Burton brewers had a two-pronged approach to keeping their beer sound during long sea voyages. Firt, they hopped the heel out of it. Not for the flavouring provided by hops but for their preservative qualities. The seond defence was a very high degree of attenuation. There was no food left for any further fermentation. Well, obviously other than by the Brettanomyces the beer contained.
But there was another, simpler method of travel-proofing your beer: pasteurisation.
"Pasteurisation of Beer.——It may interest the brewers of this country to know that a new process has been patented by Mr. Williams Kuhn, of Clermont-Ferrand (near Royat les Bains), by means of which, it is stated, beer can be preserved in casks and shipped to hot climates without any danger of alteration or decomposition. As is well known, Pasteur discovered the ferment that alone is susceptible Of producing a normal fermentation ; and since it has been possible to eliminate, by the use of the microscope, all gems that lead to alterations in the liquid, the art of the brewer may be said to have made a great stride forward. By observing with care the conditions of pure fermentation, as prescribed by Pasteur, beer can be preserved from noxious fermentations. It has not, however, been possible, so far, to avoid the difficulties attached to the exportation of beer to hot climates, for the alcoholic ferment, be it ever so pure, continues its work of transformation and of decomposition, and under the influence of high temperatures becomes so powerful as to transform all the saccharine elements into alcohol and carbonic acid gas. The beverage is in consequence modified to such a. degree as to be deprived of taste, of perfume, and of its primitive nutritious qualities. If Mr. Kuhn’s process has satisfactorily solved all the difficulties of the problem, there can be no doubt of its importance and of the field before it in this country. The fact that first-class firms, such as Raoul Pictet, of Paris, and Riedinger, of Augsbourg, have respectively taken up the French and German patents, leads us to conclude that Mr. Kuhn's method contains all it promises."This wasn't the first use of pasteurisation to preserve beer. Carlsberg were already pasteurising their beer in 1881.
"The Brewers' Guardian 1889", 1889, page 44.
It's striking that, though the author discusses the negative effect on flavour of an unwanted and uncontrolled secondary fermentation, nothing is mentioned about the changes pasteurisation itself might cause.