Efeito da substituição da pectina por casca de banana em características tecnológicas de geleia de abacaxi

Abstract

To produce jelly is a method of preserving food using heat and increasing osmotic pressure, which keeps its nutritional or sensory characteristics, increasing its shelf life. As an alternative for minimizing waste and reusing food, it is possible to add by-products from fruit residues to jellies that can provide nutritional, sensory, and technological characteristics superior to conventional products. Banana peel is a nutritious by-product, rich in dietary fiber, proteins, minerals, and pectin, which enrich jellies, pastries, or sweets and improve their quality. Based on this, this work aimed to formulate pineapple jelly with the substitution of pectin for the banana peel. Three jelly formulations were prepared, a standard formulation with 50% of fruit pulp, 50% sugar, 1% pectin (referring to the sugar mass), and 0.65% citric acid (referring to the sugar mass); and jelly formulations with 20% and 30% of banana peel (referred to the mass of sugar) as a total replacement of pectin. Processing followed the Good Manufacturing Practices and the jellies Identity and Quality Standard. For all formulations, the following analyzes were performed in triplicate: soluble solids content, titratable acidity, pH, color, and water activity. Tukey's test was used to assess the significant difference between the means of the analysis results. Still, the rheological behavior of the formulations was evaluated in a rotational viscometer with concentric cylinders with strain rate varying from 0 - 33 s-1 for the ascent curves (increase in the deformation rate over time) and descent (decrease in the deformation in time) of each formulation. Data were fitted to four mathematical models representing the rheological behavior of food fluids: Power Law, Bingham Plastic, Herschel-Bulkley, and Sisko, and the fit was evaluated using different statistical parameters. The soluble solids content presented values between 59.2 and 62.03%, and no significant difference was observed between the formulations. The jellies with the addition of banana peel had lower soluble solids than those recommended in Brazilian legislation, possibly due to insufficient cooking time. No significant differences were verified for the titratable acidity and the water activity of the different jelly formulations, and the values obtained were within the recommended by the legislation. The pH of the jellies with the highest percentage of banana peel was significantly higher than that of the other samples, possibly due to the incomplete dissolution of the organic acids during the analysis. The instrumental color measurement showed that the standard jelly, with pectin, was significantly lighter than the others and that the formulations with 30% banana peel and extra were significantly greener than the formulation with 20% banana peel. The prepared jellies showed non-Newtonian behavior with thixotropic characteristics, best represented by the Bingham model for both ascending and descending curves. This points to thinning of the formulations during the flow, which can result in energy savings for the operation. Therefore, the banana peel showed potential for application in the manufacture of pineapple jelly as a substitute for pectin, pointing to the feasibility of reusing the by-product.