% 



11 



(Antony and Nair, 1975; Bailey and Fieger, 1954; Faulkner et al . , 1954; 

 Ferrer et al . , 1989b; Fink, 1988; Madero, 1982; Madero and Finne, 1982). 

 Many methods are available for inhibiting/inactivating PPO. The 

 application of these methods or chemicals for inhibition in the food 

 industry, however, is limited. Problems related to off-flavor, off-odor, 

 toxicity, and economic feasibility all affect the application of chemicals 

 (Eskin et al., 1971). Sulfiting agents listed as Generally Recognized As 

 Safe (GRAS) by the Food and Drug Administration (FDA) since 1959 (FDA, 

 1984) have been widely used to prevent melanosis of agricultural and 

 seafood products. However, due to the recent health concern and questions 

 regarding the safety of sulfiting agents, the FDA currently proposed 

 revoking the GRAS status of these additives for use on fruits and 

 vegetables intended to be served or sold fresh or raw to consumers. The 

 V FDA also requires label declaration of these agents added to food or as an 

 ingredient whenever they are present in the finished product at a level 

 equal to or higher than 10 ppm as SOj (FDA, 1985). Furthermore, the FDA 

 requires that sulfite-treated shrimp products having residue levels 

 -'. greater than 10 ppm must bear a label stating the presence of these 

 additives (FDA, 1985). 



The maximum allowable residual level of sulfite on shrimp in the raw 

 edible portion is 100 ppm as SO2 (Marshall et al . , 1984), which is not 

 hazardous to the majority of the population. After exposure to these 

 additives even at this level, however, people still suffer adverse 

 reactions ranging from mild to severe symptoms (Lecos, 1986). Therefore, 

 the search for an alternative which can inhibit melanosis but does not 

 cause adverse reactions becomes a necessity. ; 



