Agricultural experts have called for testing on Chinese mushrooms being widely sold at local markets.
Dr Nguyen Dang Nghia from the Institute of Agricultural Science for Southern Vietnam said fresh fungi can only stay in good shape for a week at most, even under refrigeration.
However market inspectors have found that a number of imported Chinese mushrooms remained fresh for up to ten days at room temperature and up to a month under refrigeration, Nghia said.
Le Hong Vinh, deputy director of the Hanoi-based Flora Biotechnology Center which studies food and medicinal fungi said that preservative-free fungi can only be stored for one or two days at most.
Vacuum-sealed bags can extend that period to ten days, he said.
Nghia said Chinese mushrooms are “definitely” being soaked in chemical preservatives before being packaged and shipped to Vietnam.
Market management agencies and those in charge of importing produce have to roll up their sleeves and find out what sorts of preservatives are being used and what impact they might have on consumer health, he said.
Those findings will help build technical barriers to the continued import of tainted fungi, he added.
This isn't just a problem with mushrooms; lots of Chinese produce, especially fruit, contains a lot of preservatives." -- Dr. Nguyen Dang Nghia from the Institute of Agricultural Science for Southern Vietnam
Vietnamese mushroom producers said that most of the products on the local market are Chinese, although they are usually labelled as local.
Le Hoang Mong Ngoc, director of Vietnamese Mushroom Biotechnology JSC in the city, said Vietnam does not produce snow mushrooms, for example, and only produces enough shiitake to meet roughly 10 percent of local demand.
Vietnamese wood ear mushrooms however are abundant.
“This isn't just a problem with mushrooms," Nghia said. "Lots of Chinese produce, especially fruit, contains a lot of preservatives.”
Food inspectors from the National Agriculture, Forestry, Fisheries Quality Assurance Department in May announced that they had flagged nearly 500 tons of Chinese fruit and vegetables in shipments that arrived since last October for excessive levels of pesticides and preservatives.
In June, authorities in Ho Chi Minh City announced that at least 30 percent of Chinese fruit being sold at local markets, especially tangerines, pears and apples, contain excessive traces of pesticides.