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A comparison of freezing-damage during isochoric and isobaric freezing of the potato

BACKGROUND: Freezing is commonly used for food preservation. It is usually done under constant atmospheric pressure (isobaric). While extending the life of the produce, isobaric freezing has detrimental effects. It causes loss of food weight and changes in food quality. Using thermodynamic analysis,...

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Autores principales: Lyu, Chenang, Nastase, Gabriel, Ukpai, Gideon, Serban, Alexandru, Rubinsky, Boris
Formato: Online Artículo Texto
Lenguaje:English
Publicado: PeerJ Inc. 2017
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5438586/
https://www.ncbi.nlm.nih.gov/pubmed/28533970
http://dx.doi.org/10.7717/peerj.3322
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author Lyu, Chenang
Nastase, Gabriel
Ukpai, Gideon
Serban, Alexandru
Rubinsky, Boris
author_facet Lyu, Chenang
Nastase, Gabriel
Ukpai, Gideon
Serban, Alexandru
Rubinsky, Boris
author_sort Lyu, Chenang
collection PubMed
description BACKGROUND: Freezing is commonly used for food preservation. It is usually done under constant atmospheric pressure (isobaric). While extending the life of the produce, isobaric freezing has detrimental effects. It causes loss of food weight and changes in food quality. Using thermodynamic analysis, we have developed a theoretical model of the process of freezing in a constant volume system (isochoric). The mathematical model suggests that the detrimental effects associated with isobaric freezing may be reduced in an isochoric freezing system. To explore this hypothesis, we performed a preliminary study on the isochoric freezing of a produce with which our group has experience, the potato. METHOD: Experiments were performed in an isochoric freezing device we designed. The device is robust and has no moving parts. For comparison, we used a geometrically identical isobaric freezing device. Following freezing and thawing, the samples were weighed, examined with colorimetry, and examined with microscopy. RESULTS: It was found that potatoes frozen to −5 °C in an isochoric system 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 structural integrity of the potato is maintained after freezing in the isochoric system and impaired after freezing in the isobaric system. DISCUSSION: Tissue damage during isobaric freezing is caused by the increase in extracellular osmolality and the mechanical damage by ice crystals. Our thermodynamic analysis predicts that during isochoric freezing the intracellular osmolality remains comparable to the extracellular osmolality and that isochoric systems can be designed to eliminate the mechanical damage by ice. The results of this preliminary study seem to confirm the theoretical predictions. CONCLUSION: This is a preliminary exploratory study on isochoric freezing of food. We have shown that the quality of a food product preserved by isochoric freezing is better than the quality of food preserved to the same temperature in isobaric conditions. Obviously, more extensive research remains to be done to extend this study to lower freezing temperatures and other food items.
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spelling pubmed-54385862017-05-22 A comparison of freezing-damage during isochoric and isobaric freezing of the potato Lyu, Chenang Nastase, Gabriel Ukpai, Gideon Serban, Alexandru Rubinsky, Boris PeerJ Agricultural Science BACKGROUND: Freezing is commonly used for food preservation. It is usually done under constant atmospheric pressure (isobaric). While extending the life of the produce, isobaric freezing has detrimental effects. It causes loss of food weight and changes in food quality. Using thermodynamic analysis, we have developed a theoretical model of the process of freezing in a constant volume system (isochoric). The mathematical model suggests that the detrimental effects associated with isobaric freezing may be reduced in an isochoric freezing system. To explore this hypothesis, we performed a preliminary study on the isochoric freezing of a produce with which our group has experience, the potato. METHOD: Experiments were performed in an isochoric freezing device we designed. The device is robust and has no moving parts. For comparison, we used a geometrically identical isobaric freezing device. Following freezing and thawing, the samples were weighed, examined with colorimetry, and examined with microscopy. RESULTS: It was found that potatoes frozen to −5 °C in an isochoric system 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 structural integrity of the potato is maintained after freezing in the isochoric system and impaired after freezing in the isobaric system. DISCUSSION: Tissue damage during isobaric freezing is caused by the increase in extracellular osmolality and the mechanical damage by ice crystals. Our thermodynamic analysis predicts that during isochoric freezing the intracellular osmolality remains comparable to the extracellular osmolality and that isochoric systems can be designed to eliminate the mechanical damage by ice. The results of this preliminary study seem to confirm the theoretical predictions. CONCLUSION: This is a preliminary exploratory study on isochoric freezing of food. We have shown that the quality of a food product preserved by isochoric freezing is better than the quality of food preserved to the same temperature in isobaric conditions. Obviously, more extensive research remains to be done to extend this study to lower freezing temperatures and other food items. PeerJ Inc. 2017-05-18 /pmc/articles/PMC5438586/ /pubmed/28533970 http://dx.doi.org/10.7717/peerj.3322 Text en © 2017 Lyu et al. http://creativecommons.org/licenses/by/4.0/ This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/) , 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) and either DOI or URL of the article must be cited.
spellingShingle Agricultural Science
Lyu, Chenang
Nastase, Gabriel
Ukpai, Gideon
Serban, Alexandru
Rubinsky, Boris
A comparison of freezing-damage during isochoric and isobaric freezing of the potato
title A comparison of freezing-damage during isochoric and isobaric freezing of the potato
title_full A comparison of freezing-damage during isochoric and isobaric freezing of the potato
title_fullStr A comparison of freezing-damage during isochoric and isobaric freezing of the potato
title_full_unstemmed A comparison of freezing-damage during isochoric and isobaric freezing of the potato
title_short A comparison of freezing-damage during isochoric and isobaric freezing of the potato
title_sort comparison of freezing-damage during isochoric and isobaric freezing of the potato
topic Agricultural Science
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5438586/
https://www.ncbi.nlm.nih.gov/pubmed/28533970
http://dx.doi.org/10.7717/peerj.3322
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