玉米籽粒变温变湿干燥后不饱和脂肪酸与干燥系统的耦合关系

Coupling relationship between content of unsaturated fatty acid and drying system of corn grain after variable temperature and humidity drying

为了研究变温变湿干燥工艺中玉米籽粒的不饱和脂肪酸含量与干燥系统的耦合关系,根据实际烘干塔的干燥参数将整个干燥过程分成3个等时的干燥段,将每个干燥段的热风温度和相对湿度设为因素,每个因素设置3个水平,即为6因素3水平的正交试验进行探究。结果表明不饱和脂肪酸含量在3段热风温度为35℃-50℃-50℃,相对湿度为30%-45%-30%时含量最高,为6.553%。不饱和脂肪酸含量在干燥系统的所有耦合因子中与粮食绝对水势和的耦合关系最大,其次是绝对水势和差,该结论对分析和预测干燥工艺对玉米籽粒中不饱和脂肪酸含量提供了新思路,为深入研究水势理论与谷物干燥品质的关系打下基础。

The content of unsaturated fatty acid(UFA) is an important index to evaluate the quality of corn. It is not only the main fatty acid of corn, but also a very important dietary fatty acid and essential nutrient in human body. In order to study the relationship between UFA content and the drying system coupling factor of corn, an orthogonal experiment was designed. This experiment was based on the actual drying parameters of the corn dryer in Harbin grain dryer. First, the drying process was divided into three stages, each stage had different hot air temperature and relative humidity, so as to establish a six factors and three levels of sectional temperature and humidity orthogonal drying experiment. There were a total of 30 groups of experiments. Then, the content of UFA in dry corn was determined by microwave extraction and gas chromatography. Finally, the relationship between drying system coupling factor and UFA content in corn was calculated. On the premise of meeting the drying standard of edible corn, the highest content of UFA was 6.553% under the drying conditions of hot air temperature of 35 °C-50 °C-50 °C and relative humidity of 30%-45%-30%.After repeated verification, the actual optimal value was 6.547%. It is proved that the actual optimal value was consistent with the predicted value through the verification of the predicted optimal combination. Then the coupling relationship between UFA and coupling factors of the drying system( including accumulated temperature, the absolute water potential sum of the air, the absolute water potential sum of the grain, the difference between the absolute water potential sum of the air and the absolute water potential sum of the grain, the accumulated of the absolute water potential of the air, the accumulated of the absolute water potential of the grain, the difference between the accumulated of the absolute water potential of the air and the accumulated of the absolute water potential of the grain) were calculated, and the results showed that the order of coupling relationship between UFA content and drying system was as follows: STMMG(0.674 3)> DSTMMGA(0.660 2)> STMMA(0.608 9)> SGT(0.589 3)> DATMMGA(0.477 2)> ATMMA(0.315 7)> ATMMG(0.257 6)> EAT(0.203 8). The coupling relationship between UFA content and absolute water potential of grain was the best. The formula for calculating the absolute water potential of grain can explain the coupling degree between them, and also prove that the theory of water potential can analyze and predict the content of unsaturated fatty acids in corn grains.