It's not hard to figure out that port wine comes from Portugal and while many people think of Porto (which is also the destination that partially inspired the Harry Potter series!), the wine fields known for their port yield are located in the Douro Valley. While there are other grapes around the world that are made into port wine, there are none so luxurious and bold as those found in Portugal. The grapes in this area are unique to the environment and the terrain, lending themselves to the classic sweet and tart flavors that are commonly associated with dessert wines.
Traditionally, port wine is made a bit differently than other wines. Everyone has heard of grapes for wine being stomped by winemaker's feet, and here's the kicker (literally!) - in Portugal, that's exactly how port wine is made! There's a very scientific explanation for this method of crushing grapes, however, and if you're thinking that this is an old-age technique that has no place in winemaking, you'd be wrong... because it's a tradition that has been in place for centuries and is part of the reason this dessert wine is so delicious.
The Tradition Of Stomping
For those who have had the opportunity to try stomping on thousands upon thousands of grapes, it's been described as bizarre, to say the least, and almost feels like some crime is being committed. However, for those whose jobs it is to stomp grapes until they've all been evenly crushed, it's no joke - the process is quite a specific one and can be very tiresome, especially once two hours have gone by of stepping, quite forcefully, in the same spot. Sure, grapes could be crushed mechanically and machines could be implemented to help in the process, but why stop something that has worked so well for so many centuries? This fact aside, there are plenty of perfectly reasonable explanations as to why winemakers in the Douro Valley won't allow machinery to come in and take over the jobs of many.
For starters, it helps to have an understanding of the anatomy of a grape. Similar to fruits such as the kiwi, grapes have small seeds in the center of them that yield a bitter flavor that's very unlike the grape flesh or skin. Once these seeds are crushed, that same bitter flavor leeches out and mixes with the overall fresh, tart, sweet flavor of grapes that would otherwise remain sweet, which completely changes the flavor of the wine. If you still don't understand, the next time you eat a grape, be sure to chew and chew until you've bitten down on those seeds - you'll soon understand the difference in flavors.
Therefore, it's preferred that the grapes for port wine are crushed by simply stomping. Theoretically, the human foot has enough power to crush the grapes but is still soft enough that it won't crush the seeds within the grapes. This perfect balance is what allows port wine to be what it is, with all of the sweet decadence that we love about the dessert wine. The tradition, for one family-owned winery, Quinta Vale D. Maria, has been doing this since 1780. And, in case you're curious about how full those tubs are, most wineries will only fill them so that they land at about knee-level or slightly higher when everything is crushed. And how long, exactly, does it take to crush so many grapes by hand (or, rather, by foot)? The first two hours is the most serious - and crucial - part of grape-crushing. If those responsible don't keep the same pace or ensure that their movements are minimal outside of their feet and legs, it could lead to an uneven batch or the missing of grapes that were not crushed as methodically as the rest. After that, those stomping are free to walk around the tubs of grapes, stomping at will, to ensure that the rest of the mixture is evenly-crushed and uniform throughout.
Foot treading is not an easy business by any means and while it seems unusual initially, the process actually makes quite a lot of sense. And if you're enjoying a glass of port wine after dinner, you'll likely already have an appreciation for all of the effort that goes into creating this delicious wine. Not every vineyard uses the popular foot-treading technique, but those who do find ways to pass the time such as listening to music or simply just having a general conversation.