The project concerns improving the quality of the common fresh white mushroom (Agaricus bisporus).Particular attention is being focused on discolouration, textural aspects, storability and on harvesting aspects including vision systems. Storage of mushrooms in high carbon dioxide atmospheres causes increased discolouration. Under these conditions, the metabolism becomes anaerobic, as reflected by the production of ethanol. Preliminary results suggest that carbon dioxide is mostly responsible for the switch in metabolism and the yellow discolouration. The total removal of oxygen in the presence of nitrogen also triggers anaerobic metabolism. It is postulated that mushrooms can be stored in atmospheres containing less than 1% oxygen while the carbon dioxide content should be limited to a maximum of 5%. However, no packaging film to date can generate such an atmosphere and hence new films displaying high carbon dioxide permeability, are being tested. Their extremely high permeabilities towards carbon dioxide depend on the hydration of the film. Polyphenol oxidase, the enzyme responsible for enzymatic discolouration, occurs in mushroom extracts both in a latent and in an active form and levels in mushrooms appear to be sufficiently large to enable oxidation of the endogenously present phenols to take place in a few seconds. Therefore, polyphenol oxidase activity must follow a pattern of strict regulation, depending on damage- or senescence-related signals. Bacterial blotch, a major mushroom-related disease causing considerable economic damage, is possibly related to polyphenol oxidase-activity. The disease is caused by Pseudomonas spp. whose effect on mushrooms seems more related to mushroom strain than to strain of Pseudomonas. A third element of the project enhanced the development of a vision system to locate and size harvestable mushrooms. A list of factors, complicating recognition or picking of mushrooms, and containing both mushroom-biology related and picking-technology related aspects has been documented.