Comparative studies of the quality of fresh and stored mushrooms of Agaricus bisporus with two tropical Agaricus bitorquis strains

Three white strains of mushroom were grown for quality assessment tests, a commercial Agaricus bisporus strain SOMYCEL U3 currently popular in most major mushroom producing countries and two tropical Agaricus bitorquis strains, ATCC 32675 and AGC W20. Mushrooms were harvested as stage 2 mushrooms (closed buttons with universal veil intact) and stored at 18°C (± 0.5°C) for 5 days during which time colour development, the rate of fruitbody maturation and weight loss were assessed. Throughout the storage period, a reflectance colormeter was used to monitor colour changes on the tops and sides of mushroom fruitbodies. The tops of both A. bitorquis strains were significantly more yellow than the A. bisporus strain, whereas the sides were significantly less yellow. Overall, the A. birorquis strain AGC W20 was clearly the least discoloured and least yellow at the time of harvest. Although all the three strains tested gave similar fresh weight losses during storage, i.e. approximately 10% per day, ATCC 32675 exhibited a very slow maturation rate. Both U3 and AGC W20 matured at a similar much faster rate forming open cups within the 5 day storage period. ATCC 32675 also showed the least increase in the degree of discolouration with time, whether readings were taken from the sides or tops of mushrooms. A breeding programme to combine the most salient features of AGC W20 (an intensely white mushroom at harvest, high yielding with distinct flush pattern) and ATCC 32675 (very slow maturation rate during storage) is suggested.