Microbiological characteristics of wild edible mushrooms and effect of temperature during storage of Morchella conica

Abstract

Background: The continuous worldwide increase of consumption of fresh mushrooms has registered in the recent years. The major goal of this study was to determine the microbiological characteristics of wild edible mushrooms and effect of temperature during storage of Morchella conica. Methods: Wild mushrooms of the species Boletus edulis, Cantharellus cibarius, and Leccinum aurantiacum were collected in a mixed forest of Picea abies, Betula pendula, and Pinus sylvestris located in Tartu territory, Estonia. Faecal indicators, potential pathogens, spoilage bacteria, and microfungi (yeasts and moulds) were evaluated. M. conica was microbiologically investigated for 24 days under different thermal regimes, including 4, 8, 12, 15, 20, and 28 °C. The statistical analysis was conducted with SAS 9.2 software. Results: The microbial counts of wild mushrooms, ranging from 6.81 to 7.68 log10 CFU/g for total mesophilic count, were generally higher (p<0.05) than those registered for marketed samples ranging from 4.60 to 7.39 log10 CFU/g. The dynamics of total mesophilic microorganisms on M. conica stored at different temperatures indicated that stationary and death phases occurred earlier with increasing temperature and that the highest levels were registered at 28 °C at the 2nd day of storage. Conclusion: This work highlights consistent differences in terms of microbiological properties among different mushrooms species. The results clearly showed that total mesophilic populations developed at high levels quickly at temperatures more than 15 °C, but also the refrigeration did not stop the microbiological decay of mushrooms.