Effects of freezing conditions on quality changes in blueberries.

• Autores: Xuehui Cao, Fangfang Zhang, Dongyu Zhao, Danshi Zhu, Jianrong Li
• Localización: Journal of the science of food and agriculture, ISSN 0022-5142, Vol. 98, Nº 12, 2018, págs. 4673-4679
• Idioma: inglés
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• Resumen

  • Freezing preservation is one of the most effective methods used to maintain the flavour and nutritional value of fruit. This research studied the effects of different freezing conditions, -20 °C, -40 °C, -80 °C, and immersion in liquid nitrogen, on quality changes of freeze-thawed blueberries. The water distribution estimates of blueberries were measured based on low-field nuclear magnetic resonance (LF-NMR) analysis. The pectin content, drip loss, and fruit texture were also detected to evaluate quality changes in samples.; Results: The freezing curves of blueberry showed super-cooling points at -20 °C and - 40 °C, whereas super-cooling points were not observed at -80 °C or in liquid nitrogen. After freeze-thaw treatment, the relaxation time of the cell wall water (T21 ), cytoplasm water and extracellular space (T22 ), and vacuole water (T23 ) were significantly shortened compared to fresh samples, which suggested a lower liquidity. Although the freezing speed for samples immersed in liquid nitrogen was faster than other treatments, samples treated at -80 °C showed better quality regarding vacuole water holding, drip loss, and original pectin content retention.; Conclusion: This study contributed to understanding how freezing temperature affects the qualities of blueberries. The super-fast freezing rate might injure fruit, and an appropriate freezing rate could better preserve blueberries. © 2018 Society of Chemical Industry.; © 2018 Society of Chemical Industry.