Pre-storage application of some essential oils and food preservatives against black mould incidence of garlic cloves during storage

Abstract

Garlic and onion oils, potassium sorbate and sodium benzoate were evaluated for their inhibitory effect against Aspergillus niger, the cause of black mould disease under in vitro and in vivo conditions. Naturally Aspergillus niger was the most frequent fungus in the surveyed clove cultivars. Chinese cultivar showed the highest infection (72.3%) followed by Balady and Elephant cultivars (65.8 and 52.6%), respectively. Complete inhibition of fungal growth was obtained at a concentration of 4% of the essential oils and food preservatives being tested. Pre-storage coating treatment of peeled and un-peeled garlic cloves with either garlic and onion oils, potassium sorbate and sodium benzoate maintained a protective effect against black mould infection during storage for four months. The pre-storage application of essential oils indicated a superior inhibitory effect on black mould incidence in garlic cloves when compared with the food preservatives. The application of essential oils or food preservatives as pre-storage treatments at a concentration of 6% supplied protection to garlic cloves against black mould infection; the percentage of infected peeled and un-peeled cloves were between (8.3 – 48.2 and 9.5 – 76.3%), (8.7 – 41.3 and 9.4 – 63.8%) and (5.6 – 38.2 and 8.2 – 58.7%), (8.2 – 38.2 and 8.2 – 53.1%) under artificial and natural inoculation conditions, respectively. Depletion of garlic cloves followed a similar trend during the storage period. The results in the present study indicated that garlic and onion oils, potassium sorbate and sodium benzoate could be used as antifungal non-hazardous treatments and could be safely used for fresh products.

Keywords:

• Allium sativum
• Aspergillus niger
• black mould
• essential oils
• food preservatives
• storage