β-Glucan content and in vitro bile-acid binding capacity of Agaricus bisporus and Pleurotus spp.

Abstract

The cholesterol lowering properties of oats and barley, attributed to their high β-glucan content, are well established, but it remains unclear whether mushrooms, also rich in β-glucan, exhibit a similar functionality. We aimed to quantify the β-glucan content of commonly consumed Australian mushrooms and evaluated their bile acid binding capacity, the primary cholesterol lowering mechanism of β-glucan. Raw, boiled and fried Australian grown Agaricus bisporus (button, cup, flat and brown mushrooms) and Pleurotus spp. (shimeji and oyster) along with oats were freeze-dried and the β-glucan content was determined. The bile acid binding capacity of these samples was assessed using an in vitro digestion assay. The β-glucan content of freeze-dried raw A. bisporus mushrooms (4.5–8.1 g per 100 g) was similar to that of oats (7.6 g per 100 g, all p > 0.05), whereas Pleurotus mushrooms contained ∼5 times more β-glucan (32.5–37.4 g, p < 0.05). Boiling increased the β-glucan content of oyster, button, flat and brown mushrooms by 3–7% (p < 0.05), but did not affect the β-glucan content of shimeji or cup mushrooms. Frying had no effect on any mushroom type. The bile acid binding capacity of A. bisporus mushrooms (29–36%) was equivalent to that of raw oats (36%, p > 0.05), whereas the bile acid binding capacity of oyster mushrooms (22%) was lower than that of oats (p < 0.05). Both boiling and frying increased the bile acid binding capacity. The cholesterol lowering effects of A. bisporus mushrooms and the acceptability of consumption at the required levels need to be confirmed by clinical trials.