Ask Mr. Wizard

Hop Shelf Life


Liz Park — Boston, Massachusetts asks,

I often find myself buying hops by the pound . . . of last year’s crop. I find these hops still to have plenty of aroma and character and often can find them discounted. I vacuum seal my hops and will use for another year, sometimes two. Is there a reason I should be buying the new crops or are last year’s crops “good nuff” in your opinion? Also, how long can properly stored hops remain fairly fresh?


This is a great question and brings up several things that need to be considered because hops do age when stored, and using hops that are past their prime for brewing is not the best plan for brewing great beer. Let’s start with when hops are harvested and what the date on the package really means. Northern hemisphere hops are generally harvested in the month of September and Southern Hemisphere hops are generally harvested in March. When hops are harvested, they are quickly kiln-dried, baled, and put into storage. Most hop processors these days store hops cold to slow the aging process. Some brewers use these whole, compressed cones, but most use pelletized hops in the brewing process.

Hop processors typically want to process the current year’s crop while the weather is cool, meaning that Northern Hemisphere hops harvested in 2018, for example, will all be pelletized by about March of 2019. In an effort of continual improvement, many newer processing plants are designed to shorten the pelletizing window to 3 months. Suffice to say, the freshest pellets available from the Northern Hemisphere start to debut in the early part of the year following harvest, and the freshest pellets from the Southern Hemisphere come into the market in late summer to early fall of the year they are harvested. This can be a little confusing, and it may seem like the freshest hops are “old” because the harvest date for Northern Hemisphere hops are always at least one year behind the brewing date.

What happens during hop processing is critical for hop freshness. Bales of cones are unpacked, put through a machine called a bale breaker, milled into a coarse grist, blended for consistency, pelletized into little cylinders, cooled, and then packaged into a bag. The goal in this process is to minimize heat during the pelletizing process and to pack the little pellets in a bag containing as little air as possible. Some processors use vacuum sealers and others use bags that are flushed with nitrogen gas. Barrier films, made using metal foils, are used for the bags because oxygen will gradually migrate from the atmosphere into the bag if the packaging film has no oxygen barrier properties. If you can see the hops in the bags on the shelves or in your home freezer, you are not looking at a barrier film. Look for hops packaged in foil bags if you want maximum shelf life.

One thing to note about packaging is how the package feels when massaged. At one time, nearly all pellets were vacuum packed and the packages were very hard, and a soft bag was a sign of a leaking seal or a punctured bag. However, vacuum-packed bags are more prone to damage because their firmness makes them relatively easy to puncture. Nitrogen-flushed bags are soft to the touch and are not as easy to damage. The point is that soft bags have become the norm.

All of this discussion is building up to the elephant in the room; shelf life. Hop processing facilities are geared to produce pellets for commercial breweries and most of this production goes into 5-kg, 10-kg, and 20-kg (11-lb., 22-lb., and 44-lb.) bags. Using the best modern processing methods and barrier-film bags, hops can be stored for 3–5 years without substantial losses in brewing value. But most of the hops sold to the homebrewing market have either been repackaged into smaller bags, often times with no barrier properties, or they have been packed into smaller bags at the processing plants using fillers that do not have all the bells and whistles of the high-capacity lines. In other words, hops sold into the homebrewing market are best used before the next crop of hops become available. And if you have the choice between buying repackaged hops that are sold in clear bags or hops packed by the processor in foil bags, opt for the latter.

Homebrewing is a hobby, and most homebrewers strive to brew the best beers possible. Most of us can buy beer for less than it costs to brew at home when all costs, including the value of free time, are considered. Buying last year’s crop from the value aisle and repackaging using a home vacuum sealer seems like a thrifty option, but may not be the best place to reduce the cost of brewing. Thanks for the great question and hoppy brewing!

Response by Ashton Lewis.