­Isochoric refrigeration of food products

Chenang Lyu; Gabriel Nastase; Gideon Ukpai; Alexandru Serban; Boris Rubinsky

doi:10.7287/peerj.preprints.2740v1

Isochoric refrigeration of food products

Chenang Lyu^1,2, Gabriel Nastase ^1,3, Gideon Ukpai¹, Alexandru Serban³, Boris Rubinsky¹

1 Department of Mechanical Engineering, University of California, Berkeley, Berkeley, California, United States

2 College of Biosystems Engineering and Food Science, Zhejiang University, Hangzhou, Hangzhou, China

3 Department of Building Services, University Transilvany of Brasov, Brasov, Brasov, Romania

DOI: 10.7287/peerj.preprints.2740v1

Published: 2017-01-20
Accepted: 2017-01-20

Subject Areas: Agricultural Science, Biophysics, Cell Biology, Food Science and Technology, Plant Science
Keywords: refrigeration, isochoric, potato, preservation, food

Copyright: © 2017 Lyu et al.
Licence: This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, reproduction and adaptation in any medium and for any purpose provided that it is properly attributed. For attribution, the original author(s), title, publication source (PeerJ Preprints) and either DOI or URL of the article must be cited.

Cite this article: Lyu C, Nastase G, Ukpai G, Serban A, Rubinsky B. 2017. Isochoric refrigeration of food products. PeerJ Preprints 5:e2740v1 https://doi.org/10.7287/peerj.preprints.2740v1

Abstract

Background: Food preservation is essential to the growing world population, food economy. Freezing is a commonly used method for food preservation. While extending the life of the product, freezing has detrimental effects. It is causing loss of food weight and is causing changes in food quality, e.g. enzymatic browning.

Method: Freezing of food is usually done under constant atmospheric pressure (isobaric). We have developed a new technology in which biological materials are preserved at subfreezing temperatures in an isochoric (constant volume) system. Experiments were performed with a food product, potato, in a thermodynamic isochoric device designed by us, that is robust and has no moving parts.

Results: We have shown that under similar storage conditions, freezing to -5°C, the isochoric preserved potato experienced no weight loss and limited enzymatic browning. In contrast the -5°C isobaric frozen potato experienced substantial weight loss and substantial enzymatic browning. Microscopic analysis, shows that the mechanism responsible for the different results is related to the integrity of the cell and the cell membrane, which are maintain during freezing in the isochoric system and lost during freezing in the isobaric system.

Discussion: The main mechanism of cell damage during isobaric freezing are the increase in extracellular osmolality and the mechanical damage by ice crystals. In contrast, during isochoric freezing the cells in the preserved material are under conditions in which the intracellular osmolality is comparable to the extracellular osmolality and they are not affected by ice mechanical damage. The conditions during isochoric freezing result in improved quality of the preserved food products.

Conclusion: We have shown that the quality of food products preserved by isochoric freezing is better than the quality of food preserved to the same temperature in isobaric conditions. This is only a preliminary study on isochoric preservation of food. However, it illustrates the potential of the technology.

Author Comment

This is a submission to PeerJ for review.

Supplemental Information

Calorimetric measeurements table

Pressure measurement table

Weight loss potato measurements

Chalorimetric measurements picture

Microscopic Fresh potato sample - magnif. 45X

Microscopic Fresh potato sample - magnif. 80X

Microscopic Fresh potato sample - magnif. 45X with TBO

Microscopic Fresh potato sample - magnif. 80X with TBO

Microscopic Isobaric potato sample - magnif. 45X

Microscopic Isobaric potato sample - magnif. 80X

Microscopic Isobaric potato sample - magnif. 45X with TBO

Microscopic Isobaric potato sample - magnif. 80X with TBO

Microscopic ISOCHORIC potato sample - magnif. 45X_1

Microscopic ISOCHORIC potato sample - magnif. 45X_2

Microscopic ISOCHORIC potato sample - magnif. 80X

Microscopic ISOCHORIC potato sample - magnif. 45X_with TBO_1

Microscopic ISOCHORIC potato sample - magnif. 45X_with TBO_2

Microscopic ISOCHORIC potato sample - magnif. 80X_with TBO_1

Microscopic ISOCHORIC potato sample - magnif. 80X_with TBO_2