Using Spectrophotometry to
Improve your Brewing Process
Rick Blankemeier
Quality Assurance Analyst
Stone Brewing Co.
Goals
• Introduce the UV-Vis Spectrophotometer
• Provide financial justification for purchase
• Describe ways to use this device to help
breweries expand and improve their brewing
and fermentation operations
• Quick and easy access to vital info on different
assays and procedures using the UV-Vis Spec • Gives brewers the ability to find the
concentration of a certain substance in your
beer by measuring absorbancy
UV-Vis Spectrophotomer
UV-Vis Spectrophotomer
• Use
– Anyone can use a UV-spec with any level of
technical expertise
– It’s harder to operate a brewhouse than a UV-Spec
– A background in chemistry or biology doesn’t hurt
when preparing the samples, but it’s not needed
Hach DR5000
Quartz Cuvettes
UV-Vis Spectrophotomer
• Preparing Samples

water chemistry, etc.) How does that affect your process?
– How much would it save you to keep your beer on the
shelf for an extra month?
– Able to increase the batch size of your brew relatively
painlessly AND keep the flavor and quality consistent?

Expansion and QA Concerns
• Lots of successful small to mid-size breweries
planning 25-50% expansions to their capacity
• Growth for craft breweries in the 15,000-30,000
bbl/year range are expected to grow at a double-digit
rate this year
• Quality testing your beer off of the new system
needs to be a priority – compare with old system
Scaling Up Your Process Is Easy…Right?
– Scaling up recipes and your brewing process isn’t just a
matter of ratios
– You need to establish empirical standards for your beer
before you increase your capacity so you know what
analytical targets you need to meet on your new system
– Every brew system is different! Even if it’s from the same
manufacturer
– Sensory testing is important as well
(Empire)ical Standards • Gravity – Hydrometer or Density Meter

of spectrophotometer).
• Cost Benefit
– Establish color specs for your
core beers
– Gives you the ability to
adjust the color to your
needs

• Colorimetric at
430nm
• Measures
absorbency in the
blue part of the
visible spectrum of
light
Bitterness
• Measures the approximate* amount of iso-
alpha acids in a sample
• Uses liquid-liquid extraction to separate the
iso-alpha acids* from acidified wort/beer into
2,2,4-trimethylpentane (iso-octane)
• Great for establishing an empirical
specification for your core beers
• Also great for determining hop utilization *1 IBU ≠ 1 ppm iso-alpha acid
Bitterness
• Waste/Hazard Issues
– Need to dispose of iso-octane

formation
• Free radical formation leads to oxidation.
• Oxidation in beer leads to suffering (and poor
shelf-life) TBARS Assay
• Waste/Hazard Issues
– None, able to dispose of
reagents down the drain
w/o treatment
• Cost
– A $400 kit good for 60
tests
– Need a water bath that
can maintain constant
temp.
• Cost Benefit
– Less wasted energy (Save
~$1000/month)
– Improved beer shelf life • Colorimetric at 517 nm
• Measures against a
MDA standard to
generate a standard
curve

y = 0.0052x + 0.0138

Nitrogen
• Waste/Hazard Issues
– None, able to dispose of
reagents down the drain w/o
treatment
• Cost
– ~$20-25 per 16 sample group
– Water bath with temp. control
(~$900 for a 2L)
• Cost Benefit
– Fewer micro and sensory
issues
– Less haze issues

• Ninhydrin-based dying
method
• Ninhydrin color reagent
keeps for about 2 weeks
• Measures against a
glycine standard curve
• Absorbency at 575nm
• Good range is 140-300
mg/L

Beta-Glucans • Polysaccharides of D-glucose linked by β-
glycosidic bonds
• Appears primarily in wheat malts, oats, rye


• Comes primarily from darker malts, hops,
barrels/wood aging
• Imparts strong flavors – too much and it causes
astringency
• Complexes with proteins at low temperatures to
form chill haze

Polyphenols
• Waste/Hazard Issues
– None, able to dispose of
reagents down the drain w/o
treatment.
– Ammonia is concentrated and
stinky
• Cost
– ~$100 for 20 tests
• Cost Benefit
– Potential for determining
when a barrel has given up all
of its flavor
– Potential to diagnose haze
issues in beer
• Ferric iron binds to
polyphenols
• Good way to monitor
post-dryhop tannin
levels
• Absorbance at 600nm