Background. Pre-osmotic dehydration of fruits may significantly reduce free water content. It also causes fruit penetration by solution components, increasing the efficiency of products manufactured by the osmotic-convection method. A study was carried out on a laboratory and industrial scale to perform an operational evaluation of a technological line for dried cherry production. Frozen pitted cherries (Łutówka variety) were the research material. Sucrose solution, concentrated apple juice, and sucrose and glucosefructose syrup mixture (1:1) were used for OD; with 70±2 °Brix at 40, 55 °C (an industrial scale), and 50 °C (a laboratory scale) to obtain ≥ 60 °Brix of fruit extract. Industrial convection drying was carried out at 70 °C until the water activity of < 0.6 was reached.
Results and conclusion. Increasing the osmoactive solution temperature enhanced the efficiency of a process aimed at fruit saturation by an osmotic substance and shortened the treatment time. Higher dehydration efficiency resulted in shorter convective drying time. No impact of the osmotic solution type on most mass exchange indices in dehydrated fruits was found. Despite the significantly higher process efficiency of the pre-dehydration in apple juice concentrate and drying stages, there was no significant impact of the solution type on the total process efficiency expressed as the ratio of dried mass to raw material mass. In spite of the same variants of osmotic dehydration of cherries in both production scales, the dehydration time under industrial conditions was even 11times longer. The technical condition of the tested line was determined as operable. The osmotic dehydration and drying equipment was working correctly. The complexity of repair processes and time-consuming equipment cleaning were demonstrated.
pre-treatment, production scale, osmotic dehydration, cherry snacks, juice concentrate