By Greig McGill

Following on from the last post, sparging - rinsing of residual sugars from the mash bed using hot water - can be accomplished by various methods. The goal is the same. The brewer wants to extract maximum efficiency from their grains without pulling any flavour negative compounds with them. There are four (sort-of) common methods of sparging. These are; fly-sparging, batch-sparging, no-sparging, and Brew-in-a-bag (draining/squeezing). The latter two are not really types of sparging at all, but I’ll talk about it in terms of why one might want to no-sparge by way of contrast with the other methods, and what various people do with BIAB setups.

Fly-sparging is often the method homebrewers strive for, given that it’s how commercial breweries sparge. Does that make it better? Well, as with most things, it depends on equipment, tolerance for hassle, and brewer skill. The goal of fly sparging is to achieve a “rain” of sparge water over the mash, flowing in at the same rate you are running off your wort to the kettle. Generally, you perform a vorlauf - a recirculation of the first runnings - before collecting wort to the kettle. This allows formation of a good filtering grain bed, and thus clearer wort collected in the kettle. There’s no set time limit for this step, but if it takes more than five minutes or so for your wort to begin running clear, you may have some issues with your mash tun geometry, or your wort screen (false bottom, braided hose, slotted manifold, whatever you are using in your mash tun) may be allowing grain particles through.

Fly sparging is capable of producing a perfectly clear wort with a very high efficiency, when done well. The main issue with fly-sparging is due to poorly designed mash tuns and sparging arms leading to “channelling” - sparge water draining in set paths instead of evenly filtering through the grain bed, thus reducing efficiency. One technique for avoiding this is to gently stir the very top of the grain bed occasionally, thus forcing the sparge water to take new paths. Be careful when doing this or you may disturb the grain bed itself, leading to murky wort and high tannin extraction.

Speaking of tannin extraction, another thing to watch when fly-sparging is to avoid your temperature or pH climbing too high. Temperature above 80C or pH above 6 are factors which can cause higher rates of tannin extraction during fly-sparging, leading to excessive grainy astringency in the finished beer. Another potential downside to fly-sparging is that, in order to achieve maximum efficiency, a good fly-sparge should run to 90 minutes or even longer. Not all brewers want to waste that much time on a brew day!

Batch-sparging is a very common method in use amongst home brewers. It’s the simplest sparging method, requiring no special equipment, and less careful monitoring than fly-sparging. I’ve seen many home brewers use slightly different methods of batch sparging, but at its core, batch-sparging is simply “washing” the mash by draining it, then adding another batch of hot water, perhaps stirring and performing a vorlauf for clarity, then draining again.

A common criticism of batch sparging is reduced efficiency, but with care and attention to technique, batch-sparging should be so close in terms of efficiency to fly-sparging that it will make little difference to the finished beer. It’s “not how the pros do it”, but that’s no reason it’s not a useful sparging technique. As always, you need to keep an eye on temperature and pH to minimise tannin extraction, though pH should remain much more stable with batch sparging.

No-sparging is just what it sounds like! The full volume of water is added to the mash and wort is simply drained to the kettle after the mash, with no sparging performed at all. The usual reasons for doing this are; to simplify the brew day - no need to monitor pH and flow rates, to capture more of the essence of the malt, unadulterated by sparge-water, and also to avoid excess volume in the kettle when making a high gravity wort. Predicting your OG can be very difficult with this method, and reduced efficiency can be a problem due to much lower final volume if your mash tun is too small to accommodate the mash plus your additional water for a full kettle. If you have a much larger mash tun, you can work around this by increasing your grain bill to compensate.

Brew-in-a-bag techniques often incorporate many “pseudo-sparging” methods. The most common are pouring sparge water (or the previously drained wort) through the grist in the bag, “dunking” the bag in the wort, and squeezing the bag to get as much wort as possible out. Brew-in-a-bag is a popular method of home brewing, and there are many anecdotes and myths surrounding the pros and cons of these methods of pseudo-sparging. I am not a BIAB brewer, and have never tried any of these techniques. My gut feel as a brewer suggests to me that squeezing the bag may force tannins and polyphenols into the wort, but your mileage may vary. I’d love to hear any feedback from BIAB brewers out there. Perhaps we can feature this feedback in a follow-up article!

So there you go. Two actual sparging techniques, a bit about not sparging at all, and a here-be-dragons warning for BIABers! So which should you use?

The answer really depends on your preferences, though is often dictated by your equipment and your time and effort requirements. If you have a fairly small mash tun or routinely brew very large beers, fly sparging might be the best method for you, as you don’t need to add much more water all at once during sparging. That said, if you have a poorly designed false bottom or manifold in your mash tun, you might struggle to avoid channelling while fly sparging, so batch or no-sparge might be the way to go.

Of course, the other variable which you need to consider when choosing the right sparging method for you is how accurate you wish to be with your recipe design. When fly sparging, unless you perform a mash-out by raising the temperature of your mash before sparging in order to denature the enzymes and “lock in” the available sugars, it might be difficult to predict your OG accurately. Likewise, when using no-sparge, it can be very difficult to know exactly what you’ll get from any beer you brew for the first time. That’s probably not an issue if you make the same beers over and over, but if you are like most homebrewers and often brew new beers, you may struggle with hitting your numbers.

Whichever method you end up using, or are already using, hopefully this has given you some food for thought in terms of perhaps optimising your sparging setup to better suit how you like to brew. Now, go forth and sparge!