Microbiological, Physico-Chemical And Sensory Evaluation Of Locally Produced Soy- Pineapple Juice:- Okeke, ifunanya. M

ABSTRACT

 Soymilk and pineapple were processed and blended at different proportions to formulate four new products of natural soy-pineapple juice samples without addition of spices and chemical preservatives. The ratios of soymilk to pineapple juice were 80%: 20%, 70%: 30%, 60%: 40% and 50%: 50% . The samples were pasteurized and their microbiological and physicochemical changes were determined for a period of 13 days under refrigeration (4°C) and ambient temperature(28 c2°C).The microbiological analyses carried out included; Total viable count, Total coliform count, lactic acid bacteria count ,and total fungal count. The physico-chemical parameters carried out using standard methods include; pH, Titratable acidity, Total solids, protf ins, Total sugar, vitamin C, Carbohydrates, ash, crude fiber, lipids, and moisture content. The acceptability of the product was also determined through sensory evaluation using 9 poii t hedonic scale. Organisms isolated include; Bacillus subtilis, Staphylococcus aureus, Lactobacillus sp Penicililum sp, Aspergillus niger, and Sacchromyces sp. The microbial load ranged from 1.4 x 102 to 3.0 x 102cfu/mr for pasteurized refrigerated samples. Microbial loads ofsamples kept at ambient temperature (28 ± 2°C) have total viable count ranging from 2.1 xl02 to 2.5 x 102cfu/ml at 48h and then increased rapidly and steadily through out the monitoring period. The unpasteurized samples kept at refrigeration temperature (4°C) recorded the highest growth at 48h, with the total viable count ranging from 1.2 x'IO4 to 1.4 x 104 cfu/ml and this increased gradually and steadily throughout the monitoring period. There was no fungal growth on the pasteurized samples kept at refrigeration temperature (4°C) until the 7th day The total fungal count of the pasteurized samples kept in ambiem temperature (28 ±2°C) and the unpasteurized refrigerated samples ranged from 1.0 x 102 to 5.5 x 105 and 1.0 x 104 to 3.9 x 105 Cfu/ml respectively. The' physico-chemical analysis shows a gradual decrease on the pH and concomitant increase in the total titratable acio'ty of the samples during the monitoring period. For pasteurized samples at refrigeration temperature (4°C) there was a slow decrease in pH compared to pastuerized ambient stored samples. The sensory evaluation revealed that the blend of 50% soymilk and 50% pineapple juice (T4) has a mean score of 8.20 and was the most accepted blend. The microbial and physico-chemical status of the samples during storage revealed that the different storage conditions (refrigeration and ambient) affected the quality of the soypineapple juice, the juice should be consumed immediately after processing or refrigerated for only 2 days for consumption.