Production and utilization of lactase
AssigneeThe Regents of the University of California
InventorsEli V. Crisan, Steven G. Sorensen
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Abstract
Thermostable lactase produced by growth of thermophilic fungi, harvesting resulting mycelium, separating lactase from mycelium by radical rupture of cell structure or by subjecting cell structure to milder treatment which does not separate lactase from the structure, and separating cell debris. Resulting lactase has high degree of activity and is thermostable such that it can be used at relatively high temperatures, e.g. 60.degree. C., and at acid pH to catalyze hydrolysis of lactose to glucose and galactose.
Claims21
Lactase derived from thermophilic fungi and in a form suitable for use in catalyzing the hydrolysis of lactose in a dairy product to glucose and galactose, said lactase having a high enzymatic activity and being characterized by retention of such activity for a substantial period of time at a temperature of 55.degree. - 60.degree. C and a pH not exceeding 5.
Lactase that is thermostable and that has optimum activity at a pH not greater than 5.
An admixture of (1) thermostable lactase and (2) thermolabile lactase, said lactase (1) having and retaining a high degree of enzymatic activity at a temperature of 55.degree. - 60.degree. C. and a pH between 4 and 5, said lactase (2) having its optimum activity and stability at temperatures substantially below 55.degree. C. and at a pH about 7;
- each said lactase component being present in substantial proportion sufficient to effectively catalyze hydrolysis of lactose to glucose and galactose at its optimum conditions of temperature and pH.
A method of producing thermostable lactase having its optimum activity at a pH below 5 which comprises inoculating a culture medium having lactose as the sole or a major source of carbon with cells of a thermophilic fungus, said culture medium being suitable for proliferation of such cells, maintaining conditions of temperature and pH favorable to cell growth and proliferation, causing such growth and proliferation, and harvesting the resulting mycelium, said fungus being selected from a genus and species capable of producing thermostable lactase in such culture medium at a substantial rate, such lactase having its maximum activity at a pH below 5.
A method of treating a dairy product to reduce its lactose content by hydrolyzing the lactose to glucose and galactose;
- said method comprising subjecting the dairy product to contact with thermostable lactase having its optimum activity at a pH not greater than 5, said contact being at a temperature not less than about 55.degree. C and at a pH not greater than 5 and causing hydrolysis of lactose at such temperature.
Dependencies are inferred from the claim text.