Impact of low salt concentration, salt quality on natural large-scale sauerkraut fermentation

Abstract

This study examined the impact of low NaCl and mineral salt concentrations on the spontaneous large-scale (430 kg) fermentation process of white cabbage into sauerkraut and sauerkraut juice. The shelf-life and sensory quality of the juices as well as the repeatability of the manufacturing process were also studied. Three parallel trials with three different salt concentrations were carried out. The NaCl concentrations in trials 1A–C and 3A–C were 0.5% and 1.2%, respectively. In trials 2A–C, we used 0.5% mineral salt (28% KCl, 57% NaCl) that gave a NaCl concentration of 0.3%. The pH decreased somewhat faster when 1.2% NaCl was used, but the lowering of pH was much the same in all cabbage containers and no significant differences could be observed after the sixth fermentation day. The growth of lactic acid bacteria in the beginning of the fermentation process was fastest in the trials where 1.2% NaCl was used and slowest in the trials with 0.5% mineral salt. With 1.2% NaCl, the number of lactic acid bacteria was 10 8 cfu/ml on the third fermentation day, whereas with 0.5% mineral salt the same number was reached on the sixth fermentation day and with 0.5% NaCl on the fourth fermentation day. At the end of fermentation, the lactic acid bacteria count in the pressed sauerkraut juice was 10 8 cfu/ml in all trials. The lactic and acetic acid concentrations were measured from juice samples during the fermentation process. Lactic acid production was clearly lower after 2 weeks fermentation in the trials where 0.5% mineral salt was used, compared to the other trials. No major difference could be detected between the acetic acid concentrations in the different trials. The sensory quality of the juices was evaluated by a trained taste panel. The sauerkraut juice fermented with 0.5% mineral salt was considered to have the best taste. We also investigated the shelf-life of the juices and found that the number of lactic acid bacteria decreased in all juices during storage at 4°C. Also the number of yeasts and moulds, enterobacteria, mesophilic and thermophilic spores decreased during storage.