Application of isochoric impregnation: Effect on the microbial, physicochemical parameters, and shelf life of strawberries stored under refrigeration

Authors: Atci, Sumeyye; Bilbao-Sainz, Cristina; MCGRAW, VALERIE - University Of California Berkeley; LI, JIAYUAN - Non ARS Employee; Takeoka, Gary; McHugh, Tara; RUBINSKY, BORIS - University Of California Berkeley

Submitted to: Foods
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/4/2025
Publication Date: 2/6/2025
Citation: Atci, S., Bilbao-Sainz, C., Mcgraw, V., Li, J., Takeoka, G.R., Mchugh, T.H., Rubinsky, B. 2025. Application of isochoric impregnation: Effect on the microbial, physicochemical parameters, and shelf life of strawberries stored under refrigeration. Foods. 14(3). Article 540. https://doi.org/10.3390/foods14030540.
DOI: https://doi.org/10.3390/foods14030540

Interpretive Summary: This study focused on improving the shelf life of strawberries using an advanced storage method called isochoric cold storage. In this method, strawberries were placed in special solutions: one with just sucrose and another with added calcium chloride (CaCl2) and ascorbic acid (AA). The strawberries were stored in a pressurized chamber at sub-zero temperatures for one week and then kept in a regular refrigerator for three weeks. To compare, some strawberries were stored in a refrigerator with the same solutions or just refrigerated without any special treatment. The results showed that isochoric cold storage effectively prevented the growth of microbes, reduced weight loss, and helped maintain the strawberries' color and firmness better than simple refrigeration. The strawberries stored in the sucrose solution with CaCl2 and AA showed the best quality, retaining more nutrients and staying firmer. This method has the potential to keep strawberries fresh for up to four weeks.

Technical Abstract: This study aimed to evaluate the effectiveness of isochoric impregnation during isochoric cold storage for 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 impregnated at 4 °C with each solution for 1 week and 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 weight loss of 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 sucrose solution, impregnated in solutions at 4 °C, and refrigerated with no impregnation (control). The results showed that isochoric cold storage in a solution containing sucrose, CaCl2, and ascorbic acid maintained the quality of the strawberries and can effectively extend the shelf life of strawberries for up to 4 weeks.