The potency of the use of single and combined extracts of Allium sativum (garlic) and Syzygium aromaticum (cloves) against fungi causing tomato post-harvest spoilage

Abstract

Tomato is high in moisture, low in pH and contain nutrients that makes it very susceptible to attack by microorganisms particularly fungi causing more than 20% post-harvest losses. The study investigated the sensitivity of fourteen isolated fungi from spoiled tomato samples collected from six different markets within Maiduguri metropolis to extracts of garlic, and cloves singly and in combination. The sensitivity of the isolated microbes was tested (using Agar well diffusion method) with aqueous and methanol extracts of garlic, cloves and their combination. The methanol extracts of cloves and combination with garlic completely inhibited the growth of all the fungi isolated at 1.0 and 2.0 mg/mL concentrations. At 45% concentration, the aqueous garlic and combined extracts showed strong antifungal activity against all the fungi except for Aspergillus terreus , Penicillium spp, Zygosaccharomyces bailii ,Candida tropicalis , and Aspergillus ustus . Penicillium spp and Saccharomyces cerevisiae were shown to be the most sensitive against aqueous extract of garlic with 3.4 mm and 3.2 mm zones of inhibition respectively at 100% concentration, while Aspergillus parasitucus , Aspergillus oryzae, and Saccharomyces cerevisiae are the most sensitive of the combined extract at the same concentration. However, all the tested fungal isolates resisted the aqueous extract of cloves at all the tested concentrations. The combined extract, therefore, exhibited the highest level of inhibition against the growth of the tested fungi at all concentrations and may therefore have potential to arrest post-harvest tomato spoilage.