Effect of Pasteurization and Storage Temperatures on the Quality of Carrot Juices

Background and Objective:Unstandardized preparation methods and poor storage conditions of homemade fruit and vegetable juices could impact the quality of the product. Therefore, this study seek to determine the effect of unpasteurization and room temperature storage associated with homemade carrot juice on its microbiological, physicochemical and sensorial properties. Materials and Methods: Total heterotrophic bacterial count, total fungal count, pH, titratable acidity and total soluble solids of unpasteurized and pasteurized carrot juices stored at 0°C for 5 weeks; 4 and 24°C for 5 days were monitored at intervals using standard methods. Sensory evaluation of the samples involved the use of a 9-point hedonic scale. The data obtained were subjected to statistical analysis using a One-way Analysis of Variance (ANOVA) and probability value at p<0.05 was considered to be significant. Results: Total heterotrophic bacterial count (THBC) of pasteurized carrot juice stored at 0 and 4°C was within the range of <1.0-3.66 log₁₀ CFU mL^–1. The juices were within the THBC limits recommended by the International Commission on Microbiological Specifications of Food (ICMSF) and Codex Alimentarius Commission (CAC) of the Food and Agricultural Organization (FAO). The total fungal count of carrot juices stored at 4 and 24°C was <1.0 log₁₀ CFU mL^–1 with the exception of the unpasteurized juice stored at 24°C. During storage, the titratable acidity of the carrot juices increased from 0.3-2.8% whereas, the total soluble solids (6-23 °Brix) and pH (3.4-6.3) decreased with few exceptions. Based on sensory report, the pasteurized carrot juice stored at different temperatures was preferable than the unpasteurized juice. Conclusion: Personal and environmental hygiene, pasteurization and low temperature storage of homemade carrot juice are recommended to ensure that the products are good quality and microbiologically safe for human consumption.