المؤلفون: Tzoumaki, Maria V.¹, Moschakis, Thomas¹, Biliaderis, Costas G.¹ biliader@agro.auth.gr

المصدر: Carbohydrate Polymers. Jun2013, Vol. 95 Issue 1, p324-331. 8p.

مصطلحات موضوعية: *POLYSACCHARIDES, *RHEOLOGY, *MICROSTRUCTURE, *NANOCRYSTALS, *CHITIN, *COLLOIDS

مستخلص: Highlights: [•] The effect of polysaccharides in chitin nanocrystals (ChN) dispersions was studied. [•] The non-adsorbing polysaccharides cause formation of nematic ChN structures. [•] Polysaccharides induce gelation in ChN dispersions, except pullulan and chitosan. [•] Mixed ChN–κ-carrageenan (oppositely charged) dispersions form the strongest gels. [•] Mixed ChN-chitosan dispersions exhibit liquid like behavior. [ABSTRACT FROM AUTHOR]

المؤلفون: Tzoumaki, Maria V.¹, Moschakis, Thomas¹, Kiosseoglou, Vassilios², Biliaderis, Costas G.¹ biliader@agro.auth.gr

المصدر: Food Hydrocolloids. Aug2011, Vol. 25 Issue 6, p1521-1529. 9p.

مصطلحات موضوعية: *EMULSIONS, *FATS & oils, *WATER, *CHITIN, *NANOCRYSTALS, *PARTICLES, *MICROSTRUCTURE, *RHEOLOGY

مستخلص: Abstract: The aim of the present study was to investigate the oil-in-water emulsion stabilizing ability of chitin nanocrystals (colloidal rod-like particles) and the factors that may influence the properties of such systems. Chitin nanocrystal aqueous dispersions were prepared by acid hydrolysis of crude chitin from crab shells and oil-in-water emulsions were generated by homogenizing appropriate quantities of a chitin nanocrystal stock aqueous dispersion with corn oil, using an ultra-sonic homogenizer. The resulting emulsions were visually evaluated for their creaming behaviour upon storage. Additionally, the samples were studied with static light scattering, small deformation oscillatory rheometry and optical microscopy, under different conditions of nanocrystal concentration, ionic strength, pH and temperature. The chitin nanocrystals were proven quite effective in stabilizing o/w emulsions against coalescence, over a period of one month, as evidenced by static light experiments and microscopy, and this could be attributed to the adsorption of the nanocrystals at the oil–water interface. The rheological data provided evidence for network formation in the emulsions with increasing chitin nanocrystal concentration. Such a gel-like behaviour was attributed to an inter-droplet network structure and the formation of a chitin nanocrystal network in the continuous phase. The stability of the emulsions to creaming increased with an increase in nanocrystal concentration. Finally, by raising the temperature (20–74 °C), NaCl concentration (up to 200 mM) or pH (from 3.0 to 6.7) there was an enhancement of the emulsion elastic character and creaming stability. [Copyright &y& Elsevier]

المؤلفون: Tzoumaki, Maria V.¹, Moschakis, Thomas¹, Biliaderis, Costas G. biliader@agro.auth.gr

المصدر: Food Hydrocolloids. Jul2011, Vol. 25 Issue 5, p935-942. 8p.

مصطلحات موضوعية: *CHITIN, *NANOCRYSTALS, *PROTEINS, *MICROSTRUCTURE, *RHEOLOGY, *POLYMERS, *WHEY

مستخلص: Abstract: Chitin nanocrystals (ChN) and whey protein isolate (WPI) aqueous dispersions (at pH 3.0) of different polymer concentrations were mixed and examined with small deformation oscillatory measurements and polarized optical microscopy, under different conditions of ionic strength and temperature. The ChN–WPI mixed dispersions displayed a gel-like behaviour with increasing either the ChN or the WPI concentration. The network formation could be attributed to phase separation phenomena, as evidenced by the micrographs obtained, due to thermodynamic incompatibility between the two components; i.e. the addition of WPI, as a globular biopolymer mixture, in a dispersion of rod-like particles (ChN) leads to the formation of ChN-rich and ChN-poor domains. Increasing ionic strength did not significantly affect the viscoelastic properties of the network. However, heating of the ChN–WPI mixed dispersions resulted in further increase of the elastic modulus, which was irreversible upon cooling. [Copyright &y& Elsevier]

المؤلفون: Tzoumaki, Maria, Τζουμάκη, Μαρία

مصطلحات موضوعية: Νανοκρύσταλλοι χιτίνης, Δομή τροφίμων, Γαλακτώματα, Πέψη λίπους, Κολλοειδή σωματίδια, Ρεολογία, Μικροσκοπικές ιδιότητες, Chitin nanocrystals, Food structure, Emulsions, Lipid digestion, Colloidal particles, Rheology, Microscopic properties, Γεωπονικές Επιστήμες και Κτηνιατρική, Γεωπονική Βιοτεχνολογία, Άλλες Γεωπονικές Επιστήμες, Agricultural and Veterinary Sciences, Agricultural Biotechnology, Other Agricultural Sciences

الوصف: The present thesis examines the structure and functional properties of chitin nanocrystal (ChN) aqueous dispersions attempting to explore their potential to be employed in food dispersions, in order to improve the textural and the stability characteristics of the product. The first part of this study deals with the examination of the gel forming ability of aqueous chitin nanocrystal dispersions and the factors that influence the microstructural and viscoelastic properties of structured gels. Chitin nanocrystal aqueous dispersions were prepared by acid hydrolysis of crude chitin from crab shells. The resulting dispersions were studied with small deformation oscillatory rheological testing and polarized optical microscopy under different conditions of nanocrystal concentration, ionic strength, pH and temperature. The viscoelastic behavior of ChN dispersions was strengthened by increasing ChN concentration, adding NaCl, increasing pH and heating, probably due to enhancement of the attractive interactions. Additionally, the effect of mixing of ChN aqueous dispersions with soluble biopolymers, such as proteins and polysaccharides, with varying molecular characteristics was studied and it was found that in most of the cases, the network structure was enhanced, while the addition of some biopolymers did not seem to have any distinctive effect on the rheological properties. Finally, all the above gel-like materials exhibited birefringence and nematic-like ordering, when observed under a polarized optical microscope, indicative of particle ordering in the gel network structure.The ability of ChN to stabilise emulsions was investigated in the second part of this study. Oil-in-water emulsions were prepared by mixing appropriate quantities of a ChN stock dispersion and corn oil. The resulting emulsions were firstly visually assessed for their creaming behaviour, and then were studied with static light scattering, small deformation oscillatory rheometry and optical microscopy. The ChN had the ability to stabilize ...

العلاقة: http://hdl.handle.net/10442/hedi/35248Test

الإتاحة: https://doi.org/10.12681/eadd/35248Test
http://hdl.handle.net/10442/hedi/35248Test