1. Introduction
Tyrosinase (EC 1.14.18.1)plays an important role in the browning reaction of fruit and vegetable. This enzymatic browning may further result in discolouration and reducing the nutritional value of foods. In order to prevent the browning. use of food additives including reducing agent, and enzyme inhibitor (such as sulphite) had been recognised. In food browning, tyrosinase catalyses the hydroxylation of a monophenol as well as the production of o-quione and the initial reaction of melanin pigment synthesis (Kim & Uyama, 2005). During this complex process, the generation of more o-quinone will further diminish glutathione and decrease the anti- oxidant capacity in foods. In addition, melanin also found in the surface of vertebrates is present in the animal, microorganism and plant kingdoms. Previous research indicated that mammalian melanin produced in melanocytes and tyrosinase also plays a critical role for melanization in animals (Karioti, Protopappa, as & Skaltsa, 2007) Mega