Modelagem do processo de obtenção de goiaba (Psidium guajava L.) passa.

Abstract

Guava (Psidium guajava L.) presents intense metabolism, and is limited to short period of marketing fresh. Pretreatment osmotic dehydration can be used to partially reduce the initial moisture content of the fruit, resulting in a new commercial product.This work aimed to study the process of obtaining guava passes at different temperatures of osmosis and sucrose concentrations.Was used guava variety Paluma (3.0 x 2.0 x 0.9 cm) dehydrated in sucrose syrup in concentrations of 40, 50 and 60° Brix in temperatures of 30, 40 and 50 °C. The process was complemented in heated air dryer at temperatures of 50, 60 and 70 °C.The water loss and gain data of sucrose for osmotic dehydration and the drying kinetics data were fitted to Lewis model, Henderson and Pabis, Page, Peleg e Silva et alii, using the LAB Fit program.Guavas passes were submitted to physical and chemical analyzes: soluble solids, pH, acidity, ash, reducing and total sugars, Aw and color.The microbiological test was performed by coliform and Salmonella analysis, and sensory attributes (color, flavor, texture, aroma, and purchase intent) analyzed by 51 untrained tasters. Instrumental analysis of texture with TAXT plus equipment were held through fiber rupture tests and shear strength with samples more accepted in the sensory test. The results indicate osmotic dehydration Peleg model as suitable for predicting the mass transfer phenomenon. Among the variables used, the osmotic solution concentration exerted a significant influence on the amount of water and amount of sucrose, but the temperature had no significant influence.The variance analysis applied classifies linear models to describe the amount of water and sucrose to active (P <0.05) during osmotic dehydration phenomenon can predict 90% of the variation observed data. The description of the drying kinetics was best represented by the Page model with R2 values of over 0.9959.The variance analysis of physicochemical data Guava shall show a significant difference (p <0.01) in all parameters, with considerable increase in total and reducing sugars from the increase in concentration and osmotic dehydration temperature. The microbiological test satisfied the current microbiological standard, not being able to present a risk to consumer health. The samples according to commonly accepted sensory analysis were obtained at a concentration of 40 °Brix in dehydration temperatures of 30 to 50 °C followed by drying at 60 °C, and better texture of the osmotically dehydrated condition and 40 °Brix 50 °C followed by further drying at 60 °C.