STUDIES ON COMMERCIALLY CANNED JUICES PRODUCED LOCALLY IN SAUDI-ARABIA .3. PHYSICOCHEMICAL, ORGANOLEPTIC AND MICROBIOLOGICAL ASSESSMENT

Single-strength canned apple and pineapple juices (SSAJ and SSPJ) were obtained from a commercial canning plant in Saudi Arabia and were stored at controlled temperatures of 5, 24 and 42-degrees-C and under ambient warehouse conditions (average 33-degrees-C) for a 12-month period. Changes during storage in physicochemical (ascorbic acid, sucrose, reducing sugars, acidity, pH and vacuum), microbial, and sensory characteristics were studied to determine the effect of storage time and storage temperatures on the quality. Losses in vitamin C content of apple juice (AJ) and pineapple juice (PJ) stored for 12 months in the warehouse under Saudi Arabian conditions were 45.8% and 49.8%, respectively. The decrease in ascorbic acid, sucrose and vacuum and increase in reducing sugars were linearly related to the storage time. The increase in the reducing sugars was due to the hydrolysis of the sucrose under these conditions. Based on the results of sensory evaluation on month 12 of storage, panellists were able to detect significant changes in quality attributes among samples stored at different temperatures. The overall acceptability of the AJ stored at the warehouse temperature was rated as neither like nor dislike and PJ stored under the same conditions was also rated as 'neither like nor dislike', on a 9-point hedonic scale. Microbial analysis of the two types of juices revealed the absence of aerobic plate counts, coliforms, sporeformers and yeasts and moulds either on the initial analysis (month 1) or on month 12 of storage at the four different temperatures.