If you’ve always wondered how to best cook mushrooms — these Spanish scientists have your back.

Want to keep mushrooms delicious and nutritious? Grill or microwave them, researchers say. Image via Pexels.

Mushrooms are cherished foods, having a significant amount of dietary fiber and being poor in calories and fat. They also have a good protein content (20-30% of dry matter) and provide valuable vitamins (B1, B2, B12, C, D and E), as well as trace minerals such as zinc or selenium. To make things even better, they also contain biologically active compounds with potential medicinal properties.

The thing is, we lose some of this nutritional value when we cook the mushrooms (which is how the vast majority of them is consumed). Scientists from the Mushroom Technological Research Center of La Rioja (CTICH) analyzed the four most common species: Agaricus bisporus (white button mushroom), Lentinula edodes (shiitake), Pleurotus ostreatus (oyster mushroom) and Pleurotus eryngii (king oyster mushroom), with the goal of determining the best way of cooking them. All mushrooms were harvested from the CTICH research facility.

After cooking, all mushrooms were freeze-dried and compared to an original, uncooked sample — also freeze dried. They found that frying, probably the most popular cooking method, induces severe losses in protein, ash, and carbohydrates content but increased the fat and energy. Boiling, on the other hand, improved the total glucans fraction but also reduced antioxidant activity. Meanwhile, grilled and microwaved mushrooms actually had higher antioxidant content, without any noticeable drawbacks.

“Frying and boiling treatments produced more severe losses in proteins and antioxidants compounds, probably due to the leaching of soluble substances in the water or in the oil, which may significantly influence the nutritional value of the final product” says Irene Roncero, one of the authors of the paper.

“When mushrooms were cooked by microwave or grill, the content of polyphenol and antioxidant activity increased significantly, and there are no significant losses in nutritional value of the cooked mushrooms” she adds.

However, if you want to cook the best mushrooms but also take advantage of oils to make the mushrooms tastier, fret not. Researchers tried several variations and found that adding a bit of oil doesn’t affect nutrient loss. Furthermore, using olive oil can enhance the fatty acid profile of the final preparation while barely adding more calories into the mix.

Journal Reference: Irene Roncero-Ramos, Mónica Mendiola-Lanao, Margarita Pérez-Clavijo, Cristina Delgado-Andrade. Effect of different cooking methods on nutritional value and antioxidant activity of cultivated mushrooms. International Journal of Food Sciences and Nutrition, 2016; 68 (3): 287 DOI: 10.1080/09637486.2016.1244662