Evaluation of the mechanism of oil uptake and water loss during deep-fat frying of tortilla chips

Simple equation M_t/M_∞ = Ktⁿ is evaluated to describe the Fickian mechanism of oil absorption and water release during the frying of tortilla chips in nixtamalized samples with and without lime, where n is characteristic of the Fickian mechanism that changes with food physical and chemical properties. Moisture releases showed a Fickian mechanism form tortilla chips with lime (n = 0.5) due to water interaction with matrix components and non-Fickian for tortilla chips without lime (n = 0.6). Oil absorption on tortilla chips showed a Fickian mechanism for nixtamalization with lime n = 0.4 and for nixtamalization without lime, one of n = 0.3. The larger water diffusion coefficient (D_w) in the tortilla chip compared to that of oil diffusion (D_o) indicates that water release and oil absorption during frying is not a simultaneous event. During tortilla chip frying, water release fallowed a chemical mechanism due to the interactions of matrix component materials with n > 0.5, while oil absorption presented physical mechanism n < 0.5 that was time independent. Diffusion exponent n, was related to the water released or oil absorption mechanisms.