Why does Beck's taste more bitter than Heineken? Why does Beck's taste more bitter than Heineken? Is it due to the sugar content?
The answer to this question is going to depend largely on which specific beers you are referring to.  Assuming you are referring to Becks Premium Lager (as opposed to one of their other offerings), Becks has an IBU (International Bitterness Units) of 20 where Heineken has 23 IBUs.  Based on IBUs, Heineken should be more bitter but not by much.  What you're tasting could be accounted for by batch to batch variation on behalf of the brewer or the conditions that the bottles were stored (length of storage, lighting, etc.)

Furthermore, the bitterness in most of Becks' beers come from the use of darker malts, while the majority of the bitterness in Heineken comes from the use of (pellet) hops. 
This makes the bitterness in Becks tend towards roastier flavors, and the bitterness in Heineken to tend to be more herbaceous or floral. It is possible that you are more personally sensitive to one set of those flavor compounds.

Note that IBUs are an imperfect measurement of bitterness so only consider it as an approximation.  Many people say that differences in bitterness beyond 100 IBUs are indiscernible but that is often conflicted.

Answered by: the Gastrograph Team