Inhibition of mold growth on the surface of dried persimmons using combined treatments of UV-C light and clove oil

Abstract

The efficacy of clove oil, UV-C light and their combination for the inhibition of mold growth on the surface of dried persimmon fruits during the storage period of 28 days at 20 °C were investigated in this study. The inactivation kinetics of UV-C resistant mold cultures inoculated to dried persimmon surfaces were determined at UV-C doses in the range of 0.6–12.0 kJ/m2. Disc diffusion and microdilution methods were used to evaluate the antifungal activity of the clove oil against Rhizopus oryzae, Alternaria tenuissima and Aspergillus niger previously isolated from dried persimmon fruits. Minimum inhibitory concentrations of clove essential oil against R. oryzae, A. tenuissima and A. niger were 1.56% (v/v) and the minimum fungicidal concentrations were 6.25% (v/v), 3.12% (v/v) and 6.25% (v/v), respectively. UV-C treatments showed limited reductions in the number of molds inoculated to dried persimmon discs regardless of the UV-C dose. Combined treatments of UV-C and clove oil resulted in maximum reductions of 0.64 and 0.68 log cfu/cm2 for R. oryzae and A. niger, respectively. Sensory evaluation results showed that all the treatments could maintain the appearance and texture of samples, moreover the highest sensory evaluation score was obtained for the clove oil (1.56% v/v) treatments in terms of flavour and overall acceptability. Application of clove oil (1.56% v/v) to dried persimmon fruits was extended the product shelf life at least 28 days. By using combination of UV-C light and clove oil treatments, the inhibition of mold growth on the surface of dried persimmons has been achieved. Industrial relevanceUltraviolet technology is a non-thermal food processing technology as an alternative to chemicals while maintaining the quality of the food. The results obtained in this study demonstrate that combined treatment of UV-C and clove oil are a promising technology to inhibit fungal growth as well as to enhance sensory quality of dried persimmon fruits. Application of clove oil to dried persimmon fruits produced a novel and value-added product that can be preferred by consumers.