Influence of cultivar and process conditions on crispness of organic osmo-air-dried apple chips

The aim of this work was to evaluate the effect of different variables on osmo-airdried apple chips processing, in order to identify the most influencing factors on final product crispness.A 23 full factorial design was selected; cultivar (Golden Delicious and Pink Lady®), osmosis time (30, 60 and 90 min) and air drying temperature (70, 80 and 90C), were independent variables; crispness coefficient (E, kNmm-2),relative relaxation stress, water activity, color attribute L*, moisture content (gH2O/100 g solids) and panel score (crispness intensity) were dependent variables. Apple rings were immersed in sucrose, maltose or a mixture of fructose, glucose and sucrose (Aw = 0.90), and air dried to constant weight. Crispness and physicochemical properties were affected mostly by drying temperature, and less by cultivar and osmosis time. The screening test discriminated pretreated apples from not pretreated ones, the former being evaluated as crispier.Results indicate that the interaction between drying temperature and fruit tissue structure is the key factor optimizing the osmo-air-drying process, aimed at high-level crispy apple chips.