Effect of calcium-alginate and essential oil on Colletotrichum acutatum and the shelf life of the grape

Abstract

This study aimed to investigate the efficacy of three kinds of essential oil, which are cassia oil, holy basil oil, and peppermint oil on inhibition of the plant pathogen Colletotrichum acutatum by the agar diffusion method. The selected essential oil was combined with the edible film (calcium-alginate 0.25 %; 0.5 %; and 1 % (w/v)) and applied in the green grape preservation (infected with C. acutatum 5 log spores/ml). The results showed that all essential oils have antifungal activity against C. acutatum with the Minimum Inhibitory Concentration (MIC) value of cassia oil was 2.5 μl/ml, whereas holy basil oil and peppermint oil was 20 μl/ml. The result of the grape preservation showed that control samples were completely rotten after ten days of storage that lower efficient than the edible film-coated samples. After 20 days of treatment by calcium-alginate (1 % w/v), the degree of damage was 30 %. The results also indicated that the essential oil at MIC value had a negative effect on the grape preservation process, whereas the combination of calcium-alginate (0.5 % w/v) and cassia oil (1.25 µl/ml) showed the best resistance against to C. acutatum infecting on the grape, which was not rotten after 20 days of storage.