Biomaterial Database

Ionic diffusion in frozen starch gels. 1991

S Charoenrein, and D S Reid

Department of Food Science and Technology, University of California, Davis 95616.

Quality changes in food frozen by different conditions and at different storage temperatures were demonstrated using a model system. A frozen starch gel represents a frozen food matrix, and ions in the external medium represent the reactant molecules. We determined the effective diffusion rates of Zn+2 ions into frozen starch gel cylinders that were frozen at different freezing rates. The diffusion was performed at -8 degrees and -15 degrees C. The amounts of ion diffused were determined by atomic absorption, whilst the structure of the frozen samples could be simultaneously determined by scanning electron microscopy. The effective diffusion rates were found to correlate with the amount of unfrozen portion of the samples. This suggests that ions move mainly through the unfrozen portion around the ice crystals. Fast- and slow-frozen samples exhibited significantly different effective diffusion rates at -15 degrees C, which might be due to differences in size and orientation of ice crystals. Zn+2 ions moved slower at -15 degrees C than at -8 degrees C.

UI	MeSH Term	Description	Entries
D008855	Microscopy, Electron, Scanning	Microscopy in which the object is examined directly by an electron beam scanning the specimen point-by-point. The image is constructed by detecting the products of specimen interactions that are projected above the plane of the sample, such as backscattered electrons. Although SCANNING TRANSMISSION ELECTRON MICROSCOPY also scans the specimen point by point with the electron beam, the image is constructed by detecting the electrons, or their interaction products that are transmitted through the sample plane, so that is a form of TRANSMISSION ELECTRON MICROSCOPY.	Scanning Electron Microscopy,Electron Scanning Microscopy,Electron Microscopies, Scanning,Electron Microscopy, Scanning,Electron Scanning Microscopies,Microscopies, Electron Scanning,Microscopies, Scanning Electron,Microscopy, Electron Scanning,Microscopy, Scanning Electron,Scanning Electron Microscopies,Scanning Microscopies, Electron,Scanning Microscopy, Electron
D003460	Crystallization	The formation of crystalline substances from solutions or melts. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)	Crystalline Polymorphs,Polymorphism, Crystallization,Crystal Growth,Polymorphic Crystals,Crystal, Polymorphic,Crystalline Polymorph,Crystallization Polymorphism,Crystallization Polymorphisms,Crystals, Polymorphic,Growth, Crystal,Polymorph, Crystalline,Polymorphic Crystal,Polymorphisms, Crystallization,Polymorphs, Crystalline
D004058	Diffusion	The tendency of a gas or solute to pass from a point of higher pressure or concentration to a point of lower pressure or concentration and to distribute itself throughout the available space. Diffusion, especially FACILITATED DIFFUSION, is a major mechanism of BIOLOGICAL TRANSPORT.	Diffusions
D005524	Food Technology	The application of knowledge to the food industry.	Technology, Food,Food Sciences,Food Science,Science, Food,Sciences, Food
D005612	Freeze Drying	Method of tissue preparation in which the tissue specimen is frozen and then dehydrated at low temperature in a high vacuum. This method is also used for dehydrating pharmaceutical and food products.	Lyophilization,Drying, Freeze,Dryings, Freeze,Freeze Dryings,Lyophilizations
D005615	Freezing	Liquids transforming into solids by the removal of heat.	Melting
D005782	Gels	Colloids with a solid continuous phase and liquid as the dispersed phase; gels may be unstable when, due to temperature or other cause, the solid phase liquefies; the resulting colloid is called a sol.
D013213	Starch	Any of a group of polysaccharides of the general formula (C6-H10-O5)n, composed of a long-chain polymer of glucose in the form of amylose and amylopectin. It is the chief storage form of energy reserve (carbohydrates) in plants.	Amylomaize Starch,Amylum,Cornstarch,Keoflo,Starch, Amylomaize
D015032	Zinc	A metallic element of atomic number 30 and atomic weight 65.38. It is a necessary trace element in the diet, forming an essential part of many enzymes, and playing an important role in protein synthesis and in cell division. Zinc deficiency is associated with ANEMIA, short stature, HYPOGONADISM, impaired WOUND HEALING, and geophagia. It is known by the symbol Zn.