What is the difference between historical beer and 'modern' beer?

Question

This question might be a bit broad, but what I'm trying to understand is generally how the brewing process and the subsequent end result differed before the early-modern to modern era.

I had asked a question here some months back on where I could find some historical styles of beer, but without having much luck I thought I'd try to get at least an understanding of what's known about the evolution of beer from ancient to medieval to modern times.

So the question is: if I was a European medieval man drinking beer circa 6th-15th centuries what would that beer have been like? How did it differ from what we've been brewing for the last few centuries? And is that product distinct from what existed in ancient times?

Answer 1

Not only has variety improved, but so has the technology and agronomy of brewing.

Malt variety, yield, and efficiency

• Crop science has increased the size of barley kernels and the amount of starches available to convert to sugar. The common grain at the time was 6-row malt, today the most common brewing barley is 2-row.
• Understanding of the malting process has drastically improved. Today we understand how to get perfectly malted barley. Historically the malt would have been over or under modified. Under modified would have lots of unconverted starch which would leave a hazy beer that tasted rather bready. Over modified malt would would have no starch, but less sugar than possible so the resulting beer may lack body.
• Kiln dryers allow for greater variety of malt. By controlling the heat cycle, the same variety of barley can make different malt. Drying the grain in medieval times consisted of heating it over a fire. Fire dried grains would have a smokey flavor that would be present in the beer. The traditional Scottish Ale uses malt that has been dried over a fire where the fuel is peat, which is a very distinct smoke flavor. The fire also was not nearly as exact or even as a modern kiln so some kernels would be burnt and other may be under cooked, so to speak.

Water

• Needless to say, but water purity is drastcally better today than in the 6th-15th centuries. Because the brewing process boils the water, the beer was safer to drink than the water. Hence the patron saint of brewers said "Drink beer, not water."
• Dissolved mineral content of water and pH control. Medieval brewers had the water that they had. Today, a brewer can start with distilled water and add whatever minerals they desire to change the flavor profile and pH of the mash. The water pH can effect the mash efficiency and fermentation profile of the beer. This lack of water control lead to specific styles coming from specific areas. I.E. Burton upon Trent is known for pale ales, Pilsen for golden pilsners, Munich for malty lagers.Some water source mineral content.

Hops

• Ancient beers were not hoppy. Hops were not used extensively in beer until about the 12th century and were not cultivated en mass until about the 13th century. Most beers older than that were bittered with Gruit..
• The hops that were used were not high in bittering acids. The oldest common hop varieties are the Noble hops. Just like today, costs of ingredients was a major factor in brewing. Making a really hoppy beer was prohibitively expensive. Just compare an English IPA brewed from old recipes vs. an American IPA.

Yeast and Microbiology

• This is where modern technology really helps out. Louis Pasteur discovered yeast in 1857. Up until that time, the changing of sugar into alcohol was considered magic or an act of god. It was understood that the foam on top of a fermenting wort could be passed around to other vats of wort to start the process (Krausening). Others would transfer Magic Sticks from batch to batch to start fermentation.
• There are other microorganisms that can inhabit beer. Brettanomyces, Lactobacillus, and Pediococcus to name a few. These can cause a sour, acidic flavor in beer. Some ancient breweries would just let the cold night air in through an open window in order to cool the freshly boiled wort, exposing the warm sugar solution to whatever might land on it.

Technology

• Thermometers - The temperature of the mash can affect the fermentabilty of the wort. The temperature of the malting and drying affect the sugar content of malted barley.
• Chemical cleaners - All of the brewing equipment is sanitary. Modern living through chemistry.
• Food storage/availability - I can get whatever ingredients I want, whenever I need them.
• Refrigeration - I can cool the wort in controlled conditions. Beer can travel farther. I can ferment at optimal yeast temperature.
• More than can possibly be named...

The Result?

• Ancient beers would be sweeter and thicker than today's thanks to less fermentable sugars in the wort due to inconsistencies in the brewing process, and inconsistencies in the malting process and poor yeast/microorganism control. The alcohol content would be lower as well.
• Ancient beers would not be hoppy.
• Ancient beers would have to be drunk quickly before they spoiled. The other bugs in the beer would turn the beer bad after a few weeks. This also prevented the beer from traveling very from from the brewery.
• Ancient beers could vary greatly, batch to batch. The brewers of the times were very skilled with what they could work with, but they were constrained by what ingredients they could use, whether by law or availability. Flavor can be affected by fermentation temperature, so a hot day in December could ruin my beer.
• Ancient beers were dependent on the season. When was the grain harvested? When is it cool enough to ferment?

Probably more information than you need, but hopefully it helps.

Answer 2

That's a very broad question, and hard to answer.

Very early on, hops weren't well known, and beer was made without hops; this likely would have caused the beer to be sweeter than it is today. Hops were known and added to beer relatively early in the Middle Ages, though.

Today, in my opinion, the key differences are variety and technology. Not only do we have a greater variety in styles, but we have more varieties of hops, malts, and different yeasts. These create wildly different flavor profiles unheard of centuries ago. Technology has allowed us to create more consistency in beers, as well as increasing variety indirectly through different techniques used in brewing.

Here's a pretty nice article on the history of beer: https://en.wikipedia.org/wiki/History_of_beer

And if you want to try some beers brewed in traditional styles, they are out there. Here's a good list of some of the best: http://www.ratebeer.com/beerstyles/traditional-ale/59/