Desidratação osmótica precedida de secagem convectiva e tratamento com biofilmes de polpa de mamão.

Abstract

Osmotic dehydration combined with other processes, such as drying and the use of the biofilm, can be employed to improve the stability and acceptance of these products. Papaya is a fruit with considerable economic potential for domestic and foreign trade. However, its limitations are: post-harvest conservation, highly perishable and easily damaged soft structure. Thus, the control of ripening is fundamental to the increase of its lifespan. For this reason, the study was conducted with the aim of making a comparison between the stability of osmotically dehydrated and dried papaya subjected to coating with and without biofilms. The fruits were selected, washed, disinfected and coated with cassava starch biofilms at concentrations of 2, 3 and 4%, and stored for 10 days in BOD chambers at a temperature of 10°C. Treatment effects were assessed by parameters such as color, total soluble solids, titratable acidity, water activity, moisture content and pH, with three replications. We used a 22 factorial design with three central points (level 0), and star configuration (CCRD), in which we checked the influence of the variables immersion time and concentration of sucrose. From the planning done at dehydration optimal point (50° Brix for 4h), for performing the process of air drying in an oven with circulating air at temperatures of 50 and 70 ºC. To represent the drying process, 4 mathematical models were used. Models of Henderson & Pabis, logarithmic, Midilli & Kucuk and Page, adjusted to the experimental values and we recommended those that showed the best coefficients of determination (R ²) values. From the results, it was found that the use of biofilms for manioc starch and at 2 and 4% reduced the weight loss, retained the firmness and improved visual appearance, allowing storage for a longer time without loss of fruit quality. The input variable concentration of sucrose had a greater influence on the response variables evaluated (% PA, % PM, % GS and IED). The drying curves of the osmotically dehydrated papaya at a concentration of 50 ° Brix and at temperatures of 50 and 70°C, obtained experimentally, showed a typical behavior in which the temperature increase caused a decrease in drying time. It was found that all models used adjusted well to the experimental data due to the fact that all of them have determination coefficients greater than 99.8%. As a result, the model proposed by Midilli and Kucuk was the best one to fit the experimental data, obtaining coefficients of determination (R2) greater than 99.9%, and lower average percentage of deviations (P), less than 7.85%. At the end of the storage period (10 days) no papayas, independent of the treatment used for marketing, presented sufficient quality for trade.