Ascorbic acid and calcium uptake in pineapple tissue through different sucrose concentrations of impregnation solution

Incorporation of ascorbic acid and calcium in pineapple slices through impregnation processes in isotonic (similar to 14 degrees Bx) and hypertonic (50 degrees Bx) aqueous solution of sucrose was studied. Changes in water content, soluble solids, pH, mechanical and structural properties, ascorbic acid and calcium content in fruit in function of dipping time and impregnation syrup concentration were evaluated. Isotonic treatment was more effective than hypertonic treatment for the calcium and ascorbic acid incorporation in the plant tissue. Under same conditions, the ascorbic acid uptake was greater than calcium uptake. The fruit firmness was reduced during isotonic treatment and increased by osmotic dehydration, without significant effect of the nutrients addition to the impregnation solution. Additionally, changes in some physicochemical properties of impregnation solution in function of the time have been studied. Nutrient content in impregnation solutions did not register significant changes, which would allow its reuse with some conditioning of the soluble solids concentration.