Microbiological quality and storage stability of fresh fruit and vegetable juice blends sold in Kampala, Uganda

Abstract

Fresh fruit and vegetable juices rich in health, nutritional and minerals of benefits are consumed by all age groups in Kampala, Uganda. However, exposure to microbiological contamination, light and temperature effects may occur before and/or during processing thereby exposing consumers to potential health hazards. Therefore, this study sought to establish microbiological quality of fresh fruit and vegetable juices and their processing environment. It further sought to assess physicochemical parameters of juices stored in dark colored and clear bottles at room (24°C) and refrigerated (4°C) temperatures. Bacteriological counts of 385 samples of which 90 were solely fresh passion fruit juices were assessed for aerobic mesophiles and selected pathogens including Staphylococcus aureus, Listeria monocytogenes, Escherichia coli and Salmonella using standard plate counts. Physicochemical parameters were conducted to establish storage stability of the juices. Results showed that most preferred passion fruit juices contained 30% Staphylococcus aureus, 16.7% Listeria monocytogenes, and no Escherichia coli nor Salmonella spp. The pH ranged between 3 and 5 and Total Soluble Solids (° Brix) ranged between 1.4 and 5.2. Pineapple juices stored in dark colored bottles differed (p<0.05) from those kept in clear bottles. Mango juices stored in dark colored bottles at refrigerated temperatures had the lowest titratable acidity (%) of 1.65 while pineapple juice kept at room temperature in clear bottles had the highest titratable acidity (%) of 6.75. Juices stored at room temperatures differed significantly (p<0.05) in titratable acidity from those kept at refrigerated temperatures. Ascorbic acid content was lowest in pineapple juice (4.71 -5.97 mg/100 ml) and highest in passion fruit (53.2–61mg/ 100 ml) above the daily recommended nutrient intake levels of 45mg/100 ml. It is concluded that passion fruit juice in Kampala is a good source of ascorbic acid however stringent measures to ensure juice safety are needed.