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

Location: Healthy Processed Foods Research

Title: Quality changes during isochoric freezing of tilapia muscle

Author
item Bilbao-Sainz, Cristina
item Sinrod, Amanda
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: Journal of Aquatic Food Product Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/24/2020
Publication Date: N/A
Citation: N/A

Interpretive Summary: Fish is highly nutritious, but it is also very perishable since fish undergoes rapid deterioration during post-mortem. Isochoric freezing is a new freezing technology that allows preserving biological matter at subfreezing temperatures without any ice formation inside the products. We investigated the influence of isochoric freezing on some features that characterize the freshness of tilapia fish and compare isochoric freezing (-3°C/37MPa) with preservation at chilling temperature (5°C), super-chilling temperature (-3°C) and freezing temperature (-20°C). We found out that in isochoric freezing the normal degradation processes that occur during post-mortem are slowed down without the detrimental effects of ice formation, therefore the degree of microbial spoilage and lipid oxidation is low and the degree of structural damage is less than in chilled, super-chilled and frozen storage.

Technical Abstract: The aim of this work has been to evaluate the effect of isochoric freezing on quality attributes of raw tilapia muscle. Isochoric freezing was compared with ice-chilling, super-chilling and freezing. The quality attributes included color, texture, TBARS and TVB-N content. Isochoric freezing showed muscle color alterations similar to the other preservation methods. Also, all preservation methods resulted in softer fillets but the isochoric frozen fillet showed the most similar texture to that of fresh sample. Although some negative effects in the color and texture occurred during the first week of isochoric freezing, no additional modifications occurred after this time. The TBARS and TVB-N content were lower in the isochoric samples than in the chilled and super-chilled samples. These assessments were corroborated with microstructure observations. Microstructural analysis showed a marked decrease of muscle cell damage for isochoric frozen samples. Subfreezing temperatures in combination with the absence of ice crystals during isochoric freezing are probably the major reasons leading to the improved quality of tilapia muscle tissue.