Selection of anionic exchange resins for removal of natural organic matter (NOM) fractions.

Early elimination of natural organic matter (NOM) by ion exchange (IEX) in water treatment is expected to improve subsequent water treatment processes and the final drinking water quality. Nine anionic exchange resins were investigated to remove NOM and specific NOM fractions determined by liquid chromatography in combination with organic carbon detection (LC-OCD) and fluorescence excitation-emission matrices (EEM). Breakthrough of NOM was predicted by model calculations using Freundlich isotherms and IEX rate experiments. The time to breakthrough varied from 4 to 38 days. Removal of specific NOM fractions proved to vary considerably for the different types of IEX resins, ranging from 1% to almost 60%. The removal of NOM fractions, specifically humic substances, increased with an increase in water content of the investigated IEX resins and with a decrease in resin size. The best-performing IEX resins consisted of the smallest resins and/or those with the highest water content. The worst-performing IEX resins reflected the highest exchanging capacities and the lowest water contents.

beta-Glucosidase and peroxidase stability in crude enzyme extracts from green beans of Vanilla planifolia Andrews.

The extraction method for beta-glucosidase from green vanilla beans has been studied. The effect of storage of green beans and protein extracts on beta-glucosidase and peroxidase activity was investigated: the best method, resulting in the highest enzyme activities, particularly for glucosidase, was through extraction of very fresh green beans in the presence of BisTris propane buffer at pH 8. The best method for storage of the extracts was at -80 degrees C after addition of 15% glycerol, when over 90% of initial activity was still present. Peroxidase activity did not change in frozen beans or in frozen extracts.

alpha-D-Glcp-(1<-->1)-beta-D-Galp-containing oligosaccharides, novel products from lactose by the action of beta-galactosidase.

A mixture of oligosaccharides produced by beta-galactosidase using lactose as a substrate was fractionated according to degree of polymerization using gel filtration, followed by high-pH anion-exchange chromatography. The fractions obtained were analyzed using monosaccharide analysis, methylation analysis, mass spectrometry, and NMR spectroscopy. Twelve novel non-reducing oligosaccharides were characterized, namely, [beta-D-Galp-(1-->4)]n-alpha-D-Glcp- (1<-->1)-beta-D-Galp[-(4<--1)-beta-D-Galp]m, with n, m = (1, 2, 3, or 4) and beta-D-Galp-(1-->2)-alpha-D-Glcp- (1<-->1)-beta-D-Galp.