Adaptation of digestive enzymes in the small intestine and pancreas was evaluated in rats fed different types of starch. Male Sprague-Dawley rats at 6 weeks were fed 3 types of diet containing, corn starch, or two kinds of potato starch with different phosphorus contents. The changes in sucrase, maltase and lactase activities in the duodenum, jejunum, jejuno-ileum and ileum of the small intestinal tract, and α-amylase activity in the pancreas were determined at 1, 3 and 5 weeks of feeding. There were significant differences in sucrase and maltase, but not lactase activity in the duodenum among the 3 starch groups. There were no differences in jejunal and ileal disaccharidase, and pancreatic α-amylase activity among the 3 diet groups. Thus, adaptation of disaccharidase to different type of starch occurred locally in the duodenal segment but not in subsequent lower segments of the small intestine in rats.
Twenty kinds of amino acid-compounded starches were prepared by autoclaving the starch and amino acid mixture with limited water content through the Maillard reaction. Compounding with amino acids such as monosodium glutamate and lysine, having a negative or positive net charge, respectively, resulted in a marked increase in the gelatinization temperature, and great decreases in viscosity and swelling as compared with amino acids having no net charge. The pastes of the charged amino acid-compounded starches exhibited easy vaporization of water similar to that of free water resulting from the presence of swollen starch granules, whereas water in the gels of the charged amino acid-compounded starches had markedly shorter transverse relaxation time (T2) than the other gels, contributing to the improvement of starchy foods with a dry texture.
A bacterial strain which produced a cycloinulooligosaccharide fructanotransferase was isolated from soil and was identified as Paenibacillus polymyxa MG-CF6. The enzyme was then purified to apparent homogeneity from culture supernatant of the bacterium. The molecular mass of the enzyme was estimated to be 128 kDa by SDS-PAGE. Maximal activity was found to be at pH 7.0 and 45°C. The enzyme was stable from pH 6.0 to 9.0 and at temperature up to 40°C. Molar ratio of cycloinulohexaose: cycloinuloheptaose formed by this enzyme was found to be about 2.5:1. N-Terminal amino acid sequence of the enzyme was identical with a part of amino acid sequence of the same enzymes from Bacillus macerans CFC1 and Bacillus polymyxa MGL21. The gene of the enzyme was cloned from P. polymyxa MG-CF6. It consisted of 3999 nucleotides, which encodes a protein of 1333 amino acids. The deduced amino acid sequence showed 83, 95 and 98% similarity to that of Bacillus circulans MCI-2554, Bacillus macerans CFC1 and Bacillus polymyxa MGL21, respectively.
We attempted to extract (1→3;1→6)-β-D-glucan from the water-insoluble residue of Hericium erinaceum with proteolytic and chitin degrading enzyme treatments followed by microwave irradiation. Two sets of four commercially available enzymes were used in this study; Actinase E, Proteinase K, Chitinase-RS and Chitinase. The results showed that the enzyme treatment using Proteinase K and Chitinase simultaneously had the most significant synergistic effects on the amount of glucan extracted; 95.5% of the amount of glucan extractable with 5% sodium hydroxide. The structure of (1→3;1→6)-β-D-glucan obtained by this enzyme treatment was different from that obtained by extraction with alkaline solution in that the former was rich in (1→6) linkages, whereas the latter was rich in (1→3) linkages.
Totally 92.7% of glucan present in the fruiting body of H. erinaceum could be solubilized. Of this value, 42.3, 17.7 and 10.7% were extractable by alkali, enzyme, second alkali treatments, respectively, from the residue given after microwave irradiation in water. The remained 22.0% were water-soluble (1→3; 1→6)-β-D-glucan extractable by microwave irradiation in water (Ookushi et al.: J. Appl. Glycosci., 53, 267-272 (2006)). Sugar linkage analysis of the glucan extracted from the water-insoluble residue indicated the presence of three distribution profiles of (1→3;1→6)-β-D-glucan in the water-insoluble residue; (1→3;1→6)-β-D-glucan rich in (1→3) linkages forming heavily hydrogen bonded networks, (1→3;1→6)-β-D-glucan rich in (1→6) linkages forming complex networks with protein and chitin, and (1→3;1→6)-β-D-glucan rich in (1→3) linkages forming complex networks with protein and chitin.
This study was investigated the rheological properties of Stein-Hall type corrugating adhesives (SH-adhesives) composed of carrier and main portions, which were needed for enhancing initial bond (green bond) strength to make the corrugated fiberboard at high speed on the double backer. Starch slurries and main portions of SH-adhesives were individually prepared from each starch: corn, high-amylose maize (hylon-5), waxy maize, wheat, potato, sweet-potato and tapioca. All carrier portions were prepared from cooked corn starch paste only. Initial shear rigidity, maximum shear stress, shear stress-strain pattern and viscosity of these gelatinized pastes from slurries and SH-adhesives were measured by the Couett type viscometer at 85°C. The properties of those SH-adhesives pastes depended on those of their main portions pastes, and were enhanced by their carrier portions. Rigidity and maximum stress of SH-adhesives pastes were varied by starch species, and these properties of the pastes from slurries increased as similar exponential function with increasing starch concentration in each species. So, these species pastes were organized into 4 types as type-1 of hylon-5, and type-2 of corn and wheat, and type-3 of potato, sweet potato and tapioca, and type-4 of waxy in order of the rigidity size and reverse order of strain size at maximum stress. And then, the rigidity was thought to be higher in the paste remaining the more clear shape gelatinized granules. Whereas, 7 kinds of SH-adhesive made a little difference in the green bond strength measured by table test. These results suggested that the rigidity and maximum stress were not most important factors in the rheological properties of gelatinized SH-adhesives pastes which were required to enhance the green bond strength on the corrugator.
This study was investigated the rheological properties of Stein-Hall type corrugating adhesives (SH-adhesives) composed of carrier and main portions, which were needed for enhancing initial bond (green bond) strength to make the corrugated fiberboard at high speed on the double backer. Starch slurries were individually prepared from corn, high-amylose maize (hylon-5), waxy maize and wheat starch. Main portions of SH-adhesives were individually prepared from corn or wheat starch. All carrier portions were prepared from cooked corn starch paste only. Initial shear rigidity, maximum shear stress, shear stress-strain pattern and viscosity of these gelatinized pastes from slurries and SH-adhesives were measured by the Couett type viscometer at 85°C. In the concentration of caustic soda up to 0.9%, the rheological properties of 4 species pastes from slurries were organized into 3 types. As type-1, the waxy pastes always behaved the low rigidity less than 0.4 kPa and the large strain at maximum stress as 9.6-10.8, except no borax addition. As type-2, hylon-5 pastes behaved the high rigidity and the small strain at maximum stress under 0.7. On the other hand, as type-3, the rigidity of corn and wheat pastes remarkably decreased to 0.3 kPa from 6.8 kPa, and the strain at maximum stress increased to 3.8 from 0.3 with increasing caustic soda concentration. In the same way, gelatinized pastes from the SH-adhesives composing the main portion of suspended corn or wheat reduced their rigidity and increased their strain at maximum stress with increasing caustic concentration. However, the green bond strength of adhesion samples laminated by table test with those corn starch SH-adhesives showed the strongest point at some caustic concentration. By SEM, glue lines of those adhesion samples delaminated in the measurement of the green bond strength were observed that clear shape swelling starch granules reduced with caustic increase, and the gelatinization in that strongest point was proceeded to swelling the starch granule until unclear shape. These results suggested that the balance of fluidity and rigidity behaviors as the rheological properties of gelatinized SH-adhesives pastes was required to enhance the green bond strength on the corrugator.
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