RHEOLOGICAL AND MACROMOLECULAR QUALITY OF PECTIN EXTRACTED WITH NITRIC ACID FROM PASSION FRUIT RIND

Yellow passion fruit processing in Brazil releases large amounts of waste (300,000 metric tons per year) that could be used as an alternative raw material for extracting potentially 2,000 metric tons of pectin. Valorization of pectin extracted from passion fruit rind demands the establishment of a proper protocol to maintain a high standard of product quality. In this work, a central composite experimental design of 23 was used to verify the influence of different conditions on the molecular characteristics and rheological behavior of extracted pectin. The extraction conditions were time (545 min), temperature (6397C) and nitric acid concentration (892 mM). The responses significantly influenced (P < 0.05) in the trials were yield extraction, the apparent viscosity and reduced viscosity. The ideal conditions for extracting pectin with the highest apparent viscosity and with a high molecular weight were obtained with short time (5 min), medium temperature (80C) and 50 mM nitric acid. PRACTICAL APPLICATIONS Extensive efforts have been directed toward minimizing the large amounts of waste that result from the processing of passion fruit juice in Brazil. There has also been recent interest, in Brazil and in other tropical countries, in the production of pectin from passion fruit. This article shows that controlling extraction conditions can produce high molecular weight pectin and, consequently, can improve its rheological quality for use. Furthermore, it shows that it is possible to obtain pectin from passion rinds similarly to that of the citrus and apple pectin found in markets.