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物料干燥过程中收缩严重影响水份的迁移速度,对收缩现象的研究,不仅可以更准确地描述干燥过程,而且可以防止产品褶裂,保证产品质量。对加工番茄收缩特性进行了试验研究,结果发现,干燥过程中,风速和温度会对加工番茄收缩的快慢产生影响但对最终收缩系数影响不大;干燥初期,收缩系数随着含水率的降低急剧增大,当含水率达到60%时,随含水率下降物料收缩系数增加缓慢;体积收缩系数与单位体积脱水量在干燥初期大致相等,但在干燥后期体积减少量远小于物料脱水量。
Material shrinkage during drying seriously affect the migration speed of water, the study of shrinkage phenomenon, not only can describe the drying process more accurately, but also can prevent the products from cracking and ensure the product quality. The experimental study on the shrinkage characteristics of processed tomato showed that during the drying process, the wind speed and temperature had an effect on the shrinkage of processed tomato but had little effect on the final shrinkage coefficient. In the initial stage of drying, the shrinkage coefficient sharply decreased with the decrease of moisture content When the moisture content reaches 60%, the coefficient of shrinkage of materials decreases slowly with the decrease of water content. The volumetric shrinkage coefficient is almost equal to the unit volume of dehydration at the initial stage of drying, but the volume decrease at the later stage of drying is much less than the amount of material dehydration.