Brews, Buds and Preserving Flavor Post-Harvest

Columns - Growing Pains

Once cannabis and hop plants leave production, their processing journeys can diverge, but aroma and taste are increasingly important for both.

Ripe hop stigmas are receptive to wind-borne pollen.
Photos courtesy of Robert C. Clarke

Editor’s Note: This is the third article in a special series, “What the Cannabis Industry Can Learn From The Hop Market” by Robert C. Clarke and Mojave Richmond. Read Part 1 of this special series here: bit.ly/cbt-hemp-hops-1 and read Part 2 here: bit.ly/cbt-hemp-hops-2.

Cannabis and Humulus flowers follow lengthy and ordered paths from plant to product, and the respective methods used reflect their botanical similarities. Once dried, flowers are often cured before processing and packaging, and downstream products such as concentrates and extracts are made from both sinsemilla and hop flowers.

In this third installment of “What the Cannabis Industry Can Learn From the Hop Market,” we examine the similarities and subtle differences between the sinsemilla and hop industries in the post-harvest process, the examples they set, and the lessons they offer.

A mature hop cone.

Curing Flowers

Sinsemilla growers have long debated the merits of various drying methods, and the virtues of curing flowers before smoking or processing. Sinsemilla growers apply different drying and curing strategies for producing smokable flowers than they do for crops destined for concentrates and extracts. Strategies also differ among hop growers depending on whether their flowers will be used as whole hops in brewing or sold to extractors, and brewers choose hops based on their aromas matched to the goals they aim to achieve in their beer.

Bales of dried hop cones are usually stored at ambient temperatures near where they are dried and processed before bulk shipment or downstream processing, creating an accidental yet de facto curing process. Hops are also intentionally cured by aging for longer periods under cooler conditions to preserve as well as alter their chemical contents. Aromatic terpene levels decrease as these compounds volatilize during ambient storage and, in turn, the hop flower’s aroma profile changes. Overall alpha-acid content decreases as lupulone and humulone oxidize into other compounds, including aromatic fruity esters, and cured cones can express complex aroma and flavor characteristics not found in fresher hops.

Sinsemilla flowers respond to curing in similar ways. Many of the more volatile monoterpenes begin to vaporize and, over time, a sinsemilla variety’s characteristic aromas can change. Much of the monoterpene content is lost during harvesting and drying, and those of low content may disappear entirely during curing. However, not all aroma compounds add to pleasurable smoking, and careful curing allows some of the more aggressive terpenes to escape, creating a more enjoyable product.

Flavorful hop-forward ales are increasingly popular, but many brewers of more traditional beers prefer hops that have lost some of their terpene aromas during storage. Consumers also understand that beer’s fragrances and flavors continue to change after they are barreled, bottled and canned.

When considering similarities between sinsemilla and hop cultivars, myrcene is the predominate terpene found in a majority of both. Myrcene, and many other monoterpenes found in lesser amounts, volatilize and evaporate at room temperature, and the aroma and flavor characteristics change due to their increasing absence. Myrcene is a highly unstable molecule and readily converts to several other monoterpenes. Aged hops are often more citrusy than when freshly dried, which may result from myrcene converting to more stable limonene.

The sesquiterpenes caryophyllene and closely related humulene along with farnesene are less volatile, meaning they remain in the hop flowers for longer and are used to characterize differing hop varieties.

Hop bines grow rapidly as they reach for the sun.

Storage and Transport

After drying, hop and sinsemilla flowers are stored before use. Hop bales are carefully monitored for humidity, and a 9% to 10% moisture content assures that no spoilage organisms can ruin the cones. This is a good rule of thumb for sinsemilla, as well, although moisture content below 10% can cause flowers to become brittle. With that in mind, it is advisable to dry smokeable sinsemilla flowers to 10% to 12% moisture content, cure them until they reach the desired state, seal them to prevent any further unwanted change, and then store them frozen to both preserve their fragrances and flavors while preventing spoilage. Flowers destined for extraction may be fresh frozen before drying if being utilized for their aroma profile, or if they’re being used solely for cannabinoid extraction, they can be more thoroughly dried to prevent spoilage and stored at ambient temperatures for longer because their aromatic content is of little importance.

Brewers interested in capturing the full fragrance and flavor of individual hop cultivars recommend that hop cones, as well as hoppy beers, should be stored and transported under refrigeration to prevent loss of their aromatic components. Sinsemilla and its products should also be refrigerated at every step along the processing path, from harvesting, drying and packaging through transport and storage to retail, and the supply chain should move quickly so products will be as fresh as possible at point of sale.

Hop emerges in the spring from perennial rhizomes.

Quality Control: Evaluating Flowers

Another similarity between the hop and sinsemilla industries is that careful evaluation of dried flowers for quality control purposes is mandatory in both. Hop cones and sinsemilla buds must be evaluated in the context of each individual variety, and there can be wide differences in appearance and aroma between harvest batches. Both the terroir where they were grown as well as differing drying and curing processes determine quality. Natural color varies between varieties based on location and weather and is not as important as other criteria. However, discoloration can indicate pest damage, late harvest timing or poor drying conditions.

Sinsemilla and hop buyers must be familiar with the characteristic appearances and aromas of differing varieties. They first look for seeds, then excess leaves and stems. The next steps include carefully searching for mold, pest damage, and other signs of poor cultivation and processing, inspecting the resin glands, and finally checking the moisture content.

Moisture can be tested by pressing down lightly with a flattened palm on a pile of loose hop cones or sinsemilla buds, which should feel firmly resistant when compressed and spring back when released. The sample should fall apart when rubbed firmly, but not shatter, which may indicate overdying, late harvest, old, stale flowers, or low essential oil content. An electronic meter can also be used for an accurate measure of moisture content.

Humulus lupulin glands should be bright yellow or light orange. In contrast, Cannabis resin glands range from clear through milky white to golden, and eventually to amber as they mature. Darker glands in both cannabis and hop flowers are a sign of oxidation caused by late harvesting or excessive heat during drying.

The aroma of both hops and buds is often the seminal attraction as well as a deciding factor in a consumer’s purchasing decision. Flowers are first smelled without crushing to detect earthy, musty or fermented odors resulting from spoilage caused by incomplete drying or poor storage conditions. A pinch or light rub to bruise the flower reveals green, grassy notes indicating premature harvesting or hasty curing, as well as freeing the most volatile aromatic compounds. Warming flowers in the palm and crushing them more fully releases the aromatic constituents, and crumbled flowers should feel sticky or oily, indicating the presence of fully mature glands.

Hop buyers refer to laboratory analyses when available but rely on their keen senses to make final purchase decisions. They must always keep the final product in mind, and it is most productive to discuss observations and make selections as a team. This strategy holds true of sinsemilla purchases as well.

Developing hop meristems remain white under the soil surface until they reach sunlight.

Processing and Products

Hop cones can be either milled and pressed into pellets, concentrated by mechanical means, or extracted with solvents, which transforms them into more uniform, transportable, and storable products for brewers. These same processes are employed by cannabis companies today, but often at more sophisticated levels tailored to producing much broader ranges of consumer products. Brewing a consistent beer is the aim of brewers, and pellets and extracts offer more consistent inputs. Even though pelletizing and extracting hops makes them more uniform commodity products, many specialty brewers still prefer using whole hops because they enhance their brews with more complex aromas.

Hop products are made with various degrees of processing ranging from simple to quite complex. Hop “plugs” are made by compressing whole cones, much like tiny bricks of weed. Hop “pellets” are made by milling dry hop cones and cold-pressing the powder into what resemble animal feed pellets. Grinding and pelletizing causes the hops to degrade; lupulin glands burst, some of the alpha-acids oxidize, and many of the aromatic constituents disappear. Mechanical processing of sinsemilla flowers can also result in degradation and loss of the desirable aromatic constituents that attract consumers.

Hops are milled and pressed under cold conditions, and the resultant pellets are refrigerated to preserve their bitter acid and aromatic essential oil content. Hop pellets are more convenient to store and transport than baled or bagged cones but spoil faster than whole flowers—even when refrigerated.

Hop pellets are sold at retail in small vacuum packs flushed with nitrogen or carbon dioxide to chase out oxygen, but warm temperatures can volatilize the terpenes and cause the packages to swell. Sealed packages of hashish can also swell with evaporating terpenes. Once pressed, hop pellets store well, just like sieved hashish is better for long storage than dry sinsemilla flowers. Both hops and sinsemilla lose much of their floral essence during processing.

In contrast to hops, where the flowers and their associated products are used by brewers to produce beer, the majority of sinsemilla flowers are sold directly to the consumer as a final product. For this reason, it’s far more critical for sinsemilla brands to have complete control of the “cold chain” from processing through retail.

Hop seedling emerging from the soil. Hop seedlings look much like hemp.

Enhanced Hop Pellets

“Enhanced” hop pellets are made by grinding and sieving the hop cones at near freezing to concentrate the resin glands and produce hop powder with reduced chlorophyll content and increased bitter acid and aromatic compounds. The most commonly produced are Type 90 pellets, meaning that they are 90% green bract material and only 10% lupulin glands, which is approximately the ratio found in whole cones, and are basically just ground up hop flowers. More concentrated Type 45 “lupulin enriched” pellets are made up of only 45% green matter and 55% lupulin glands and are the equivalent of a crude farmer’s hashish.

Further concentrated lupulin enriched hop pellets are milled at minus 20 degrees Fahrenheit, which reduces the stickiness of the glands and makes them easier to separate from unwanted bract material, much as sinsemilla flowers are frozen to facilitate isolating their sticky resin glands when making sifted hashish. Highly enriched pellets are most often produced from aromatic hop cultivars and are popular with brewers featuring unique varietal fragrances and flavors in their beers.

Hop Extracts

Hop essential oil extracts, both generic and varietal, are commonly used in the brewing industry to add more of a dry-hopped aroma. Extracts impart less of a “green” flavor because the hop biomass is discarded, but many of the subtle aroma and flavor notes of whole hops are missing as they are from sinsemilla extracts. Cannabis edibles and vape pens also rely heavily on extracts for their consistency and ease of use, and fragrances and flavors often coming from other botanical sources can be added during product formulation.

Most hop extracts are produced by either liquid solvent or supercritical carbon dioxide extraction, which are also methods commonly used to make sinsemilla extracts. Hop extracts are lower in aromatic compounds and can be stored at room temperature longer than hop flowers or pellets, but as with cannabis extracts, they should be refrigerated or frozen for long-term storage.

As hop cones ripen, the stigmas redden and soon fall.

Our Connected Futures

Beginning with their botanical similarities, sinsemilla and hop flowers follow parallel paths through processing, yet there remain distinct differences between their final product uses.

Sinsemilla can either be dried, stored, and directly used or further transformed into concentrates or extracts, much like hop cones. However, during the brewing process, elevated temperatures and metabolism by yeast alter the hop essential oil contents, and many of the aroma characteristics of fresh hops never make it into beer.

Commercial hop cultivation is restricted to regions where hop crops flourish, and sinsemilla growers will ultimately find their hotspots, as well. While hops are grown locally and exported globally to be used in various ways, most sinsemilla flowers, due to regulatory burdens, are produced and consumed locally. Yet as regulations are relaxed across regions, we see cannabis venturing from its source to be processed into downstream products ranging from gummy bears to vape pens.

Hops are dried at high temperatures, which reduces their aromatic terpene content, and then the quickly dried cones are pressed into large bales and stored for months at ambient temperature. Sinsemilla growers learned to avoid these conditions decades ago to decrease both the degradation of aromatic terpenes and risk of spoilage during storage.

Looking forward, experiments with isolating chilled lupulin glands are just beginning, while cannabis resin gland concentration and extraction technologies have been rapidly progressing on many fronts. Hop extracts are still favored by many brewers for their bitter acid content, but little attention has been paid to producing more aromatic extracts for the new wave of hop-forward brewers. Has anyone tried squeezing rosin from hops?

While our nascent legal sinsemilla industry certainly has much to learn from more experienced hop producers, the hop industry may also be learning from sinsemilla. Until recently, hop growers and distributors have had little incentive to up their game in terms of processing and packaging. As hoppy pale ales continue to boom in popularity, suddenly hop aromatics have become a driving force in marketing, presenting opportunities for hop breeders and growers in concert with brewers to distinguish themselves before an increasingly receptive audience.

Sinsemilla breeders and growers have long recognized that fragrances and flavors can influence purchasing decisions, and brewers are coming to similar conclusions. There are still many lessons to be learned.

Robert C. Clarke is a freelance writer, photographer, ethnobotanist, plant breeder, textile collector and co-founder of BioAgronomics Group, specializing in smoothing the transition to a wholly legal and normalized cannabis market. rob@bioagronomics.com

Mojave Richmond is the developer of many award-winning varieties such as S.A.G.E., which served as a springboard for creating many notable cultivars. Richmond is a founding member of international consulting company BioAgronomics Group. info@bioagronomics.com