Extracellular enzymes, polygalacturonase, pectinlyase and xylanase were produced from Aspergillus sojae by solid state fermentation on wheat bran medium. The growth and enzyme production were highest at 50% added moisture and 35°C. The pectinolytic enzyme preparation, which was extracted from the fermented bran, was used for the improvement of jute cuttings. Enzyme-treated fibre contained less amount of hemicellulose and pectic materials than untreated fibre and was improved in fibre quality. A commercial enzyme, Flaxazyme (Novo), was examined comparatively.
Sodium carboxymethyl starches (Na-CMSs) with different degrees of substitution (DS) were prepared from potato starch (PS) and their moisture sorption properties were investigated. Little or no difference in moisture content was found between Na-CMSs (DSO≤0.3) and PS. The moisture-sorption isotherms of Na-CMSs (DS≥0.6) rose appreciably at a water activity of 0.7. Appearance of new sorption sites due to sorption and swelling required a certain number of residual hydroxyl groups (DS≤0.6). It was increasingly difficult for hydroxyl groups to appear at the surface of Na-CMSs with higher DS, and their new sorption sites had weaker activity. The entropy change of the moisture sorption on PS was considerably lower than that on the Na-CMSs. Moisture sorption on Na-CMSs (1) and (Z), and that on Na-CMSs (3)-(5) seemed to be composed of three and two energetic states, respectively. Moisture sorption on Na-CMSs (3)-(5) apparently holds a constant, energetically stable state after a drop in entropy change, while sorbed moisture affects the Na-CMSs because of their unstable porous structure. The Henderson, Chung and Pfost and Smith equations all fit the moisture-sorption isotherms of Na-CMSs. The constants of their equations indicated that the stability of the Na-CMS structure to moisture sorption gradually decreased with increasing DS, and that the bound fraction of sorbed moisture decreased while the condensed fraction increased.
Cyclomaltodextrin glucanotransferase (CGTase) from Bacillus stearothermophilus formed amylose-granules from α-cyclodextrin (α-CD). The formation of amylose-granules was mainly affected by the substrate concentration and the temperature of reaction condition. The maximum yield was 96% when the enzyme acted on 35% of α-CD at 30t. The amylose-granules were spherical with the diameter of 3-20 pm, and were soluble in alkaline solution but insoluble in hot water. The dissolved amylose formed iodine complex having Amax of 560-580 nm and was almost hydrolyzed to maltose by the action of β-amylase. The amylose had number-average molecular weight of 5500-7000, i. e., 34-43 glucose units. The granules gave B-type similar to potato starch on X-ray diffraction and were observed polarized-cross on microscopy. CGTases from other bacteria also produced the similar amylose-granules to those by Bacillus stearothermophilus enzyme.
The retrogradation of gels formed from various mixtures of waxy corn and corn starches was studied by X-ray diffraction and rheological methods. The X-ray diffraction patterns of individual gels of waxy corn and corn starches changed markedly with increasing storage time, while the mixed gels had intermediate change. The increase in storage modulus of the gels was in the order of corn starch, mixed starch and waxy corn starch, although the values for waxy corn and the mixed starches were relatively similar. The 20% gels mixed at 1 : 1 had lower values for the storage modulus than the 10% corn starch gels, which indicates that the addition of waxy corn to corn starch tended to be detrimental to the gel strength. The crystallinity-time profiles of the starch gels varied according to the ratio of waxy corn starch to corn starch. The retrogradation of the waxy corn starch according to the two analysis techniques that were used was similar, while the storage modulus of the corn starch continued to change with time after the crystallinity had reached a constant value. The retrogradation process for each of the three mixed starch gels was different, and was affected by the initial storage temperature.
The enzymatic transglucosylation of three kinds of α-glucosidase (from rat intestine, rice seed and Aspergillus) with lactose as an acceptor was studied. We found out that the three a-glucosidases were capable of synthesizing trisaccharide, which corresponds to glucosyl lactoside (O-β-D-galactopyranosyl-(1→4)-O-β-D-glucopyranosyl α-D-glucopyranoside) on gas-liquid chroma-tographic analysis, the same as the case of cyclomaltodextrin glucanotransferase (CGTase) reported. The maximum yield of the trisaccharide (3.0%) was obtained with rat intestinal a-glucosidase, and the other two a-glucosidases gave same yield (2.3%). β-Galactosidase converted the trisaccharide into the disaccharide which corresponds to neotrehalose on GLC analysis, and galactose, α-Glucosidase from rice seed also hydrolyzed the trisaccharide into lactose and glucose. These results suggest that the trisaccharide is glucosyl lactoside, and it is the common transglucosylation product of all α-glucosidases used in this study. Neotrehalose was also observed in all the reaction mixture. The α-glucosidases seem to recognize the anomeric hydroxyl group of lactose as a transglucosylation site as well as CGTase.
1. Starch granules were prepared from mature kernels of six types (A-F) of foxtail millet (Setaria italica Beauv.) which were collected in different places of Asia and grown in the field of Plant Germ-plasm Institute, Kyoto University. The amylose content of A, B, C, D, E, and F were 31, 31, 22, 14, 0, and 0%, respectively, measured by an enzymatic and chromatographic method. Gelatinization temperatures of onset, peak and conclusion, and heats of gelatinization measured by differential scanning calorimetry were in the ranges of 6469, 70-77 and 7684°C, and 10.18 J/g, respectively. Foxtail millet starch granules were digested by amylase 2-3 times faster than maize starch granules. Waxy starch granules tended to be digested faster than non-waxy starch granules.2. Highly significant positive correlation was observed between blue value (absorbance at 680 nm) and Amax (wavelength at the maximum absorbance) obtained from absorption curves of starch-iodine complexes. Blue value was also positively correlated with fraction I measured by the enzymatic and chromatographic methods and negatively with heat of gelatinization.
O-β-D-Galactopyranosyl-(1→4)-β-D-glucopyranosyl α-D-glucopyranoside(glucosyl lactoside, GL-95) was hardly hydrolyzed by human saliva, artificial gastric juice and porcine pancreas, but was hydrolyzed about 30% by rat intestinal aceton powder in vitro. GL-95 was selectively utilized by Bifidobacterium, and hardly utilized by Clostridium, Eubacterium and Escherichia.