modeling apparent density during drying of grapes pretreated with ultrasound and carboxymethyl cellulose

drying foodstuffs can have negative effects on quantitative and qualitative characteristics of the products, including porosity and bulk density. therefore, novel technologies can be used to improve these characteristics. in this study, apparent density changes during drying grapes pretreated with ultrasound for 10, 20 and 30 minutes, and carboxymethyl cellulose (cmc) at three concentrations of 0.1, 0.2 and 0.3 percent was evaluated. in order to dry the grapes, a tunnel dryer was used and the samples apparent density was calculated during drying. the results showed that apparent density of the grape samples is increased with increasing ultrasound time and decreasing cmc concentration. furthermore, apparent density was modeled through existing models in the literature as well as the models proposed in this study. one of the proposed models (model 6, table 2) was selected as the most appropriate model to predict changes in the apparent density of the grapes during drying.