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Sulfiting agents have been widely used to prevent melanosis in 

 agricultural and seafood products. Due to health concerns, the use of 

 sulfiting agents as food additives has been re-evaluated by FDA and in 

 some products, banned for use (Lecos, 1986). It has become necessary to 

 search for alternatives that show effective inhibition on melanosis but 

 are devoid of health concerns to consumers. 



Kojic acid (5-hydroxy-2-hydroxymethyl-7-pyrone) is a fungal 

 metabolite produced by many species of Aspergillus and Pem'ci Ilium 

 (Kinosita and Shikata, 1964; Parrish et al . , 1966). It possesses 

 antibacterial and antifungal activity (Morton et al., 1945). Saruno et 

 al . (1979) demonstrated that kojic acid from Aspergillus albus inhibited 

 mushroom tyrosinase activity. This compound was also shown to inhibit 

 melanosis in pink shrimp (Applewhite et al . , 1990). Kojic acid mixed with 

 ascorbic acid and citric acid constitutes a Japanese product which is used 

 as a tyrosinase inhibitor in foods. Since only limited information was 

 available on the inhibitory effect of kojic acid on PPO, this study was 

 undertaken to investigate the inhibitory activity of this compound on 

 mushroom, plant (potato and apple), and crustacean (white shrimp, Florida 

 spiny lobster, and grass prawn) PPOs and to elaborate on mechanisms 

 involved. 



Materials and Methods 



Mushroom {Agaricus bispora) tyrosinase with an activity of 2,200 

 units/mg solid was purchased from Sigma Chemical Co. Russet potatoes and 

 Red Delicious apples were purchased from a local supermarket. Fresh 

 Florida spiny lobster {Panulirus argus) tails were obtained from Dr. R. A. 



