1. l ANALYSIS
12 z Brewer and Distiller International December 2016 www.ibd.org.uk
There are many ways to accidentally
introduce caustic into beer and
often, the more automated the system,
the easier it is to do. In manual or less
automated plants, brewers often have
to add concentrated caustic solution
(50% NaOH) to the vessel or makeup
tank and start the clean-in-place (CIP)
either manually or via automation.
In larger, more automated systems,
bulk chemical tanks are often directly
connected to the makeup tank and
this is connected to the process ves-
sel. In the automation on the human/
machine interface (HMI), there are
usually prompts to the user to confirm
the concentration of the makeup tank
against an inline conductivity meter by
titration. Once the operator confirms,
the process proceeds through a series
of pre-set steps.
The basics steps of a typical brew-
house CIP programme are as follows:
reclaimed water rinse, detergent cycle
and fresh water rinse. Less frequently,
acid descaling of heat exchange sur-
faces is performed. While the purpose
of automation is to minimise the need
for human intervention, improve ef-
ficiency and ensure consistency in the
process, there are times when it is
still necessary for a person to visually
inspect, titrate or otherwise intervene.
Additionally, as those who work
in an automated facility can confirm,
automated processes do not always
proceed as programmed; errors can
occur in computer programs, valves
can break, proximity switches fail or
other unusual events happen. Any of
the these can lead to the inadvertent
introduction of chemicals into the beer.
Rinse water checks
The simplest quality check to prevent
chemical inclusion is to check the pH
of the fresh rinse water from the ves-
sel being cleaned; this should be car-
ried out at the end of the cycle before
putting it back into production. The
pH of fresh water rinse collected from
the CIP’d vessel should match that of
the incoming fresh rinse water. If it
doesn’t, the rinse should be extended
to remove all residual cleaning chemi-
cal. This can be done using a pH meter
in the laboratory, handheld pH meter
on the floor or using pH strips.
It is also possible to use a colour-
changing indicator such as phenol-
phthalein to check whether the rinse
water is alkaline. In order to prove
caustic is present, further investiga-
tion is required. In addition to care-
fully monitoring rinse water pH,
in-process wort and beer pH should
be routinely measured and specifica-
tions established. Commonly, the
process specification pH ± 0.15 is
used. However, this should be verified
for all processes.
Remembering the basic chemistry
class, let’s review the pH equation:
pH = -log[H+
]. This simple equation
shows that the pH is equal to the neg-
ative logarithm of the concentration
of protons (H+
) in solution. This means
that the greater the H+
concentra-
tion, the lower the pH will be and vice
versa. Additionally, for a change in pH
of 1, there must be a ten-fold change
iStock.com/JordanRusev
Sodium in beer
Beyond the basic pH check
By Aaron Golston
Sodium is not an element usually found in beer at
significant levels. Generally, 0.5-3.5 mg/500mL is present
in finished beer which comes from raw materials such
as malt and hops. But there is another potential and
unacceptable source of sodium in beer – cleaning chemicals
and more specifically, sodium hydroxide (NaOH).

2. ANALYSIS l
www.ibd.org.uk Brewer and Distiller International December 2016 z 13
in the H+
concentration. Changes in H+
concentrations could be due to: the
expansion of high-gravity aging stock
across the filter with deaerated water,
the blending of two beers together,
intentional pH adjustment for quality,
sensory or food safety reasons – or
the inclusion of caustic or acid from
cleaning.
Considering the range of pH values
(± 0.15) allowed from the process
target, it is possible to have chemical
inclusion and still be in specification
but it is also possible to observe a
large pH change without an inclusion
(Table 1). Critically evaluating pH from
the previous process stage to the cur-
rent can help prevent contaminated
product from reaching the consumer.
Routine process control
As mentioned previously, pH measure-
ment of rinse water and in process
samples is the first line of defence
against water, wort or beer usage or
release that has been contaminated
with chemicals. Establishing a pro-
gramme that routinely monitors the
process will help limit the amount of
affected production, should such an
event occur.
However, measurements are only
valid if they are generated using a
properly maintained and calibrated
instrument. The collected data should
be kept in a spreadsheet or database
and routine evaluated visually. There
are many benefits to observing data
visually, not least of all being that
trends are easier to observe. On the
off-chance that a potential event is
observed, it is important to verify the
inclusion analytically with supplemen-
tal analyses before letting the product
continue in the process.
Another and often overlooked indi-
cator for contamination is the ratio of
real extract to alcohol in the beer. Both
the real extract and alcohol need to
be measured in weight analyte/weight
beer (w/w) to calculate the ratio.
Changes in ratio during normal beer
processing are minimal, if no blend-
ing of different beers or wort streams
across the filter occurs.
If blending does occur, the ratio
can be predicted, as both alcohol and
real extract dilute linearly. The intro-
duction of caustic into beer will leave
the real extract relatively unchanged
or it will increase – but the alcohol will
decrease. This results in the ratio in-
creasing thus indicating to the analyst,
operator or management that some-
thing has occurred. Further investiga-
tion and testing is needed before the
process continues further (Table 2).
Sodium analysis
In order to investigate a potential caus-
tic inclusion, sodium analysis must
be performed. This is usually carried
out by Atomic Absorption Spectropho-
tometry (AAS), Inductively Coupled
Plasma/Optical Emission Spectrom-
etry (ICP-OES), or Inductively Coupled
Plasma/Mass Spectrometry (ICP-MS).
However, Ion Selective Electrodes
(ISE) can also be used but lack the
flexibility of the spectrometer alterna-
tives and can experience interference
from other ions in solution. Which-
ever system is chosen to monitor the
process, the procedure must be tested
and validated across all brands and
Caustic Rinse
water
Acid
Condensate
Bulk
caustic
Bulk
acid
Steam
From
brewhouse
To
brewhouse
P&ID of a typical brewhouse CIP set
Green beer Bright (filtered) beer Difference
Original Gravity (°P)
Alcohol by Volume (%, v/v)
Alcohol by Weight(%, w/w)
Real Extract (%, w/w)
14.62
6.22
4.86
5.34
14.17
6.01
4.70
5.16
- 0.45
- 0.21
- 0.16
- 0.19
Ratio (RE/ABW) 1.10 1.10 0
Apparent Extract (°P)
pH
3.16
4.15
3.05
4.35
- 0.11
+ 0.20
Table 1. Fabricated example of pH change from fermentation to bright beer
Beer Beer with 4% Caustic Difference
Original Gravity (°P)
Alcohol by Volume (%, v/v)
Alcohol by Weight (%, w/w)
Real Extract (%, w/w)
14.62
6.22
4.86
5.34
14.11
5.84
4.56
5.40
- 0.51
- 0.38
- 0.30
+ 0.06
Ratio (RE/ABW) 1.10 1.18 + 0.08
Apparent Extract (°P)
pH
3.16
4.15
3.32
4.79
+ 0.16
+ 0.54
pH control chart of in-control process with event
Table 2. Laboratory created example of ratio change due to caustic inclusion
pH
5.00
4.90
4.80
4.70
4.60
4.50
4.40
4.30
4.20
4.10
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30

3. l ANALYSIS
14 z Brewer and Distiller International December 2016 www.ibd.org.uk
processes to ensure the accuracy of
the results. In the laboratory, any of
the listed options are suitable to de-
liver the necessary information to the
process managers to enable decision
making.
As with any experiment or analysis,
a control must be analysed in addi-
tion to the sample. Ideally, the control
would be from the same batch of beer
but this is not likely since at most
breweries one batch equals one tank.
Therefore, it is necessary to select
another batch as the control which
meets the following criteria: be of the
same brand, produced shortly before
or after the suspect batch – and not be
suspected of contamination.
In addition to the experimental
control, an instrumental control and
zero should also be used to validate
the calibration of the instrument. An
important point to note is that the
sample concentration must be within
the calibration range of the instru-
ment and ideally should be in the
middle of the range. Values obtained
outside the calibration range must be
diluted and re-run. This is analytical
chemistry best practice – because
the calibration curve can deviate
from linearity outside of the cali-
brated range yielding artificially high
or low results.
In a properly controlled process,
the sodium levels should be fairly
consistent batch to batch for a specific
brand but this should be verified dur-
ing method development and valida-
tion. However, there will be variation,
which is why the difference between
the control and sample should be
used to assess the potential level of
contamination and concentration in the
sample.
Some companies set a hard limit
for the control/sample difference and
anything greater than the limit is
deemed contaminated and beer is
subsequently disposed of. This is most
often done to protect consumer health,
company image and legal liability.
Other companies judge each situation
on a case by case basis, which can add
unnecessary ambiguity to an already
complicated situation. An example of
hard limit control/sample difference
utilised by some companies is 15 ppm
sodium.
Next steps…
Once it has been confirmed that the
tank is contaminated, the next logical
thing to do is to determine the level
of caustic in the vessel. This seems
daunting and potentially irrelevant but
it is quite shocking to see how a small
volume of caustic can do significant
damage.
In order to determine the volume
that went into the vessel, a few pieces
of information are needed: concentra-
tion of the caustic in plant solution
(Ccaustic
), volume of the contaminated
vessels contents (VS
) and the differ-
ence in sodium level in the contami-
nated vessel and the control (CS
– CC
).
Unlike pH, sodium concentration
changes are directly proportionate
to the amount added to the solu-
tion. With this information, the total
volume of caustic added to the vessel
can be calculated.
In addition to the responsibility of
providing safe beer for consumers to
drink, there are laws in some coun-
tries that clearly state it is illegal to
release product that is adulterated.
However, regardless of the level of
contamination, it is always best to err
on the side of quality / food safety and
dispose of all contaminated product.
Plant Caustic Solution (Ccaustic
): 3% NaOH (vol/vol)
3% NaOH (vol/vol) = 30g NaOH / L * (22g Na / 40g NaOH) = 16,500 ppm Na
Control: 1000 bbls (VC
): beer with 2 ppm sodium (CC
)
Sample: 995 bbls (VS
): beer with 18 ppm sodium (CS
)
Vs
(L) * (Cs
– Cc
) (ppm Na) = Vcaustic
(L) * Ccaustic
(L) (ppm Na)
116,748 L beer * (18-2) ppm Na = Vcaustic
(L) * 16,500 ppm Na
Vcaustic
(L) = 116,748L * 16ppm Na
16,500 ppm Na
= 113.3 L 3% NaOH solution = 0.96 bbls
Example of how to calculate the volume of caustic contamination
(L - R) Atomic Absorption Spectrophotometer, Inductively Coupled Plasma / Optical Emission Spectrometer and Inductively Coupled Plasma/Mass
Spectrometer from Agilent Technologies
An ion selective probe (ISE) for sodium from
Mettler