炸用油品质对外裹糊鱼块深度油炸过程中传质动力学的影响

Effect of frying oil quality on kinetic modeling for mass transfer of BBFNs during deep-fat frying

为了研究炸用油品质对外裹糊鱼块深度油炸过程中传质动力学的影响,本试验将基本外裹糊鱼块分别在新鲜和加热10 h的大豆油中170℃油炸30、60、90、120、150、180 s,测定油炸外裹糊鱼块水分和油脂含量,采用菲克第二定律(Fick's second law)和一级动力学方程(First order kinetic model)分析油炸过程中的传质动力学。结合表面油脂和表面渗透油脂含量的变化,及苏丹红染色试验模拟油脂吸收,探讨炸用油品质影响外裹糊鱼块深度油炸过程中传质动力学的机制。结果显示,两组油炸外裹糊鱼块外壳水分含量随时间的增加而降低,鱼块水分含量先降低后升高再降低;新鲜大豆油组外壳油脂含量在0—120 s升高,120—180 s降低,加热10 h大豆油组外壳油脂含量在0—150 s升高,150—180 s降低。菲克第二定律拟合的水分蒸发的传质系数分别为0.0058(10 h)和0.0045(0 h),一级动力学方程拟合的油脂吸收的传质系数分别为0.058(10 h)和0.057(0 h)。与新鲜大豆油组相比,加热10 h大豆油组水分含量明显减少,油脂和表面油脂含量明显增加,苏丹红染色油脂渗入外裹糊鱼块较深,说明炸用油品质显著影响了外裹糊鱼块深度油炸过程中的传质动力学。随着加热时间延长,油脂氧化成的醛、酮、羟基增多,易发生聚合和氧化聚合作用,生成带支链的二聚体、三聚体等极性物质,炸用油的黏度增加,导致传质系数较大。

Fresh soybean oil were heated at 170C for 10 h,then BBFNs （breaded and battered fish fried at 170℃ for 30 to 180 s （30, 60, 90, 120, 150,and 180 s） using fresli （0 h） and heath） to measure content of moisture and fat,respectively. The kinetic modeling of mass transfer during deep-fat fry-ing was performed by using Ficks second law and First order kinetic model. Furthermore,the content of surface fatand penetrated surface fat was measured and fat absorj^tion during deep-fat frying was simulated bexperiment in Sudan red dyed oil to investigate the mass transfer mechanism of BBFNs during deep-fat frying. Theresults showed that moisture content of tlie crust from two kinds of fried BBFNs decreased witli an increasetime,while moisture content of core firstly decreased,then increased,and finally decreased. Fat content of thecrust （Oh） increased before 120 s of frying time,and decreased from 120 to 180 s. However,fat content of tiiecrust （10 h） increased before 150 s of frying time,and decreased from 150 to 180 s. The mass transfer coefficients of moisture evaporation,which was fitted by Ficks second law were 0. 0058 （10 h） and 0. 0045（0 h）, respective-ly,while the mass transfer coefficients of oil absorption,which was fitted by First order kinetic model were 0. 058（10 h） and 0.057 （0 h） . Compared to fresii soybean oil group,moisture content of fried BBFNspared using soybean oil heated at 170℃ for 10 h,significantly decreased and fat content increased,and the higherpenetration levels of Sudan red-dyed oil were also presented. The findings indicated that transfer of BBFNs was significantly affected by the quality of frying oil during deep-fat frying. Aldehyde, ketone,and hydroxyl produced through oil oxidation increased with an increase of heating time,while the viscosityoil was also increased since these products were prone to aggregation and oxidation polymerization to produce someof polarity compounds, such as dipolymer and tripolymer,resulting in an increase of mass transfer coefficient ofBBFNs heated at 170℃ for 10 h.