SOLAR DRYING OF BANANA FORTIFIED WITH CALCIUM BY OSMOTIC DEHYDRATION

DELLA ROCCA PATRICIA; BRUNO, E.; ROCHE L.; CAMPAÑONE, L.A.

Conferencia; 5th International ISEKI_Food Conference; 2018

The objective was to study the solar drying of banana pretreated by osmotic dehydration (OD). Solar drying of vegetables is a way to make renewable energy contribute to social development. During this pretreatment, the banana slices were impregnated with calcium so as to obtain a product that was high quality and nutritional with a final humidity content of 20 % (wb, wet base). Besides, the influence of the osmotic dehydration and solar drying were analyzed over the bioactive compounds (total phenolic compounds content and the antioxidant activity).The material used were bananas, specie Musa Cavendish. These were peeled, cut into slices of 0, 5 cm and were immersed in an aqueous solution of sucrose (40% m∕m), calcium chlorine (5% m∕m), L (+)-ascorbic (5% m∕m) and citric acid (1 % m∕m) (55° Brix). The experiments were carried out at 40 ºC. The solution to banana mass ratio was 4:1 and the solution was stirred at 120±5 rpm.The calcium concentrations were measured by a flame atomic absorption spectrophotometer. The texture parameters were determined by a Stable Micro Systems texturometer, model TATX2i. The total phenolic compounds were determined by the Folin Ciocalteu method and the antioxidant activity was determined by DPPH technique.The calcium content of fresh banana (3, 3 ± 0, 5) mg∕100g of sample was incremented significantly after 1 hour of OD (67 ± 1) mg∕100 g of sample. The addition of calcium allows to preserve the texture of the samples after drying, since it promotes the cross linking of pectin polymers. In the texture profile analysis (TPA), it can be appreciated that the strength of the banana diminishes with the OD, and therefore, the total drying process reduces the adhesion of the product.The total phenolic compounds was 4 mg GAE (gallic acid equivalents)∕g dry solid and the antioxidant activity (AA) was 2,59 % for the fresh banana, 3,68 mg GAE∕g dry solid and AA: 3,09 after 1 hour of OD, 2, 97 mg GAE∕g dry solid and AA: 0,53 % after 1 hour of OD and 7 h of solar drying.The advantages of this drying method (7 h solar drying with 1 h pretreatment by OD) were the low energy intake and the possibility to obtain a product with an additional mineral value at low cost. The OD improves the nutritional and textural characteristic of the solar drying banana, however a decrease of the antioxidant capacity was produced during the solar drying.