RELATIONSHIPS BETWEEN HYDROCOLLOID COATING AND MUSHROOM STRUCTURE

Agaricus bisporus edible mushrooms were coated with different gum-base d coatings, including alginate and alginate-ergosterol, with or withou t emulsifier. The structures of the different parts of the mushroom ti ssue were studied by SEM. Various penetration modes of coating and cro sslinking solutions into the tissue were examined. The techniques of I CP and X-ray analysis were used to quantify the presence and depth of penetration of minerals into the mushroom tissue before and after coat ing. Critical surface tension of the ''solid'' upper surface of the mu shroom 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 sur face. Coated mushrooms were found to have a better appearance, a bette r color, and an advantage in weight in comparison with the uncoated on es. The alginate-ergosterol-Tween coating combination was most suitabl e for maintaining the size and shape of the coated mushroom.