Improving the Storage Stability and Keeping Quality of Modified Papaya Juices Stored under Refrigeration Conditions

Abstract

Fresh papaya puree was blended with orange, strawberry, mango and guava to improve the nutritional and quality properties of the mixed juices. The produced juices were evaluated for their nutritional, physicochemical, microbiological and sensory characteristics. The effect of pasteurization (at ~ 65ºC/20 min) and/or chemical preservatives (0.05% potassium sorbate + 0.05% potassium metabisulphite) on the quality and shelf stability of papaya juices was also investigated during cold storage (at ~ 4 o C) for 6 months. The results showed that, the combined action of the thermal treatment and chemical preservatives (T 3 ) on the quality and shelf stability of papaya juices was better than using either of them alone. During refrigerated storage, the values of moisture, pH, ascorbic acid and total phenolics significantly decreased as the storage time increased. While, the total soluble solids and titratable acidity values significantly increased. Despite this decrease, all juice samples remained satisfactory sources of ascorbic acid and phenolic compounds over the storage period. The sensory quality of papaya juices remained acceptable for up to six months. The total bacterial counts were less than 10 2 cfu/g for all juice samples. Yeasts and moulds were absent during refrigerated storage. Consequently, no potential microbial risk was associated with the storage conditions. As a conclusion, the papaya fruits could be successfully used singly or in combination with orange, strawberry, mango and guava to obtain delicious and healthy nutritious juices. The modified papaya juices (75% papaya + 25% orange/strawberry/mango/guava) had acceptable quality attributes, improved nutritional value, improved shelf stability and microbiological safety.