Processing and shelf-life assessment of mixed-fruit juice from pineapple, orange, paw-paw and guava

摘要

Mixed fruit juice was produced with pineapple (40%), orange (30%), pawpaw (20%) and guava (10%). Different samples of the product were treated (preserved) with different levels (0.04%, 0.06% and 0.08%) of sodium ben-zoate, pasteurized and stored on ambient shelf for three months. pH, titrat-able acidity, soluble solids, ascorbic acid and total microbial count were analyzed on the fresh and stored samples at one and three months. pH of all the samples significantly (P < 0.05) decreased with added benzoate during storage. Titratable acidity for the samples increased after three months. Total soluble solids (brix) decreased with storage and addition of benzoate but insignificantly, while brix/acid ratio significantly decreased with added benzoate and storage period from 18.60 (in fresh sample) to 16.13 (after three months); 16.0 to 13.86 and 15.40 to 12.73 for samples with 0.04%, 0.06% and 0.08% benzoate respectively. Ascorbic acid content also showed significant decrease in all samples, and sample preserved with 0.8% benzoate retained highest ascorbic acid content and lowest microbial count (Saccharomyces cerevisiae and Lactobacillus species) after 3 months storage. Staphylococcus aureus and Penicillum species were identified in the control and 0.04%-benzoate-preserved samples. Overall acceptability result between the fresh and stored samples showed insignificant difference.