Abstract:  A feasible way to produce lactulose, employing milk ultrafiltrate as source of lactose and egg shell as catalyst, is proposed as an alternative means for utilising these industrial wastes. Influences of catalyst loadings, lactose concentration and pH on lactose isomerisation were studied. Optimal production of lactulose was reached at 98℃, employing 6 mg/ml of catalyst loading within 60 min of reaction. Quantities of lactulose of 1.18 g/100ml and low levels of secondary products (epi-lactose, galactose and organic acids) were produced under these conditions of reaction. Methodology to remove coloured by-products from lactulose syrup in a range of 65%～92% was established.

Key words: lactulose, egg shell, lactose isomerisation, milk ultrafiltrate