Effect of plasma‐activated water generated by surface DBD on inactivation of pathogens Pseudomonas tolaasii and Lecanicillium fungicola and enhancement of storage quality of button mushroom

Abstract

AbstractPseudomonas tolaasii and Lecanicillium fungicola are the bacterial and fungal pathogen that causes brown spots and dry bubble diseases and spoilage of fresh mushroom. The objective of this study was to consider the efficacy of plasma‐activated water (PAW) on the inactivation of P. tolaasii and L. fungicola and storage quality of button mushroom. Button mushrooms were immersed for 10 min in PAW generated by four types of plasma feeding gas at activation times 5, 10, 15, and 20 min, designated PAW‐5, PAW‐10, PAW‐15, and PAW‐20, respectively. The results indicated that the bacteria and fungi growth was controlled by PAW treatment through 21 days of post‐harvest storage. The lowest bacterial and fungal population was 3.6‐log CFU g−1 and 4.7‐log CFU g−1 after treatment with PAW‐20 generated by hydrogen peroxide bubbled with air (H2O2‐air), which was significantly lower than that of control (6.57 and 7.49 log CFU g−1) or soaking in distilled water (7.65 and 8.57 log CFU g−1), respectively. The plasma created by H2O2‐air gas formed the highest concentration of H2O2, NO2−, and NO3− species in PAW. The findings of water friendship and firmness showed that immersion in PAW could delay the softness of the mushroom. In addition, treatment with PAW significantly inactivated polyphenol oxidase (PPO) and peroxidase (POD) enzymes. Meanwhile, significant changes were registered in the color, antioxidant activity and phenolic content of mushrooms treated with PAW and the control groups. Thus, PAW treatment may be considered as an alternative method for fresh keeping of button mushroom.Practical ApplicationsChemical, radiation, and physical methods (modified‐atmosphere packaging and refrigeration) used to increase the shelf‐life of edible mushrooms cause discoloration, a decrease in nutritional value, and tastelessness. Activated water technology with cold plasma is one of the non‐thermal and environmentally‐friendly methods that, while solving the mentioned problems, ensures food safety without significant impact on sensory or nutritional characteristics. The results presented in this study introduce plasma‐activated water as an effective method for inactivating disease‐causing pathogens and lesions in button mushrooms. This technology is a suitable alternative method for the disinfection of edible mushrooms due to maintaining freshness and physicochemical characteristics as well as inhibiting the activity of browning enzymes and pathogenic microorganisms.