Atsuyoshi Nakayama

Chitosan and gelatin based edible films: state diagrams, mechanical and permeation properties

Films of chitosan and gelatin were prepared by casting their aqueous solutions (pH≈4.0) at 60°C and evaporating at 22 or 60°C (low- and high-temperature methods, respectively). The physical (thermal, mechanical and gas/water permeation) properties of these composite films, plasticized with water or polyols, were studied. An increase in the total plasticizer content resulted in a considerable decrease of elasticity modulus and tensile strength (up to 50% of the original values when 30% plasticizer was added), whereas the percentage elongation increased (up to 150% compared to the original values). The low-temperature preparation method led to the development of a higher percentage renaturation (crystallinity) of gelatin which resulted in a decrease, by one or two orders of magnitude, of CO2 and O2 permeability in the chitosan/gelatin blends. An increase in the total plasticizer content (water, polyols) of these blends was found to be proportional to an increase in their gas permeability.

Edible films made from gelatin, soluble starch and polyols, Part 3

The thermal and mechanical properties of edible films based on blends of gelatin with soluble starch plasticized with water, glycerol or sugars were investigated. Two different methods, known as ‘the high temperature’ and ‘the low temperature’ methods, consisting of casting aqueous solutions of blends at 60 and 20 °C, respectively, were employed for the preparation of films. With increasing water, glycerol or sorbitol content, a drop of elasticity modulus and tensile strength (up to 50% of the original values for 30% plasticizer) was observed. The tensile strength and percentage elongation increased with high gelatin contents (> 20% ww). The development of a higher percentage renaturation of gelatin (reaching 70% for 5% water content) by the ‘low temperature’ method caused a reduction in gas and water permeabilities. The former decreased by one or two orders of magnitude for O2 and CO2, respectively. The semi-empirical model for calculation of gas permeability and the semi empirical equations for upper and lower limits of tensile moduli of composites were applied with limited success and the obtained values were compared to those experimentally determined.

Edible films made from hydroxypropyl starch and gelatin and plasticized by polyols and water

Two methods, known as the low and the high temperature methods, which consist of casting aqueous solutions of hydroxypropyl starch and gelatin at 20 and 60°C, respectively, were employed for film preparation. The physical (thermal, mechanical and gas/water permeation) properties of these composite films, plasticized with water or polyols, were studied. An increase in the total plasticizer content resulted in a considerable decrease in elasticity modulus and tensile strength (up to 60% of the original values when 25% plasticizer was added), whereas the percentage elongation increased (up to 200% compared to the original values). The low temperature method led to the development of higher percentage renaturation (crystallinity) of gelatin which resulted in a decrease, by one or two magnitude orders, of CO2 and O2 permeability in the hydroxypropyl starch/gelatin blends. An increase in the total plasticizer content (water, polyols) of these blends was found to be proportional to an increase in their gas permeability.

Edible films made from sodium casemate, starches, sugars or glycerol. Part 1

Abstract The physical properties of edible films, based on blends of sodium caseinate with starches of different origin (corn and wheat) plasticized with water, glycerol or sugars, were studied. An increase in water or sugar/glycerol content resulted in a considerable decrease in the modulus of elasticity and in the tensile strength of films. The tensile strength and the water vapor permeability decreased with an increase in sodium casemate contents (> 10%w/w). The development of crystallinity caused a reduction in gas and water permeabilities. Semi-empirical models for calculation of gas permeability and tensile strength and tensile moduli were applied with limited success and the obtained values were compared to those experimentally determined.

Novel star-shaped polylactide with glycerol using stannous octoate or tetraphenyl tin as catalyst: 1. Synthesis, characterization and study of their biodegradability

Abstract Novel star-shaped polyesters were synthesized by reacting l -lactide (LLA) with glycerol (GL) in the presence of stannous octoate or tetraphenyltin as catalyst. These polymers were characterized by nuclear magnetic resonance, Fourier-transform infra-red spectroscopy, differential scanning calorimetry (d.s.c.) and thermogravimetric analysis. D.s.c. curves showed that these polymers are semicrystalline when the ratio LLA/GL is higher than 20/1 (mol/mol). When this molar ratio falls below 20/1, the polymers are amorphous. The molecular-weight distribution of these polymers was studied with gel permeation chromatography measurements, which showed that the M n decreased proportionally to the glycerol content in the polymer. The potential biodegradability of these polymers was assessed with the aid of enzymatic and alkali hydrolysis.

Production of N-acetyl-D-glucosamine from α-chitin by crude enzymes from Aeromonas hydrophila H-2330

The selective and efficient production of N-acetyl-D-glucosamine (GlcNAc) was achieved from flake type of alpha-chitin by using crude enzymes derived from Aeromonas hydrophila H-2330.

Enzymatic production of N-acetyl-D-glucosamine from chitin. Degradation study of N-acetylchitooligosaccharide and the effect of mixing of crude enzymes

N-Acetyl-D-glucosamine (GlcNAc) was produced from chitin by use of crude enzyme preparations. The efficient production of GlcNAc by cellulases derived from Trichoderma viride (T) and Acremonium cellulolyticus (A) was observed by HPLC analysis compared to lipase, hemicellulase, and pectinase. b-Chitin showed higher degradability than a-chitin when using cellulase T. The optimum pH of cellulase T was 4.0 on the hydrolysis of b-chitin. The yield of GlcNAc was enhanced by mixing of cellulase T and A. q 2003 Elsevier Science Ltd. All rights reserved.

Synthesis and degradability of a novel aliphatic polyester based on l-lactide and sorbitol: 3

Abstract Reaction of L -lactide (LLA) with sorbitol (SB) in the presence of stannous octoate (Sn oct), tetraphenyl tin (TPhT) and several other catalysts gave a series of novel polyesters. Several techniques such as nuclear magnetic resonance (n.m.r.) and Fourier transform infra-red ( FT i.r.) spectroscopy, gel permeation chromatography (g.p.c.) and differential scanning calorimetry (d.s.c.) were used in order to characterize these polymers. The crystallinity of the polyesters was found to depend on the molar ratio of LLA to SB, i.e. when LLA/SB > 20/1 or > 40/1 (for Sn oct or TPhT, respectively) the polyesters are semicrystalline (from d.s.c. results) whereas at molar ratios of LLA to SB which are lower than those mentioned above the polymers become amorphous. High SB contents have an adverse effect on the thermal properties (i.e. lower T g , T m , and ΔH m ) and the molecular weight distribution (lower M n , and M w ) but they enhance their biodegradability. The latter was tested in terms of enzymatic and alkali hydrolysis. Both total organic carbon (TOC) and g.p.c. measurements confirmed the degradation of the polyesters at different hydrolysis modes.

Ring-opening copolymerization of succinic anhydride with ethylene oxide initiated by magnesium diethoxide

Abstract The ring-opening copolymerization of succinic anhydride (SA) with ethylene oxide (EO) was carried out by using mainly magnesium diethoxide (ME) as an initiator. ME was superior with respect to polymerization yield and number-average molecular weight (Mn) of the copolymers obtained. The copolymers were found to be alternating copolymers independent of feed monomer molar ratio. The yield and the Mn of the copolymers increased with the polymerization temperature and the time within 48 h. There was a maximum of Mn at a time of 48 h, at 100°C. The Mn of the alternating copolymers was as high as 1.3 × 104. The Mn of the copolymers increased proportionally with the increase of monomer/initiator molar ratio (M/I) up to M/I = 400. From analysis of the end-groups of low Mn of copolymers by 1H n.m.r., these copolymers were a mixture of two copolymers having different end groups. One had ethyl ester group connecting with SA at either end group, the other had ethyl ester group connecting with SA and hydroxyl group connecting with EO.

Chemical modification of chitosan. Part 15: Synthesis of novel chitosan derivatives by substitution of hydrophilic amine using N-carboxyethylchitosan ethyl ester as an intermediate

The Michael type reaction of chitosan with ethyl acrylate has been investigated. Although this reaction was quite slow in the case of chitosan, the reiteration of the reaction was an effective means for increasing the degree of substitution (DS) of ethyl ester. The N-carboxyethylchitosan ethyl ester as an intermediate was successfully substituted with various hydrophilic amines, although the simultaneous hydrolysis of the ester to carboxylic acid also occurred. Water-soluble chitosan derivatives were obtained by substitution with hydroxyalkylamines and diamines.