MICROBIOLOGICAL ASSESSMENT OF LIME-PRESERVED FRUIT JUICE

ABSTRACT

Fruits commonly used in juice processing are exposed to a variety of spoilage microorganisms. Due to this, the use of chemical preservative have been practiced industrially to inhibit microbial colonization ensuring shelf life improvement. The negative health impact of these chemicals calls for the utilization of an alternative health friendly preservative. Hence, this study was aimed to determine the efficacy of lime as a preservative in extending the shelf life of fruit juice and also how it influences the physico-chemical properties of fruit juice. Lime samples were purchased from an open market, washed, peeled, processed into juice and freeze-dried. Likewise, pineapple and watermelon fruits were   purchased, processed into juice and different concentrations (5g,10g and15g)of lime which acted as natural preservative were added aseptically. Also, a portion of the fruit juice was heated at 1000C for3 secs (pasteurized sample) and another portion was prepared separately with no treatment (control).  The processed juice were stored for 72hrs and all analyses were conducted at 24hrs interval. Bacterial and fungal isolates were enumerated and identified using cultural based method while physio-chemical assessment was done using protocols described in AOAC manual. Generally, for the preserved samples, the increase in bacterial and fungal count was less than that observed in the control. The bacterial isolates belongs to the genera Lactobacillus, Bacillus, Staphylococcus, and Escherichia, while the fungal isolates were Mucor sp, Aspergillus sp. And Yeast cells. Samples with lime as preservative had higher T.A and lower pH in comparison to those without lime preservative. Due to the acidic nature of lime, lime preserved juice was more acidic but extended the shelf life for 24 hours and 48 hours depending on the concentrations.