Evaluation of phenolic compounds in strawberry (Fragaria ananassa Duch) coated with nopal mucilage (opunta ficus indica) dehydrated by convection

The objective of the project was to evaluate the effect of drying, indirect solar and drying oven (40, 50, 60 °C) on the concentration of phenolic compounds in strawberry slices coated with nopal mucilage (Opuntia ficus indica) measured with the spectrophotometric method. The strawberry was sliced (0.2 cm of thickness) and coated with nopal mucilage by immersion during 3 s. The mucilage was extracted by thermal treatment (80 °C) in the ratio 1:2. Three drying temperatures (40, 50 and 60 °C) were tested in the oven drying. The indirect dryer uses a combined solar technology (thermal - photovoltaic): solar
collector for water heating and photovoltaic system for the fan. Solar dryer worked with temperatures between 40 and 60 ° C. The determination of total polyphenols was carried out using the Folin - Cicaltecau method, in which Gallic Acid was used as reference reagent, the samples were read at 750 nm. The determination of the antioxidant activity consisted in the DPPH radical technique (2,2- diphenyl-1-picrylhydrazyl), using Ascorbic Acid and analyzed at 517 nm. The concentration of total phenols in strawberry dehydrated at 60 ° C was greater preserved. Strawberry coated with nopal mucilage has a conservation of phenolic compounds in conventional dryers and indirect solar.