This study compares two different procedures for purification of lactulose-derived galactooligosaccharides (GOS) using fresh Saccharomyces cerevisiae yeast or activated charcoal with water or ...ethanol/water solutions for selective removal of monosaccharides. Yeast fermentation allowed the complete removal of monosaccharides without any losses of di- and oligosaccharides; however besides ethanol, glycerol and higher alcohols difficult to remove are also produced. The presence of higher alcohols affects the sensory quality of the lactulose-derived GOS and may limit its use in certain food applications. Fractionation of these oligosaccharides using activated charcoal was compared with that of lactose-derived GOS the latter being the most strongly adsorbed. When water was utilised as solvent, all monosaccharides were removed, as well as about 20% of unreacted disaccharides. Removal of tri-, tetra- and pentasaccharides was not observed. Using water/ethanol mixtures, desorption of oligosaccharides increased with ethanol content, allowing the selective recovery of different sugar fractions.
The hydrolysis of plant glucosinolates by myrosinases (thioglucosidases) originates metabolites with chemopreventive properties. In this study, the ability to hydrolyze the glucosinolate sinigrin by ...cultures or protein extracts of Lactiplantibacillus plantarum WCFS1 was assayed. This strain possesses myrosinase-like activity as sinigrin was partly hydrolyzed by induced cultures but not by protein extracts. The 11 glycoside hydrolase GH1 family proteins, annotated as 6-phospho-β-glucosidases, were the proteins most similar to plant myrosinases. The activity of these proteins was assayed against sinigrin and synthetic glucosides. As expected, none of the proteins assayed possessed myrosinase activity against sinigrin or the synthetic β-thio-glucoside derivative or against the β-glucoside. However, all 11 proteins were active on the phosphorylated-β-glucoside derivative. Moreover, only eight of these proteins were active on phospho-β-thioglucose. These results supported that, in L. plantarum WCFS1, glucosinolates may undergo previous phosphorylation, and GH1 proteins are the glycosidases involved in the hydrolysis of phosphorylated glucosinolates.
High-yield purification of commercial lactulose syrup Julio-Gonzalez, Lesbia Cristina; Hernández-Hernández, Oswaldo; Javier Moreno, F. ...
Separation and purification technology,
10/2019, Volume:
224
Journal Article
Peer reviewed
Open access
Display omitted
•A selective hydrolysis of lactose system was designed for lactulose purification.•Activated charcoal treatment allowed complete removal of monosaccharides.•The overall recovery of ...the purification lactulose process was 80% and 94% of purity.
A simple process for purifying lactulose in commercial lactulose syrups was developed. The objective was to establish a selective enzymatic hydrolysis of lactose and epilactose and further removal of monosaccharides by activated charcoal and water/ethanol solutions. Four commercial β-galactosidases from different microorganisms were tested obtaining significant differences in their activities towards the three disaccharides present in the lactulose syrup. β-galactosidases from Bacillus circulans (Biolactasa® NTL*2) and Bifidobacterium bifidum (Saphera® 2600 L) showed a reduced enzymatic activity towards lactulose and a high enzymatic activity towards lactose. These two enzymes were chosen to optimize the lactose hydrolysis methodology using Response Surface Methodology (RSM). Once chosen the optimum enzymatic conditions to selectively hydrolyse lactose present in the lactulose syrup, the hydrolysed sample was treated with activated charcoal and water/ethanol solutions to eliminate all monosaccharides. The proposed method offers a product with high purity (>94%) and high recovery (>80%) of lactulose.
► Lactulose was not detected in any of analyzed samples. ► High furosine content indicates that lactose hydrolysis took place before UHT process. ► GOSs were detected in all commercial lactose-free ...UHT dairy products analyzed. ► In low lactose milk GOS formation may be improved controlling lactose hydrolysis.
In this work a study of mono-, di- and galactooligosaccharide (GOS) content as well as the determination of thermal indicators of different commercial lactose-free UHT (LF-UHT) milks and dairy drinks has been carried out. Moreover, GOS formation during hydrolysis of lactose in a commercial UHT milk using Lactozym® pure 6500 was also studied. Presence of GOS was detected in all analyzed samples ranging from 950 to 4350mg/L in LF-UHT milks and from 600 to 2260mg/L in LF-UHT dairy drinks. Their GOS contents correlate roughly with the remaining lactose content of samples. During enzymatic hydrolysis of lactose in commercial UHT milk, the GOS formed reached a maximum about 10,000mg/L when 75–90% of lactose was hydrolyzed and then gradually decreased to values considerably lower than 5000mg/L when over 99% of the lactose was hydrolyzed. Therefore, GOS formation during low lactose milk manufacture might be improved by controlling enzymatic lactose hydrolysis so that it would be possible to elaborate low-lactose milk products able to satisfy the physiological requirements of the majority of intolerant groups and with a GOS content high enough to confer beneficial effect as prebiotic.
The increasing interest for prebiotic carbohydrates as functional food ingredients has promoted the synthesis of galactooligosaccharides and new lactose derivatives. This review provides a ...comprehensive overview on the chromatographic analysis, structural characterization, and bioactivity studies of lactose‐derived oligosaccharides. The most common chromatographic techniques used for the separation and structural characterization of this type of oligosaccharides, including GC and HPLC in different operational modes, coupled to various detectors are discussed. Insights on oligosaccharide MS fragmentation patterns, using different ionization sources and mass analyzers, as well as data on structural analysis by NMR spectroscopy are also described. Finally, this article deals with the bioactive effects of galacto oligosaccharides and oligosaccharides derived from lactulose on the gastrointestinal and immune systems, which support their consumption to provide significant health benefits.
This comprehensive work addresses, for the first time, the heterologous production, purification, biochemical characterization and carbohydrate specificity of MelA, a cold-active α-galactosidase ...belonging to the Glycoside Hydrolase family 36, from the probiotic organism Lactobacillus plantarum WCFS1. The hydrolytic activity of MelA α-galactosidase on a wide range of p-nitrophenyl glycoside derivatives and carbohydrates of different molecular-weights showed its high selectivity and efficiency towards the α(1 → 6) glycosidic bonds involving the anomeric carbon of galactose and the C6-hydroxyl group of galactose or glucose units. MelA α-galactosidase also presented a high regioselectivity, efficiency and diversity in accommodating donor and acceptor substrates for the synthesis of α-GOS through transgalactosylation reactions. The catalytic mechanism of MelA for the production of α-GOS was elucidated, revealing its great preference for the transfer of galactosyl residues to the C6-hydroxyl group of galactose units to elongate the chain of α-GOS having either a terminal sucrose (raffinose family oligosaccharides, RFOS) or a terminal glucose (melibiose, manninotriose and verbascotetraose). Our findings indicate the feasibility of using MelA α-galactosidase from Lactobacillus plantarum WCFS1 in the hydrolysis of RFOS and in the efficient and versatile synthesis of α-GOS with appealing functional properties in the context of food and nutraceutical applications.
Chitooligosaccharides possessing remarkable biological properties can be obtained by enzymatic hydrolysis of chitin. In this work, the chitosanase activity of soluble and immobilized ...glycosyltransferase (Branchzyme) toward chitosan and biochemical characterization are described for the first time. This enzyme was found to be homotetrameric with a molecular weight of 256 kDa, an isoelectric point of 5.3, and an optimal temperature range of between 50 and 60 °C. It was covalently immobilized to glutaraldehyde–agarose with protein and activity immobilization yields of 67% and 17%, respectively. Immobilization improved enzyme stability, increasing its half-life 5-fold, and allowed enzyme reuse for at least 25 consecutive cycles. The chitosanase activity of Branchzyme on chitosan was similar for the soluble and immobilized forms. The reaction mixture was constituted by chitooligosaccharides with degrees of polymerization of between 2 and 20, with a higher concentration having degrees of polymerization of 3–8.
The production, biochemical characterization, and carbohydrate specificity of LacA β-galactosidase (locus lp_3469) belonging to the glycoside hydrolase family 42 from the probiotic organism ...Lactobacillus plantarum WCFS1 are addressed. The β-d-galactosidase activity was maximal in the pH range of 4.0–7.0 and at 30–37 °C. High hydrolysis capacity toward the β(1 → 4) linkages between galactose and glucose (lactose) or fructose (lactulose) was found. High efficiency toward galactosyl derivative formation was observed when lactose and glycerol, xylitol, or erythritol were used. Galactosyl derivatives of xylitol were characterized for the first time as 3- O -β-d-galactopyranosyl-xylitol and 1-O-β-d-galactopyranosyl-xylitol, displaying high preference of LacA β-galactosidase for the transfer of galactosyl residues from lactose to the C1 or C3 hydroxyl group of xylitol. These results indicate the feasibility of using LacA β-galactosidase for the synthesis of different galactosyl-polyols, which could be promising candidates for beneficial and appealing functional and technological applications such as novel prebiotics or hypocaloric sweeteners.
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