Influence of osmotic dehydration on texture, respiration and microbial stability of apple slices (Var. Granny Smith)

In order to analyse the feasibility of obtaining minimally processed apple samples, the effect of osmotic dehydration, at atmospheric pressure (OD) and by applying a vacuum pulse (PVOD), on mechanical properties, respiration rates and microbial stability of apple slices was analysed throughout storage at 10 °C. Treatments were carried out until reaching 20 and 30 °Brix in the samples. They caused a decrease in the values of the force dependent mechanical parameters, especially when applying vacuum pulse, whereas a small increase was observed when 1% calcium was applied. Nevertheless, these parameters were better preserved during storage when sample concentration was 20 °Brix and vacuum was applied. Osmotic treatments reduced oxygen consumption and, only when samples had 30 °Brix did CO2 generation increase. During storage, treated samples showed lower respiration rates than the control ones, which remain practically constant during storage when they had 20 °Brix. A greater microbial stability was obtained in dehydrated samples, especially in PVOD treated ones.