Effect of Sample Preparation Equipment Parameters on Determination of Fatty Acid Value in Corn
A kind of high purity corn was selected as the test sample,and the effects of sample preparation equipment,sieve hole distance and feeding time on the determination results of fatty acid value were studied.The test results show that:(1)Under the same conditions,using different sample preparation equipment(1# machine,2# machine)for 80 g quantitative continuous sampling in ten successive trials.It was observed that the maximum powder temperature reached 39.1 ℃ with the 1# machine,and at the third sampling,the powder temperature reached 33.1℃,leading to a significant increase in fatty acid values with a variation coefficient of 5.38％over ten determinations.The highest powder temperature of the 2# machine was 30.6 ℃,and the coefficient of variation of fatty acid value was 0.90％over ten determinations.(2)Select the 2# machine with small coefficient of variation of fatty acid value,select three kinds of sieve hole distance(1.25,1.5,1.75 times)and set 4 different feeding times(30,40,50,60 s)to form 12 groups of test parameters.Each group of test parameters were compared by 80 g quantitative repeated test for 10 times.When the sieve hole distance was 1.75 times,the fatty acid value fluctuates greatly and the absolute difference exceeds the 2 mg KOH/100 g range allowed by the national standard.From the point of view of feed efficiency,the optimum sieve hole distance was 1.25 times.From the point of view of the material requirements,service life and processing difficulty of the sieve,the optimum hole distance of the sieve was 1.50 times.The optimum feeding time was 30 s from the point of view of feed efficiency and coefficient of variation.
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