From barrel ageing beer to sourcing intensely bitter hops, Dan Saladino reports on the latest trends in American brewing that are starting to influence British beer styles.The US "craft beer" scene started to take shape 30 years ago. Prohibition in the 1920s and post-war industrialisation brought an end to one of the world's most diverse brewing cultures.In 1979 President Jimmy Carter made home brewing legal again, and soon after, a network of adventurous brewers started to emerge. Known as craft brewers, they operate on a small scale and use traditional brewing techniques but also place great emphasis on experimentation and innovation.American brewer and editor of The Oxford Companion to Beer, Garrett Oliver puts their quest for new flavours down to the US losing its own brewing culture and so being free to explore all others. Now a young generation of brewers in the UK are looking at these new US styles and discovering techniques like barrel aging as well embarking on experiments with new, intensely flavoured, hop varieties.