Polysaccharides traditional methods

Humic substances are those organic compounds found in the environment that cannot be classified as any other chemical class of compounds (e.g., polysaccharides, proteins, etc.). They are traditionally defined according to their solubilities. Fulvic acids are those organic materials that are soluble in water at all pH values. Humic acids are those materials that are insoluble at acidic pH values (pH < 2) but are soluble at higher pH values. Humin is the fraction of natural organic materials that is insoluble in water at all pH values. These definitions reflect the traditional methods for separating the different fractions from the original mixture. 

Traditional methods for dyeing cotton depended on formation of insoluble dye molecules on the fibers, or of hydrogen bonds between the dye molecules and the fibers, or both. However, two classes of dyes that react covalently have now been used extensively in the production of colored polysaccharide derivatives. The diazine and triazine types of... 

Both the advantages and disadvantages of the fermentation approach to polysaccharide production now will be examined (Table VII). Advantages of fermentation over traditional methods are firstly in medium preparation. The raw materials such as carbohydrate substrates,nitrogen sources and inorganic salts normally are readily available and, in many fermentations, it... 

Recently, numerous approaches have been studied for the development of cheaper and most effective adsorbents containing biopolymers. The most widespread biopolymers are polysaccharides [190], chitin [167, 139, 7] and cyclodextrin [157, 26, 32]. These biopolymers reach the increasing demand for treatment of industrial wastewater before their use or disposal. Because the pollutants creates environmental and health diffieulties, associated with heavy metals and pesticides and their deposit through the food chain [39]. Traditional methods for the elimination of heavy metals from industrial wastewater may be inefficient or costly, particularly when metals are present at low concentrations [30, 184]. Chitin, chitosan and oligosaccharides represent interesting and attractive alternative adsorbents because of their particular structure, physico-chemical characteristics, chemical stability, high reactivity and excellent selectivity towards metals. Moreover, Ihey are abundant, renewable and biodegradable resources and have a capacity to associate by physical and chemical interactions with a wide variety of molecules [22, 131]. 

For monitoring the extent of polysaccharide hydrolysis, l.c. methods that sepeu ate and analyze the non-fermentable oligosaccharides (d.p. 3-30) derived from cellulose, hemicellulose, and pectins are useful, and have already been described (see Section III,l,c). For determination of the monosaccharide composition of completely hydrolyzed, plant polysaccharides, l.c. is especially useful and has been applied to the compositional analysis of hydrolyzed plant fiber,wood pulps,plant cell-walls,and cotton fibers.In these representative examples, the major sugars of interest, namely, glucose, xylose, galactose, arabinose, and mannose, have traditionally been difficult to resolve by l.c. The separa-... 

The ultimate combination of HPLC and AC is effectuated in High Performance Affinity Chromatography (HPAC).47 The development of this hybrid technique was highly assisted by the use of modified silica. Traditional polysaccharide supports may not be used for HPAC, because they lack mechanical stability to withstand the high pressure drops, inherent to this method. Modified silica beads are well suited. These may be coated with active groups as in normal AC applications. Additionally, if the separation requires the use of an organic stationary phase, the silica beads are modified with a silane or polymer with subsequent deposition of polysaccharides such as dextrans, agarose or cellulose.50... 

Microbial polysaccharides from Xanthomonas campestris, notably xanthan gum for use in food industry, have been studied. Other polysaccharides like dextrans, pullulans, scleroglucan were isolated from several microbial sources. Incorporation of xanthan gum in traditional Indian fermented foods like Idli and Dosa has been investigated in elaborate details. Other products with supplementation of xanthan gum which have been investigated include orange and lemon squash, commercial tomato soup, yogurt preparations with or without CMC. Immunological methods for detection of xanthan gum in... 

Vaccines have been prepared traditionally by use of viruses or organisms killed by compounds such as formaldehyde or by attenuated viruses or live organisms. These are selected for a low degree of virulence after repeated passages through live animals or cell cultures. Newer methods utilize purified viral proteins, bacterial capsular polysaccharides, or... 

Practical applications are again stressed in the Chapter by Lonngren and Svensson (Stockholm) on Mass Spectrometry in Stmctural Analysis of Natural Carbohydrates. They build on the fundamentals of carbohydrate mass spectrometry, as laid down by Kochetkov and Chizhov in Volume 21, and demonstrate the profound analytical value of mass spectrometry for structural analysis of complex polysaccharides. In particular, this tool has dramatically increased the scope of the traditional methylation linkage-analysis procedure, especially when used in conjunction with gas-liquid chromatographic methods of separation. The latter topic is the subject of complementary Chapters by Dutton, one already published in Volume 28 and the other scheduled for publication in Volume 30. 

Extraction of botanical polysaccharides has traditionally been successfully carried out using the popular method of hot water extraction [1,2,5,71-77,85] and it is applicable in a variety of plant cell wall structures and water solubility of polysaccharide constitutes [65]. Briefly, the procedure involves large quantity of medicinal plant material/mushroom to be powdered, and then homogenized to maintain uniformity within and between the samples collected at different times. The powdered sample is then subjected to hot water extraction by autoclaving for approximately 2 h at 121 °C [5]. Autoclaved sample is filtered after allowing it to cool to room temperature, and the supernatant is then precipitated using 95% aqueous ethanol (supema-tant EtOH=l 4, v/v) for about 15 h at 2.5 °C to remove nonpolar... 

It is evident from the literature that microwave-assisted extraction (MAE) method is much faster, consumes less solvent, and efficient in terms of yield than traditional reflux extraction of polysaccharides (Table 1) [86,87]. However, caution should be exercised to limit the microwave irradiation power as higher power can potentially cause structural modification of polysaccharides [81]. 

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