Effects Of Osmotic Dehydration At Different Conditions On The Quality Of Semi-Dried Pumpkin Slices

Abstract

This study aimed to investigate the changes in the chemical and physical properties of pumpkin dried at 70°C after undergoing pretreatment with sucrose and erythritol solutions at concentrations of 30% and 50%, with and without the assistance of ultrasound. The water loss (WL) and solid gain (SG) during pretreatment were examined to assess the effectiveness of the process. The highest water loss was observed in samples treated with ultrasound-assisted osmotic dehydration (USOD) in a 50% sucrose solution, while samples treated with a 30% erythritol solution (30E) exhibited the highest solid gain. Furthermore, the experimental data obtained during the drying process were fitted to four theoretical models to predict the drying kinetics of the pumpkin. Among these models, the Midilli et al.'s model showed the best fit to describe the process. The drying time of the USOD 30E sample was the shortest, at 176 minutes, representing a decrease of 50.28% compared to the control sample to reach a final moisture content of 20%. Significant differences in the chemical and physical properties of the pumpkin were observed after pretreatment with osmotic solutions, with and without ultrasound. Regarding carotenoid content and DPPH (2,2-diphenyl-1-picrylhydrazyl) activity, the USOD samples showed no significant difference from the untreated samples (p > 0.05). However, the control samples had the highest total phenolic content. Additionally, the OD and USOD samples exhibited lower hardness, lower shrinkage ratio, brighter color, and higher overall organoleptic scores compared to the non-pretreated samples. The findings of this study demonstrated that OD and USOD treatments had the potential to conserve energy, reduce drying time, and potentially improve the quality of fruits after drying.