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http://dx.doi.org/10.13103/JFHS.2022.37.2.80

Changes in Quality of Expired Tofu During Storage at Different Temperatures  

Kim, Su-jin (Department of Food and Nutrition Yeungnam University)
Kim, Se-Hun (Food Microbiology Division Food Safety Evaluation Department National Institute of Food and Drug Safety Evaluation)
Bang, Woo-Suk (Department of Food and Nutrition Yeungnam University)
Publication Information
Journal of Food Hygiene and Safety / v.37, no.2, 2022 , pp. 80-86 More about this Journal
Abstract
The purpose of this study was to examine the microbiological and physicochemical changes on packaged tofu stored at temperatures of 5, 13, 23, and 30℃, and measure the consumable period from the expiry date to ultimately evaluate the microbiological safety on the extension of the consumable period. From the investigation, the pH value of tofu at each storage temperature (5, 13, and 23℃) showed a slight decrease over the storage period, although there was no significant change. The hardness of packaged tofu decreased more rapidly as temperature and storage time increased and the tofu started to show signs of decomposition at the same time. Analysis on the microbial change of tofu at different storage temperature revealed that the number of general bacteria also increased as the temperature increased. It was further found that packaged tofu takes 25 days at 5℃, 7 days at 13℃, and 1 day at 23℃ from the expiry date until the general bacteria count is at least at the early decomposition level which is 10℃ log CFU/g. However, no coliform bacteria was detected from tofu after storing at 5, 13 and 23℃. When packaged tofu was stored at 5℃, the L value changed significantly after 26 days, whereas the a and b values showed no significant change during the storage period (P>0.05). When storing tofu at 13℃ and 23℃ the L value decreased after 8 and 3 days, respectively. However, both a and b values increased (P<0.05).
Keywords
Shelf-life; Packed tofu; Storage temperature; Food safety;
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