I'm not going to speak to the continuity of the Pabst's recipe or its recognizably 130 years later, though beer brewing -- is both ancient and among the first food production techniques to be regulated by government. Founded by German American Jacob Best, the company that would eventually become Pabst brewed in a German style. That style -- which, in Germany, has been regulated for centuries and remains so regulated to this day -- is fairly consistent in terms of ingredients, additives, and flavorings but otherwise may vary extensively. While quality and presentation may differ. As /u/righthandofdog and other users point out, the PBR of 1893 and the PBR of today were likely very different beers because they would have been brewed in different styles under different conditions with different distribution models.

The 1893 World's Fair -- officially -- did not rank the beers submitted for evaluation. Beers were to be scored and those that got a score above 80 were awarded a bronze medallion. The actual scoring worked somewhat differently with judges creating categories and ranking beers within them, but -- again -- the fair did not hand out ribbons of any color and made no official pronouncement about the superiority of Pabst's or any other beer.

Pabst's had been doing fairly well at other, more local fairs for some time, however, and the company had taken to afixing a blue ribbon to the bottles for branding purposes BEFORE the Chicago World's Fair. This branding was fairly unique, and customers took to asking for "the blue ribbon beer." Consequently, Pabst would carry that branding through, even when it made the move from bottles to cans in the post-war years.

The conflation of the blue ribbon on the bottle with the blue ribbon of the Chicago World's Fair is a natural one but one that Pabst would certainly have been hesitant to dispel. The 1893 exhibition celebrated the 400th anniversary of Colombian contact and the prestige and association with the modern -- the fair debuted the Ferris wheel, shredded wheat cereal, and Juicy Fruit gum -- lent national credibility to Pabst.

Modern PBR is likely a very different beverage.

Edit - after more reading and digging, it sounds like a hoppy lager like Pilsener Urquel or Peroni would be pretty close to the old PBR, though it would have been sweeter and used cirn instead of barley.

I'm not a zymyrgist / brewing history person, just a homebrewer with an interest in history, but Freiderich Pabst would have have almost for sure have been making a german pilsener, with barley - the most popular german style which would have fit Milwaukee's large german population. German Reinheitsgebot brewing purity laws, only allow expensive barley, but the US doesn't care.

There were a batch of different events that happened around the same time that came together to make Milwaukee the brewing capital of the US. In the 1880s, breakfast cereals exploded, with Battle Creek Michigan on the other side of lake Michigan as epicenter. So there would have been easy access to various new sources of grain to experiment. Barley was replaced with cheaper rice and corn, resulting in a far lighter mashbill all around the US. Midweastern corn would have been the cheapest and easiest to source, so it replaced much of the barley and the lighter flavors and lower price helped it take over the market of tradition pilseners.

Around the same time railroads and ice houses made year round refrigeration possible (and quite affordable in the great lakes region) - that led to the rise of lighter lager beers, which use a different yeast and are are easier and cheaper to make than pilseners because they are essentially refrigerated the whole time allowing differences in incoming mash or weather to be ignored. Lagering is the secret sauce that allows true industrial level production of beer.

With those changes in place, the Great Chicago fire of 1871 destroyed most of the breweries in a large city only 90 miles away. Milwaukee brewers would have grown their production quickly, but once they started shipping tons of beer by rail 100 miles away to chicago, it was just a matter of scaling up to start hitting other rail connected cities. That world's fair was chicago reclaiming itself back in business after the fire, but was a chance for the Milwaukee breweries to put a stake in the ground for being modern and american and not old-fashioned.

The lighter, easier to drink style with very consistent quality from batch to batch, year to year, city to city started the explosion of large breweries - and then 1920 and prohibition rolled along in 1920 and just decimated local beer production. Only the absolute largest companies were able to switch to other products (like malt syrup for malted milk, but also as a "baking product" that you could easily use to home brew beer illegally, or coors porcelain business for labware).

A fresh pilsener urquel or Warsteiner on draft is going to be pretty close to whatever PBR was back in the day. The minerality of the local water and variations in grain and hopping will make it a far fresher, more grassy flavor profile. Modern PBR, like all american adjunct lagers is much sweeter from the corn used in brewing and will tend to be purposely less distinctive when it comes to hopping or water selection.

One of the reasons India Pale Ales kicked off the american microbrewing explosion (and the reason they are almost always the first beers brewed by new micros) is that the combination of heavier malt sweetness and high bitterness by hopping during the boil allow a brewer to do a lot of tweaking to improve flavor/consistency batch to batch. Part of the reason there will often be 3-4 different IPAs at small places is the brewer dealing with variations in the raw materials he can source. A clean pilsener is a VERY difficult beer to make and there's no way a micro can make a lager that can compete with the price point of beer factories like PBR.

Brewer here. The short answer to "would a PBR taste the same today as it did in the late 1800s" is probably not.

There are a variety of factors that contribute to that assumption, ranging from changes to raw ingredients, production, and packaging.

Right out of the gate, the history of PBR is fuzzy at best. Pabst's own website doesn't give a date for their introduction of their flagship beer that would eventually have its name changed to Pabst Blue Ribbon. The only information given was that the brewery was started in 1848 and in 1882 they started to put blue ribbons on Best Select, the beer that would be re-branded as PBR.

That immediately poses a couple questions. Is Best Select the original beer that was being produced in 1848, or was it a new brand introduced at a later date? If it was introduced later, when was it introduced?

One of the biggest reasons for needing that information is due to yeast. As an American Light Lager, PBR is fermented using lager yeast (S. pastorianus), one of the two main yeast strains used in brewing, the other being ale yeast (S. cerevisiae). Louis Pasteur discovered that yeast was responsible for fermentation in 1876, and lager yeast was not isolated until 1883, allowing more control over the fermentation process. Before modern equipment that allowed for closed fermentation came about, brewers would take the krausen that forms during the peak of fermentation and transfer some of it to a new batch of beer, unknowingly transferring yeast to the next batch. Prior to the isolation of the two strains, the yeast used was a mixture of the two strains, with lager yeasts performing better at lower temperatures (50F-ish) while ale strains performed better at warmer temperatures (70F-ish). Isolation allowed for using the exact strain of yeast that is desired by the brewer. If PBR was first brewed in 1848, then the modern version certainly doesn't taste the same due to the difference in yeast. If it was introduced later, there is a possibility that the yeast used today is the same as the late 1800s. Budweiser has been using the same yeast since the 1800s, and Pabst could be doing the same, although I haven't been able to find any source confirming that.

Like with any large brand, the PBR recipe is kept a secret, however, as an American Light Lager, there are only so many variations that can take place due to how simplistic the style is from a recipe standpoint. Most likely, it's a simple recipe of pale or pilsner base malt with corn, rice or a bit of both as adjuncts. Over the last 100 years, malt has changed dramatically, especially when it comes to what brewers use. There are two main varieties of barley, 2-row and 6-row. 6-row is the dominant varietal grown in the US, however, 2-row is the dominant varietal used in brewing. Historically, 6-row was used more due to its availability, but 2-row is a more efficient malt. Many traditional American beer styles still call for 6-row as a portion of the malt used, and many macro-breweries still use it due to cost. PBR almost certainly had 6-row in its recipe when it was first released, but even ignoring the possibility of a switch to 2-row, barley breeding programs have changed the makeup of American grown barley, with the majority of modern barley strains being introduced in the 20th Century. That's without even going into advances in malt modification that has been shown to affect flavor.

As for hops, again, without a recipe, it is impossible to know what hops are used. Comet is widely speculated as the hop used due to its popularity prior to the 1970s and with it being one of the oldest varietals grown in the US. While Wisconsin does have some hop production, the majority of American hops are currently grown in the Pacific Northwest. Assuming that Pabst sourced their hops locally in the 1800s, the hops would have been whole cone hops vs the modern pelletized hops used in production brewing today. The big difference between the two that is important for this discussion is oxidation. Whole cone hops are much more prone to oxidation, and in an age before modern packaging that could protect the hops, the oxidation could have affected the taste of the finished product, something that modern brewing doesn't have to contend with.

When it comes to packaging, cans were not introduced until the 1930s and stainless steel kegs were not introduced until the 1960s. So if modern day PBR tastes the same as it did in the 1800s, it would be from a glass bottle, not out of a can or on tap.

Perhaps the biggest indicator for me, without making what is, at the end of the day, speculation, that PBR does not taste the same as it did in the 1800s, is the history of the production brewery itself. After finding itself in economic troubles, Pabst closed the original Milwaukee brewery in 1996 and began contracting all PBR production through Stroh Brewery. Stroh also owned Old Milwaukee, which is based in Milwaukee, I cannot find anything that indicated where PBR was physically being brewed at. It could have been Milwaukee, or possibly at Stroh's main facility in Detroit. If it was brewed in Detroit, adjustments to the water profile used in the beer would have to take place to match the water profile of Milwaukee. Also, the water profile of Milwaukee has changed (fluoridation being the big one), and again, due to trade secrets, it is unknown what water adjustments Pabst does or does not do.

This is all without going into changes in brewing equipment that has occurred over the last 150 years, along with the modern chemicals that are used for cleaning and sanitation. Also the fact that, while large breweries have incredible QA/QC programs, the multiple changes in ownership and where PBR has been brewed, using different equipment, all could potentially impact the taste of the finished product.

While I have personal reasons as a brewer at a small independent brewery to dislike the macro-breweries, I still have to appreciate the history of these historic brands. While the beer might not taste the same, the legacy of these brands and the fact that they are still in production today is fantastic. I can link any sources that you would like, but a decent amount also comes from my knowledge of the industry itself.