TÜV SÜD: Quality criteria for wild and cultivated mushrooms
Munich. Edible mushrooms are in high demand among consumers at this time of the year. Germans consume around 3 kilograms per capita and year, preferring button mushrooms over all other species. Together, cultivated button, oyster, shiitake, mu-err and enokitake mushrooms account for 85% of global fresh-mushroom production. TÜV SÜD’s food experts provide information about the advantages of cultivated mushrooms, freshness criteria and preservation.
Almost 60,000 tonnes of edible mushrooms were harvested in German mushroom farms last year. Most of the mushrooms harvested in Germany are white button varieties (98 %). The slightly more expensive brown cremini mushrooms contain slightly less water and have a more intense flavour. While the percentage of organically grown mushrooms has increased slightly in recent years, it is still relatively low overall. Shiitake, oyster and other special mushrooms make up the remaining 2 %. The percentage of processed mushrooms decreases from year to year. Fresh, cultivated mushrooms are available throughout the year in food stores. Grown on controlled substrate, they thrive well regardless of the weather and any seasonal influences. Another advantage is that cultivated mushrooms, in contrast to wild mushrooms, are not exposed to any adverse environmental influences (e.g. heavy metal or radioactivity) during growth.
Wild chanterelle, porcini and other forest mushrooms take up and accumulate soil-borne pollutants. When they are enjoyed during the mushroom season in moderate amounts of not more than roughly 250 g/week, their pollutant levels do not pose any risks to healthy adults. However, even 29 years after the nuclear disaster in Chernobyl forest mushrooms still contain measurable levels of radioactive loads. For this reason, periodic checks and measurements are conducted on random samples from Eastern Europe (e.g. Belarus or Ukraine). Wild mushrooms in Germany, especially those growing in Southern Bavaria and the Bavarian Forest, may still contain higher pollutant levels. However, only forest mushrooms with a radioactive contamination of under 600 becquerel per kilogram may generally be sold in Germany.
Criteria for freshness and preservation
A healthy mushroom is juicy, firm and free from stains, visible mould and soft spots. This applies to both mushrooms bought in the supermarket and mushrooms collected in the forest. Mushrooms can be open on the underside of the cap. They do not go bad if the gills on the bottom side of the cap are visible. Quite the contrary, in fact – only then do they develop their full taste. Fresh mushrooms can be frozen to preserve them up to six months. Before placing them in the freezer they are cleaned, cut into slices and briefly blanched. Like deep-frozen products from the supermarket, deep-frozen mushrooms should be heated directly and not thawed before preparation. Coarse dirt particles are gently brushed off. After that, mushrooms should very briefly be rinsed under running water to clean them. Mushrooms should generally be stored at cool temperatures (2 to 4 degrees). Under good conditions, button mushrooms will keep 3 to 4 days, shiitake and king trumpet mushrooms around 7 – 10 days.