Hop harvest is one of the most highly anticipated annual events on a brewer’s calendar. The ability to review and select hops for the next year is not only a highlight but offers brewers the opportunity to have direct influence over the raw ingredients they use in their beers. Once those hops arrive at your brewery, keeping them in top condition for future use is a priority. Here are some best practices for keeping hops in great shape and some advice if you want to age your hops for other uses.
Expert Topic sponsored in part by Berkeley Yeast
Keep Your Hops Really Cold
Hops are a highly perishable product, with great sensitivity to heat and higher temperatures, which cause the alpha acids to degrade quickly. One recently published four year study on the subject compared the behavior of alpha acids and aroma compounds in Citra and Perle pellets packed in oxygen free foils at cold (37°F) and ambient (77°F) temperatures. The results were stark, with the degradation of alpha acids in cold storage below five-percent while similar losses neared 40-percent for hops stored at ambient temperatures. For aroma hops, losses were more severe, with cold storage loss around 15-percent and ambient storage loss around 30-percent. Experts also suggest keeping cold hops at a consistent temperature.
While industry organizations and hop dealers continue to fund research, early results suggest that freezing hops may be your best for long term storage. Many breweries lack ample storage space for substantial supplies of frozen hops and most would use their on-hand supply before seeing any degradation after only a few months when compared to refrigerated hops. But if your plans don’t involve using certain hops until well into the future, freezing is your best option.
Avoid Oxygen At All Costs
Oxidation is a key threat to hops and farmers and hop suppliers go to extended lengths to protect recently harvested hops from oxygen exposure. Once hops arrive at your brewery, whether in pellet or whole leaf form, minimizing oxygen exposure is key. Vacuum-sealed packaging is industry standard, as are nitrogen or carbon-dioxide flushed bags that help reduce oxygen content. If you open a bag and don’t use its full contents, resealing the package with a CO2 purge is recommended. Small breweries might consider buying foodsaver or plastic vacuum seal bags as opposed to simply duct taping bags closed, especially if the hops won’t be used in soon to be brewed batches.
Maintain A Proper Inventory System
Optimizing recipes to use the entire bag of hops is the best option for hop freshness but that can’t always be achieved. Once a hop bag is opened, the clock starts to tick. Understanding the status of your hop inventory and the nature of opened bags helps maintain consistency and quality and avoids needless waste. Labeling opened bags by date of opening and employing a first-in, first-out approach to hop usage keeps degradation to a minimum. Also remember to regularly check your hop inventory for any signs of spoilage, such as off-aromas, discoloration, or even mold.
Aging Hops
Not every brewer wants to brew with fresh hops. The history and practice of using aged hops in certain styles, including wild, sour, and lambic beer, is well-established. For breweries looking to age their own hops, finding the balance between aged hops offering desirable fruit aromatics and lowered preservative effects and off-notes, like iso-valeric and butyric acids require a deft hand. Starting with dry hops to avoid mold, store the hops in a warm, dry area. Bags can be sealed by hand instead or stored in a plastic bag instead of vacuum sealed, to allow for some degradation by oxygen. As they age, hops will turn a dull brown color, with pelletized hops taking longer to degrade that whole cone hops. Yakima Chief Hops even offers an Aged Hops Program, with the company selecting certain bales and varieties for additional aging under consistent temperatures and humidity levels. The company has undertaken substantial efforts to identify which varieties possess characteristics and aging abilities and are lab monitored for quality control.