Evaluation of the Antimicrobial Properties of Garlic Extract Against Common Food Spoilage Organisms in Ibadan

Consumer demand for natural antimicrobial agents as alternatives to synthetic food preservatives has grown substantially globally, and garlic (Allium sativum) is among the most studied botanical sources of bioactive antimicrobial compounds. This study evaluates the antimicrobial properties of aqueous, ethanolic, and methanolic garlic extracts against Aspergillus flavus, Penicillium expansum, Escherichia coli, and Staphylococcus aureus, which are common food spoilage and pathogenic organisms. Garlic bulbs were sourced from Bodija Market in Ibadan, Oyo State, South West Nigeria. Extracts were prepared at concentrations of 25, 50, and 100 mg/ml, and antimicrobial activity was evaluated by the agar well diffusion method and minimum inhibitory concentration determination. The allicin content of each extract was quantified spectrophotometrically. The ethanolic extract at 100 mg/ml produced the largest inhibition zones for all test organisms, with the greatest efficacy against Staphylococcus aureus and Aspergillus flavus. Allicin content correlated significantly with antimicrobial activity. Minimum inhibitory concentrations ranged from 6.25 to 25 mg/ml for bacterial isolates and 12.5 to 50 mg/ml for fungal isolates. The study draws on recent literature on plant-based food preservation and contributes empirical data for the application of garlic extract as a natural food preservative. Findings are relevant to food manufacturers, the National Agency for Food and Drug Administration and Control, and product developers pursuing clean-label preservation solutions. Keywords: garlic extract, antimicrobial, food preservation, allicin, Ibadan