Long-term frozen storage of kimchi Yangnyeom sauce: impact of cryoprotectants on microbial viability and fermentation stability

The long-term transportation of kimchi causes excessive fermentation, leading to packaging expansion or bursting. A novel strategy was hypothesized: the frozen export of kimchi Yangnyeom sauce alone, with subsequent kimchi preparation at the destination. Carrageenan, inulin, trehalose, and maltodextrin were incorporated to mitigate lactic acid bacteria (LAB) viability loss during long-term frozen storage, with physicochemical and microbial properties analyzed during 24 weeks of storage at −18°C (frozen) and 4°C (refrigerated). During refrigerated storage, LAB populations rapidly increased, accompanied by a decrease in reducing sugar content and a rise in titratable acidity after eight weeks – refrigeration is unsuitable for long-term distribution. Conversely, frozen storage resulted in a gradual decline in reducing sugars and a slower increase in titratable acidity. Cryoprotectant supplementation mitigated the reduction in LAB during frozen storage. Trehalose alleviated the decrease in reducing sugar and LAB counts. Inulin and maltodextrin accelerated fermentation, probably because of their prebiotic activities – they are unsuitable for long-term storage. Carrageenan exhibited negligible effects at all tested concentrations. The findings suggest the feasibility of frozen storage and long-term distribution of kimchi Yangnyeom sauce supplemented with trehalose. Future research should evaluate the quality of kimchi prepared using stored sauces and assess applicability under export conditions.