Using Spectrophotometry to Improve your Brewing Process pot

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

– Degas
• Same procedure to check fermenting beer gravity via
hydrometer
• Sonicate
– Usually don’t want to filter samples for clarity
• Centrifugation at 2000-3000rpm
– Sometimes the procedure calls for heating/cooling
of samples


UV-Vis Spectrophotomer
• Cost
– UV-Spectrophotometer
• $5000-$7500 plus warranty and service contract
• $300-$400 for quartz cuvettes
• Cost Benefit Analysis
– Mostly deals with “what-if” scenarios and finding
root causes
– Skewed towards packaging breweries for
consistency’s sake

Justification

• How can you justify a $7500+ purchase?

– How much would it cost you to dump a batch of beer?
$5000? $10000?
– Forced to change suppliers -> how does it affect your
beer?
– Change an aspect of the brewing process (grist profile,

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

• pH – pH Meter
• IBUs - Spectrophotometer
• Color – Spectrophotometer
• ABV – Anton Paar Alcolyzer or Ebulliometer
Analytical Testing
• Level 1
– Color Analysis (ASBC Method Beer 10A)
– Bitterness (ASBC Method Beer 23)
• Level 2
– Beta-Glucans (Custom Method)
– Polyphenols (ASBC Method Beer 35)
• Level 3
– FAN (ASBC Method Beer 31)
– TBARS (Method on the kit)

Color Analysis
• One of the simplest assays using a
spectrophotometer
• Measures SRM
• Good to establish color thresholds for your
core brands
• Diagnose specialty grain or grainout issues

Color
• Waste/Hazard Issues
– None, able to dispose of
reagents down the drain w/o
treatment
• Cost
– Little to none (besides cost

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

in special solvent waste
containers after measurement
• Cost
– ~$200-300/month in chemicals
and centrifuge tubes
– $300/year in disposal fees
– A centrifuge that can spin at
2000-3000 rpm
• Cost Benefit
– Hop savings through utilization
study (~$5,000/month)
– Scalability through establishing
specs




• Measures
absorbency at
275nm
• Uses 6M HCl and
iso-octane
• Abs x 50 = IBU

TBARS Assay
• TBARS = Thiobarbituric Acid Reactive
Substances
• Measures the concentration of oxidative
precursors in wort due to lipid peroxidation.
• Overheating your brew leads to free radical

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

R² = 0.9923
0
0.1
0.2
0.3
0.4
0.5
0.6
0 50 100 150
Standard Curve
Standard Curve
Linear (Standard
Curve)
nmol/
Abs
Free Amino Nitrogen (FAN)
• FAN represents the concentration of individual amino
acids, ammonia, and end-group α-amino nitrogen in
small peptide chains and proteins
• Basically, it measures the bioavailability of nitrogen to
yeast.
• Adjunct brewers have to worry about low FAN levels
• Too much FAN = potential micro issues and fusel oil
formation in high gravity beers
• Don’t worry about adding nutrients like urea!
• High FAN can also lead to haze issues and some amino
acids can also lead to higher diacetyl formation rates in
fermenting beer

Free Amino

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

malts, and in barley malt to a lesser extent
• It’s the sticky stuff in your mash that causes
stuck lauters and angry brewers.
• It also can lead to haze issues post-fermentation

Beta-Glucans
• Waste/Hazard Issues
– None, able to dispose of
reagents down the drain w/o
treatment
• Cost
– ~$1.50 per test
• Cost Benefit
– Diagnose haze issues in beer
– Utilize enzymes to help with
poor lauters or haze issues
• Congo Red Assay –
measures absorbency at
540 and 477 nm (green-
blue visible wavelength)
• Measures the amount
of beta-glucans that are
bound by the dye
• Based on an assay used
primarily in histology –
diagnosis of fungal
infections
Polyphenols/Tannins

• 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

Summary
• Establish empirical standards for your beer
• Scale up your brewery keeping those
standards in mind
• Cost vs. cost benefit – well worth the purchase
• If you have any questions about the
procedures or anything else, you can reach me
via e-mail
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