Processing and Storage Characteristics of Sudanese guava fruit concentrate

This study aimed at the investigation of processing characteristics of white and red pulp guava (Psidium guajava L.) fruits grown in Sudan. The physical and chemical characteristics of the fruits before processing were studied. The two cultivars were processed to concentrates by evaporation under normal atmospheric pressure. The two concentrates were evaluated organoleptically against a control of Indian commercial concentrate. The storage quality of concentrates prepared from both pulps was also examined every 45 days. The microbiological parameters studied included total viable count, lactic acid bacterial count, yeasts and moulds count, and coliforms bacterial count, Staphylococci, sporoformer bacteria and Salmonnela. Significant difference (P 0.05) was observed between the two varieties in weight (71.68, 59.69 g), diameter (4.50, 3.73 cm) and level of solids (17.00, 19.00%) for white and red guava fruit, respectively. In general, the two varieties were found rich in potassium (38.23, 37.29 mg/l00g), sodium (17.03, 12.67 mg/l00g), calcium (12.68, 11.82 mg/l00g), magnesium (7.22, 61.70 mg/l00g) and iron (3.66, 1.57 mg/l00g) for white and red guava fruits, respectively. White pulp guava is characterized by high level of vitamin C (250 mg/l00g), and similar levels of sugars compared to the red pulp guava. The pulping process has significantly (P 0.05) reduced levels of vitamin C and sugars. Concentration of the juice to 17.00 and 19.00% total soluble solids in white and red guavas, respectively, resulted in further losses in vitamin C (134.9; 125.4 mg/l00g, respectively), and increase in total sugars (from 3.17 to 15.32% in white one, and from 3.34 to 16.14% in the red one). Significant difference (P 0.05) was observed between the two concentrates (17-19°Brix) prepared from the white pulp and red pulp guava for acceptability testing. The latter pulp concentrate was found superior in colour, flavor and taste, and better in after taste and consistency. However, the two juices prepared from the concentrates showed insignificant differences (P 0.05) in all the quality attributes mentioned earlier. Concentrates of pulps from white and red guava stored for slightly more than one year showed similar changes in total soluble solids, pH and acidity. However, the loss in ascorbic acid of red pulp guava concentrate was significantly (P 0.05) more (from 125.4 to 10.91 mg/l00g) compared to white pulp concentrate (from 134.9 to 16.02 mg/l00g). Non reducing sugars seemed to have witnessed interconversion into reducing sugars during storage of concentrates as evidenced by significant (P 0.05) decrease in the former with concomitant increase in the latter sugars. The microbial storability results showed that the two concentrates were found to be free from microorganisms up to 12 month of storage