Optimization of modified atmosphere packaging for shelf-life extension of freeze-dried kimchi starter culture

Abstract

Ensuring the long-term stability of freeze-dried lactic acid bacteria (LAB) starters is vital for improving the efficiency of fermented food production and reducing storage- and distribution-associated costs in the food supply chain. This study aimed to enhance the storage stability of a kimchi starter by optimizing the gas composition of modified atmosphere packaging (MAP), a sustainable preservation approach applied to diverse agricultural and food products. A simplex lattice design was employed to evaluate the effects of CO₂, O₂, and N₂ ratios on the viability of Latilactobacillus curvatus WiKim0094 under accelerated shelf-life test conditions (37 °C and 55 °C for 10–20 days, representing ambient and stressed storage, respectively). Reduced O₂ and elevated CO₂ and N₂ concentrations were found to significantly improve cell survival. Inactivation kinetics were modeled to estimate the half-life of Lb. curvatus WiKim0094 under different packaging atmospheres. The optimized MAP condition (28% CO₂ + 72% N₂) extended the half-life to 74.9 days, over fivefold longer than that under atmospheric air (13.4 days), demonstrating enhanced stability. Growth profiling in MRS medium and validation in kimchi juice showed that MAP-stored powders retained rapid growth initiation and high dominance (71% at day 7), whereas air-stored cultures showed 30% slower growth and approximately 10% lower dominance. Overall, these findings highlight MAP as a practical and scalable preservation technology for maintaining the viability and activity of starter cultures, thus supporting sustainable cold-chain management and improved quality of fermented foods in the agri-food industry.