Part of the Methods in Biotechnology book series (MIBT, volume 16)
α-Galactosidase Assay in Fermented Soymilk Products
The enzyme alpha-galactosidase (α-gal) (EC. 126.96.36.199) hydrolyzes the α-1,6-galactosidic bonds present in melibiose, raffinose, and stachyose. These carbohydrates, which are found in plants, cannot be metabolized by humans (1), these sugars being responsible for intestinal disturbances, such as flatulence. Many attempts to reduce these antinutritional factors by soaking (2), germination (3), and water extraction at different times and ratios (4) have been made. Enzyme treatment of soymilk with α-gal from molds and yeasts is well documented (5, 6, 7, 8); however, little is known about this enzyme isolated from lactic acid bacteria. The presence of this enzyme has been reported in Bifidobacterium genera, whereas in lactic acid bacteria, it is produced only by some strains of Lactobacillus, Leuconostoc, and Pediococcus (9, 10, 11, 12). The method developed to study α-gal from several sources (8, 13) is based on the absorbance measurement at 400 nm of the p-nitrophenol (pNP) released by the action of the enzyme (α-gal) upon its specific substrate, p-nitrophenyl-α-D-galactosidase (pNPG).
KeywordsLactic Acid Bacterium Glass Bead Enzyme Extract Sample Blank Sodium Carbonate
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