INFLUENCE OF A BLANCHING PRETREATMENT ON COLOR, OIL UPTAKE AND WATER ACTIVITY OF POTATO STICKS, AND ITS OPTIMIZATION

ABSTRACT The objective of this research was to study the influence of different blanching conditions on potato stick color, oil uptake and water activity (Aw ), and optimize the process by means of the desirability function. Color was expressed as properties of L*a*b*and L*C*h*spaces, some of which were fitted by Box–Behnken quadratic models. The blanching optimum conditions were as follows: a concentration of ascorbic acid of 0.2 g/100 g potato, a time of 5.5 min and a temperature of 69C. Responses obtained when using these conditions were −1.68 a*value and −86.31° h*value, which represent a hue in potatoes unaffected by the enzymatic browning. Regarding oil uptake, some of the blanched sticks absorbed 31% less oil than the control. Regarding Aw, all blanched samples presented lower values than the control, suggesting that blanching increases the shelf life of fried potatoes. PRACTICAL APPLICATIONS This article presents that the optimized blanching process conditions were able to control the enzymatic browning in potato sticks prior to frying, and thus improved their quality. Furthermore, some blanching conditions were found to decrease by 31% the oil uptake in potato sticks, leading to healthier fried potatoes. Finally, blanching significantly decreased the Aw in all fried potato sticks evaluated, suggesting that this process is also a way to increase the shelf life of fried potatoes.