Desidratação osmótica seguida de secagem de goiaba para obtenção de passas.

Abstract

Guava (Psiduim guajava L.) is used not only for fresh consumption as well as to attend a substantial demand for industrial canning enabling, by its dehydration, a new ingredient in food industry. In order to serve this market, this research was conducted with the aim of processing the 'Paluma' guava using combined techniques of osmotic dehydration and conventional drying to obtain raisin of guava Guavas were used in the maturity stages, immature and mature, pretreated in sucrose solution, with two concentrations (40 and 50 °Brix) and submitted to drying in an oven with air circulation, at four temperatures (40, 50, 60 and 70 °C). Data were treated according to the models of Henderson and Pabis; Midilli, Page and Thompson. It was made the physicochemical characterization of fresh guavas after each process step. The data of physicochemical analysis were treated following a completely randomized experimental design with three replications for each step of the process of osmotic dehydration and drying. For data analysis was used the Assistat 7.0 software. It was analyzed the texture of the raisin of guavas as for tests of fiber rupture, resistance to compression and cutting, using the TAXTplus equipment - "Texture Analyser", Stable Micro System. There was a sensory analysis with the developed products through a 5-point hedonic scale, analyzing the attributes of appearance, color, aroma and flavor and tests were applied for acceptance and purchase intent. Data were interpreted by analysis of variance and means were compared by applying the Tukey test. The main conclusions from this research were that the higher sucrose concentration and high drying temperature leads to high water removal in osmotic dehydration and drying, respectively. For the same drying temperature, the sucrose concentration on osmotic pretreatment solution did not influence the drying time to obtain raisin of guavas; the Page model represents better the experimental data of drying, with the lowest DQM; pH of guavas at mature and immature stages was lower than 4.04 throughout all process, to obtain raisin of guava; there is a concentration of acidity as the water content of guavas reduces; immature guavas after osmotic dehydration lose vitamin C and, after drying process, there is a concentration of this nutrient; In mature guavas there is an addition of vitamin C after dehydration osmotic and loss after drying process; the ash content of immature guavas throughout the process (in fresh way after osmotic dehydration and after drying) was higher in percentage terms, than in mature guavas; the softer samples were those obtained in temperatures of 40 °C disregarding maturation stage, being influenced by the osmotic solution in which were immersed; the most accepted samples, according to sensory analysis, were those that obtained the highest percentage for purchase intent, which were immature dehydrated guava obtained in osmotic solution of 50 °Brix and drying at 40 °C, and raisin of guava, osmotically dehydrated at 50 °Brix and drying at 50 and 70 °C, respectively.