Improving the physical properties crunchiness of potato crisps by pretreatment techniques and vacuum frying

Vacuum frying with pre-treatment of potato crisps are potentially effective processes on the improving the crispness of potato crisps. Pre-drying and subsequent sugar dipping are considered as an advantageous process as the pre-treatment of potato crisps to reduce considerable amount of oil uptake. In this study, potato crisps were blanched, pre-dried, and dipped in the solution of sugar (23.07%, in 2 seconds) before vacuum frying at 120 oC, 110 oC with vacuum pressures, which is 150 mbars. The results were collected by testing the crispiness of the potato crisps with the three-point-support method and using an Instron Universal Testing Machine through the texture parameters: Maximum Peak Force; Slope of Initial Tangent, Hardness, Stiffness, Firmness, Modulus of Elasticity and Maximum Tensile Stress. There was a significant improving in physical properties of crisps observed. Crisps that had been pre- treatment and vacuum- fried at 110 oC (150 mbars) had much improving in crispness (50%) including the hardness (170%), stiffness (140%), firmness (50%) and modulus of elasticity (60%) compared with normal frying at 180 oC without pretreatment and vacuum frying. The effect of vacuum frying and the pre-treatment technique on the improving the physical properties of crisps was evaluated. The shrinkage of potato crisps after frying was also considered in this research. The color and microstructure of potato crisps with pre-treatments and vacuum frying have also been obtained.