Effects of chitosan with different molecular weights on storage quality and fungi inhibition of mini-cucumber

The effect of low (LWC, 30 kD), medium (MWC, 150 kD) and high molecular weight chitosan (HWC, 300 kD) coatings on storage quality and fungi inhibition of mini-cucumber was evaluated. Chitosan coatings significantly reduced the weight loss, and delayed the color change and sensory score of mini-cucumber when compared with the control. Chitosan coatings significantly retarded the decrease of DPPH free radical scavenging rate and total phenol content, and inhibited the total number of bacterial colonies and the viable numbers of yeast and molds in mini-cucumber. Chitosan coatings also significantly reduced the disease incidence and disease severity of mini-cucumber artificial inoculated with Botrytis cinerea. LWC coating showed superior preservation effectiveness and antifungal activity to MWC and HWC coating. Compared with the control, LWC coating prolonged the shelf life by 6 days which was evaluated by sensory score, and reduced the total number of bacterial colonies and viable numbers of yeast and molds in mini-cucumber by 4.20 log10 CFU/g and 2.72 log10 CFU/g, respectively. These results suggested that chitosan molecular weights affected preservation effectiveness and antifungal activity against B. cinerea and LWC could be used to prolong the shelf life of mini-cucumber and maintain its quality after harvest.