Hop Shelf Life

Smell them. If they are not "cheesy" then they are ok but will have lost some alpha acids & other oils so you'll need to use more to achieve the same bitterness/aroma/flavor.

Here's a calculator you can use for the approximate AA loss. http://www.brewerslair.com/index.php?p=brewhouse&d=calculators&id=cal16&u=eng

 

Smell them, if they are cheesey, don't use. If they smell fine, then they are most likely OK. Degradation happens due to heat and O2. Ziplocs are not O2 barrier bags. Best is to vacuum pack and store in the freezer.

 

“I have them still in the foil packs (that are opened, but the flap is folded over) in a zip lock that did my best to get as much air out as I could.” That is exactly the way I store unused hop pellets that come in foil (Mylar) bags. As was previously mentioned, zip lock bags are not oxygen impermeable but I doubt that vacuum sealer bags are oxygen impermeable either. My ‘strategy’ is that by tightly sealing the foil bag (which is oxygen impermeable) and then sealing that in a zip lock bag mitigates oxidation. I also only use pellet hops and the pellet form provides a measure of protection from oxidation. Storing the hops in the freezer helps as well since oxidation occurs more slowly at cold temperatures. My personal experience is that I am able to store hops this way for 1-2 years.

Below is a link to an article on this topic. The ‘executive summary’ of the article is:

“How Long Will Hops Last?

Like most things in brewing, the answer is, "It depends." If you keep them very cold and free from oxygen, hops should last a few years. It's not uncommon for hop brokers to be selling pelletized and vacuum-sealed hops from two or three seasons ago. Commercial breweries continue to use last year's crop well into the current year's harvest. This is not to say that the oils and a-acids will be exactly the same as when you purchased them, but the hops won't be "bad"; hops are not considered "bad" until they get below 50% of their original a-acid value (5), at which point the degree of oxidation will produce a definitely cheesy aroma.”

http://brewingtechniques.com/library/backissues/issue2.1/garetz.html

Cheers!

 

Ray Daniels "Designing Great Beer" has a thorough analysis of hop decline over time at different temps. as others have noted, it depends. and it depends by a large margin. Cascade for example is nearly unusable after a few months of cold storage and mere weeks at ambient. the variety of oils present is the defining criteria, and while you may find that the hops don't stink your AA% can drop alot. enough to throw off a recipe.

so i suppose the answer is that you can use them if they smell good, but you may not end up with the bitterness, aroma and flavor you expected. that is usually ok by us homebrewers, though consider fresh hops if you are really trying to nail a recipe.

i'll try to look up Tettnang and Cascade in Daniels tonight and post the data, or if someone else has it handy.
Cheers.

 

Ocassionally, I have a partially used hop bag from a current batch that I will save for a later batch. I usually try to use the opened bags within a month. I keep them in ziplocks in the freezer. I tend to use these partial bags as part of the bittering addition of the subsequent batch; I like to also get part of that addition from a freshly opened bag. I try to avoid using previously opened bags for flavor or dry hops.

 

Within the Brewing Techniques article (see link above) there is a link to a table which lists percent loss for common hop varieties (see a copy of the table below). The percent loss factor is for storing at room temperature in for 6 months with no oxygen barrier packaging.

So, you can easily see that Cascade is amongst the most ‘vulnerable’ hop variety from a storage perspective. Cascade will lose 50% of its alpha acids if you store it for 6 months at room temperature in an oxygen permeable bag.

There is a formula provided within the article to calculate hop alpha acid loss accounting for the factors of: hop variety, storage temperature and storage method.

Table I: Values for percent lost* for common hop varieties. +

Variety Percent Lost (%)

Cascade 50
Centennial 37
Chinook 32
Cluster 17
Crystal 49
East Kent Goldings 45
Eroica 40
Fuggle 37
Galena 15
German Spalter 45
Hallertauer (domestic) 45
Hallertauer Hersbrucker 40
Hallertauer Northern Brewer 25
Hallertauer Mittelfrueh 46
Hersbrucker (domestic) 50
Liberty 55
Mt. Hood 45
Northern Brewer (domestic) 20
Nugget 25
Perle (domestic) 15
Pride of Ringwood 44
Saazer (Czech) 50
Spalt (domestic) 50
Strisselspalt (France) 35
Styrian Goldings++ 37
Tettnang Tettnanger 42
Tettnanger (domestic) 42
Willamette 37

*At 20° C (68 F) for 6 months with no barrier packaging.

+Data from references 5 and 8.

++Styrian Goldings are actually Fuggles grown in Yugoslavia.

 

“I try to avoid using previously opened bags for flavor or dry hops.”

So, I have taken the ‘opposite’ approach to using previously opened bags of pellet hops. I know that alpha acids degrade with time; there are equations that estimate this effect.

I also highly suspect that essential oils of hops degrade over time but I have never seen this quantified. So, I have mostly used my ‘old’ hops for flavor and aroma. I have never noticed that the flavor/aroma of the hops has decreased greatly with my storage methods (foil bag within a zip lock bag in a freezer). I have used hops that have been 1-2 years old and the flavor/aroma of the hops has still been very ‘good’.

Cheers!

 

According to the guys at Gorst Valley farms, the foodsaver type material is O2 barrier, as it is made from layers of a couple of plastics (forget which ones). Ziplocs are polyethylene, and are not O2 barrier. They were said to be good if you use the hops in 2 months.

Cascade has poor storage qualities, but brewers use it year round. The 50% loss factor is for 68F For 6 months. Sierra Nevada has most of their Cascade in cold storage in WA state, at a warehouse and bring it down as needed. Those factors are for the AA.

There are many Noble type hops on the table above that are at 50% or above. Liberty at 55% was a little surprising.

Edit - some oxidation of essential oils result in desired flavor and aroma. Geranol and Linalol (SP for both) give some of the aromas hopheads want, and those are from oxidation.

 

Freezer bags are thicker and better than your general storage bag. Not an O2 barrier but definitely much better.

I typically buy bulk in the foil bags. After measuring out the hops I fold the foil package tightly then store those in a freezer bag. I've used hops up to a year or so old and they definitely lose aroma & bitterness but are by no means stale or unusable.

 

Jeff,

I suppose it depends on what type of vacuum sealer bags you purchase. Aluminized Mylar vacuum bags are certainly oxygen impermeable:

“Mylar bags (foil pouches) will insure your food will be available when you need it. Made of a multi-layer poly and aluminum foil laminated together. Mylar bags (foil pouches) are used for long term food storage because the metal barrier protects food from moisture, light and oxygen. Air cannot get in or out of a properly sealed mylar bag.”

I personally have only seen clear plastic vacuum bags and I doubt that they are oxygen impermeable.

There are apparently all types of bags that can be purchased for a vacuum sealer: http://www.keepfreshbags.com/

Cheers!

Jack

 

Yes, mylar is the best. Then the foodsaver type stuff, then freezer bags, then a burlap hop sack.

Edit
The foodsaver bag material is a poly-nylon laminate and is stated to be a Barrier bag by the Gorst Valley guys. The reason the mylar is best is it also keeps light out (moot point in the freezer), and those are N2 flushed at packaging.

The Gorst Valley guy called the ziploc type bag "unacceptable" (his words). He was a pro and wants the highest quality hops. In reality we can use use the ziploc bags for a month or 2.

 

By doing this as a bitterness addition, I know I am getting some alpha and the type of hop doesn't matter so much to flavor because I am boiling off the aromatics. I don't have to worry as much about a particular type of hop aroma not playing well with the hop aromas I want out of the beer.

I'm down on the hop numbers game lately. The best we do is take one estimate (%Alpha), combined it with another estimate (Alpha degradation), combine it with a third estimate (Hop utilization, using models designed for someone elses brew system) and spit out an IBU level.

 

“The best we do is take one estimate (%Alpha), combined it with another estimate (Alpha degradation), combine it with a third estimate (Hop utilization, using models designed for someone else’s brew system) and spit out an IBU level.” Isn’t that the ‘definition’ of math magic!?!

Cheers!

 

I don't use Cascades for bittering anyway...so who cares how much alpha it loses? Rotate stock, use what is oldest, and pray the Southern Hemisphere is almost ready to give up it's bounty at a reasonable price.