Given Dan 19th, 2018

1. Understanding S. diastaticus or
“What I Learned to Stop Worrying
and Love Saison”
Nate Ferguson
Escarpment Laboratories

2. Escarpment Laboratories - Who Are We?
• Yeast lab in Guelph, ON
• Production of liquid
yeast, blends & bacteria
• Microbial and chemical
quality control (QC)
services
• Free advice!

3. ● What is S. diastaticus
○ Glucoamylase
● Why is it a problem?
● How do we protect
ourselves against it
● How do we screen for it
○ PCR
○ Starch Plates
● How do I handle it?
Understanding S. diastaticus

4. Saccharomyces cerevisiae var diastaticus
Saccharomyces diastaticus was first described by
Andrews and Gilland in 1952 for its ability produce
abnormal attenuation through the consumption of
starch and dextrins (1)
It is able to do this by excreting a glucoamylase
enzyme which breaks down starches and dextrins
into easy to consume glucose

5. Glucoamylase Activity
Glucoamylase is very similar to amylase found in grain,
however, the end result is glucose instead of maltose and
dextrins from beta and alpha amylase respectively

6. Saccharomyces cerevisiae var diastaticus
This degradation occurs by the hydrolysis of starch which
is facilitated by the glucoamylase GA1, GA2 and/or GA3
encoded by the genes STA1, STA2 and STA3
respectively(2)
These glucoamylases are able to break down the 1-4
linkages in amylose while skipping the 1-6 linkages
found in amylopectin allowing for near complete
dextrin degradation

7. Starch structure in malt

8. Starch and Beer
Why is this a problem?
Beer contains dextrins
that contribute body and
mouthfeel to the final beer.
These dextrins are not
consumable by S. cerevisiae
however they are easily
digested by diastaticus

9. Why S. diastaticus can be a problem
S. diastaticus contamination will cause
• An increase in ABV (Dextrin→ Sugars→ Alcohol)
• Can cause phenolic off flavours (most are POF+)
• Over carbonation of product
• Worst case “bursting” or explosion of packaging
causing harm to customers!
If you have multiple of the above than you likely
have a diastaticus issue!

10. For those saying

11. Short Answer = YES!
E.G. If you beer finishes at 1.016 (4°P) and is brought down to 1.004(1°P) that
will produce roughly 14g/L of CO2 in the beer which is equivalent to 7
volumes of CO2
This at 4°C will make the pressure inside the bottle approx. 100 PSI which
will increase as it warms. This increase pressure is what leads to bursting
Let's look at some bottles and their max PSI
Is it really that big a deal?

12. Bottle PSI for Breakage (Approx)
What does 100 PSI mean for different bottles
Different bottles can handle different amounts of PSI before bursting
● Standard bottle or Stubby = 7 bar = 101 PSI
● 500mL = 12-16 bar = 174-232 PSI (high temp)
● 750mL “Champagne” = 20-28 bar = 290-406 PSI
● 330 “Champagne” = 16 bar = 232 PSI
● Cans = Variable but around 100-200 PSI(high temp)*
Most storage vessels for beer are
not stable at 100 PSI*

14. That’s a lot of Pressure!
…...and this can cause you lots of problems!

15. How do I protect my beer and customers
from S. diastaticus?
Obvious answer: Do not infect your beer with S. diastaticus
Easier said than done
Many desirable yeast strains are S. diastaticus such as
● Saison yeast
● Trappist (some)
● Wit (some)
● Weizen (some)

16. If you wish to use these strains a Risk Management Plan is
needed
Any risk MGMT plan needs to be 2 pronged to be effective
1. Risk Reduction (Proactive)
– measures that reduce likelihood of an error occuring
– Measures that reduce the impact an error has
2. Product screening (Reactive)
– Ensure no product leaves that is faulted
– Catch issues before they become larger
How do I protect my beer and customers
from S. diastaticus?

17. 1) Risk Reduction of S. diastaticus contamination
If you choose to work with this organism ~ there are a
few things core practices you can implement to
A. Reduce the chance of cross contamination
B. Reduce the impact it will have on your product
Risk Reduction is always the best method for handling
a potential issue so we will start here

18. A) Reducing the Chance of Contamination
The single best thing you can do to reduce the risk of cross
contamination is to have designated fermenters for each
organism or more practically designated tank each “risk
levels” (more later)
E.G. improperly CIP tank with Cali that is then inoculated
with Cali = Okay
improperly CIP tank with diastaticus that is then
inoculated with Cali = BIG PROBLEM

19. A) Reducing the Chance of Contamination
The Obvious issue here - Who has that many tanks to do this
Shameless plug - soon to be your local yeast supplier
A more practical solution - proper record keeping
If tank A had a diastatic organism in it before than it needs a
more thoroughly CIP’d and a greater degree of monitoring
during the next fermentation

22. Managing the risk goes beyond fermentors especially if you
have shared pieces of equipment (you do!) such as
● Filters/Centrifuge
● Brite Tanks, Yeast Brinks
● Packaging Lines
E.G. Beer A with diastaticus is filtered, CIP is missed/flawed,
etc, Beer B with lager yeast is then filtered
Result: Your lager is now at risk of bursting
The Risk of Shared Equipment

23. The Risk of Shared Equipment
The risk of cross contamination occurring can be reduced by
introducing a risk tier system based on the properties and risks
of each cell
We use the following
Level 1: Low risk
• Cali, English Ales, Vermont ales, Lager strains, etc
Level 2: POF positive
Belgian ales, weisse, wit, etc
Level 3: High Risk
diastaticus positive, Brett, bacteria, etc

24. The Risk of Shared Equipment
In practice, risk tiers would be applied like this
E.G. package all Tier 1 followed by Tier 2 and then Tier 3
If a contamination does occur from shared equipment it is
minimally noticeable
● Cali in a Wit isn't great…..but isn't not very noticable
If we were to reverse the order than the risk of a
contamination being damaging increases
● Wit yeast in a blonde ale is…...very noticable

25. There are some additions things we can do to reduce the
impact that a diastaticus contamination will have on our
product
The simplest answer is “all beers get diastaticus” but that is
not practical
The most impactful thing we can do to reduce the impact
is to make all of our beers ferment dryer
B) Reduce the impact it will have on your product

26. B) Reduce the impact it will have on your product
To use our example before, If our 4°P F.G. was instead 3°P
prior to diastaticus contamination than we would only see 9.4g/L added
● 4 vols of CO2 added, PSI 55PSI 4°C (still gushing, not bursting)
If the beer finished at 2°P - 4.7g/L added
● 2.4 Vols of CO2 added, 38.7PSI @ 4°C (less likely to gush, no bursting)
The lower we can make the F.G. of our beer the less impactful this
organism (and all contamination organisms) will be to your product

27. B) Reduce the impact it will have on your product
How do we lower the F.G. of our beer?
-Mashing protocols
-Additional Enzyme activity (Brut style beers)*
Mashing protocols require no additional ingredients and
produce the most consistently stable product so let's look
at those first

28. Solid Lines = total Extract
Dashed Lines = Fermentability

29. Reducing Dextrins, Mashing - Duration
Mashing longer we will increase the fermentability and
lower the F.G. of our finished beer *(This is Foam Negative)
This will effectively reduce the amount of things that S.
diastaticus can consume making out product less likely to
referment
Additionally - if diastaticus fermentation occurs then we
will produce less CO2 in the finished product!

30. So - I want to use diastaticus
but also want some sweetness in my beer?
This is still possible through a heavier use of maillard and
caramel based grains
Malts such as
• Crystal malt
• Victory/Caramunich/etc
• Roast or toasted grains
Caramelized or maillard dextrins/sugars are not
consumable by S. diastaticus

31. How do I protect my beer and customers
from S. diastaticus?
Summary so far:
● Record keeping and being aware of what risks each strain and tank pose
to your brewery as a whole is key
○ Ideally separate equipment, better yet facilities
● Dryer beers reduce the impact that refermentation due to contamination
will have on your product
○ Mash rests or enzyme additions are best
● Risk Tier based systems can aid you in making important scheduling and
sequencing decisions with risk reduction in mind (Tier 1/2/3)

32. Where does S. diastaticus come from?
Many common saison strains are S. diastaticus
From Escarpment Labs
-Old World Saison
-New World Saison
-French Saison
-Dry Belgian
They can be used for good!

33. How do you screen for S. diastaticus?
Screening for S. diastaticus is not easy!
Diastaticus cells looks the same under the microscope
and on a plate as normal yeast cells
The most common method of detecting S. diastaticus is
PCR screening of STA1, the gene that produces the
glucoamylase

34. Visual Differences - Do not exists

35. Using PCR to screen for STA1
The most common technique used to screen for
diastaticus is PCR to screen for the presence of STA1
which produces the glucoamylase responsible for starch
and dextrin degradation into glucose
This process takes about 3-4 days and from our
experience requires some fine troubleshooting for some
strains

36. Molecular
Weight
“Ladder”
French
Saison
Vermont
Ale
Foggy
London
Screening for the STA1 which produces glucoamylase GA1
-Lanes which produce large volumes of the correct size
band are positive for STA1
● French Saison - Contains STA1
○ Confirmed S. diastaticus
● Vermont Ale - no STA1
○ free of S. diastaticus
● Foggy London- no STA1
○ free of S. diastaticus

37. Not all diastaticus strains are equal
PCR is great at checking if a strain poses a gene for an
action, however, it does not tell us how active it is
We devised a plating method to look at how aggressively
each strain secreted glucoamylase - Functionality test
The plates are composed of starch and an indicator that
binds to it
Clear plate = very diastatic

39. Starch Plates - Results
We saw with this test that different organisms can be
MORE or less diastatic than each other, requiring more or
less time to activate upon the beer
This poses some issues for the brewer
● If the strain is slow than diastatic onset may occur
later…...potentially after the beer has left the facility
● If the strain is fast than it can take hold in a ferment
quickly causing large problems in short time

40. Starch Plates Are Sensitive to 0.1% contamination

41. Starch Plates
There are some strains that do not grow on these plates
but are positive for STA1 which require more research
These plates will never replace STA1 PCR however they do
offer an affordable method for breweries to check their
process

42. Other Mediums
Some facilities are recommending a media called LCSM which
selects cells based on copper resistance
● Only copper resistant cell lines grow
There is no functional correlation between copper resistance
and STA1 however most strains that are STA1 are also copper
resistant
● Some non-STA1 strains are also copper resistance which can
leads to false positives from this plating method

44. How do you screen for S. diastaticus?
Summary:
● The gold standard for screening is STA1 PCR however
this requires additional equipment, time and knowledge
● Starch plates work great but are not as rapid as PCR
and may take many days
● LCSM might work but is more error prone
● Proper record keeping is still your first line of defence

45. Want Protocols for these tests?
You can find our protocol for STA1 PCR on our blog (Thanks Alex!)
Demystifying diastaticus (Part 1)
You can read more about our starch plate protocol on our blog too (Thanks Iz!)
Demystifying diastaticus (Part 2)
We publish new information on this and many other topics as we complete new
experiments

47. So….I want to use this strain...But safely
They key to handling this strain is to ensure that you are
indeed CIPing your equipment properly
-Many breweries do not manually inspect CIP
Ensuring that you do not cross contaminate your brews
through shared equipment is the key to keeping these
organisms seperate

48. What organisms pose the greatest risk to your beer?
The classic organisms that pose a threat to your beer have
always been Lacto. Pedio & Brett.
In our new brewing reality S. diastaticus is a more
frequent and impactful threat to your beer
S. diastaticus is everywhere, is more dangerous and
is harder to screen for!

49. Why is this now an issue…...
This is all speculative but
1. Saison yeast are becoming more popular
2. Product distribution is enlarging (longer shelf time)
3. Product is not pasteurized and/or filtered
4. Brewhouses are being upgraded - old inefficient
machinery tends to dry beers out more (inability to
mash out = longer mash). New brewhouse produces a
beer with more dextrins due to tech improvements
5. Breweries are growing and CIP gets left out and/or
does not scale properly with tanks

50. S. diastaticus is a risk
Unless your supplier is doing genetic testing for the
organism then there is still a threat of diastaticus
contamination from the supply side
No level of CIP will fix that
Look for suppliers that mobilize quickly and are proactive
with this threat like Omega labs, Escarpment labs and
Lallemand

51. What has Escarpment Labs Done to ensure you
do not accidently get S. diastaticus
● All core strains have been screened for genetic and functional STA1
○ Additional strain testing is ongoing
● Risk Tier systems are in place for all processing equipment
○ Tier 1 → Tier 2 → Tier 3
● New equipment coming soon dedicated to just Tier 3 - diastaticus only
vessels
● Developing new strains/methods that are STA1 negative to reduce cross
contamination risk for customers (coming soon)
● Providing as much information to our clients (like this presentation, the blog,
etc) to make clients aware of the risks associated with certain strains

52. Don't let this be your beer!

53. Understanding S. diastaticus or
“What I Learned to Stop Worrying and Love Saison”
Summary:
● Controlling S. diastaticus is all about keeping track of where the organisms is
within your facility and ensuring that proper CIP and checks are performed to
ensure ti does not spread
● Risk level management, proper record keeping and lab screening can ensure
that you do not have contaminations
● Anything this organisms touches requires more labour and time to ensure it
does not spread
● Failure to control this organism can result in dangerous and costly product to
you and your customers

55. Thank You
Questions? Comments?