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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PeerJ Inc.
2017-05-01
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| author | Chenang Lyu Gabriel Nastase Gideon Ukpai Alexandru Serban Boris Rubinsky |
| author_facet | Chenang Lyu Gabriel Nastase Gideon Ukpai Alexandru Serban Boris Rubinsky |
| author_sort | Chenang Lyu |
| collection | DOAJ |
| 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. |
| first_indexed | 2024-03-09T07:53:40Z |
| format | Article |
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| institution | Directory Open Access Journal |
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| language | English |
| last_indexed | 2024-03-09T07:53:40Z |
| publishDate | 2017-05-01 |
| publisher | PeerJ Inc. |
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| series | PeerJ |
| spelling | doaj.art-7dddbb2fa38d40b6a4e5c4161212076b2023-12-03T01:21:04ZengPeerJ Inc.PeerJ2167-83592017-05-015e332210.7717/peerj.3322A comparison of freezing-damage during isochoric and isobaric freezing of the potatoChenang Lyu0Gabriel Nastase1Gideon Ukpai2Alexandru Serban3Boris Rubinsky4Department of Mechanical Engineering, University of California Berkeley, Berkeley, CA, USADepartment of Mechanical Engineering, University of California Berkeley, Berkeley, CA, USADepartment of Mechanical Engineering, University of California Berkeley, Berkeley, CA, USADepartment of Building Services, Transilvania University of Brasov, Brasov, RomaniaDepartment of Mechanical Engineering, University of California Berkeley, Berkeley, CA, USABackground 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.https://peerj.com/articles/3322.pdfRefrigerationIsochoricPotatoPreservationFoodIsobaric |
| spellingShingle | Chenang Lyu Gabriel Nastase Gideon Ukpai Alexandru Serban Boris Rubinsky A comparison of freezing-damage during isochoric and isobaric freezing of the potato PeerJ Refrigeration Isochoric Potato Preservation Food Isobaric |
| 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 | Refrigeration Isochoric Potato Preservation Food Isobaric |
| url | https://peerj.com/articles/3322.pdf |
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