Effect of vacuum impregnation with calcium lactate on the osmotic dehydration kinetics and quality of osmodehydrated grapefruit

Abstract

The effect of calcium lactate (2%) on osmotic dehydration kinetics and on the respiration rate, mechanical properties and shelf-life of fresh, vacuum impregnated (VI) and pulsed vacuum osmodehydrated (PVOD) grapefruit was evaluated. An isotonic solution was used for VI and a 55°Brix sucrose solution for PVOD treatments. Vacuum pulse was carried out at 50 mbar for 10 min and osmotic treatment was extended to 180 min. An increase from 5 to 8 days in the shelf-life of grapefruit was achieved due to sample dehydration and to 11 days if calcium is added to the osmotic solution, with no effect on the mechanical properties of the sample. This effect seems to be related with the decrease in the cellular respiration rate caused by dehydration and enhanced with the presence of this ion. Nevertheless, the water effective diffusion coefficient is reduced from 3.64 × 10 −11 to 1.80 × 10 −11 m 2/s when calcium lactate was added during the osmotic treatment.