添加不同成分的外裹糊鱼块深度油炸过程中的传质动力学

摘要

In the present study, xanthan gum (0.4%), soybean fiber (2%), and whey protein (4%) were separately added to the batter made up of medium-gluten wheat flour, corn starch, baking powder, salt, and water. Breaded and battered fish nuggets (BBFNs) were fried at 170 ℃ for 30 to 180 s (30, 60, 90, 120, 150, and 180 s) in fresh soybean oil to measure moisture and fat content. Kinetic modeling for mass transfer during deep-fat frying was performed by Fick's second law and first order kinetic model. Furthermore, surface oil and penetrated surface oil content were measured and oil absorption was simulated using frying experiments in Sudan red dyed oil to investigate the mass transfer mechanism of BBFNs during deep-fat frying. The results showed that moisture content of the crust of three fried BBFNs decreased with the increase of frying time, while moisture content of the core firstly decreased, then increased, and finally decreased. Fat content of the crust increased from 0 to 120 s of frying, and then decreased from 120 to 180 s. For BBFNs with soybean fiber, xanthan gum, and whey protein, the mass transfer coefficient of moisture evaporation (0.003 8, 0.003 3, and 0.003 9 s-1, respectively) was fitted to Fick's second law, while the mass transfer coefficient of oil absorption (0.062, 0.059, and 0.061 s-1, respectively) was fitted to a first order kinetic model. The oil penetration levels for the three fried BBFNs were not significantly different from 30 to 60 s of frying, while the highest level for BBFNs with whey protein and the lowest level for BBFNs with xanthan gum were separately presented from 90 to 180 s. These findings indicated that moisture evaporation and oil absorption in BBFNs during deep-fat frying were affected by separate addition of soybean fiber, xanthan gum, and whey protein in the batter, resulting in a significant difference in mass transfer coefficient among the BBFNs.%将大豆纤维、黄原胶和乳清蛋白分别添加到基本外裹糊(中筋小麦粉、玉米淀粉、泡打粉、食盐)中制成外裹糊鱼块,在170 ℃大豆油中油炸30、60、90、120、150 s和180 s,测定油炸外裹糊鱼块的水分及油脂、表面油脂和表面渗透油脂质量分数,采用菲克第二定律和一级动力学方程分析油炸过程中的传质动力学,通过苏丹红染色实验模拟油脂吸收.结果显示:大豆纤维组、黄原胶组和乳清蛋白组外壳水分质量分数均随油炸时间的延长而降低,而鱼块水分质量分数先降低后升高再降低;油炸0~120 s时,大豆纤维组、黄原胶组和乳清蛋白组外壳油脂质量分数均升高,油炸120~180 s时降低.菲克第二定律拟合大豆纤维组、黄原胶组和乳清蛋白组水分扩散系数分别为0.0038、0.0033 s-1和0.0039 s-1;一级动力学方程拟合大豆纤维组、黄原胶组和乳清蛋白组油脂吸收的传质系数分别为0.062、0.059 s-1和0.061 s-1.油炸30~60 s,3 组外裹糊鱼块的油脂渗透幅度差异不显著;油炸90~180 s,乳清蛋白组油脂渗透最深,黄原胶组最浅.表明外裹糊中分别添加大豆纤维、黄原胶和乳清蛋白影响了外裹糊鱼块深度油炸过程中的水分蒸发和油脂吸收,导致传质系数差异明显.