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REMOVAL OF OLIGOSACCHARIDES FROM SOY MILK BY AN ENZYME FROM ASPERGILLUS SAITOI
Author(s) -
SUGIMOTO H.,
BUREN J. P. VAN
Publication year - 1970
Publication title -
journal of food science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.772
H-Index - 150
eISSN - 1750-3841
pISSN - 0022-1147
DOI - 10.1111/j.1365-2621.1970.tb04836.x
Subject(s) - chemistry , protease , hydrolysis , enzyme , chromatography , raffinose , substrate (aquarium) , soy milk , melibiose , soy protein , invertase , enzyme assay , biochemistry , food science , sucrose , biology , ecology
SUMMARY As part of a program to reduce the flatulence‐inducing tendency of soy milk, a method for the enzymatic removal of galacto‐oligosaccharides by means of an enzyme preparation from Aspergillus saitoi was investigated. It was found that a partially purified preparation possessing both α‐galactosidase and invertase, yet free from protease, could be obtained easily from a commercial A. saitoi acid‐protease product by means of a simple molecular sieving procedure. The α‐galactosidase exhibited its optimum pH between 5.0 and 5.5, and seemed to be stable between pH 4.0 and 8.0. The optimum temperature was found at about 55°C; however, the enzyme itself was inactivated by maintaining it at 70°C for 30 min. These properties appeared suitable for the enzymatic treatment of soy milk. p‐Chloromercuribenzoate, N‐bromosuccinimide, HgCl 2 , AgNO 3 or CuCl 2 showed strong inhibitory effects on the enzyme. The presence of 1 x 10 ‐2 M galactose caused only slight inhibition. Km value of the enzyme with melibiose as a substrate was found to be 3.11 x 10 ‐3 M and the molecular weight of the enzyme estimated to be about 290,000 on the basis of a gel filtration technique. Investigations by means of thin‐layer chromatography indicated that the addition of small amounts of this enzyme preparation to soy milk resulted in complete hydrolysis of galacto‐oligosaccharides. The practicability of the present method was also discussed from an economic viewpoint.