IMPACT OF CHEMICAL PRESERVATIVES

Mushrooms serve as the fruiting bodies of fungi. Unlike higher plants, they lack chlorophyll, the green pigment found in leaves that enables plants to utilize water, carbon dioxide, and solar energy for photosynthesis. Consequently, mushrooms are unable to synthesize their own food and rely on higher plants for sustenance. They possess high nutritional value, characterized by elevated levels of protein, vitamins, minerals, fiber, and trace elements, alongside low or negligible calorie and cholesterol content. Due to these factors, mushrooms are particularly prone to spoilage. The objective of this study was to investigate the impact of chemical preservatives on the shelf life, sensory evaluation, bacteriological quality, and nutritional composition of mushrooms, with the aim of assessing their suitability for extended storage. Freshly harvested oyster mushrooms (Agaricus spp.) were sourced from the African Centre for Mushroom Research and Technology Innovations (ACMRTI) at the University of Benin, Benin City. The preservatives utilized included hydrogen peroxide and citric acid, administered at concentrations of 0.5%, 1.5%, 2.0%, and 2.5%, with water serving as the control. Samples were stored in a refrigerator for a duration of six days and analyzed at two-day intervals. The analyses conducted encompassed sensory evaluation, bacterial count, biochemical tests, antibiotic susceptibility tests, and virulence factor assessment. The results indicated that a concentration of 2.5% hydrogen peroxide yielded the lowest bacterial count, recorded at 1.3 ± 8.5 x 10² cfu/g, and exhibited the highest overall appearance score of 3.9 ± 1.7. Identified bacterial isolates included Klebsiella pneumoniae, Moraxella catarrhalis, Pantoea agglomerans, Bacillus subtilis, Cronobacter sakazakii, Bacillus cereus, Escherichia coli, Corynebacterium jeikeium, Serratia marcescens, Aeromonas hydrophila, and Enterococcus faecalis. The isolates that occurred most frequently (11 instances) were Bacillus subtilis, Escherichia coli, and Enterococcus faecalis. The Multiple Antibiotic Resistance Index (MARI) revealed that Escherichia coli had the highest value of 0.9, while Corynebacterium jeikeium had a MARI of 0.4. The study illustrates that chemical preservatives effectively reduce microbial load, significantly slowing microbial growth, mitigating spoilage, and consequently extending the storage period of mushrooms.