Understanding hop analysis is key to producing beer of consistent quality.
Hops are a natural ingredient produced by a highly specialised horticultural system in temperate regions around the world, which means they are subject to seasonal and lot-by-lot variations. Hop analysis gives brewers the opportunity to optimise their process to achieve consistency and efficiency.
This information is intended to be a high-level practical introduction to interpreting hop analyses, and their relationship with brewing performance and beer quality to help you brew the best craft beer!
Hop requirements in the brewery
The basic attributes of hops should meet the following requirements:
- Normal colour, specifications, flavour and aroma
- Intact and appropriate packaging and product type
- Accurate labelling as to variety, origin, production date and bittering potential
- Free from contamination and safe for use in beer production
Certificates of analysis and specifications
Brewers can use CoAs to anticipate process changes required to achieve consistent brewing results, and to verify compliance with hop specifications.
Our products at Hops Connect Canada, are supplied in sealed, oxygen barrier laminated foils that have been back-flushed with inert gas (carbon dioxide or nitrogen) and packed in cardboard cartons.
As a minimum, each carton should be labelled with variety, producer, crop year, production date, batch identification numbers, product type, net weight and bittering potential (alpha acid contents and analysis method). There is no standardisation of CoA information. In their most basic form a CoA will cover the same information as the carton labels, but some more detailed CoAs may include additional information such as essential oil content, moisture content or agricultural chemical residue reporting.
Typical hop analyses and their significance
Analysis
Significance
Crop year
Hop metabolites are inherently unstable. When packaged and stored appropriately, bittering potential is maintained until at least the best before date. But aroma or flavour potential decrease over time. Bittering, aroma and flavour potential decrease rapidly once foils are opened.
Origin
The scale on which each hop variety is produced can vary significantly. The production of some varieties is highly localised, while other varieties are produced by multiple growers, across multiple regions or even continents. Controlling the origin of each hop variety may help to minimise variability of performance in beer.
Variety
Most commonly refers to a hop genotype clonally propagated then harvested and processed as a variety. This term extends to proprietary blends or trademarks that cover the product from particular genotypes.
Type
Dried whole hop cones are best suited to breweries with dedicated infrastructure (ie. hopback or “torpedo” systems). T90 and T45 pellets are suitable for use in kettle, whirlpool or dry hopping scenarios.
Batch
An identifier that facilitates traceability both at the brewery and the supplier.
Typically represents: 2 – 40 metric tonnes
Gland Fill
Indicative of hop cone maturity, oil content and overall health.
Typical values: 1 – 5
Dry Matter (%)
Indicative of hop cone maturity at the time of picking which is directly related to cone weight, alpha acid and oil content.
Typical values: 18 – 28%
Mean Cone Weight (mg)
Indicative of hop cone maturity. Kiln operators use this measurement as a guide for drying times.
Typical values: 100 – 500mg
Alpha acid (%)
The percentage composition (by weight) of alpha acid in the product at the time of packaging. It is directly relevant to dosing for target bitterness.
Typical values: 2% (traditional European varieties) – 20% (more modern varieties)
Beta acid (%)
The percentage composition (by weight) of beta acid in the product at the time of packaging. It is directly relevant to dosing for target bitterness.
Typical values: 1% – 12%
Alpha/beta ratio
Indicative of a hop plants chemistry. Can be used to classify identity by chemotype.
Hop storage index (HSI)
Indicative of the level of oxidation of alpha acids. Can be used to calculate original alpha acid content which may give a better estimate of bittering potential in some circumstances. At harvest, hops in field are typically 0.20 to 0.25. In the case of processed and packaged hops, HSI values less than 0.35 are low, 0.35 to 0.40 are moderate, and values more than 0.40 are high. Hops with high HSI may have reduced or negative impact in beer.
Typical values: 0.25 – 0.35
Oil content (ml/100g)
A high oil content is more likely to be associated with strong fruit characters, while lower oil content is more likely to be associated with distinct floral, herbal or spicy characters.
Typical values: 0.5 – 3.0ml/100g
Moisture content (%)
A high oil content is more likely to be associated with strong fruit characters, while lower oil content is more likely to be associated with distinct floral, herbal or spicy characters.
Typical values: 0.5 – 3.0ml/100g
Moisture content (%)
Little direct impact on performance in beer, but is indicative of compliance with hop specifications. Low moisture content (<7%) indicates over-drying and potential loss of performance in beer, while high moisture content (>10%) indicates the potential for poor stability in storage.
Typical values: 7 – 10%
Essential Oil Profile (% composition)
Hop essential oils can be used as varietal fingerprints, but very few compounds are flavour active. Myrcene, Caryophyllene, Humulene, Farnesene and Selinene typically constitute the highest percentage of composition. But Geraniol, Linalool and β-Citronellol which typically constitute relatively low percentage of composition (<1%) have been shown to be flavour active in beer. Low molecular weight sulphur containing compounds that are responsible for intense fruit characters in some hop varieties are not measured in standard essential oil profiles.
Typical values: geraniol 0 – 1%, linalool 0 – 1%, farnesene 0 -10%, selinene 0 – 15%, caryophyllene 0 -20%, humulene 2 – 30%, myrcene 20 – 60%
High performance liquid chromatography (HPLC)
Indicative of alpha and beta acid chemistry of cultivars developed in our plant breeding program.
Drivers of variability in analytical hop quality outcomes
Low
High
Alpha
Low
Average season, early harvest, post harvest deg.High
Good season, mid-late harvest, processing good
Beta
Low
Average season, early harvestHigh
Good season, mid-late harvest, processing good
Alpha:Beta Ratio
Low
Early harvestHigh
Later harvest
Moisture
Low
Overdried (<7%)High
Under dried (>10%)
Oil
Low
Average season, early harvest, post harvest lossHigh
Good season, late harvest, processing good
H.S.I.
Low
Early harvest, good post harvest handling (<0.3)High
Difficult season, later harvest, problems post harvest (>0.4)
1. Low α, oil; High α:β ratio, H.S.I; Late harvest, degradation post harvest
2. Low α, α:β ratio, oil, H.S.I; Early harvest, handled well post harvest
3. Low H.S.I; High α, α:β ratio, oil; Late harvest, good post harvest conditions
4. Low H.S.I; Normal α, α:β ratio, oil; Consistent timing of harvest, good post harvest conditions
1. Low α, oil; High α:β ratio, H.S.I; Late harvest, degradation post harvest
2. Low α, α:β ratio, oil, H.S.I; Early harvest, handled well post harvest
3. Low H.S.I; High α, α:β ratio, oil; Late harvest, good post harvest conditions
4. Low H.S.I; Normal α, α:β ratio, oil; Consistent timing of harvest, good post harvest conditions
Accuracy and inter-laboratory error in hop analysis
When assessing compliance with hop specifications, it is important to note many of the methods published by European Brewery Convention (EBC) and American Society of Brewing Chemists (ASBC) for measuring the above analytes have high standard deviations and inter-laboratory error. The ASBC run an international check sample service that is focused on the analysis of bitter acids using titration, spectrophotometry and high performance liquid chromatography (HPLC). There are currently no inter-laboratory comparisons made for determination of moisture content, oil content or essential oil profiles.
Food safety issues
Hops that are used in brewing are a food ingredient. This means producers are required to ensure all typical food safety requirements are met. Suppliers should be able to provide allergen and residue statements. At Hops Connect Canada, upon request, we can provide you with HAACP, ISO, GMO & Kosher certificates from our growing regions.
Beyond CoAs
Hop CoAs and label information describe the hops at the time of packaging. Chemical changes that affect performance in beer may occur if the hops are transported, stored and/or handled improperly at any stage of the supply chain.
All of your hops at Hops Connect Canada are transported from origin in reefer containers and stored in our Canadian cold-storage facilities at 0 degrees Celcius to ensure the highest quality product.