We recently sat down with Virgil McDonald, the master brewer at Haas Innovations Brewery in Yakima. Virgil has been developing a number of experimental brews using Haas’s new hop bitter product, FLEX™, a CO₂ hop extract designed to be flowable at room temperature, and targeted for dosage at brewkettle fill. We wanted to get a firsthand report of what it’s like to brew with FLEX™.

Tim Kostelecky: Virgil, can you give us a little background on FLEX™. What is it?
Virgil: Well, it’s pretty simple, really. FLEX™ is something that helps deal with two big issues that brewers have when bittering beers, especially highly hopped beers. Number one, unlike T90 hop pellets, FLEX™ contains no vegetative hop material to absorb your valuable wort. Hop solids act like sponges, and when the whirlpool trub is separated from the liquid wort, a significant portion of the liquid is drawn out with it. Needless to say, that’s expensive and unnecessary. FLEX™ also improves efficiency because its bitterness utilization is better than with hop pellets. The number-two big benefit is that FLEX™ is easy-to-use. It’s flowable at room temperature, so you can just measure and pour. Anyone who has used regular CO₂ extract knows what a pain it is using a thick hop resin.

TK: What makes it flowable? Does it have some sort of emulsifier added…or is it just magic?
Virgil: <Laughing> I’d actually say it’s more on the magic side. Our innovations group is pretty good that way. No, there are no emulsifiers or similar additions…just pure hops. The formulation provides a visually appealing and nicely flowable product. We know that ease-of-use is important to brewers, and that was our primary objective when looking at an alternative to pellets.

TK: FLEX™ was designed for beer bitterness. Does it supply all the hop bitterness for a beer?
Virgil: No, but FLEX™ certainly provides a major portion of it in a typical hop bill. Other hops (usually pellets) will contribute some bitterness when they’re added to the kettle or even to the whirlpool, but not at the efficiency of bitter hops at the kettle fill or the beginning of boil. This is especially true with some of the newer, high-alpha flavor hops such as Citra® and Mosaic®, which get to between 11 and 14 percent alpha acids. It used to be that aroma hops had a relatively insignificant bitterness contribution, because they were typically low in alpha. That is not the case with many of the newer flavor varieties.

TK: How about the timing for dosing? Would it be OK to add FLEX™ late in the kettle, or even to the whirlpool?
Virgil: No, FLEX™ is designed only for early dosing in the kettle. You’ll get the best utilization of a nice, clean bitter—and no flavor contributions from the hop oils. FLEX™ does contain hop oils, but these are derived from bitter hops and, typically, they’re not desirable for the beer flavor. FLEX™ lets you start with a clean slate in developing your hopping profile, using your aroma and flavor hops.

TK: You mentioned that FLEX™ can significantly reduce the hop load and process loss for the whirlpool. What kind of improvement can a brewer expect?
Virgil: That depends on how aggressively you’re hopping, especially if you’re targeting high IBUs, let’s say over 50 or 60. That’s where you’ll really see a difference both in whirlpool performance and in the reduction of process losses. And it’s not only absorption that’s an issue. Some brewers are using whirlpools designed in the day of low hopping rates, so they are undersized when using big hops. There are too many solids to effectively draw off a nice clear wort from the trub pile. To reduce the solids going to the chiller and fermenter, some brewers have to use a standpipe to ensure a clear wort. This, of course, wastes even more wort.

TK: How about the alpha acids utilization, how does FLEX™ compare with T90 Pellets?
Virgil: Typically, you can expect about a 10–15% improvement in bitterness utilization using FLEX™ over pellets. To be clear, that’s 10 to 15 relative percentage points. For example, if you’re getting about 25% with your pellets, you can expect to be in the high 20’s with FLEX™, possibly higher. This is because FLEX™ is in a liquid form, so it disperses immediately into the wort, starting the alpha isomerization reaction more readily. When using pellets, it takes a bit of time for the solid pellets to release the alpha acids into the wort, and this little bit of time is significant.

TK: Other than bitterness, does FLEX™ affect beer flavor, compared with T90 Pellets?
Virgil: Not if it’s added early in the kettle boil. Any flavor components from the hops will be effectively boiled off, which is what we want to achieve. That’s what your precious aroma and flavor hops are for. FLEX™ just stays out of the way and won’t interfere. Clean bitterness is what it’s all about.

TK: At the Haas Innovations Brewery, you’ve always been a proponent of using regular CO₂ extract as the primary bittering component in your beers…and anyone who’s had the opportunity to try your beers knows they’re pretty impressive. Now with FLEX™ available, are you converting?
Virgil: I am using FLEX™ for all of my trial beers. If brewers want to taste FLEX™, we will be showcasing them here at the Innovations Center during Hop Harvest.

TK: Still, I know some brewers are hesitant to move beyond hop pellets to FLEX™…
Virgil: Just try it. I think you’ll be sold right out of the gate. If a brewer is concerned about FLEX™ possibly being a highly processed product, and that goes against his or her particular philosophy or brewing creed, I assure you FLEX™ is a product of the “kind” extraction of hop components with pure CO₂—nothing more complex than that. We like to use the tag-line for FLEX™: It’s hops…pure and simple.

For more information on FLEX™, please contact your Haas representative.