Physico-chemical changes during extraction and clarification of guava juice

Abstract

Pink guavas (Psidium guajava L. var. pomifera) from Ibiapaba plateau (SerraGrande), in Ubajara county, CE, Brazil, were used in this work. The liquefaction of the pulp was done with 600 ppm of a pectinoiytic enzyme at 45^o C for 120 min. The pulp so treated was pressed and the pressed juice was clarified using Baykisol-30 and Hydrogel as fining agents. There were statistically significant changes during the processing of the clear guava juice conceming pH, viscosity, acidity, soluble solids, reducing sugar, ascorbic acid, tannins, colour and turbidity in each phase of the processing: natural pulp, pulp treated by enzyme, cloudy juice, clear juice and clear juice preserved by Hot-Pack method. A significant decrease (62.92%) of viscosity and an increase in the rate of solids (25.74%), reducing sugars (275.10%), ascorbic acid (6.65%) and tannins (11.53%) between the two first phases of the processing were observed. As for colour and turbidity, an absorbance decrease occurred between the integral juice (95.30%) and the clarified juice (96.49%).