Novel isochoric cold storage with isochoric impregnation to improve postharvest quality of sweet cherry

Authors: Bilbao-Sainz, Cristina; Chiou, Bor-Sen; Takeoka, Gary; Williams, Tina; Wood, Delilah - De; POWELL-PALM, MATTHEW - University Of California Berkeley; RUBINSKY, BORIS - University Of California Berkeley; McHugh, Tara

Submitted to: ACS Food Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/26/2022
Publication Date: 9/8/2022
Citation: Bilbao-Sainz, C., Chiou, B., Takeoka, G.R., Williams, T.G., Wood, D.F., Powell-Palm, M., Rubinsky, B., McHugh, T.H. 2022. Novel isochoric cold storage with isochoric impregnation to improve postharvest quality of sweet cherry. ACS Food Science and Technology. 2(10):1558-1564. https://doi.org/10.1021/acsfoodscitech.2c00194.
DOI: https://doi.org/10.1021/acsfoodscitech.2c00194

Interpretive Summary: Cherry has a short harvest season, from May to mid-July in the Northern Hemisphere and only for a few weeks in any specific region. Also, postharvest cherries are extremely difficult to handle since they decay rapidly. In this study we evaluated the potential of isochoric cold storage, also called isochoric freezing, with and without pressure-assisted isochoric impregnation to maintain the quality of sweet cherries for 30 days. The impregnation solution consisted of an isotonic solution of 17% sucrose and 1% ascorbic acid. Cold storage under isochoric conditions at -5°C effectively retarded the deterioration of cherry quality parameters and decay caused by bacterial and fungal growth. The subfreezing temperature during isochoric preservation could decrease the respiration rate of sweet cherries, thereby slowing deteriorative metabolism and ultimately, delaying senescence. Also, the absence of ice crystals inside the cellular tissue reduced cell damage during storage. The reduced deterioration of fresh cherries was enhanced by isochoric impregnation with a sucrose/ascorbic acid solution. This treatment better maintained the physicochemical properties of cherry fruit, including, weight, firmness, skin color and tissue integrity, compared with fruits stored at 3 °C and conventional freezing at -5°C. Isochoric impregnation increased the ascorbic acid content of cherries by six times over that of fresh cherries, increasing their nutritional value. Furthermore, this treatment effectively controlled the growth of mesophilic aerobic microorganisms, yeasts and molds.

Technical Abstract: Isochoric cold storage with isochoric impregnation is a novel preservation technology that could be used to minimize quality loss of fresh fruit during post-harvest life while increasing its nutrient content. In this study, the effects of isochoric cold storage at -5°C, with and without isochoric impregnation with sucrose/ascorbic acid solution, on the physicochemical, nutritional and microbiological qualities of sweet cherry were investigated and compared with refrigeration at 3°C and isobaric cold storage at -5°C. Isochoric cold storage better preserved fruit quality for 30 days when compared with refrigeration and isobaric cold storage. Isochoric stored cherries impregnated with sucrose and ascorbic acid exhibited smaller weight loss (7.1%), lower browning, similar texture, higher anthocyanins retention (74%), 6 times higher ascorbic acid content and 19% higher antioxidant activity than fresh cherries. In addition, these cherries did not show microbial contamination (total mesophilic aerobic bacteria, yeasts and molds). The use of subfreezing temperatures during isochoric preservation helped to slow down quality deterioration due to senescence processes and microbial growth, while the absence of ice crystals inside the cellular tissue helped to preserve the integrity of the cherry fruits.