基于低场核磁共振技术研究大米冻融过程中水分状态变化

Change of water state in the process of freeze-thaw in rice by low field nuclear magnetic resonance

中文关键词:  大米  低场核磁共振  水分  冻融

英文关键词:rice  low field nuclear magnetic resonance  water  freeze-thaw

中文摘要:

      目的 确定大米反演峰的含义和大米冻融过程中水分迁移变化规律。方法 以苏州地产粳米(苏香粳100)为研究对象, 采用低场核磁共振技术作为检测手段, 分析不同温度(?30、?18、0、4、10、15、20 ℃)对弛豫时间、峰总面积、峰面积比的影响, 进而研究分析冻融过程中温度变化对大米本身的水分状态变化的影响。结果 大米中结合水与自由水在冻融过程中会出现一定程度的转化; 降温过程中大米结合水含量先降低再升高后降低, 升温过程中大米结合水含量逐渐升高; 15 ℃时大米自由水含量最低。结论 15 ℃适合大米贮藏, 冷冻大米可以长期贮藏, 适宜解冻后蒸煮。

英文摘要:

      Objective To determine the meaning of rice inversion peak and the rule of water migration in the process of rice freezing and thawing. Methods With japonica rice (Suxiangjing 100) from Suzhou as object, the effect of different sample temperature (?30, ?18, 0, 4, 10, 15, 20 ℃) on relaxation time, peak area and peak area ratio was studied by low field nuclear magnetic resonance (LF-NMR), then the effect of temperature change on the moisture state of rice during freezing-thawing was studied. Results The bound water and free water in rice could be transformed into each other under given conditions during freezing and thawing. During cooling, the bound water content of rice decreased first, then increased, and decreased finally. During heating, the bound water content of rice increased gradually, and the free water content of rice was the lowest at 15 ℃. Conclusion 15 ℃ is suitable for rice storage, and frozen rice is suitable for long-term storage and thawed before cooking.