Isomerized Hop Extract
Iso-α-acids (IAA) are the native bittering acids found in traditionally hopped beer. Isomerized Hop Extract (ISO) is a standardized solution of iso-α-acids (30% w/w) produced from CO2 hop extract using an all aqueous process. Isomerized Hop Extract is used to replace kettle bittering hops to improve hop utilization, or to adjust bitterness in beers that may have been under-hopped in the kettle. For precise control of beer bitterness, Isomerized Hop Extract should be added post-fermentation to adjust the bitterness of the beer to the target bitterness units. It may also provide an economic alternative to kettle hopping when performing high-gravity brewing. Isomerized Hop Extract will contribute to foam stand and cling, similar to that of traditional bitter hopping (whole hops, pellets, or CO2 extract). Isomerized Hop Extract will also act as a natural antimicrobial agent when added to beer. It provides good utilization with comparatively low costs. Isomerized Hop Extract is classified by the U.S. FDA as a modified hop extract that may be safely used in beer in accordance with US FDA regulation 21 CFR 172.560 (b) (2-5).
Description: A pale yellow to amber aqueous solution of the potassium salts of iso-a-acids
Concentration: Standard concentration is 30.0% ± 0.5 of iso-α-acids by HPLC
pH: 8.0 – 10.0
Density: 1.075 g/mL (approximately) at 20 °C (68 ° F)
Viscosity: 10 - 20 mPas at 20°C (68°F)
Solubility: Soluble in pH-adjusted de-mineralized water, and in alcohol
α-acids: < 0.7%
β-acids: < 0.3%
Isomerized Hop Extract (ISO) is normally used after fermentation and before final filtration. Utilization of Isomerized Hop Extract in final beer is typically between 60 - 90% depending on the time and efficiency of dosing. If Isomerized Hop Extract is used in the brewhouse, utilization may be expected at 50 - 60%. The preferred point of post fermentation addition is close to a region of turbulent beer flow, e.g. on the suction side of a centrifugal pump. The dosing pump should be adjusted to deliver the Isomerized Hop Extract over approx. 70% of the total transfer time. It is advisable to make the addition prior to the final filtration step. Local high concentrations of iso-α-acids should be avoided in the beer stream and the addition point should be well separated from that of any other additions. Isomerized Hop Extract may be added at ambient temperature without prior dilution directly to beer. Dilution is not advised, but if necessary, the use of de-mineralized water and a pH adjustment to 9 - 10 with KOH is recommended. Do not use sodium bases to adjust the pH of dilution water; caustic soda or sodium hydroxide form poorly soluble salts with most hop acids. The amount of Isomerized Hop Extract needed for dosing is calculated based on the product concentration and the assumed utilization. Conducting trials at the brewery will determine the correct dosage of Isomerized Hop Extract in regard to sensory bitterness. Isomerized Hop Extract will give similar bitterness as that of traditional iso-a-acids. Following dosing, we recommend cleaning lines and dosing pumps with warm slightly alkaline de-mineralized water or ethanol immediately after each use.
Use Rate Calculations:
As mentioned for all other brewing products, trials are the best way to determine in-house efficiency and dosing rates for each product. We will assume 80% utilization of IAA.
Dosage = BU x 0.360
Dosage = milliliters of IAA to be added per BBL of beer post fermentation
BU = is the desired amount of bitterness units imparted by ISO
Note: Use rates may vary depending on the brewing process and the desired hopping level.
** If you would like to change the efficiency from 80%, adjust the 0.80 in the equation.
75% efficiency will change this value to 0.75 and 85% efficiency will adjust to 0.85.
You are going to make a beer and would like to provide all of your bitterness using Isomerized Hop Extract post fermentation. You are brewing on a 30 BBL system and want this extract addition to give you 18 IBUs in your finished beer. Assume 80% efficiency.
Dosage = 18 x 0.360 = 8.1 ml/bbl * 30 BBL = 243 mls ISO
You are going to make an Imperial IPA on your 30 BBL system and would like to provide some of your bitterness from Tetra-Hydro Isomerized Extract post fermentation while utilizing traditional hops throughout the boil. You decide to make a bittering addition, a flavor addition and a final aroma addition at knockout. You will also be dry hopping in the tank. Your target IBU’s for the brew are 100 from which 60 of those will come from the first bittering addition. You decide to split that bittering addition up 60/40 between IAA and Kettle Hops. Assume 80% efficiency.
Isomerized Hop Extract is normally supplied in 250 ml high-density polyethylene containers.
Also available in 20 kg high-density polyethylene containers.
Storage and Best-by Recommendations:
Store Isomerized Hop Extract in full, closed containers at 36 – 46°F. Prolonged storage at high temperature can cause deterioration. Isomerized Hop Extract performs best if used within 24 months from the time of production if stored as recommended.
The determination of iso-α-acids comprises three types of methods, the specific measurement of iso-α-acids by means of HPLC.
We will be pleased to offer support on the use of Isomerized Hop Extract in brewing. For assistance, please contact our knowledgeable staff at 1-800-952-4873 or e-mail firstname.lastname@example.org