Relationships between Hydrocolloid Coating and Mushroom Structure

Agaricus bisporus edible mushrooms were coated with different gum-based coatings, including alginate and alginate-ergosterol, with or without emulsifier. The structures of the different parts of the mushroom tissue were studied by SEM. Various penetration modes of coating and cross-linking solutions into the tissue were examined. The techniques of ICP and X-ray analysis were used to quantify the presence and depth of penetration of minerals into the mushroom tissue before and after coating. Critical surface tension of the "solid" upper surface of the mushroom was estimated using the Zisman plot. The alginate-based coating solutions were tested for their surface tension and contact angles on the mushroom tissue. Reduction in the surface tension and the contact angles of the coating solutions lead to better wettability of the surface. Coated mushrooms were found to have a better appearance, a better color, and an advantage in weight in comparison with the uncoated ones. The alginate-ergosterol-Tween coating combination was most suitable for maintaining the size and shape of the coated mushroom.