[Dry matter losses in mushroom (Lactarius rufus) by blanching].
According to recommended international standards edible fungi are blanched before salting and freezing. A study was conducted on the solution losses of Lactarius rufus due to blanching. Weight losses, changes of dry matter, raw fat, total nitrogen, amino nitrogen and ash contents as well as the pH value were determined when various methods of blanching were used. 3 min blanching at 95-100 degrees C was able to inactivate catalase and peroxydase while 6 min blanching was needed for inactivating polyphenoloxydase totally. After blanching there were 1/10 - 1/100 of spores left. During the 3 min blanching in water five times the quantity of mushrooms the losses of dry matter were about 10%; when doubling the quantity of blanching water the losses increased to 2-3 fold. The doubling of blanching time had no significant influence on the losses. The soluble dry matter content of blanched mushrooms was less than 50% of that of the fresh. Total nitrogen of fresh mushrooms was equal to that of the blanched but the amino nitrogen decreased to one tenth by blanching. The mineral element content of blanched mushrooms was about the half of that of the fresh. Blanching caused a slight decrease in the pH value. The necessity of the blanching of all edible fungi before freezing was discussed.
[Dry matter losses in mushroom (Lactarius rufus) by blanching]. According to recommended international standards edible fungi are blanched before salting and freezing. A study was conducted on the solution losses of Lactarius rufus due to blanching. Weight losses, changes of dry matter, raw fat, total nitrogen, amino nitrogen and ash contents as well as the pH value were determined when various methods of blanching were used. 3 min blanching at 95-100 degrees C was able to inactivate catalase and peroxydase while 6 min blanching was needed for inactivating polyphenoloxydase totally. After blanching there were 1/10 - 1/100 of spores left. During the 3 min blanching in water five times the quantity of mushrooms the losses of dry matter were about 10%; when doubling the quantity of blanching water the losses increased to 2-3 fold. The doubling of blanching time had no significant influence on the losses. The soluble dry matter content of blanched mushrooms was less than 50% of that of the fresh. Total nitrogen of fresh mushrooms was equal to that of the blanched but the amino nitrogen decreased to one tenth by blanching. The mineral element content of blanched mushrooms was about the half of that of the fresh. Blanching caused a slight decrease in the pH value. The necessity of the blanching of all edible fungi before freezing was discussed.