GB 5009.3—2016《食品安全国家标准 食品中水分的测定》的关键问题探讨及方法优化

Exploration of key issues and method optimization of GB 5009.3—2016 National food safety standard-Determination of moisture in foods

中文关键词:  水分测定  国家标准  关键问题

英文关键词:moisture determination  national standard  key issues

中文摘要:

      目的 分析GB 5009.3—2016《食品安全国家标准 食品中水分的测定》中直接干燥法操作步骤中影响恒重的关键因素, 并优化减压干燥法、蒸馏法和卡尔·费休法的试验条件。方法 样品中水分含量测定参照GB 5009.3—2016进行。同时, 改变实验条件探讨直接干燥法中影响恒重的关键因素; 改变真空压力优化减压干燥法的条件; 比较不同的试剂(二甲苯试剂、卡尔·费休试剂)对检测结果的影响。结果 直接干燥法中, 样品温度、干燥器内冷却时间和样品粉碎程度等3个方面是影响恒重的关键因素; 减压干燥法中, 真空度提高到–0.1 MPa, 并在干燥箱内加入有效干燥剂, 可快速挥发出样品中的水分, 提高检测效率; 蒸馏法中分析纯甲苯或二甲苯试剂的制备提纯可删除; 卡尔·费休法可采用低毒性的无吡啶卡尔·费休试剂。结论 对该标准中的4个检测方法分别进行优化, 解决了反复烘干难以达到恒重、使用有毒有害试剂等问题。本研究提供的合理化建议, 增加了该标准的可操作性, 提高了实验室的检测效率。

英文摘要:

      Objective To analyze the key factors affecting constant weight in the direct drying method and to optimize the experimental conditions for vacuum drying, distillation, and Karl Fischer methods as specified in the GB 5009.3—2016 National food safety standard-Determination of moisture in foods. Methods The determination of moisture content in samples was conducted according to GB 5009.3—2016. The study altered experimental conditions to explore key factors affecting constant weight in the direct drying method, optimized conditions for vacuum drying by adjusting vacuum pressure, and compared the effects of different reagents (xylene, Karl Fischer reagent) on detection results. Results In the direct drying method, sample temperature, cooling time in the desiccator and the degree of sample pulverization were identified as key factors affecting constant weight. For vacuum drying method, increasing the vacuum to –0.1 MPa and adding an effective desiccant to the drying box could rapidly evaporate moisture from the sample, improving detection efficiency. In the distillation method, the preparation and purification of analytical-grade toluene or xylene could be omitted. The Karl Fischer method could use a low-toxicity, pyridine-free Karl Fischer reagent. Conclusion The 4 detection methods in this standard are optimized separately to solve problems such as difficulty in achieving constant weight after repeated drying and the use of toxic and harmful reagents. The rationalization suggestions provide in this study have increased the operability of the standard and improved the testing efficiency of the laboratory.