It has been demonstrated in recent studies that the level of Vitamin D² in White/Brown mushrooms can be increased significantly (up to 100% of the Daily Value), by exposure to ultraviolet light for a few minutes, either pre-harvest or post-harvest.  When this technology is perfected, Super-D mushrooms may be available, to the public, as a vegetable source of Vitamin D.

How the World is Working to Add More Vitamin D to Mushrooms

In order to incorporate a UV treatment system into a commercial mushroom farm, some technical questions must be answered.  For example:

• Where is the best location for UV-treatment, in the growing rooms (pre-harvest) or in the packing room (post-harvest)?
• What is the best source of UV light, distance from the mushrooms and duration of exposure?
• What is the shelf life of treated mushrooms?
• Do white mushrooms discolour?  How much?
• If so, are brown mushrooms the preferred variety?
• Does the level of Vitamin D decrease with time?

In Canada, Mushrooms Canada is sponsoring research at the Guelph Food Technology Centre (GFTC) to determine the appropriate UVB light dosage to achieve 100% RDA levels (400 IU) in fresh, white and brown mushrooms. The study includes shelf-life, discolouration and microbiology of the treated products.

The Australian Mushroom Growers Association (AMGA) has initiated a study of intermittent UV-light exposure in a growing room, pre-harvest. Vitamin D² will be measured in the mushrooms, 4 and 8 days post-harvest.  The objective is to license a Vitamin D² process for mushroom growers.

In the USA, The Mushroom Council and the Agricultural Research Service of the USDA are studying the time and dosage of UVB light treatment up to 4 days post-harvest and Vitamin D² degradation during storage.

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