Hop Storage: Vacuum Sealed vs. Non-Purged Baggie

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This homebrew experiment was originally published on Brulosophy.com.

One of my first purchases when I started buying my brewing ingredients in bulk was a vacuum sealer to remove oxygen from the bags I stored hops in. It’s commonly touted this step, particularly when combined with cold storage, can prolong the life of hops in terms of both bitterness potential as well as flavor and aroma. While I can’t be too sure I ever experienced the perils of poor hop storage, the fact that hop suppliers often made it a point to ship their product in the most oxygen-free manner possible was enough to convince me it mattered enough, and the relatively low price of a vacuum sealer was at the very least good insurance.

But not everybody owns, or has a desire to acquire, a vacuum sealer, and I’m aware of some homebrew shops who sell hops packaged loose in plastic baggies. Furthermore, I recall reading a post in a brewing forum about a person who received bulk hops in which the package had been compromised, allowing oxygen in, which had him worried they were ruined. I immediately thought back to the times I used to keep leftover hops in a sandwich baggie stored in my freezer for weeks, and while I often thought the character changed over time when smelling them fresh, I can’t say it ever seemed to have a negative impact on the finished beer. Needless to say, I became curious as to how these different storage methods impact hops and designed an xBmt to test it out!


To evaluate the differences between a beer made with hops stored in a non-purged plastic baggie and the same beer made with hops stored in a vacuum sealed bag.


I received a sealed 1 lb/0.45 kg bag of fresh Motueka hops on November 16, 2016 and immediately split them up, placing half in a vacuum sealed bag and the remainder in a standard sandwich zipper bag that was not purged of oxygen.


The hops were placed in my freezer where they remained until May 31, 2017, nearly 6 months, which the crew and I agreed was long enough for any impact of storage to occur. Given the nature of this xBmt, I thought a fairly hop forward beer using notably flavorful hops was appropriate.

Tight Squeeze Pale Ale

Recipe Details

5.5 gal 60 min 32.0 IBUs 4.0 SRM 1.054 1.012 5.4 %
Actuals 1.054 1.009 5.9 %


Pale Malt (2 Row) US 11 lbs 91.67
Weyermann Vienna 1 lbs 8.33


Motueka 46 g 60 min Boil Pellet 3.4
Motueka 28 g 30 min Boil Pellet 3.4
Motueka 28 g 5 min Boil Pellet 3.4
Motueka 28 g 3 days Dry Hop Pellet 3.4


Flagship (A07) Imperial 75% 60°F – 72°F


Water Profile: Ca 69 | Mg 0 | Na 8 | SO4 104 | Cl 49

I made a starter of Imperial Organics A07 Flagship yeast a couple days ahead of time, enough to split between two 5 gallon batches. The night before brewing, I weighed out the grains and collected the RO water for the following day’s brew.


After adjusting the water to my desired profile first thing the following morning, I turned the element in my kettle on and began recirculating the water. While waiting for strike temperature to be reached, I milled the previously weighed out sets of grain.


With strike temperature reached, I mashed in one batch then did the same to the second batch about 20 minutes later to make my brew day less hectic. Both batches were mashed for 60 minutes at the same temperature.


At the end of each mash rest, I removed the grain bags and let them drip until the same pre-boil volumes were reached.


As the first mash rest was coming to a close, I dug up the hops from my freezer and weighed out the additions for each batch.


Each wort was boiled for 60 minutes with hops added as noted in the recipe.


Following each boil, I quickly chilled the wort to slightly warmer than my groundwater temperature before racking equal amounts to identical fermentors.


Hydrometer measurements confirmed both worts were at a similar OG.

Left: Sealed 1.053 OG / Right: Loose 1.052 OG

The fermentors were placed in my chamber and allowed to finish chilling to my target fermentation temperature of 66°F/19°C, at which point I evenly split the decanted starter between them and dosed each with the same amount of pure oxygen.


The beers was showing similar signs of fermentation just 12 hours later.

Left: Sealed / Right: Loose

I noticed decreased fermentation activity 3 days later and added the dry hop charge to each beer.

Hydrometer measurements taken 5 days after dry hopping showed both beers at reached the same FG.

Left: Sealed 1.009 FG / Right: Loose 1.009 FG

I proceeded with cold crashing the beer, fining with gelatin, and transferring them to kegs.


The beers were burst carbonated overnight, after which I set the gas to serving pressure and let them sit another few days before presenting them to tasters. The beers looked exactly the same… condensation sucks.

Left: Sealed / Right: Loose


A total of 16 people of varying levels of experience participated in this xBmt. Each participant was served 1 sample of the beer made with vacuum sealed hops and 2 samples of the beer made with hops stored in a non-purged baggie then asked to identify the sample that was unique. While 9 tasters (p<0.05) would have had to correctly identify the unique sample in order to reach statistical significance, only 4 (p=0.83) picked the odd-beer-out, indicating participants in this xBmt were unable to distinguish a beer made with vacuum sealed hops from one made with hops stored loose and non-purged in a standard zipper baggie for 6 months.

My Impressions: When I opened the hops for this xBmt after being stored for 6 months, I expected there to be a difference in flavor and aroma between the beers, as the vacuum sealed hops smelled fantastic and fresh while the hops store loose in a baggie had a noticeable “freezer” scent to them, a mix of meat, plastic, and freezer burn. In 6 blind triangle test attempts, I was able to tell the beers apart 5 times, perceiving the subtlest hint of that freezer flavor in the beer made with loose stored hops. I’m convinced my performance likely would have been worse if I hadn’t smelled the hops beforehand, the difference was just that slight.


The focus of this xBmt was specifically on whether vacuum sealing hops helped to preserve quality as compared to hops stored in a regular sandwich baggie without having the oxygen purged. Oxygen is absolutely present in any normal freezer, which led me to believe this xBmt would lead to easily distinguishable beers, but apparently I was wrong, as tasters were unable to reliably tell apart a beer made with vacuum sealed hops from one made with hops stored in a plastic baggie, even after a whopping 6 months.

Well, there you have, vacuum sealers are a waste of money, hops can be stored in baggies without issue.

Except that’d be a really stupid conclusion to draw from this single xBmt result, particularly since oxidation is very real and vacuum sealing hops, at the very least, provides cheap insurance against staling. My hypothesis at this point, admittedly influenced by my ability to detect a very slight difference between the beers, is that the non-purged hops had begun to oxidize but that the cold temperature of my freezer slowed the reaction down. If this is the case, a future iteration of this xBmt where both sets of hops are stored at room temperature ought to produce a different result.

I certainly have no intent to ditch the incredibly simple process of vacuum sealing my hops, as it not only lends me some peace of mind knowing they’re less exposed to oxygen, but it also allows me to store more in my freezer because the bags take up less space. That said, I no longer believe storing hops loose in a baggie for a few days is anywhere near as detrimental as I used to think.