A novel gene ( BbFFase9 ), with an ORF of 1557 bp that encodes β-d-fructofuranosidase from Bifidobacteriaceae bacterium , was cloned and expressed in Escherichia coli . The recombinant protein (BbFFase9) was successfully purified and showed a single band with a molecular mass of 66.2 kDa. This was confirmed as a β-d-fructofuranosidase and exhibited a high specific activity of 209.2 U/mg. Although BbFFase9 was a soluble protein, it exhibited excellent tolerance to proteases such as pepsin, trypsin, acidic protease, neutral protease and Flavourzyme®, indicating its potential applicability in different fields. BbFFase9 exhibited typical invertase activity, and highly catalyzed the hydrolysis of the α1↔2β glycosidic linkage in molecules containing fructosyl moieties but with no detectable fructosyltransferase activity. It was optimally active at pH 6.5 and 50 °C and stable between pH 6.0 and 9.0 at a temperature of up to 45 °C for 30 min BbFFase9 could also effectively hydrolyze galacto-oligosaccharides, which are a flatulence factor in soybean meal, thus releasing new types of product such as melibiose and mannotriose, or degrading them into invert sugars, the sweeter fructose and glucose. This study is the first to report the application of this type of β-d-fructofuranosidase.
The composite adsorbent consisting of sodium alginate (SA) and quaternary ammonium-functionalized chitosan (QACS) was prepared using the calcium slow-release method to remove high-molecular-weight invert sugar alkaline degradation products (HISADPs) from the beet juice. The SA/QACS composite adsorbent has a honeycomb porous structure. Comparing the single-component QACS dispersion and SA adsorbent, the incorporation of SA increased the storage/elastic modulus ( G′ ) and loss/viscous modulus ( G′′ ) of the SA/QACS composite hydrogels, while the incorporation of QACS enhanced the adsorption capacity of the SA/QACS composite adsorbents. Specifically, when 5 % QACS and 2 % SA were added, both G' and G" of the SA/QACS adsorbent were approximately 100 times greater than those corresponding to the QACS dispersion. Concurrently, its maximum adsorption capacity attained 164.5 mg/g, which was superior to that of the SA adsorbent. The adsorption isotherms and adsorption kinetics further demonstrated that the Langmuir model and the pseudo-second-order (PSO) model were congruent with the adsorption data of the SA/QACS composite adsorbent concerning HISADPs. Overall, these findings highlight the potential of the SA/QACS adsorbent as an effective adsorbent for the removal of HISADPs from beet juice.
危险品化学品经营许可证（带存储）