Physico-chemical and film-forming properties of bovine-hide and tuna-skin gelatin: A comparative study

A bovine-hide gelatin and a tuna-skin gelatin, both characterized on the basis of their amino acid composition and molecular weight distribution, were used to prepare edible films by casting with glycerol and sorbitol added as plasticizers. The molecular weight distribution of the tuna-skin gelatin exhibited appreciably higher quantities of β-components (covalently linked α-chain dimers), whereas bovine-hide gelatin showed a certain degradation of α₁-chains being indicative of a greater proteolysis. Intrinsic differences in the gelatin attributes affected in diverse manner some of the physical properties of the films. Thus, water vapour permeability was higher in the bovine-hide gelatin film, whereas deformability was considerably higher (10 times higher) in the tuna-skin gelatin film. In contrast, breaking force and water solubility were basically unaffected by gelatin origin. Analysis of the thermal properties revealed both films to be wholly amorphous with similar glass transition temperature values thanks to the plasticizing effects of the glycerol and sorbitol and the low moisture contents.     

Nanocomposites for food packaging applications

Most materials currently used for food packaging are non-degradable, generating environmental problems. Several biopolymers have been exploited to develop materials for eco-friendly food packaging. However, the use of biopolymers has been limited because of their usually poor mechanical and barrier properties, which may be improved by adding reinforcing compounds (fillers), forming composites. Most reinforced materials present poor matrix–filler interactions, which tend to improve with decreasing filler dimensions. The use of fillers with at least one nanoscale dimension (nanoparticles) produces nanocomposites. Nanoparticles have proportionally larger surface area than their microscale counterparts, which favors the filler–matrix interactions and the performance of the resulting material. Besides nanoreinforcements, nanoparticles can have other functions when added to a polymer, such as antimicrobial activity, enzyme immobilization, biosensing, etc. The main kinds of nanoparticles which have been studied for use in food packaging systems are overviewed, as well as their effects and applications.     

Osteointegration of poly-(3-hydroxybutyrate-co-3-hydroxyvalerate) scaffolds incorporated with violacein

This work reports on the production and in vivo evaluation of biodegradable scaffolds of poly-(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) incorporated with violacein, an antibiotic and antitumoral agent. PHBV produced in a bioreactor by Chromobacterium violaceum was pressed and partially sintered to produce scaffolds with 3 mm of diameter and 3 mm of height. The scaffolds were microstructurally characterized and exhibited suitable micromorphology for bone ingrowth. The PHBV-violacein scaffolds were implanted in femur of Wistar rats, extracted and analyzed after 30 and 60 days of surgery. Histological evaluation revealed that no inflammatory reaction occurred and new bone tissue was formed in the implant. The results indicated that PHBVs with violacein are potential candidates for application in regenerative bone tissue engineering.     

Synthesis and characterization of star-shaped block copolymer of poly-(?-caprolactone) and poly(ethyl ethylene phosphate) as drug carrier

A series of novel 4-arm biodegradable star block copolymers of poly(?-caprolactone) and poly(ethyl ethylene phosphate) were synthesized via ring-opening polymerization of 2-ethoxy-2-oxo-1,3,2-dioxaphospholane using hydroxyl terminated 4-arm star-shaped poly(?-caprolactone) and stannous octoate co-initiation system. Gel permeation chromatography (GPC), NMR and FT-IR were used to demonstrate the structure and analyze their compositions. The self-assembly behavior of these star-shaped copolymers in aqueous solution was studied by ¹H NMR and fluorescence technique, and the results indicated those copolymers formed nanoparticles in aqueous solution with hydrophobic poly(?-caprolactone) core and hydrophilic poly(ethyl ethylene phosphate) shell. The critical micelle concentration was relative to the length of poly(?-caprolactone) and poly(ethyl ethylene phosphate) block. Paclitaxel was encapsulated in the micelles and the release behavior demonstrated that a longer hydrophobic block resulted in slightly slower release rate from the micelles. These copolymer micelles were biocompatible and potential as drug-delivery vehicles for pharmaceutical application.     

可生物降解润滑剂的发展概况

随着社会的发展和进步,人类对环境的关注日益加强,可生物降解润滑剂的研制势在必行。综述了可生物降解润滑剂的定义、组成、应用及研究现状,并指出了研究可生物降解润滑剂过程中值得重视的问题。     

复合改性大豆分离蛋白可生物降解材料的性能研究

采用微波辐射和马来酸酐(MA)接枝技术对大豆分离蛋白(SPI)进行了复合改性,产物经甘油和水增塑后,通过热压成型得到一种SPI可生物降解材料。研究了微波功率、微波处理时间和MA添加量对该改性材料的力学性能、耐水性能和光学性能的影响,并利用扫描电镜(SEM)观察了材料的微观结构。结果表明:该复合改性SPI可生物降解材料,呈现较好的微观网状结构,并具有良好的综合性能。其拉伸强度为11.48 MPa,断裂伸长率为240.3%,吸水率为33.4%,透光率为39.5%。     

Chloride-free biodegradable organic acid hydrolyzed zinc silicate coating

Partially hydrolyzed ethyl silicate has widely been used as a binder to formulate inorganic zinc silicate paint for anticorrosive coating applications. Hydrochloric acid is used most popularly to catalyze the hydrolysis of ethyl silicate. Although different acids have been tried as catalysts for ethyl silicate hydrolysis, no attempt has been made to make stable paints out of those hydrolyzed silicate binders. In this study, environment benign biodegradable organic acids such as oxalic acid, citric acid, lactic acid and acetic acid were used for the hydrolysis of ethyl silicate and compared with the hydrolysis using conventional hydrochloric acid. The hydrolyzed silicate sols were pigmented further with silica powder and evaluated for their stability. Of the various organic acids catalyst used, only oxalic acid catalyzed sol acted as a stable binder system. The pigmented binder was then mixed with metallic zinc to formulate anticorrosive inorganic zinc silicate paint. The resultant coatings were characterized for various physical, surface, mechanical and chemical resistance properties such as drying, hardness, adhesion (cross hatch) and solvent resistance. Corrosion resistance properties were analyzed by means of salt spray, open circuit potential (OCP) and electrochemical impedance spectroscopy (EIS). The results revealed that the physical, mechanical, chemical and anticorrosive properties of the coating hydrolyzed with hydrochloric acid and oxalic acid are comparable. Thus, a chloride free biodegradable organic acid hydrolyzed inorganic zinc silicate primer is reported and due to its long term stability same also can be scaled up commercially.     

The application of near-infrared (NIR) and Raman spectroscopy to detect adulteration of oil used in animal feed production

Basic vegetable blends (BVB’s) and soya oils, used in the animal feed industry, are sometimes adulterated with transformer and mineral oil as a means of illegally increasing profit. A set of BVB’s and soya oil samples adulterated with transformer oil and mineral oil were characterised using both NIRS and Raman spectroscopy. Applying chemometrics to the NIRS and Raman spectral data, very good calibration and prediction statistics were obtained for transformer and mineral oils. Using NIRS, R² values greater than 0.99 were obtained with corresponding values for root mean squared error of calibration and prediction (<0.57 and <0.55, respectively). Using Raman, R² values greater than 0.97 were obtained with the root mean squared error of calibration (<2.01) and prediction (<1.92) calculated. Furthermore, using a qualitative approach it was possible, using PCA, to discriminate between 100% soya and BVB. This study demonstrates that both NIRS and Raman technology can be successfully applied as rapid screening techniques for the detection of oil adulteration and fraud in the food and feed industry.     

Effect of Basic Factors of Preparation on Characteristics,Hydrolytic Degradation,and Drug Release From Poly(ester-anhydride) Microspheres

Functional poly(ester-anhydride) microspheres were prepared using emulsion solvent evaporation (ESE) and phase inversion methods (PIM). The poly(ester-anhydride)s were obtained by polycondensation of sebacic acid (SBA) and oligo(3-allyloxy-1,2-propylene succinate) terminated with carboxyl groups (OSAGE). The effects of various parameters, including: polymer and emulsifier concentrations, stirring speed and molecular weight of polyvinyl alcohol (PVA) used as emulsifier on size, size distribution and morphology of microspheres obtained by ESE technique were examined. The size of microspheres obtained was in the range 2–30 µm and depended mainly on the stirring rate in emulsion formulation process, as well as concentration of polymer solution used. Molecular weight of PVA, and its concentration in aqueous phase, significantly influenced tendency to agglomeration of microparticles formed, but only slightly changed the size of microspheres. The present study demonstrated that the ESE method can be useful to formulate, from functional poly(ester-anhydride)s, small (2–3 µm) or large (20–30 µm) microspheres with relatively narrow size distribution. Such microspheres were loaded with three model compounds (rhodamine B, p-nitroaniline, and piroxicam) with different water solubility and their release characteristics were examined. In the present study microparticles were also obtained by alternative phase inversion method to compare mainly stability of polymers during formulation of microspheres by both techniques.     

Biodegradation Study on the Starch-LDPE Film by Soil Micro-organism

Abstract

Degradation of low density polyethylene (LDPE) film containing starch as the biodegradable additive has been studied by isolating a soil microbe identified as Pseudomonous species. The degradation of the film was monitored by mechanical property and the surface starch concentration by UV-spectrophotometry at different intervals of time. The degradation depends on the accessibility of starch i.e., the carbon source in the starch-LDPE film. By adding external carbon source like, monosaccharide and disaccharide sugars some changes in the rate of biodegradation was observed. The ultimate fall in tensile strength was higher for the film when exposed to a nutrient medium without any external carbon source. Mostly the added sugar helps in the growth of micro-organisms. Among the various external carbon sources, maltose was found to be the best. In case of maltose the loss of tensile strength was 50% in 58 days, but the film without additional sugar showed a fall in tensile strength of 48% in the same period.