Effects of Selected Plant Preservatives on Microbial Load and Shelf Life of Palm Wine

Abstract

In this study, ten different freshly tapped palm wine were collected at the point of tapping from traditional palm wine tappers and transported to the laboratory for analysis. Then 1.0 ml dilution was plated on nutrient agar for total heterotrophic bacterial count and on Saboraud dextrose agar for fungal count. It was incubated at 30oC for 24 hours for bacteria and 48 hours for fungi. The preservative potential of plants were determined by setting up sixteen sterile plastic bottles each containing 100ml of palmwine and four separate sterile plastic bottles containing 2.5, 5, 10 mg/ml of the dried blended plant preservative and the control. Aliquot (0.1ml) each for the test tubes containing mixture of palm wine and the preservative were plated out using spread plate technique on nutrient agar and Saboraud dextrose agar at constant intervals of 24, 48, 72 and 96 hours respectively. Incubation was done for 24 hours at 37oC for bacterial and 48 hours at 30oC for fungal growth. A ten member panel consisting of regular palm wine bar customers were drafted to evaluate the acceptability of the products based on the taste, colour and overall acceptability using a 9-point hedonic scale. There was a gradual reduction in the bacterial load of palmwine from 1.13 x107 to 4.60 x106 CFU/ml and 1.03 x107 to 2.01 x106CFU/ml for ginger and nutmeg at 5g/ml after 72 hours. The fungal load of palmwine reduced from 1.30 x107 to 1.80 x106 CFU/ml and 1.03 x107 to 1.80 x106 CFU/ml for ginger and nutmeg at 5g/ml and 10g/ml after 72 hours. The scores of the colour, flavor and taste were high which shows their acceptability by consumers. There was a gradual reduction in the microbial load of palm wine treated with the plant preservatives thus suggesting their usefulness in extending the shelf life of palmwine which would make a significant contribution towards the search for low cost preservative for palmwine.