玉米脂肪酸值测定影响因素分析

Analysis of Influencing Factors for the Determination of Corn Fatty Acid Value

通过研究0.01 mol·L^-1氢氧化钾标准滴定溶液在室温下放置不同天数对玉米脂肪酸值测定结果的影响发现,在室温下放置3 d内的氢氧化钾乙醇滴定液测得的脂肪酸值在允许误差范围内;放置到第5 d,检测结果超过允许误差。一份均匀的玉米样品在连续粉碎后,由于磨膛发热,样品温度从36.4℃升至47.4℃,脂肪酸测定值从44.8 mg/100 g增加至51.7 mg/100 g,测定结果比真实值显著偏高。脂肪酸提取液过滤后移液,加入无二氧化碳蒸馏水及酚酞指示剂后在室温下、不加盖、放置0~20 min,脂肪酸值测定结果几乎无变化。

Study on the influence of 0.01 mol·L^-1 potassium hydroxide standard solution stored at room temperature for different days on the corn fatty acid value determination results,it was found that the fatty acids value was within the scope of permissible error,measured with the potassium hydroxide ethanol standard solution stored at room temperature for 3 d.When stored on the 5th day,the test results exceed the permissible error.After a uniform corn sample was continuously crushed,the sample temperature increased from 36.4℃to 47.4℃due to heating in the grinding chamber,and the measured value of fatty acids increased from 44.8 mg/100 g to 51.7 mg/100 g,which was significantly higher than the actual value.The fatty acid extract was filtered,then distilled water without carbon dioxide and phenolphthalein indicator were added,the sample solution was stored at room temperature,without cover,for 0~20 min,and the determination results of fatty acid value had almost no influence.