Galactose is found in many oligosaccharides, galactomannans, glycoproteins and glycolipids, which are widely distributed in plants microorganisms and animals. α-Galactosidase (α-Gal) catalyzes the hydrolysis of 1,6-linked α-galactosyl residues and transgalactosylation. α-Gals are classified into four glycoside hydrolases families (GH): 4, 27, 36 and 57. The majority of known α-Gals belongs to GH families 27 and 36.α-Gals are of particular interest in view of their biotechnological applications.
Purple sweet potato pigment is a natural food pigment, the stability is important to its quality assurance. The effects of metal ions on the stability of purple sweet potato pigment were investigated. The results showed that Mg2+and Fe3+ were conductive to pigments stability in the initial storage, and with the concentration increased, the pigment was more stable. But K+, Ca2+, Na+, Cu2+, Mg2+ and Fe3+ had brought the color density, the color intensity and the preservation rate of purple sweet potato pigment down in the long-term storage.
Anthocyanins, which possess strong antioxidant activities, are abundant in purple sweet potato wine. In the present study, changes in the antioxidant activity of purple sweet potato wine during storage were investigated. The results showed that purple sweet potato wine had high 2,2-dipheny-l-picrylhydrazyl (DPPH) free-radical and superoxide-radical scavenging activities, which were stable during storage periods. Compared with these two scavenging activities, the hydroxyl-radical scavenging activity of purple sweet potato wine was concentration-dependent and only presented relatively obvious scavenging activity at high concentrations. This hydroxyl-radical scavenging activity was also stabile during storage periods. The results are valuable in purple sweet potato wine research and development.
The conditions for purification of soyasaponin by macroporous resin adsorption strategies were analyzed. The results showed that macroporous resin D3520 was a suitable resin for the purification of soyasaponin. Static adsorption assay showed that 20:1 (w/w) D3520/soyasaponin at 40 oC for 2h adsorption were optimal for soyasaponin purification. In the column chromatography, 0.5BV (bed volume)/h flow rate would be suitable to reach higher purity of near 90 % soyasaponin.
The α-galactosidase from rice cleaved not only α-D-galactosyl residues from the non-reducing end of substrates such as melibiose, raffinose and stachyose, but also liberated the terminal galactosyl residues attached O-6 position of the reducing-end mannosyl residue in mannobiose and mannotriose. In addition, the enzyme tore off the stubbed galactosyl residues attached inner-mannosyl residues in mannopentaose. It also could catalyze efficient degalactosylation of galactomannans, such as guar gum and locust bean gum.
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