable food (e.g., vegetables), and improve the nutritional value, taste, and/or safety properties of the final products [2]. In another study addressing spontaneous fermentation of cauliflower (20 ◦C, 8% w/v NaCl), the initial Enterobacteriaceae count of about 4 log CFU·g−1 increased up to the highest value of about 5 log CFU·g−1 on day 5 of the process, dropped below 5 log CFU·g−1 on day 7, and decreased remarkably to about 2 log CFU·g−1 after 25 days [34]. Strains belonging to Enterococcus spp. are resistant to a broad range of temperatures and pH values, as well as being tolerant to salts and acids. This enables them to adapt to various food environments. They take an active part in the fermentation of traditional cheeses and sausages, developing their characteristic sensory traits [39]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
