Influence of osmotic pretreatments on the quality properties of deep-fat fried green plantain

Modification of the surface properties of materials is a promising approach to reduce the uptake of oils during frying. In this work, the quality characteristics of plantain chips subjected to a pretreatment consisting of osmotic drying in sugar solutions (29 and 45° Brix; 40 and 80 °C) were evaluated. True density, apparent density, porosity and moisture content were measured in pretreated samples (PS) before frying. Image ESEM was used to evaluate microstructural changes on the surface and in cross-sections at different depths. Global oil absorption (GOA) and fatty acid profile were monitored in surface and deep cross-sections (DCS). The color parameters of chips (L*, a*, b*, ΔE), browning index, crispness, crunchiness and hardness were evaluated during frying. Oil absorption in the crust was lower in samples subjected to pretreatments with a higher temperature. PS showed high gelatinization in both the surface and DCS, thus changing crust physical properties, total oil uptake and fatty acid profile. An exponential correlation between porosity (ε) and GOA was found, while a second order correlation was found between ε and the fatty acid profile. The characteristics of texture and color, as desired by the consumer, were reached more quickly in the PS at 29° Brix and 40 °C.