真空法降低油炸制品含油量

Reduction of Oil Uptake in Deep Fried Products by Vacuum Method

以圆柱形土豆条为研究对象,对油炸和冷却过程中样品表面和内部温度、水蒸气压力以及不同阶段吸油量变化规律进行测量与分析,发现油炸过程中由于水蒸气持续从多孔壳层逸出,阻碍了油进入食品中,土豆样品中70%左右油是在冷却阶段进入食品壳层中的,而且导致吸油的动力——蒸汽冷凝形成的壳层内外压差对环境气压很敏感。在油炸样品冷却阶段,将油炸土豆条置于不同真空环境进行冷却,发现绝对压力80kPa的条件下冷却时,总吸油率从40%降至13.6%,说明冷却过程的真空条件能降低壳层内、外压差驱动力,有效促进表面附着油滴落,阻碍其被吸入食品结构中,从而降低油含量。

Surface and internal temperatures,water vapor pressure and oil adsorption rate changes in different stages were measured during the deep-frying and cooling processes of cylindrical potato strips.It was found that continuous water vapor escape from the porous shell layer could prevent oil from entering potato strips during the deep-frying process.During the cooling process,over 70% of oil was absorbed into the porous shell layer,providing an impetus for oil absorption—The difference in water vapor pressure between the inside and outside of the shell layer was very sensitive to ambient pressure.Cooling of fried potato strips was studied in different vacuum environments.The results obtained showed that under an absolute pressure of 80 kPa,the total oil absorption rate was decreased from 40% to 13.6%,suggesting that vacuum environments could reduce the water vapor pressure difference between the inside and outside of the shell layer,effectively promote the detachment of adherent oil droplets from the surface,impeding their absorption into the structure of fried potato strips and therefore reducing oil uptake.