Frozen mushrooms quality as affected by strain, flush, treatment before freezing, and time of storage

Four strains of mushrooms (Agaricus bisporus)-U3, hybrids of U3 (3/1, M-300), and in-between strain No. 200-were treated before freezing: washed ia water, washed in water containing sodium metabisulfite (3g.L-1), and washed in water containing sodium metabisulfite (5g.L-1) then immersed in boiling water far 20 s. Appearance and whiteness of frozen mushrooms were most affected by the washing in water containing sodium metabisulfite, The residue of sulfur dioxide changed from 52 mg.kg(-1) after 1 d to 27 mg.kg(-1) after 90 d of storage. The whitest mushrooms (fresh and frozen) were for Mo. 200 strain. Short-time immersion in boiling water markedly increased toughness of stored frozen mushrooms.