Tragacanth gum containing Zataria multiflora Boiss. essential oil as a natural preservative for storage of button mushrooms (Agaricus bisporus)

The effect of tragacanth gum (TG) coating incorporating 100, 500 and 1000 ppm Zataria multiflora Boiss. essential oil (ZEO) compared to chemical protection with sodium metabisulphite (SM) on browning and postharvest quality of button mushrooms (Agaricus bisporus) was evaluated upon 16 days of storage at 4 °C. Mushroom weight loss, browning index (BI), firmness, percentage of open caps, total phenolic compounds, ascorbic acid and microbial activity were measured. Mushroom coated with tragacanth gum containing Zataria multiflora Boiss. essential oil (TGZEO) maintained 93.47% tissue firmness and showed reduction in microbial counts from yeasts and moulds in comparison with the control. In addition, TGZEO decreased up to 52.23% BI and promoted the accumulation of the phenolic compounds (86.0%) and ascorbic acid (72.8%). The efficiency of TGZEO treatment was better than that of TG or SM treatment alone. Our study suggests that TGZEO has the potential to improve the quality of button mushroom and extend its shelf-life up to 16 days.