Drying kinetics of apple slices (Pyrus malus L) pachacamac variety osmotically pretrated

Abstract

It was determined the effect of two concentrations of sucrose syrup (40 and 50 Brix) of osmotic pre treatment and the effect of three temperatures of drying air (50, 60 and 70° C) on the diffusivity effective coefficient and the general acceptability sensorial test of apple slices (Pyrus malus L) Pachacamac variety . Apple slices of 60 mm diameter and 4 mm thick were immersed in 1% solution of citric acid and 0.5% sodium bisulfite (w / v) for 10 minutes at room temperature and osmotically dehydrated in two sucrose solutions (40 and 50 ° Brix) with 0.5% citric acid (w / w) at 20 ° C with constant agitation (110 rpm) during twelve hours. Convective drying was performed with an air speed of 2 m / s. The weights of the slices were monitored until there was no significant difference between them. It was constructed the drying curve and was calculated the effective diffusion coefficient for each treatment, until final moisture of 12%. Statistical analysis was performed to determine significant differences between treatments. The results showed that high temperature of drying air (70 ° C) provides higher effective diffusion coefficient and that only the drying air temperature had a significant effect. It was found by the Kruskal-Wallis test significant difference in the general acceptability sensorial test between treatments, and the Mann Whitney test determined that treatment 5 (50 ° Brix, 60 ° C), had the best sensorial response, with a value of, corresponding to " I like moderately" on the hedonic- scale.