At the end of the 18th century, an enterprising brewer named Hodgson, motivated by the wide-open Indian beer market, solved the problem. He invented a new style of beer, brewing it to a high alcohol level and using more hops than any previous beers. While there is not enough alcohol in any beer to offer serious protection from microorganisms, having more of it will certainly not hurt. The real genius of his recipe is in the hops.
High hop levels can preserve a beer’s flavor in two ways: they have a limited ability to protect beer from spoilage by some microorganisms, and, more importantly, their bitterness can mask stale flavors. While the beer arriving in India would certainly have suffered from oxidative staling during the long voyage, it could still taste acceptable because of the masking effect of alcohol and hops.