Otimização da desidratação osmótica de uva Crimson Seedless (Vitis vinifera L.)

Abstract

Crimson Seedless Grapes (Vitis vinifera L.) is one of the most important seedless variety, due to its attractive bunch medium, and large dark pink berries. It features excellent sensory characteristics due to its firm texture and crisp flavor that varies from sweet to neutral and uniform color. Stands out as the second most important seedless variety of the São Francisco. Osmotic dehydration is presented as a good alternative to reduce the water activity of this grape, allowing its storage for long periods and improving its stability and quality. This study aimed to relate the influences of different parameters for efficient osmotic dehydration of fruit, in order to reduce post-harvest losses as well as offer new alternatives for the producer. To optimize the osmotic dehydration preliminary test was conducted with independent variables: temperature (T) (20ºC to 40ºC), immersion time (t) (0.5 to 4.0 hours, with breaks every 30 minutes) and concentration of osmotic solution (C) (35ºBrix, 50ºBrix and 60ºBrix) was the dependent variable moisture loss (ML). Then 26-2 fractional design was used, having as independent variables: T (30ºC and 50ºC), t (1.0 and 4.0 hours), NaOH (0% and 2%), bleach (0 and 1 minute), perforated in the fruit (0 and 16 holes/cm2) and C (30ºBrix and 60ºBrix) and the dependent variables and solids ML and incorporation of solid (IS). Proceeding was conducted a factorial design 23, with independent variables: T (30ºC to 50ºC), t (1 to 4 hours) and C (40ºBrix to 50ºBrix), being constant bleaching (30 seconds) and perforated (8 holes/cm2); the dependent variables were ML, IS and DEI (Dehydration Efficiency Index). The best conditions for osmotic dehydration using DEI as a parameter was the application of bleach for 30 seconds, 8 holes/cm2, osmotic solution at 42ºBrix, immersion time of 1.6 hours and temperature of 46 ° C. The response surface models obtained were predictive of ML and IS, except for DEI. The product selected best set Page's equation (R2 = 0.995).