Isochoric cold storage for postharvest preservation of green grapes

Authors: Atci, Sumeyye; MCGRAW, VALERIE - University Of California Berkeley; BERMEO, GABRIEL - Volunteer; McHugh, Tara; RUBINSKY, BORIS - University Of California Berkeley; POWELL-PALM, MATTHEW - Texas A&M University; Bilbao-Sainz, Cristina

Submitted to: Journal of Food Processing and Preservation
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/14/2026
Publication Date: 3/27/2026
Citation: Atci, S., McGraw, V.S., Bermeo, G.P., McHugh, T.H., Rubinsky, B., Powell-Palm, M.J., Bilbao-Sainz, C. 2026. Isochoric cold storage for postharvest preservation of green grapes. Journal of Food Processing and Preservation. 2026(1). Article 9470620. https://doi.org/10.1155/jfpp/9470620.
DOI: https://doi.org/10.1155/jfpp/9470620

Interpretive Summary: This study explored a novel method to extend the shelf life and improve the quality of green grapes using isochoric cold storage (ICS). Grapes were treated in isochoric chambers, which maintained a constant pressure and temperature of -1.5 °C/16 MPa for 7 days, and then stored at refrigeration temperatures (4 °C) for up to three weeks. The results showed that grapes treated with this method experienced slower spoilage and decay compared to those stored in conventional refrigeration. The ICS-treated grapes had significantly lower microbial counts, resulting in less rot, while those stored under standard refrigeration conditions deteriorated quickly, showing weight loss, color fading, and texture softening.This approach reduces the reliance on synthetic fungicides by using a safe, physical process to preserve fruit quality. It highlights the potential of isochoric cold storage combined with solution-based refrigeration as a sustainable alternative for maintaining the freshness and safety of fresh produce, especially green grapes, during extended storage. This method could benefit industries and consumers by ensuring higher quality, reducing waste, and providing safer food storage options.

Technical Abstract: The research aimed to assess the impact of isochoric cold storage on prolonging the shelf-life of green grapes. The experimental design included placing grapes in an impregnation solution within isochoric chambers at -1.5 °C/16 MPa for a duration of 7 days. This was followed by storage either with or without the solution at 4 °C for up to 3 weeks. A separate set of grapes was stored in the same solution in a refrigerator at 4 °C for 7 days, and then either with or without the solutions at 4 °C for up to 3 weeks. Fresh grapes were also stored directly at 4 °C for 4 weeks as a control group. The quality of the green grapes was evaluated at 7-day intervals throughout the storage period. This study found that microbial counts were significantly reduced, leading to less grape decay in isochoric impregnated grapes. Meanwhile, microbial counts of refrigerated grapes were significantly higher after 4 weeks of storage. Grapes stored in conventional refrigeration quickly lost quality, showing rapid weight loss, color changes, softening, and shifts in the SSC/TA ratio. In contrast, isochoric impregnated grapes and refrigerated grapes in a solution experienced slowed quality deterioration. This innovative, safe method enhanced overall quality and safety attributes, offering a promising alternative to synthetic fungicides. The findings suggest that combining isochoric impregnation with refrigerated storage in a solution can effectively extend the shelf life of grapes.