Kinetic Modeling For Mass Transfer Of Battered And Breaded Fish Nuggets During Deep-fat Frying

The objective of this study was to investigate kinetic modeling for mass transfer of breaded and battered fish nuggets(BBFNs)during deep-fat frying.The moisture and fat contents of three kinds of fried BBFNs including the general BBFNs(The batter was made up of medium-gluten wheat flour,corn starch,baking powder,salt and water),the BBFNs,which was deeply fried using soybean oil(fresh and heated for 10 h at 170?),and the low-fat BBFNs(Soybean fiber,xanthan gum,and whey protein were separately added to the batter)were measured and kinetic modeling for moisture evaporation and oil absorption of BBFNs was performed during deep-fat frying.Furthermore,the mechanism of mass transfer was also investigated through analysis of surface fat and penetrated surface fat content and simulation of fat absorption during deep-fat frying using the frying experiment in Sudan red dyed oil.The findings will be benefit for developing low-fat fried battered and breaded fish products in industrial scale.The main contents and conclusions are as follows:1.Kinetic modeling for mass transfer of general battered and breaded fish nuggets during deep-fat frying.The general batter was prepared through mixing medium-gluten wheat flour,corn starch,baking powder,salt,and water.BBFNs were respectively fried at three kinds of temperatures(160,170,and 180?)for 30 to 180 s(30,60,90,120,150,and 180 s)using fresh soybean oil to measure the content of moisture and fat.The kinetics modeling of mass transfer during deep-fat frying was performed by Fick's second law and First order kinetic model.Furthermore,the content of surface fat and penetrated surface fat was measured and fat absorption during deep-fat frying was simulated by using the frying experiment in Sudan red dyed oil to investigate the mass transfer mechanism of BBFNs during deep-fat frying.The results showed that moisture content of crust decreased with an increase of frying time,while moisture content of core firstly decreased,then increased,and finally decreased.Fat content of crust and surface oil content increased before 120 s of frying time,and decreased from 120 to 180 s.However,the content of penetrated surface oil slightly increased from 30 to 60 s,then a heavy increase was presented after 60 s of frying time.For 160,170,and 180?of frying temperature,the mass transfer coefficient of moisture evaporation fitted by Fick's second law were 0.0041(R~2=0.96),0.0042(R~2=0.90)and 0.0045(R~2=0.88),and mass transfer coefficient of oil absorption fitted by First order kinetic model were 0.055(R~2=0.95),0.059(R~2=0.93)and 0.066(R~2=0.92),respectively.The penetration level of Sudan red dyed oil into fried BBFNs increased with an increase of frying temperature and frying time.The findings indicated that the higher frying temperature and the shorter frying time increased the speed of moisture evaporation and oil absorption,resulted in more amount of oil penetrated into fried BBFNs.Fick's second law and First order kinetic model can excellently describe the mass transfer kinetics of BBFNs during deep-fat frying.Furthermore,the analysis of surface oil,penetrated surface oil,and Sudan red-dyed experiments highlighted the mass transfer mechanism of BBFNs during deep-fat frying.2.The effect of frying oil quality on mass transfer of BBFNs during deep-fat frying.Fresh soybean oil were heated at 170?for 10 h,then general BBFNs were fried at 170?for 30 to 180 s(30,60,90,120,150,and 180 s)using fresh(0 h)and heated soybean oil(10 h)to measure the content of moisture and fat,respectively.The kinetics modeling of mass transfer during deep-fat frying was performed by using Fick's second law and First order kinetic model.Furthermore,the content of surface fat and penetrated surface fat was measured and fat absorption during deep-fat frying was simulated by using the frying experiment 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 from two kinds of fried BBFNs decreased with an increase of frying time,while moisture content of core firstly decreased,then increased,and finally decreased.Fat content of the crust(0 h)increased before 120 s of frying time,and decreased from 120 to 180 s.However,fat content of the crust(10h)increased before 150 s of frying time,and decreased from 150 to 180 s.The mass transfer coefficient of moisture evaporation,which was fitted by Fick's second law were 0.0058(10 h)and 0.0045(0 h),respectively,while the mass transfer coefficient of oil absorption,which was fitted by First order kinetic model were 0.058(10 h)and0.057(0 h).Compared to fresh soybean oil,moisture content of fried BBFNs,which prepared using soybean oil heated at 170?for 10 h,significantly decreased and fat content increased,and the higher penetration levels of Sudan red-dyed oil were also presented.The findings indicated that kinetic modeling for mass transfer of BBFNs was significantly affected by the quality of frying oil during deep-fat frying.Aldehyde,ketone,and hydroxyl through oil oxidation increased with an increase of heating time,while the viscosity of frying oil was also increased since these products were prone to aggregation and oxidation polymerization to produce some of polarity compounds,such as dipolymer and tripolymer,resulted in an increase of mass transfer coefficient of BBFNs heated at 170?for 10 h.3.Kinetic modeling for mass transfer of BBFNs(soybean fiber,xanthan gum,and whey protein were separately added to the batter)during deep-fat frying.BBFNs,which xanthan gum(0.4%),soybean fiber(2%),and whey protein(4%)were separately added to the batter,were fried at three kinds of temperatures(160,170,and 180?)for 30 to 180 s(30,60,90,120,150,and 180 s)using fresh soybean oil to measure the content of moisture and fat,respectively.The kinetics modeling of mass transfer during deep-fat frying was performed by using Fick's second law and First order kinetic model.Furthermore,the content of surface fat and penetrated surface fat was measured and fat absorption during deep-fat frying was simulated by using the frying experiment 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 from three kinds of fried BBFNs decreased with an increase of frying time,while moisture content of core firstly decreased,then increased,and finally decreased.Fat content of crust increased before 120 s of frying time,and decreased from 120 to 180 s.The change of moisture and fat content was similar to general BBFNs.However,fat content of the crust from xanthan gum group increased before 150 s of frying time,while decreased from 150 to 180 s.For three kinds of BBFNs(soybean fiber group,xanthan gum group,and whey protein group),the mass transfer coefficient of moisture evaporation,which was fitted by Fick's second law,were 0.0027?0.0026?0.0029(160?),0.0038?0.0033?0.0039(170?),0.0039?0.0038?0.0054(180?),respectively,while the mass transfer coefficient of oil absorption,which was fitted by First order kinetic model,were 0.052?0.051?0.053(160?),0.062?0.059?0.061(170?),0.063?0.061?0.065(180?),respectively.The penetration level of Sudan red dyed oil into fried BBFNs increased with an increase of frying temperature at the same time.For the same temperature,the penetration levels of three groups have no significant difference from 30 to 60 s of frying time,while the highest level for whey protein group and the lowest level for xanthan gum group were separately presented from 90 to 180 s.The film formed by whey protein was easily brocken when the central temperature of core was higher than that of denaturation,resulted in the biggest mass transfer coefficient among three kinds of BBFNs.Xanthan gum can bind a great many of free water through carbonyl and carboxyl groups.Moreover,the film with high intension,which is formed through the interaction of xanthan gum and the starch in the batter was very stable during deep-fat frying,resulted in the smallest mass transfer coefficient.Soybean fibre can also bind a lot of free water through carbonyl and carboxyl groups.Moreover,soybean fibre can increase the expansion capacity and intension of gluten network structure.However,the smoothness of batter was declined due to big particle size of the fibre,so the mass transfer coefficient is higher than that of xanthan gum group.