Introduction

This is a very big question so I’m going to be giving a very broad strokes answer. Let’s start off with a TL:DR

EVERYTHING about how beer tastes has changed MASSIVELY over the past few centuries. If you had a bar hopping time machine, you’d find an absolutely astounding variety in the taste of beer. If you see any beer marketing that tells you how they’ve been making their beer the same way for centuries or that they’ve revived an old style of beer that is generally going to be a big steaming pile of bullshit.

Instead of trying to go chronologically I’m going to hit on a few big developments that changed how beer tastes.

Beer Purity Laws

Beer purity laws are generally not about beer safety or making beer that tastes good. Instead they’re about things like taxes and keeping the price of bread down. For example, the UK used to heavily tax brewing malt so the government didn’t want people using other ingredients in their beer. Restrictions on what you could put in the beer in the UK were thankfully repealed with the Free Mash Tun Act of 1880. Meanwhile, the 1516 Bavarian Reinheitsgebot beer purity law was put in place to keep the price of bread down by trying to keep people from using wheat to make beer out of instead of bread. Then later after German unification the Reinheitsgebot was extended to northern Germany as part of negotiations to get Bavaria into Germany as that’d make Bavarian brewers happy. Before this while lager was dominant in Bavaria, northern Germany had a huge variety of different styles of beers (much like Belgium) and the Reinheitsgebot helped kill many of those older styles off, although some do still survive.

TL:DR Beer Purity Laws are generally bad things that made beer more boring.

Use of Pine Boughs to Filter the Mash

In the real old days (and surviving into modern times in some farmhouse breweries in Norway etc.) people used pine boughs to filter the grain out. This would give the beer a piney flavor.

Use of Hops

Before hops started being used in the late Middle Ages beer tasted VERY different. Hops are a good preservative and without them you have some choices:

-Use another preservative. The problem is things that do a good job of killing bacteria are also generally bad for yeast. Some places used gruit (herb and spice mixes) but those didn’t always work that well and were expensive so their use was pretty limited.

-Drink the beer really fresh. The fresher you drink it the less time bacteria has to come in and fuck things up. The problem with this is you can’t store beer or ship it to other places and sell it. But a lot of beer was made for a specific event (like a wedding), brewed fresh, and then all drunk for that event. This really fresh beer would’ve been a bit sweet and murky since the yeast might’ve not finished fermenting yet, but probably still pretty tasty.

-Brew sour beer. Sour beer isn’t too bad really as long the strain of bacteria souring your beer tastes OK.

-Make the beer hella strong. Alcohol itself is a preservative.

-Be really careful about sanitation. Possible, but hard without understanding what bacteria even are, but I’m sure some really skilled brewers pulled it off.

In practice unhopped beer would be some mix of things on this list. This would’ve been very different than modern beer but not bad. Even after hopped beer showed up in England, the older unhopped beer (called “ale” at the time to distinguish it from hopped “beer”) stuck around for centuries and a lot of people loved it. For example, in Shakespeare’s plays a bunch of characters talk about how much they love ale and hate beer. However, since hops are a useful preservative, especially if you’re making the brew in bulk and shipping it around, the hopped drink eventually won out but the last remnants of the old school stuff (called “west country while ale”) only died off in the 1800’s. It was apparently white-colored, sweet and sour, thick and murky. The closest thing you could find to it today would be Korean makgeolli (sour rice beer, but even that’s not the same since the ingredients are process of making it are different, but still the closest thing you can find, and I enjoy it a lot even if it’s a bit of an acquired taste).

Of course, the line between hopped and unhopped beer wasn’t always absolute and a lot of farmhouse and small-scale brewers would put a little bit of hops into the more old fashioned brew.

Another thing is that some of this old school unhoppped ale wasn’t boiled which would make it a bit more think and murky (boiling makes proteins etc. drop out) and spoil faster, but not necessarily taste any worse, just different.

TLDR: unhopped old school ale was some weird shit and stuck around well into the modern period.

Hop Breeding Programs

In the old days people used wild hops or relatively weak strains of cultivated hops. While the older variety of hops are still used today, many of the hops used in modern beers have only been developed in the last few decades.

Why does this matter?

Well, the modern hops tend to be a lot stronger so you can make a hoppy beer without putting in a shit ton of plant matter into the boil which gives you a cleaner taste.

Also, traditional European hops tend to taste earthy/floral/herbal if you like beer that tastes piney/fruity/dank then that comes from North America wild hops, generally crossbred with European domesticated hops. For a long time these North American hops were looked down on for harsh and catty flavors but breeding programs to make them taste better (compare the older Cluster hops to newer Citra hops for example) and changing tastes has made these American flavors more popular and has inspired newer breeding programs back in Europe as well.

Also, with stronger modern hops you can not only use less hops but boil them less. Why would that make a difference? Well, there are two things in hops that affect beer flavor: acids and oils.

Hop acids make beer bitter and to get them out of the hops and chemically change them so that they don’t evaporate you have to boil the everliving fuck out of them. Meanwhile hop oils give beer flavor (and a little bitterness) and they tend to evaporate if you boil them. So in the old days people would have mostly just the acids and not much of the oils (although they did have SOME oils as many brewers would add in hops at different points in the boil), while these days craft brewers have the option of more easily putting more (very delicious) hop oil in their beer since they can get their hands on dirt cheap bittering hops (hop varieties with lots of acids) as well as other varieties of hops with more oils than in the old day. Of course, this doesn’t apply to modern lagers which generally use just a tiiiiiny amount of very high acid hops to save money and get a clean flavor.

TL:DR modern hop varieties are freaking delicious (I especially enjoy galaxy hops) and people in the old days didn’t have access to them. Even the tasty (but mild) old school hops they used were often boiled so much you didn’t get much flavor except bitterness out of them.