Kinetic studies of the enzymatic hydrolysis of molasses were conducted using glucoamylase. Central Sugar Refinery SDN BHD contains 13–20% glucose. The molasses was diluted and the kinetic experiments were conducted at 67 °C with 100–1000 mg/l of glucoamylase. The glucose contents of the molasses were enhanced after hydrolysis of molasses solution with 1000 mg/l glucoamylase. A Lineweaver–Burk plot was obtained based on enzyme kinetic data. The rate constant, Km and maximum reaction rate,Vmax for 500 mg/l of glucoamylase were 100 mmol/l (18 g/l) and 5 mmol/l min (0.9 g/l min), respectively. The maximum reaction rate,Vmax for 1000 mg/l of glucoamylase was doubled, to 100 mmol/l (18 g/l) and the rate constant, Km was the same for 500 mg/l of glucoamylase. The substrate inhibition model was noncompetitive based on the resulting Lineweaver–Burk plot for enzyme concentration of 500 and 1000 mg/l.

Introduction

Amylolytic enzymes are classified into α-amylase and glucoamylase which are involved in the complete conversion of starch to sugar. α-Amylase (1,4-α-glucan-glucanohydrolases) is an extracellular enzyme which hydrolyzes starch into maltose, glucose and maltotriose by attacking the α-1,4-glycosidic bonds in starch and related substrates. Glucoamylase (α-1,4-glucan-gluco- hydrolases) acts on starch by splitting glucose units from the nonreducing ends. Amylolytic enzymes can be produced from a variety of sources, including fungi (Najafpour et al., 1999), and bacteria. The α-amylases are widely used for liquefaction and saccharification of starchy substances in the food, confectionary and beverage industries (Bolton et al., 1997). A primary use is in the production of sweetener and reduction of dough viscosity to improve the texture and appearance of bread. It is also present in pharmacologically active digestive aids, used in the process of recovering sugar from scrap candy and is involved in the manufacture of syrups in chocolate. Saccharomycopsis fibuligera has been used to ferment 20% solid starchy waste from poultry processing waste to single cell protein (Najafpour et al., 1994). Also Saccharomycopsis fibuligera has been used to ferment premalted 20% wheat starch (Gogoi et al., 1987) and α-amylases from other microorganisms have been used to convert cassava starchy waste and in the saccharification of sugar beet pulp (Ejiofor et al., 1996; Micard et al., 1996).