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Dry Hop Essences Dry Hop Essences - Hop oil fractions containing the water soluble aroma and flavor characteristics usually conferred upon cask conditioned ales by dry hopping.

General description: Dry Hop Essences are ethanolic solutions of the water soluble fraction of hop essential oil. They, therefore, contain all the oil constituents that would be taken up by a beer from a post-fermentation, dry-hopping treatment.

The essences, therefore, provide an accurate, consistent and reliable means of control of dry hopping. Furthermore, the form and solubility features of the Dry Hop Essence remove the contamination, settling and other problems associated with traditional dry hopping with leaf hops.

The Dry Hop Essences are varietal specific preparations that retain the aroma and flavor characteristics of the varieties from which they were prepared. They are also obtained by purely physical fractionation methods with no chemical processing whatsoever.

Preparation: Hops are extracted using liquid CO2 at a temperature of 7-10° C and a pressure of 50-55 kg/cm². CO2 is removed and the extract recovered at a temperature of 14-15° C.

Under carefully controlled conditions, the essential oils are high-vacuum distilled and separated from the whole extract. The water - insoluble hydrocarbons are removed from the whole oil by a counter-current extraction technique. The remaining oil fraction is then taken up in 80% ethanol that renders it miscible with aqueous solutions like beer.

Composition: The Dry Hop Essences are presented as 1% w/w solutions of the water soluble hop oil fraction in 80% ethyl alcohol. The active constituents of the preparation consist of the total oxygenated components of the oil including oxides, expoxides, alcohols, ketones and esters. Only the relatively insoluble major hydrocarbons have been removed. The exact balance of constituents will be representative of the hop variety from which the oil fraction was derived.

Uses and advantages in brewing: The Dry Hop Essences are designed to be the final flavor/aroma addition or adjustment to an otherwise finished beer. The preferred method of use is by dosing into the beer stream during transfer to the bright beer tank, racking vessel or other appropriate vessel. The essences have no direct effects on bitterness and this allows independent control of flavor/aroma and bitterness, especially when used in conjunction with ISOHOPCO2N (See ISOHOPCO2N Product Information Leaflet).

Dry Hop Essences are particularly useful in the development of new beer types with characteristic but consistent and repeatable aroma and flavor notes.

Method of use: The recommended rate of usage for the Dry Hop Essences is between 10 and 30 ppm (microliters/liter) of the product in the final beer. Therefore, at 10 ppm, 1 liter of essence would be sufficient for 1,000 hl or 852 bbl (U.S.) of beer. The required quantity of essence should be dosed by metering pump into the beer stream prior to the bright beer tank or racking vessel. The dosage rate should be adjusted to ensure that injection occurs over a minimum of 85% of the beer transfer time.

Typical brewing performance: In lighter beers, pronounced flavor enhancements have been observed with some Dry Hop Essences at concentrations as low as 10 ppm of the product (100 ppb of the active ingredient). In heavier beers, it is probable that amounts up to 30 ppm (300 ppb of the active ingredient) would be needed for a discernible effect.

Options: Each Dry Hop Essence is a single product specific to a particular hop variety. Theoretically, a Dry Hop Essence can be prepared from any variety. There are, however, certain limitations on the range of varieties currently produced in this form. These limitations are summarized in the following section.

Availability: Dry Hop Essences are all prepared on a varietal specific basis. They can be prepared fairly quickly from those varieties that are routinely available as whole oil preparations.

Varieties in this group include:
East Kent Golding
Hersbrucker
Styrian Golding
Wye Northdown
Wye Challenger

Small sample quantities of other varieties are being produced according to need. This group includes:

Saaz
Cascade
Mount Hood

Given sufficient notice and minimum requirements it is possible to provide small sample quantities of other hop varieties that, so far, have not been developed in this way.

Dry Hop Essences are not widely available as they are produced only by English Hop Products, Ltd., and distributed only by English Hop Products and Hopunion.

Method of evaluation: Pilot trials and evaluations are recommended to gain experience with Dry Hop Essences in brewing plants of any size. The desired rate of essences should be added as described in the "Method of Use" section. Taste tests will suggest further rate adjustments.

The fact that Dry Hop Essences can be used so late in the brewing process - coupled with their ease of use - makes them very easy to evaluate in small quantities of beer. The following methods describe how Dry Hop Essences can be evaluated on a 355 ml bottle of beer. The first method requires the use of a laboratory microsyringe, whilst the second accommodates the absence of a microsyringe by following a dilution procedure.

The beer chosen for test should not have been dry hopped or significantly late hopped and should not contain a high level of aroma hops as part of the grist. The initial rate of testing should be at an essence rate of 20 ppm (microliter/liter).

Using a microsyringe: Dilute 1 ml Dry Hop Essence to 10 ml with Hop Oil Solvent (80 - 100% ethyl alcohol) and mix well. Using a microsyringe of 100 microliter capacity, add 70 microliters of the diluted essence to a 355 ml bottle of beer as follows:

- chill beer to normal drinking temperature
- remove the crown cap
- introduce the essence beneath the beer surface in the bottle
- tap the side of the bottle to induce fobbing and expulsion of the air
- recap the bottle using a manual crown capper
- invert the bottle several times to ensure mixing
- re-chill the beer for at least two hours
To be fair, the control bottle against which the beer is tested should be dosed in a similar fashion with a similar quantity of Hop Oil Solvent (or alcohol).

Using a standard syringe: Dilute 1 ml Dry Hop Essence to 100 ml with the beer. Stir gently but for several minutes to ensure thorough mixing without excessive foaming. Using a syringe graduated in 1/10 ml divisions, add 0.70 ml of the prepared beer suspension to the test beer in a bottle according to the above procedures.

In each case one simply varies the amount of diluted Dry Hop Essence added to the bottle to evaluate a range of rates until the desired effect is achieved.

Physical properties: Colorless to pale yellow, clear, mobile liquid.

Chemical properties: Miscible with water to give a cloudy solution.

Packaging: Normally available in 250 ml glass bottles. Larger quantities can be provided upon request in 1 liter bottles at a small cost saving.

Storage: Dry Hop Essences should be stored in a cool place and according to any local regulations governing the storage of flammable liquids.