Estabilidade de polpa de uvaia (Eugenia pyriformis Cambess) congelada

Abstract

Brazil has a wide diversity in native fruit species, with great nutritional potential. Uvaia (Eugenia pyriformis Cambess) is one of these promising fruits, but little explored in the current agroindustrial scenario, due to its high perishability. Processing appears as an alternative to encourage consumption and promote the conservation of pulps of exotic fruits such as uvaia. Thus, the objective of this work was to evaluate the effect of freezing on the stability of uvaia pulp during long-term storage. For this purpose, fruits from Coqueiral - MG, Brazil, were selected, washed, sanitized and frozen until the necessary amount for the accomplishment of all the analyzis was reached. Then, the fruits were unfreeze under water, pulped and homogenized and the pulp was packed (50 g) in low density polyethylene plastic bags. The pulps were freezed under two diferente methods, forced air (AF) and static air (AE), and stored for 12 months. The following analyzis were performed, each three months: soluble solids, pH, titratable acidity, color (L*, °h and C*), total carotenoids, vitamin C, antioxidant activity by ABTS*, FRAP and phosphomolybdic complex methods, total phenolic compounds, profile of volatile and phenolic and microbiological (total and thermotolerant coliforms, filamentous fungi and yeasts). Thus, there was a tendency to reduce pH, increase in acidity, browning and loss of intensity in the color of uvaia pulps. The content of soluble solids was not influenced by the type of freezing and remained stable throughout storage. The antioxidant activity, carotenoid content and total phenolics decreased during storage. Freezing by AF was more effective than AE in maintaining these variables. The vitamin C content decreased during storage, but was not influenced by the freezing method. Five phenolic compounds were identified in the uvaia pulp, with gallic and chlorogenic acid being the most expressive. Twelve volatile compounds were identified, ethyl hexanoate, octanol, myrcene and germacrene D being the major volatiles. The time factor caused a reduction of nine of the twelve volatile compounds identified, although less pronounced in freezing by AF. The microbiological quality of the pulp was preserved during storage, despite the freezing method. So, the frozen uvaia pulp can be considered a vehicle of bioactive compounds, with antioxidant activity, microbiologically safe, even after 12 months of storage, being the AF freezing more effective than AE.