Study On Processing Method Of Low Oil Content Potato Chips Based On Pore Characteristics

Fried foods appeal greatly to the consumers because of their distinctive taste,attractive color,and unique flavor,but its high oil content can be a potential threat to human health.Consequently,it is of great significance to clarify the oil absorption mechanism during frying and to decrease the oil absorption of fried food.This study takes fried chips as the research material,and clarifies the law of pore characteristics affecting oil absorption.Based on the relationship between pore properties and oil absorption,the pore characteristics of fried potato chips were regulated by different pretreatment methods to reduce the oil content of potato chips.Firstly,the changes of the basic characteristics in potato chips during frying were studied.After frying 160 s,the oil content of potato chips increased from 1.10% to 60.77%.The oil gradually permeates from the surface to the inside of the potato chips.The edges of the potato chips have a higher oil distribution than that in the rest.During the frying process,the porosity of potato chips increased,while the bulk density,total pore volume and average pore volume decreased.During the frying process,the oil absorption of potato chips was correlated with the change of pore characteristics,and the correlation analysis between pore size distribution and oil content showed that the pore volume of 10 ?m?100 ?m and 100 ?m?200 ?m in potato chips had a significant positive correlation with oil content(p < 0.05).In order to reduce the fat content of fried potato chips,the pore distribution of potato chips was regulated by ultrasonic pretreatment before frying.By using ultrasonic at 360 W for 60 min,the percentages of pore volume with the diameters of 10 ?m?200 ?m in the fried potato chips were reduced by 12.37%,compared with unpretreated potato chips.Moreover,the total oil content of fried potato chips was reduced by 27.66%,compared with that of unpretreated potato chips.Ultrasonic pretreatment can change the ratio of free water and mechanically bound water in potato chips by affecting the properties of potato starch,which can reduce the intensity of water evaporation in potato chips.The decrease in the intensity of water evaporation reduces the formation of large pore size(10 ?m?200 ?m)during frying,which can reduce the oil absorption of potato chips.Ultrasonic pretreatment can improve the crispness of fried potato chips,but it has no effect on their color.In order to further reduce the oil content of fried potato chips,potato slices were pretreated by hot air drying to regulate the pore distribution before frying.When potato slices were dried to 50% and 20% of their initial mass,the percentages of pore volume with the diameters of 10?m?200 ?m in potato chips was reduced by 29.78% and 50.94%(compare with the unpertreated sample),respectively.When potato slices were dried to 80%,50% and 20% of their initial weight,the oil contents of hot air drying pretreated samples decreased by 12.67%,28.24% and62.07%,respectively(compare with the unpertreated sample).Compared with the fried potato chips without pretreated,the fried potato chips with hot air drying before frying had less microstructural damage and less irregular cell deformation.However,the high degree of drying pretreatment will have an adverse effect on the color and crispness of the potato chips.According to the effect of reducing oil absorption,the ultrasonic pretreatment condition of360 W and 60 min was selected to combined with hot air drying,and the pore distribution of potato slices was regulated.When the potato chips were pretreated by ultrasonic combined with hot air drying to 50% and 20% of the initial weight,the percentages of pore volume with the diameters of 10 ?m?200 ?m were reduced by 42.82% and 56.64%,respectively(compared with the unpretreated potato chips).Compared with the ultrasonic pretreated potato chips,the percentages of pore volume with the diameters of 10 ?m?200 ?m were decreased by 34.80%and 50.56%,respectively.When the ultrasonic pretreated potato slices were dried to 80%,50%and 20% of the initial weight,the total oil content of fried potato chips decreased by 24.03%,37.64% and 60.42%,respectively(compared with unpretreated potato chips).The total oil content of fried potato chips pretreated by ultrasonic combined with hot air drying decreased by 7.42%,24.10% and 51.76%,respectively(compared with ultrasonic pretreated potato chips).Compared with hot air drying,the surface of fried potato chips pretreated by ultrasonic combined drying had more pores and micro-channels.This study results show that the oil absorption of potato chips closely related to the change of pore characteristics during frying.Ultrasonic pretreatment,hot air drying pretreatment,and ultrasound combined hot air drying pretreatment can regulate the pore characteristics of potato slices,which could reduce the oil absorption of potato chips.Compared with the single pretreatment method,ultrasonic combined with hot air drying pretreatment has a better effect on reducing the fat content of potato chips.