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
There are a number of reasons why you may perceive Becks as more bitter.
Firstly, some of the bitterness you are perceiving is a factor of the beer's age. Beers like Becks, Heineken, Amstel, Yuengling, Miller/Coors/Budweiser, etc. aren't as strongly hopped as IPAs. Nonetheless, hops are still the primary flavoring agent in these beers.
Some background first. Hops are flowers. Their bitter flavor comes from the release of the flower's alpha acids, which are among the most prominent resins and volatile oils within the flower itself. These alpha acids are extremely sensitive to oxygen and begin to break down upon exposure to oxygen -- even the trace amounts inside a sealed bottle or keg.
Thus, any beer relying on hops as a primary flavoring agent is essentially "on the clock" from the time it's brewed. When fresh (<30 days after bottling/kegging), these hops taste as they were intended. As time progresses, the hop flavors fade and are replaced by a skunky hop flavor which some people (myself included) perceive as being overly bitter. Advanced palates can distinguish between these flavors, but it's often difficult to separate them without proper training.
Additionally, most mass-market beers (including all of the above) are pasteurized. Anything that's been pasteurized will have a shelf life. General guidelines are to avoid anything older than ~90 days for pasteurized beer, and try to find <30 days when possible. I check bottling dates religiously before making a purchase.
Note that some types of unpasteurized beer (Ex: traditional Belgian lambic) actually improve with age and can be cellared under proper conditions for upwards of 30 years!
Another reason is due to the Heineken flavor profile itself. Just as alpha acids are sensitive to oxygen, the malted grain in beer is quite sensitive to direct sunlight. Even 15-20 minutes of exposure to the sun can irreparably skunk a beer. This is why most beer bottles are dark in color and 6pk holders have high cardboard sides.
Even though both Becks and Heineken are sold in green bottles, which allow significantly more light through than dark bottles, the Heineken flavor profile is decidedly more skunky. And that's not to say it's bad; it's simply part of the flavor profile they have nurtured. This skunky malt flavor is the dominant flavor in Heineken, and it frequently masks some of the underlying hop bitterness -- including bitterness from aged hops.
If you want to see what this flavor tastes like, grab two cans of Bud/Miller/Coors Light. Pour one into a clear glass and put it in direct sunlight for 15-20 minutes. Pour the other one at the same time but leave it in an opaque container shielded from sunlight. It's a pretty distinctive flavor.
Finally, everyone's tastebuds perceive flavors a little differently. It's entirely possible that another person tasting the same two beers from the exact same bottles comes to a different conclusion about bitterness.
In short, there are a number of factors at play here, and it may require a bit of effort to isolate them. But hey, that's the fun part!
It's basically because of the ingredients - the two beers contain different amounts of sweet and bitter flavors which balance out to give you the perceived bitterness.
Some will say that it's because of higher hop bitterness, measured in IBUs (International Bitterness Units), but this is really only part of the picture. You can have a beer with a larger number of IBUs but also a large amount of residual sweetness such as caramel malts) and this will generally taste sweeter than a beer that has a lower IBUs and almost no residual sweetness.
Each brewer designs a beer with a taste profile in mind, and then seeks ingredients and sometimes process changes to arrive at this desired flavor profile. This often requires several iterations until the desired result is reached, and even then it may not be possible to reach it every time, so the brewer may also choose to blend beers from different batches to arrive close to the desired result. The same is true for Heineken - their Quality Assurance team will have been given clear guidelines on the spec for the beer, both as hard and fast measurable, objective facts (IBUs, Color, carbonation, diacetyl, fusel alcohols, esters etc...) and also as subjective - how it tastes.
So the final answer about why one beer is more bitter than another is because their respective breweries have decided that's the flavor they want, and they have crafted a brew to produce their chosen flavor profile.