Microstructural characterization of vacuum-fried matrices and their influence on starch digestion

Abstract

During vacuum frying, starch gelatinization may be limited due to the water boiling point depression, which reduces starch digestibility. In addition, relevant structural changes are induced, which could affect the accessibility of amylolytic enzymes to the site of action. To differentiate the effect of structural changes in the food matrix over the effect of starch gelatinization on starch digestibility, we characterized the microstructure using x-ray micro-computed tomography (micro-CT), confocal laser scanning microscopy (CLSM) and environmental scanning electron microscopy (ESEM), and we also studied the starch in vitro digestibility in two different systems: vacuum (9.9?kPa, Twater-boiling-point?=?45?°C) and traditional atmospherically-fried dough (170?°C) with a similar degree of starch gelatinization (60 %). Vacuum-fried matrices had a much higher oil content (?51.3 % dry basis) than their atmospheric counterparts (?20.3 % dry basis), as confirmed through micro-CT and CLSM.