The presence of different types of phosphates in malt, and the important influence which, according to their nature, they exercise in the brewing process by way of the enzymes affected by them, have been made the subject of research mainly by Fernbach and A. Hubert, and by P.E. Petit and G. Labourasse. The number of enzymes which are now known to take part in the brewing process is very large. They may with utility be grouped as follows:—
Name. | Rôle or Nature. | ||
In the malt or mash-tun. |
| Cytase | Dissolves cell walls of of starch granules. |
Diastase A | Liquefies starch | ||
Diastase B | Saccharifies starch. | ||
Proteolytic Enzymes | (1) Peptic. | ||
Catalase | Splits peroxides. | ||
In fermenting wort and yeast. |
| Invertase | Inverts cane sugar. |
Glucase | Splits maltose into glucose. | ||
Zymase | Splits sugar into alcohol and carbonic acid. | ||
Bibliography.—W.J. Sykes, Principles and Practice of Brewing (London, 1897); Moritz and Morris, A Text-book of the Science of Brewing (London, 1891); H.E. Wright, A Handy Book for Brewers (London, 1897); Frank Thatcher, Brewing and Malting (London, 1898); Julian L. Baker, The Brewing Industry (London, 1905); E.J. Lintner, Grundriss der Bierbrauerei (Berlin, 1904); J.E. Thausing, Die Theorie und Praxis der Malzbereitung und Bierfabrikation (Leipzig, 1898); E. Michel, Lehrbuch der Bierbrauerei (Augsburg, 1900); E. Prior, Chemie u. Physiologie des Malzes und des Bieres (Leipzig, 1896). Technical journals: The Journal of the Institute of Brewing (London); The Brewing Trade Review (London); The Brewers' Journal (London); The Brewers' Journal (New York); Wochenschrift für Brauerei (Berlin); Zeitschrift für das gesammte Brauwesen (Munich).
(P. S.)
[1] They were classified at 28 lb in 1896, but since 1897 the standard has been at the rate of 32 lb to the bushel.
[2] Inclusive of rice and maize.
[3] Exclusive of rice and maize.
[4] As a rule there is no separate "collecting vessel," duty being assessed in the fermenting vessels.
BREWSTER, SIR DAVID (1781-1868), Scottish natural philosopher, was born on the 11th of December 1781 at Jedburgh, where his father, a teacher of high reputation, was rector of the grammar school. At the early age of twelve he was sent to the university of Edinburgh, being intended for the clerical profession. Even before this, however, he had shown a strong inclination for natural science, and this had been fostered by his intimacy with a "self-taught philosopher, astronomer and mathematician," as Sir Walter Scott called him, of great local fame—James Veitch of Inchbonny, who was particularly skilful in making telescopes. Though he duly finished his theological course and was licensed to preach, Brewster's preference for other pursuits prevented him from engaging in the active duties of his profession. In 1799 he was induced by his fellow-student, Henry Brougham, to study the diffraction of light. The results of his investigations were communicated from time to time in papers to the Philosophical Transactions of London and other scientific journals, and were admirably and impartially summarized by James D. Forbes in his preliminary dissertation to the eighth edition of the Encyclopaedia Britannica. The fact that other philosophers, notably Etienne Louis Malus and Augustin Fresnel, were pursuing the same investigations contemporaneously in France does not invalidate Brewster's claim to independent discovery, even though in one or two cases the priority must be assigned to others.