Research of Methods to Improve the Processing of Hops (Humulus lupulus L.)

View the project final report

Commodities

• Agronomic: hops

Practices

• Farm Business Management: value added

Experimentation with low temperature methods of oasting and pelletizing of hops for brewing can improve the final oil content, thus improving the quality and value of the product.

This harvest season I intend to address both phases of the processing that degrade the lupulins.

First, to improve the oasting method I want to experiment with high airflow instead of heat to dry the hops. I will accomplish this by building drying boxes with screen bottoms, and use fans to provide airflow. After the cones are harvested, they will be placed in the racks and stirred occasionally to ensure even drying. I will closely monitor the moisture levels, and will introduce heat with propane heaters only as a last resort to save the crop if the airflow oasting fails.

To address the pelletizing process, I will use a pill-making machine to create compressed hops tablets. The pill-making machine will generate some heat during the compression, but significantly less in comparison to traditional pelletizing machinery. Once I determine if making tablets at low temperature is successful, I will then focus future research towards economic feasibility; including time to produce the product, cost of equipment, electrical consumption, etc.

To properly compare my tablets with the pellets, I will have a portion of my harvest pelletized using traditional methods. I will compare the weight of the hops that enter the processing with the final output. I will also send samples for lab testing to obtain lupulin (alpha and beta) levels.  

I will provide these tablets to the head brewer at the Firehouse Brewery, Mike Kilroy, and a home brewers club called the Ale Riders, both in Rapid City, SD. Their feedback will be valuable in determining how the tablets compare to pellets. I too will be brewing identical batches of beer, with the only difference being pelletized or tablet hops. Again, the Ale Riders will help me compare the flavor of the different beers. 

I will harvest my hops plots this year, 2017, in mid-August through mid-September. I will immediately oast the hops as described above. If time permits, I will make tablets after the oasting. If not, the dried hops will be stored in a freezer until I can finish processing. I plan to experiment with 100 pounds, and have the rest pelletized in Omaha, Nebraska using current industrial methods. Once processing is finished, I will mail samples to Alpha Analytics lab to obtain lupulin levels. I will then begin brewing test batches. Once the beer is ready, approximately 6 weeks, I will then take my beers and samples of my tablets to the Firehouse brewer and the Ale Riders monthly meeting. I will attend the meetings of the Ale Riders for the next three months to obtain their feedback and gather surveys. All lab values and feedback should be gathered by the end of January, 2018. 

As with the results of my current SARE project (See: FNC16-1036 - Examination of the Productivity of Four Hops Varieties (Humulus lupulus L.) in Two Soil Types in Southwest South Dakota), I will submit my results to Chris Graham, an extension agronomist at the South Dakota State University, to have my findings shared on the iGrow website. In addition, I will share my report with my fellow members of the South Dakota Hops Growers Association (currently being developed), and Kim Brannen, the President of the South Dakota Specialty Producers Association. Also, the 100+ members of the Ale Riders and my brewer relations will continue to generate awareness and interest of growing hops in South Dakota. 

For the oasting process, successfully drying the cones to 8-12% moisture within 48 hours will indicate that this method is successful. I will weigh the hops before and after oasting, and compare with fully dried (o%) hops to determine final moisture content.

For my low temperature pelletizing tests, I will compare the weights of the hops before and after pelletizing or making tablets. I will also compare lupulin content as analyzed by the lab, and finally gather surveys from brewers in regards to flavor and performance during brewing.