Author: Cade Jobe

It’s well-documented that oxidation, particularly that which occurs on the cold-side, leads to stale off-flavors and poor shelf stability in finished beers. This effect is especially apparent in heavily hopped beers like New England IPA (NEIPA), hence the reason many brewers of such styles take extensive measures to keep cold-oxidation at bay.

One method for reducing cold-side oxidation is to transfer the finished beer under CO2 pressure when packaging, an approach that has been shown to work rather well, though it requires gear that some may not have access to. Another option that’s been getting some attention lately involves adding a chemical antioxidant to the beer to stave off the effects of oxygen exposure. Available at most homebrew supply stores, both sodium metabisulfite (SMB) and potassium metabisulfite (Campden), when dissolved, allow free sulfite ions to bind with free oxygen in solution, leading to reduced oxidation reactions.

I was intrigued when blind tasters in a recent xBmt were able to distinguish a Kölsch dosed with SMB at packaging from one that didn’t receive SMB, as it supported the idea that a chemical option could be a viable way to avoid cold-side oxidation. However, in that xBmt, both beers went into kegs that were purged with CO2 prior to being filled. I was curious of the impact SMB might have on an arguably more sensitive NEIPA when transferred without any attempt to limit oxygen ingress at packaging, so I designed an xBmt to test it out.

| PURPOSE |

To evaluate the differences between beers packaged in non-purged kegs either with or without sodium metabisulfite (SMB).

| METHODS |

For this xBmt, I went with a NEIPA recipe that’s heavy on the late hop additions in order to keep the bitterness low and the juicy goodness high.

Seeker

Recipe Details Batch Size Boil Time IBU SRM Est. OG Est. FG ABV 5.5 gal 60 min 40.3 IBUs 3.9 SRM 1.064 1.015 6.4 % Actuals 1.064 1.01 7.2 % Fermentables Name Amount % Pale Malt (2 Row) US 9 lbs 64.86 Oats, Flaked 2.5 lbs 18.02 Wheat Malt, Pale (Weyermann) 2.375 lbs 17.12 Hops Name Amount Time Use Form Alpha % Hallertau Magnum 7 g 60 min Boil Pellet 11.1 Centennial 7 g 5 min Boil Pellet 10 Citra 7 g 5 min Boil Pellet 12 Loral 7 g 5 min Boil Pellet 11.5 Mosaic (HBC 369) 7 g 5 min Boil Pellet 12.3 Centennial 7 g 1 min Boil Pellet 10 Citra 7 g 1 min Boil Pellet 12 Loral 7 g 1 min Boil Pellet 11.5 Mosaic (HBC 369) 7 g 1 min Boil Pellet 12.3 Citra 28 g 5 days Dry Hop Pellet 12 Loral 28 g 5 days Dry Hop Pellet 11.5 Mosaic (HBC 369) 28 g 5 days Dry Hop Pellet 12.3 Yeast Name Lab Attenuation Temperature Juice (A38) Imperial Yeast 74% 64°F - 74°F Notes Water Profile: Ca 51 | Mg 20 | Na 38 | SO4 51 | Cl 54 Download Download this recipe's BeerXML file

I started off my brew day by collecting the proper volume of water for a 10 gallon/38 liter batch, adjusting it to my desired profile, then hitting the flame to heat it up.

While waiting on the water to warm, I weighed out and milled the grain.

Once the water was appropriately heated, I incorporated the grains then checked to make sure I hit my target mash temperature.

The mash was left to rest for 60 minutes.

During the mash rest, I measured out the kettle hop additions.

When the 60 minute mash was complete, I sparged to collect the target pre-boil volume then boiled the wort for another 60 minutes before chilling it with my IC. A hydrometer measurement showed the wort was right at the expected 1.064 OG, after which it was racked to a 14 gallon Ss Brewtech Brew Bucket that got placed in my chamber before I pitched two pouches of Imperial Yeast A38 Juice.

With signs of fermentation absent after 12 days, I took a hydrometer measurement indicating FG had been reached.

At this point, I measured out a 0.3 g of SMB and added it to one of two sanitized kegs.

In order to emphasize any impact of the SMB on oxidation, I forwent my typical CO2 purging process and racked the beer directly into open kegs, making sure each received the same volume.

The filled kegs were placed in my keezer and burst carbonated. I began taking samples a week later and noticed a fairly obvious difference in appearance.

Just 5 days later, the beer packaged without SMB was beginning to look much darker.

I began serving the beers to blind tasters around 3 weeks after packaging, a point at which both appeared to have changed color, though the non-SMB batch more noticeably so.

| RESULTS |

A total of 34 people of varying levels of experience participated in this xBmt. Each participant was served 2 samples of the beer packaged with SMB and 1 sample of the beer packaged without SMB in different colored opaque cups then asked to identify the unique sample. A total of 17 tasters (p<0.05) would have had to accurately identify the unique sample in order to reach statistical significance, which is exactly how many did (p=0.034), indicating participants in this xBmt were able to reliably distinguish a NEIPA packaged with SMB from one packaged without SMB.

The 17 participants who made the accurate selection on the triangle test were instructed to complete a brief preference survey comparing only the beers that were different. A total of 9 tasters reported preferring the beer with SMB added at packaging, 5 liked the beer packaged without SMB, and 3 had no preference despite noticing a difference.

My Impressions: Out of 5 semi-blind triangle test attempts, I chose the odd-beer-out every time, regardless of time in the keg. While I initially preferred the non-SMB beer, which I felt like it had a more pronounced hop character, my preference switched after a week in the keg. To my palate, the SMB beer maintained its hop character while the non-SMB beer developed an undesirable harshness. Both beers were tasty until the effects of oxidation fully set in, which seemed to occur quicker in the beer packaged without SMB.



| DISCUSSION |

Brewers today are increasingly conscious of the negative effects oxygen can have on beer, especially on the cold-side once fermentation is complete. In concert with other preventative measures, dosing finished beer with an antioxidant like SMB seems like it could be a great way to further limit cold-side oxidation and produce better-tasting, longer-lasting beer. The fact tasters in this xBmt were able to distinguish a NEIPA racked to a non-purged keg with SMB from one that didn’t receive SMB suggests the chemical had a perceptible impact.

Equally as interesting as the triangle test data is the observed difference in appearance between the beers. NEIPA affected by cold-side oxidation tends to take on a brownish/purple hue, which is exactly what happened to the non-SMB sample in this xBmt. Indeed, the beer dosed with SMB maintained a lighter appearance in comparison to the non-dosed version, but it did start to turn over time, which I’m compelled to believe is a result of being racked to an open keg. This being the case, while adding SMB did seem to have some oxidation-buffering capability, it apparently wasn’t enough to overcome the careless packaging.

These results provide further evidence that metabisulfites work to reduce the negative impact of cold-side oxygen exposure, and as such, I look forward to further exploring ways to use them to my benefit. That said, these xBmt findings also made it abundantly clear to me the importance of limiting oxygen exposure during packaging, validating my current use of a closed-transfer process.

If you have any thoughts about this xBmt, please do not hesitate to share in the comments section below!

Support Brülosophy In Style!

All designs are available in various colors and sizes on Amazon!

Follow Brülosophy on:

If you enjoy this stuff and feel compelled to support Brulosophy.com, please check out the Support page for details on how you can very easily do so. Thanks!

Advertisements

Share this: Facebook

Twitter

Pinterest

Tumblr

Email



Like this: Like Loading...