Changes in the ethanol-soluble carbohydrate content of Agaricus bisporus mycelium and sporophores grown on semi-defined media and commercial compost were studied. The accumulation of mannitol in the sporophore during its growth was not accompanied by an increase in mycelial mannitol. The other major soluble carbohydrate of the sporophore, trehalose, decreased throughout the growth of the sporophore; a parallel decrease was observed in the mycelium. The main accumulation of mannitol was in the pileus and stipe of the sporophore and was accompanied by a decrease in the soluble protein content of these tissues. Before fruiting, glucose and sucrose were present in the mycelial samples in similar quantities to mannitol, but their levels decreased during fruiting. Small quantities of glucose were present in the sporophore. The results are discussed in relation to the possible functions of the soluble carbohydrates.

The COz production and soluble carbohydrate content were studied in the cultivated mushroom (Agaricus bisporus) during storage at 18 "C. The pattern of postharvest respiration was seen to be dependent on the maturity of the sporophore at harvest. A post-harvest respiratory peak was observed and this appeared to correspond with the phase of rapid gill development which occurs after harvest of immature, fruit bodies. The disappearance of significant quantities of mannitol from the sporophore during storage seemed to indicate that this was one of the main respiratory substrates during storage, although it was evident that other substrates were utilised. The results obtained are discussed in relation to the postharvest development of the sporophore and the function of its tissues.

A rapid and accurate method for the estimation of protein concentration is essential in many fields of protein study. The Lowry method ( Chapter 1 in vol. 1 of this series) has been widely used, but is susceptible to interference from a wide range of compounds commonly present in biological extracts. Although interference can be avoided by trichloracetic acid precipitation of the protein prior to assay, this lengthens the procedure.

Mushrooms (Agaricus bisporus) were picked at the "button" stage (velum differentiated but unbroken) and stored for 3 to 5 days at 2 or 18 "C in styrene punnets (pre-packs) overwrapped with one of a range of plastic films. Concentrations of carbon dioxide and oxygen were measured inside the pre-packs at intervals. When the packs were opened, internal and external browning, loss of weight and diameter of the mushrooms were measured and subjective assessments of quality were made. These parameters were compared with those of mushrooms stored in unwrapped punnets.As a result of the mushroom respiration, the internal atmosphere of the prepack was rapidly modified until, after about 24 h, a rough equilibrium concentration of C 0 2 and O2 was established in the range 4 to 10% C02 and 11 to 17 % 0, at 2 "C or 8 to 15 % C02 and 1 to 2 % O2 at 18 "C; the mean concentration was dependent on the type of film. An equation, applicable to five out of six films that were tested, is proposed to describe the relationship between the equilibrium C 0 2 concentrations at 18 "C and the permeability data of the film.At 18 "C, the gas changes inside the pre-packs prevented opening of the pileus and, in combination with prevention of water loss by the film, slowed down deterioration of the mushrooms. However, concentrations of C02 much above or below 10 to 12% were associated with increased internal browning. At 2 "C overwrapping generally caused slight external browning of the pileus.The relevance of the results are discussed in relation to the commercial marketing of pre-packed mushrooms.

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