The process of lactose hydrolysis is simple and does not require
special equipment in dairy plants (Zadow, 1986). When using
a single-use enzyme for lactose hydrolysis, several factors must be
considered. These include substrate concentration, pH of operation,
maximum temperature and contact time permissible, enzyme
activity and cost. An extensive contact time at 35e45 -
C may be
required to reduce costs, but with milk this usually results in
extensive microbial growth. Alternatively, overnight holding at
refrigeration temperature may be employed (Zadow, 1986). Soluble
lactases used are generally of microbial origin (Greenberg &
Mahoney, 1981; Mahoney, 1997) (Table 1).