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Research Project: Preservation of Food By Isochoric (Constant Volume) Freezing

Location: Healthy Processed Foods Research

Title: Preservation of grape tomato by isochoric freezing

Author
item Bilbao-Sainz, Cristina
item Sinrod, Amanda
item Dao, Lan
item Takeoka, Gary
item Williams, Tina
item Wood, Delilah - De
item Chiou, Bor-Sen
item Bridges, David
item Wu, Vivian
item LYU, CHENANG - University Of California
item RUBINSKY, BORIS - University Of California
item McHugh, Tara

Submitted to: Food Research International
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/14/2021
Publication Date: N/A
Citation: N/A

Interpretive Summary: Isochoric freezing is an alternative preservation technique that allows to preserve food at subfreezing temperatures with no internal ice formation. In this study we used isochoric freezing to preserve tomatoes for up to 4 weeks. We found out that tomatoes are not suitable for traditional freezing due to their considerable texture degradation, color alteration, and nutritional loss during the freezing process and subsequent frozen storage. However, Isochoric freezing maintains tomatoes’ physicochemical and nutritional properties as the absence of ice crystal formation and low processing pressures during freezing reduces cell damage in tomato tissues. This study may find application in the commercial preservation of tomatoes and as a potential solution to “food desert” areas where residents have low access to fresh healthy foods, specially fruits and vegetables.

Technical Abstract: This study investigated the potential of isochoric freezing to preserve tomatoes. Isochoric freezing was compared with freezing under isobaric conditions and with preservation techniques used in the food industry: cold storage at 10°C and individual quick freezing (IQF). Physicochemical and nutritional properties were evaluated weekly for four weeks. Preservation under isochoric conditions maintained the mass, volume, color, nutrient content (ascorbic acid, lycopene and phenolics) and antioxidant activity of the fresh tomatoes. Also, isochoric preservation led to minimal texture damage. In comparison, mass loss of tomatoes stored at 10°C for 3 weeks contributed to changes in overall visual quality and firmness as well as significant losses in nutrient content. The greatest mass, volume, texture, and nutrients losses were obtained for tomatoes subjected to IQF and isobaric freezing. The results show that isochoric freezing has the potential to preserve tomatoes while maintaining physicochemical and nutritional properties similar to those of fresh tomatoes.