Agriculture and Agri-Food Canada
Did you know that mushrooms are the only source of vitamin D in the produce section of the grocery store, making them a unique and nutritious part of the Canadian diet? Similar to humans, mushrooms produce vitamin D when exposed to UV light from the sun or a sunlamp. This reaction is thanks to ergosterol—the mushroom equivalent to cholesterol—which converts to vitamin D2 when exposed to UV light.
To keep mushrooms fresh longer and to preserve their vitamins, Dr. Suqin Shao, an Agriculture and Agri-Food Canada (AAFC) researcher in Guelph, is looking at new ways to sterilize and store mushrooms. She recently examined the use of UV-C light, which is typically used in food sterilization, and cold storage (4 degrees Celsius) for their effects on the ergosterol and vitamin D2 content of brown and white button mushrooms.
Dr. Shao found that UV-C treatment prior to cold storage increased vitamin D2 in the caps and stems of both brown and white button mushrooms. When a higher dose of UV-C was used, it resulted in a higher concentration of vitamin D2.
She also found that in most of the mushroom samples tested, cold storage caused vitamin D2 levels to drop and ergosterol to rise, indicating that the reverse reaction was taking place. This study is the first ever to report this reversible reaction. However, even though cold storage reduced vitamin D2 levels, the UV-C treated mushrooms still had more vitamin D2 at the end of the storage period compared with untreated mushrooms because the treated mushrooms had started out with more vitamin D2, and both treated and untreated mushrooms were losing vitamin D2 at the same rate.
These findings are useful to guide post-harvest handling of mushrooms and could help strengthen the value of Canadian mushrooms—an important agricultural product, with a total value of $527 million reported for fresh and processed mushrooms in 2017. Canadian growers produced 132,556 tons of mushrooms in 2017, most of which (94.1 percent) was sold to the fresh market.
Key Discoveries (Benefits)
- Most Canadians don’t realize that mushrooms are the only produce that contain vitamin D, a key nutrient which is often challenging to get given our long, dark winters.
- AAFC’s Dr. Suqin Shao looked at new ways to sterilize and store mushrooms to keep them fresh longer and preserve their vitamins.
- Her research showed that mushrooms, like people, produce vitamin D when exposed to UV light (from the sun or a sunlamp, for instance). These findings could help farmers manage their post-harvest handling and storage of mushrooms to strengthen their value and offer more nutritional benefit to consumers.