Structures of the ' masked repeating ' type seem to occur generally in K-carrageenans from Chondfus crispus and Gigartina species and will account for the analytical variation between one sample and another. Most-possibly all--of the variation is in the 4-linked units which occur as 3.6-anhydrogalactose, 3.6-anhydrogalactose 2-sulphate, galactose 6-sulphate, and galactose 2.6-disulphate. In K-carrageenan from G. stellata, as from C. crispus, all galactose units are believed to have the D-configuration. Samples from Chondrus were similar to each other and had a lower content of both types of 2-sulphate than those from Gigartina. The separation of a Chondrus sample into a series of subfractions which differed in the relative proportions of the various 4-linked units, suggests that K-carrageenan might normally contain a mixture of related molecules. Evidence is given that absorption bands shown by sulphated 3.6-anhydrogalactose units in the 800-850 cm.-I region of the infrared spectrum cannot be interpreted in the simple stereochemical terms used previously. However, many carrageenans show a band at about 805 cm.-l which is characteristic of 3,6-anhydrogalactose sulphate and potentially useful because it is easily recognised, even in the presence of other sulphate esters. Gel formation by K-carrageenan is enhanced by removal of 6-sulphate with conversion into 3.6-anhydrogalactose, but is much less sensitive to an excess of 2sulphate. The variation of gel strength with polysaccharide structure provides some evidence on the molecular basis of gel formation.
Some benefits accruing from the application of brewing science to the production of Scotch Malt Whisky are described. The major function of a distillery laboratory is to provide meaningful information to the production units to allow them to function in an optimal manner. The major areas of activity are, to ensure that the raw materials used (barley, malt, yeast, water) are of the most suitable quality, that plant cleanliness is of the highest possible order and that the process is operated as efficiently as possible. The effect of lack of maintenance of these standards is described, as are the practices to be followed to ensure their maintenance.
L-Carrageenan has been characterized by chemical methods to provide a firm basis for interpretation of data from X-ray diffraction and optical rotation, and so to confirm the carrageenan double helix. This polysaccharide was isolated from the red seaweed Eucheuma spinosum and shown by methylation analysis and partial fragmentation, and by other evidence, to have a masked repeating structure in which D-galactose 4-sulphate and 3,6-anhydro-~galactose 2-sulphate residues are arranged alternately in linear chains, with formal replacement of approximately one in every ten anhydride residues by D-galactose 2.6-disulphate. Treatment with alkaline borohydride converts this structure to a genuinely alternating copolymer.A polysaccharide from E. cottonii has similarly alternating 1.4-and 1,3-1inked residues but is distinctive in that it has not detectable 2-sulphate. It therefore corresponds more closely than any other known natural polysaccharide to an idealized K-carrageenan.PHYSICAL measurements have recently revealed that certain carrageenans have spectacular conformational properties. X-Ray diffraction analysis of oriented specimens has shown that K-and i-carrageenans can exist as double helices in the solid state. When these same polysaccharides are heated and cooled in aqueous solution they show optical rotation changes which are believed to represent the double-helix-to-coil t r a n~i t i o n .~-~ The reversible association of K-carrageenan with certain galactomannans can be regarded as ' polysaccharide quaternary structure'. All this behaviour is new and unexpected for polysaccharide~,~ and suggests that polysaccharides might after all be valuable in advancing the general theory of polymer conformations. We now report the chemical characterization of two substances that could be useful for this purpose.
A method for the determination of the fermentability of unboiled, filtered, malt Hot Water Extracts has been developed. The wort is fermented under carefully controlled conditions, using fresh dis tillers' yeast. Knowledge of a malt's extract and fermentability allows calculation of its fermentable extract content, which allows spirit yield prediction, and the method is in use as a basis for Malt Purchase Specifications.
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