Process optimization of centrifugal dehydration–hydrocolloid pretreatments for quality preservation of frozen kimchi

The growing global demand for kimchi has led to the adoption of frozen distribution as a strategy to extend shelf-life. However, freezing can cause quality deterioration through ice crystal-related structural damage, resulting in texture softening and reduced microbial viability. We evaluated pretreatment strategies to improve the quality stability of frozen kimchi, focusing on the combined use of centrifugal dehydration and formulation-based cryoprotectant/hydrocolloid additions. Five pretreatment approaches were tested, including centrifugal dehydration, glucose addition, and hydrocolloid incorporation using sodium carboxymethyl cellulose and xanthan gum. Centrifugal dehydration was the primary factor reducing moisture content and thawing loss and thereby improving texture retention during frozen storage. Glucose and hydrocolloid treatments exhibited limited, index-dependent additional effects, with modest differences observed in selected parameters such as reducing sugar (RS) levels, lactic acid bacteria (LAB) counts, and antioxidant-related indices (total phenolic content (TPC) and DPPH radical-scavenging activity (DPPH)). Principal component analysis (PCA) suggested that the RS levels, LAB counts, and texture variables were associated with overall quality variation among treatments during frozen storage. Overall, centrifugal dehydration serves as an effective baseline pretreatment for frozen kimchi, while glucose/hydrocolloid additions may offer incremental stabilization in specific quality indices, warranting further validation under longer storage durations and diverse distribution conditions.