Assessment of Microbiological and Keeping Quality of Ocimum Gratissimum and Vernonia Amygdalina Crude Extract on Sarotherodon Galilaeus Snacks

Abstract

Evaluation of antimicrobial and keeping qualities potentials of Ocimum gratissimum (OGE), Vernonia amygdalina (VAE), and Ocimum gratissimum plus Vernonia amygdalina (OVE) crude extracts on fish snack made from Sarotherodon galilaeus, was carried out to determine their for suitability for food preservation. Twelve fish samples grouped into three class sizes (A, B, C), were used. They were gutted, filleted, cut into pieces, staked on palm frond sticks, and fortified with extracts, spiced and dried with a smoldering fire. The snacks were allowed to cool and kept in Aluminum foil, Brown paper and polythene sheet. Snacks analysis for microbial and keeping qualities was carried out using NA agar for bacteria and PDA for fungi using standard methods. Data collected were subjected to ANOVA using SAS® 2008 version 9.1. Mean pH value ranged from 9.60±0.1 to 11.10±0.15 for freshly produced snack, untreated snacks had the least mean pH value (9.60±0.1) and the highest mean bacteria count (9x102±2.65). Fungi counts (5x102±2.08 to 8x102±6.08) were not significantly different between the samples. It was observed that snacks treated with Ocimum gratissimum crude extract had the highest pH value and the lowest bacteria and fungi load; hence it was more effective for fresh snack preservation. Five bacteria and eight fungi were isolated and identified. Result of pH and microbial analysis after storage showed that the pH values ranged from 9.50±0.00 to 10.17±0.06. For treated snacks, snacks packaged in aluminum foil had the least pH value and the highest microbial load, snacks packaged in brown paper had the highest pH value and the highest microbial load. For packaged snacks, snacks treated with the mixture of Ocimum gratissimum and Vernonia amygdalina cude extraxts was more effective as it had the lowest bacteria and fungi load. Microbiological analysis revealed that Staphylococcus aureus and Aspergillus spp were the dominant bacteria and fungi isolated; however, their counts were within the acceptable limit of International Commission on Microbiological Specification. Polyethylene bag gave the best result for packaging materials as it showed no deleterious quality change in the snacks. Addition of plants extract and composite spice to the fish fillet had effect on the microbial and shelf life of the product. Key Words; Fish snack, Microbiological analysis, Ocimum gratissimum, Sarotherodon galilaeus, Vernonia amygdalina.