Cell water balance of while button mushrooms (Agaricus bisporus) during its post-harvest lifetime studied by quantitative magnetic resonance imaging

A combination of quantitative water density and T-2 MRI and changes therein observed after infiltration with 'invisible' Gd-DTPA solution was used to study cell water balances, cell water potentials and cell integrity. This m ethod was applied to reveal the evolution and mechanism of redistribution o f water in harvested mushrooms. Even when mushrooms did not lose water duri ng the storage period, a redistribution of water was observed from stipe to cap and gills. When the storage condition resulted in a net loss of water, the stipe lost more water than the cap. The water density in the gill incr eased, probably due to development of spores. Deterioration effects (i.e. l eakage of cells, decrease in osmotic water potential) were found in the out er stipe. They were not found in the cap, even at prolonged storage at 293 K and R.H. = 70%. The changes in osmotic potential were partly accounted fo r by changes in the mannitol concentration. Changes in membrane permeabilit y were also indicated. Cells in the cap had a constant low membrane (water) permeability. They developed a decreasing osmotic potential (more negative ), whereas the osmotic potential in the outer stipe increased, together wit h the permeability of cells. (C) 1999 Elsevier Science B.V. All rights rese rved.