Application of Isochoric Impregnation: Effects on Microbial and Physicochemical Parameters and Shelf Life of Strawberries Stored Under Refrigeration.

Abstract

This study evaluates the effectiveness of isochoric impregnation during isochoric cold storage in extending the shelf life of strawberries. Strawberries in two different impregnation solutions-(1) sucrose solution and (2) sucrose solution containing calcium chloride (CaCl₂) and ascorbic acid (AA)-were first stored in an isochoric chamber at -2 °C/48 MPa for 1 week, followed by refrigeration at 4 °C for 3 weeks. For comparison, strawberries were also immersed in each solution for 1 week at 4 °C then refrigerated at 4 °C for 3 weeks. Additionally, a control group of fresh strawberries was stored at 4 °C for 4 weeks. The quality of the strawberries was assessed at 1-week intervals throughout the storage period. Isochoric cold storage effectively inhibited microbial growth and reduced the weight loss of the strawberries compared to refrigerated storage. Also, isochoric cold storage resulted in strawberries that retained their color attributes, whereas refrigeration led to a significant change in their color attributes. Isochoric impregnated strawberries in the sucrose solution containing CaCl₂ and AA showed better mechanical properties and higher nutrient contents (anthocyanins and ascorbic acid) than those impregnated in the sucrose solution, impregnated in the solutions at 4 °C, and refrigerated with no impregnation (control). The results demonstrated that isochoric cold storage in a solution containing sucrose, CaCl₂, and ascorbic acid effectively maintained the quality of the strawberries, as indicated by parameters such as firmness, color retention, and reduced microbial growth. This method extended the strawberries' shelf life by up to 4 weeks.