Fortified apple (Males spp., var. Fuji) snacks by vacuum impregnation of calcium lactate and convective drying

It was studied the mass transfer dynamics during calcium impregnation in sliced apples into a vacuum chamber for producing fortified snacks, evaluating the effect of vacuum impregnation (VI) at different pressure levels followed by a vacuum pulse on the drying kinetics and snacks quality. A model allowed to estimate the relative deformation of the sample, the loss of native solution, and the fraction of the sample filled by the impregnating solution. Calcium concentration became ten times bigger in impregnated samples, and vacuum intensity did not result in significant differences in the calcium content. However, 50 mbar in vacuum pulse decreased the calcium concentration by 35%. In air-dried apples, the final drying time was influenced by the vacuum pulse applied, reducing from 8.5 to 6.5 h. VI followed by a vacuum pulse presented higher drying rates than only impregnated and blanched apples. The model was validated by predicting the amount of calcium into the final snacks. The structural analysis confirmed the modification in the food matrix caused by the pretreatment; as a consequence, the snacks' texture profile did not show differences among procedures, however drying time was around 30% longer without the vacuum pulse.