Physiological and Metabolomic Interpretation of Pulsating Pressurized N2 Treatment Delays Quality Deterioration of Fresh-cut Eggplant

Abstract

Fresh-cut eggplant is prone to quality deterioration such as browning, water loss, and microbial growth during storage. This study explored and compared the effects of continuous and pulsating pressurized N₂ on the quality of fresh-cut eggplant during 12 days of cold storage. Fresh-cut eggplant strips were subjected to continuous N₂ treatment at 1.0–1.5 MPa for 3–6 h and pulsating N₂ treatment at 1.5 MPa for 3 h with on/off ratios of 1:1, 2:1, and 3:1. All samples were then stored at 4℃ and 90% relative humidity (RH), and physiological, biochemical, and microbial indicators were measured every 2 days. Results showed that pressurized N₂ effectively delayed browning, water loss, the increase in respiration, microbial growth, and MDA accumulation during storage. The 1.5 MPa for 3 h treatment showed optimal preservation effects, and pulsating N₂ treatment with a 2:1 on/off pulsation ratio exhibited superior performance compared with continuous pressurization. Pulsating N₂ treatment enhanced PAL activity and promoted lignin and suberin polyphenolics (SPP) deposition at wound sites, contributing to improved tissue stability. Metabolomic analysis revealed that pulsating N₂ regulated amino acid metabolism, glutathione metabolism, lipid metabolism, and phenylalanine-related metabolism, which were associated with antioxidant responses, membrane stability, and wound healing. Thus, pulsating pressurized N₂ represents a promising strategy for maintaining the quality and extending the shelf life of fresh-cut eggplant.