Anti-mildew effect and inhibition mechanism of the slightly acidic electrolyzed water treatment of bamboo

Bamboo is a renewable biomass material prone to a mildew infection. Current research is attempting to discover an environmentally friendly and low-cost anti-mildew agent for bamboo, such as the antimicrobial agent electrolyzed water (EW). In this study, an ultrasonic pretreatment and EW impregnation are conducted on bamboo strips. An orthogonal experiment (L9(3(3))) is used to evaluate the effects of the process parameters of EW treatment, including the pH value, temperature, and time, on anti-mildew effect of bamboo. The optimal parameters are obtained from the area of mildew infection of the bamboo strips after 28 d. Additionally, the inhibition mechanism of EW in the optimum process is explored. The results reveal that the anti-mildew effect of bamboo strips under ultrasonic pretreatment combined with slightly acidic electrolyzed water (SAEW) treatment is the best, followed by those treated with the SAEW without pretreatment, and the untreated group. The optimal parameters for the ultrasonic pretreatment process of bamboo are a power, temperature, and duration of 180 W, 60 degrees C, and 60 min, respectively, whereas those of the EW process include a pH value of 6.0 at 60 degrees C for 120 min. The investigation of the inhibition mechanism reveals that SAEW changes the mycelium morphology of Aspergillus niger, Penicillium citrinum, and Trichoderma viride, as well as destroys the cell wall integrity of the mycelia, thus resulting in the release of nucleic acids and blocking the growth of mildew.