ABSTRACT
Lactose intolerance is becoming a health state that
requires the restriction of dairy products in the diet of people suffering from
this condition. But milk and dairy products, due to a well-balanced composition
in the main macro and micronutrients, cannot be missing from the diet of the
consumer of any age. For these reasons, in recent years, in the milk processing
industry, the production of low-lactose or lactose-free dairy products is explored.
To reduce the lactose content of dairy raw materials, various industrial and
biotechnological methods were used: enzymatic hydrolysis of lactose,
baromembranous methods, bioconversion of lactose by lactic bacteria and others.
The most widely used lactase enzymes in the industry are mesophilic enzymes
from filamentous fungi (Aspergillus spp.) and yeasts (Kluyveromyces spp.). Therefore, the aim of this study was to evaluate the
effect of the commercial enzyme β-galactosidase
on the hydrolysis of cow’s milk at different enzyme concentrations, temperatures
and pH. Two commercial enzymes β-galactosidase obtained from Bacillus licheniformis and β-galactosidase obtained from Kluyveromyces lactis, were used in this
study, according to information provided by the manufacturer. The thermal
stability of lactose, the effect of milk pH, the effect of temperature, duration
of hydrolysis and the amount of enzymes on the lactose hydrolysis degree and
the sweetness degree of milk were determined. Research has identified the
optimal parameters for obtaining a high degree of lactose hydrolysis in the use
of these enzymes. Therefore, to ensure a high lactose hydrolysis degree (over
80%), the following lactose hydrolysis regimens were identified: temperature
4°C - 6°C, 0.3% Bacillus licheniformis enzymes, duration 4 hours; temperature 4°C - 6°C, 0.3% enzymes from Klavyromyces lactis, duration 12 hours and
temperature 38°C - 40°C, 0.15% enzymes from (Bacillus licheniformis or Klavyromyces lactis), duration 2 - 3
hours. The results obtained allow the efficient use of Bacillus licheniformis and Klavyromyces lactis enzymes in industrial
processes for the manufacture of “lactose-free” or “low-lactose” drinking milk
and fermented dairy products for people with lactose intolerance.