Maintaining the quality and increasing shelf life of button mushroom by using essential oil of some medicinal plants in packaging containers

Button mushroom (Agaricus bisporus L.) is considered as valuable source of nutrients and a crop with medicinal characteristics due to its high amounts of vitamins, protein and bio-active compounds. The lack of cuticle layer in button mushroom has made it sensitive to microbial agents and browning disorder. Due to high sensitivity rate of button mushroom to microbial corruption, different methods such as coating, modified atmosphere packaging and treatment with anti-microbial solutions are used to reduce corruption speed and post-harvest wastes. The essential oils of medicinal plants are part of plant secondary metabolites which have anti-microbial, anti-cancer and antioxidant characteristics and can eliminate reactive oxygen species in plant cells and tissues. The positive roles of essential oils of medicinal plants in increasing the maintainability of different crops such as apple, banana and button mushroom during cold storage have been proven in various studies. According to reports using essential oil of some medicinal plants such as Cinnamomum zeylanicum, Mentha pulegium and Zataria multifloraat post-harvest stage can extend crops shelf-life and maintain their qualitative indices. The purpose of the current study was to evaluate the influence of using the essential oil of some medicinal plants in packaging containers on some of most important post-harvest characteristics of button mushroom.

The current study was carried out at Ilam University during 2022-2023. In this research, the influence of essential oil of some medicinal plants including Thymus spicata, Mentha piperita and Satureja bachtiarica at different concentrations (0, 500 and 1000 ppm) on some qualitative indices of button mushroom such as tissue firmness, cap opening rate, radical scavenging activity, organoleptic properties and antioxidant enzymes activity was investigated during cold storage at 4 °C. The post-harvest characteristics were evaluated at three different storage durations including 0, 4 and 8 d after harvesting.

According to obtained results, the weight loss increased and tissue firmness, total soluble solid content and total acidity decreased with increasing storage duration. All treatments could significantly reduce weight loss and maintain tissue firmness, total soluble solid content and total acidity of mushrooms except T. spicata treatment at 1000 ppm concentration. The recorded data on 8 d, showed that the highest H2O2 content and the lowest radical scavenging activity was related to T. spicata treatment and control while the mushrooms treated with S. bachtiarica at 1000 ppm concentration had the lowest H2O2 content and the highest radical scavenging activity. Results demonstrated that cap opening remarkably decreased and tissue firmness and marketability of mushrooms maintained by using essential oils of S. bachtiarica at two concentrations of 500 and 1000 ppm and M. piperita at concentration of 500 ppm. Results of organoleptic test indicated that using essential oil of S. bachtiarica and M. piperitaat concentration of 500 ppm led to enhance marketability and acceptability of mushrooms as well as improved their taste and odor. The lowest evaluated acceptability rate by panel members was related to mushrooms treated with essential oil of T. spicata and M. piperita due to change in their taste and appearance of brown spots. In this study, maintaining qualitative characteristics of button mushroom induced by treatment with essential oil of medicinal plants could be related to two main factors included anti-microbial and antioxidant characteristics of essential oils. Based on several reports, anti-microbial properties of essential oil and extract of medicinal plants can cause lower respiration rate and water loss in treated crops during storage. Also, the reduced amounts and activity rate of reactive oxygen species was observed in different horticultural crops treated with essential oils during post-harvest stage. In the current study, increasing catalase and peroxidase enzymes activity, maintaining total phenol and water content and decreasing polyphenol oxidase enzyme activity could be considered as main reasons for extending shelf-life of mushrooms treated with essential oil of S. bachtiarica and M. piperita.

Based on obtained results of the present study, using essential oil of S. bachtiarica as natural and low-risk compound for maintaining the quality and extending shelf-life of button mushroom during storage at 4 °C is recommendable.