The antioxidative property of a hydrophilic extract prepared from the fruiting body of edible mushroom ( Flammulina velutipes) was evaluated. The mushroom extract contained ergothioneine (ERT) at a level of 3.03 +/- 0.07 mg/mL, showed higher 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity, and suppressed lipid oxidation of bigeye tuna meat more effectively than authentic L-ERT added at the same concentration. The authentic L-ERT had stronger total reducing power than the mushroom extract and inhibited the formation of metmyoglobin (metMb) more significantly in bigeye tuna meat. Lipid oxidation in beef and fish meats to which the mushroom extract had been added was "virtually" controlled during storage on ice. Ground beef and bigeye tuna meat with the extract added kept their natural colors unchanged for longer than 12 and 7 days of ice storage, respectively. Contrary to this, browning in meat color was observed in the control samples without the extract after 6 and 2 days of storage, respectively, when stored under similar conditions. There was significant correlation between meat color and chemical parameters, including total lipid hydroperoxides, thiobarbituric acid reactive substances, and metMb. However, there was no significant correlation between pH value and meat discoloration. These results suggest that ERT in the hydrophilic extract of F. velutipes plays an important role as a color stabilizer of meats.

The results of this study clearly showed that ESH prepared from different mushroom species stabilized the colour of fish meats, and the extract from the F. velutipes was the most effective.

The ability of a hydrophilic extract prepared from edible mushroom (Flammulina velutipes) to stabilize fresh color of bigeye tuna (Thunnus obesus) meat was evaluated to compare it with certain other antioxidants. The fresh color shelf life of bigeye tuna meats, to which were added as 1, 3, or 5 mL of mushroom extract to 100 g of minced bigeye tuna meat, prolonged duration of ice storage by more than 2, 4, and 6 d, respectively, in comparison with the control tuna meat without mushroom extract. The addition of 5 mL of mushroom extract to 100 g of minced bigeye tuna meat was more effective than adding ascorbic acid sodium salt (500 ppm) or alpha-tocopherol (500 ppm) with regard to oxidation of lipid in the tuna meat. The color changes significantly correlated with lipid oxidation as well as metmyoglobin formation in the tuna meat. These results clearly show that the mushroom extract is a potential antioxidant, which has the ability to stabilize fresh color of tuna meat during ice storage.

Chitin and chitosan, valuable marine biopolymers, recovered from shrimp waste, are an abundant by-product of the shrimp processing industry in Vietnam, at an estimated 200000 metric tons per year. The obtained chitin and chitosan are characterized by their purity and functional properties. The polymers show good quality with low residual ash and protein content (<1%). The antioxidant potency of chitosan is evaluated by several different in vitro systems, including 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging, total reducing power, and inhibition of lipid peroxidation. The DPPH free radical scavenging, total reducing power, and lipid peroxidation inhibition activities of chitosan at varying concentration (0.125 to 1.0 mg/mL) range from 3.7 to 16.8%, 0.05 to 0.15, and 1.7 to 15.1%, respectively. This study demonstrates that chitin and chitosan, of good quality and having characteristics compatible with a broad range of applications, can be prepared from white shrimp waste.

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