Effect of Liquid Nitrogen Quick-Freezing on Biochemical activity and Quality of Pitaya Blocks
In this study, the effects of quick-freezing through sprayingof liquid nitrogen (-40, -60, -80, and -100 °C) and slow- freezing (-18 °C) on microorganism biochemical activity and fruit quality were studied with pitaya (Stenocereusgriseus L) blocks as raw materials. The rate of freezing of the sample...
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| Main Authors: | , , , |
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| Format: | Article |
| Language: | zho |
| Published: |
Journal of Refrigeration Magazines Agency Co., Ltd.
2020-01-01
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| Series: | Zhileng xuebao |
| Subjects: | |
| Online Access: | http://www.zhilengxuebao.com/thesisDetails#10.3969/j.issn.0253-4339.2020.03.091 |
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| Summary: | In this study, the effects of quick-freezing through sprayingof liquid nitrogen (-40, -60, -80, and -100 °C) and slow- freezing (-18 °C) on microorganism biochemical activity and fruit quality were studied with pitaya (Stenocereusgriseus L) blocks as raw materials. The rate of freezing of the sample accelerated with decreasing freezing temperature, and the freezing time was reduced from 1.25 to 0.367 min as freezing temperature declined. However, the sample exhibited low temperature fracturing after quick-freezing at -100°C. The liquid nitrogen quick-freezing treatment inhibited the activity of polyphenol oxidase, and the residual activity of polyphenol oxidase decreased to 47.27%after -80°C freezing, while it increased to 301.09% after the slow-freezing treatment. The texture of the sample after liquid nitrogen quick-freezing was better than that of the slow-freezing treatment and the rate of juice loss was between 8.88% and 10.50%. In contrast, the rate of juice loss was as high as 38.29% after the slow-freezing treatment. The content of titratable acid, soluble solids, total phenol, anthocyanin, and ascorbic acid increased with the decreased freezing temperature of liquid nitrogen. The -80°C liquid nitrogen quick-freezing treatment maintained the best quality of the sample. |
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| ISSN: | 0253-4339 |