Reducing Shrinkage in Canned and Frozen Mushrooms

The process involving a preliminary soaking of the mushrooms in water for 20 min followed by a chill storage period followed by a further water soak for 2 hr, and known as the 3S process, gave a considerable reduction in total shrinkage in both brown and white strain canned mushrooms compared with the control samples. Water uptake by the mushrooms in the 3S process was greatest when the soaking water temperature was between 20 and 30°C and had a pH of 8. Citric acid in the blanch water enhanced the colour of the canned 3S treated mushrooms. Blanching in water at pH 8 gave better weight retention in the canned 3S product than when pH values were lower and the addition of starch to the blanch water also reduced blanching loss. Prestoring mushrooms for 72 hr prior to the 3S process had no effect on total shrinkage values but gave a less white canned product. The use of the 3S process on mushrooms for freezing resulted in better weight retention after blanching, but a less white product, compared with mushrooms that received a straight water soak, or no water soak.