This document summarizes research on beer foam and the impact of lipids on foam stability. It finds that some roasted malts contain foam-negative lipids, while others enhance foam. Experiments isolate foam-active and inhibitory lipids in specialty malts through extraction, thin-layer chromatography, and foam testing of recovered lipid fractions. Key findings include identifying hydroperoxy lipids in some malts that inhibit foam and characterizing the foam properties of lipid classes extracted from different malts. The document evaluates various analytical techniques for studying lipids and their relationship to beer foam quality.

1. Papal Bull: Recent work on
Beer Bubbles
Charlie Bamforth

2. “I maintain that widgets have done more for foam
quality than all the eminent biochemists in the history of
this industry”
“Thank you for the copies of your book….on goalkeepers….
Were I unkind I might suggest that it is less (than) clear
which publication (this or the papers on beer proteins) would
be of greater value to someone wishing to establish a
practical means of improving the quality of beer foam!”

3. Foam
Positives
polypeptide
iso- -acids
Maillard products
PGA
Me 2+
N2
Negatives
Lipid
Detergents
Ethanol

4. Shaking procedure
Shake 10x, 15” arch, within 3 seconds
Remove cap, stand 30 minutes
Measure liquid and foam height
Kapp & Bamforth J. Sci Food Ag, 2002

5. Problems with beer foams – how to
interpret

6. ultrafiltration
Molecular weight <1,000
Molecular weight > 1,000

7. Ultrafiltration
90-mm static
ultrafiltration cell
1,000 nominal MW
membrane to
separate low and high
MW fractions
Shake test “as is” and
with varying additions
of egg albumin

8. Y-axis: foam stability by Kapp and Bamforth shaking method
X-axis: addition of egg albumin
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
0 0.5 1 1.5
mg/mL protein
foam
height
after
30
min.
(cm)
Control
Retentate
Permeate
In pack

9. Sepharose Sepharose + Lipid
Binding Protein
Shaking test for foam stability

10. "In-pack" Beer Untreated
Control
Sepharose
Sepharose with Lipid Binding
Protein
Foam height after 30 min. (cm)
Pale Ale 0.93 0.30 1.10*
Lager 2.13 1.83 1.87
Light Lager 1.73 0.97 1.60*
Lager 1.03 1.07 1.37‡
Light Lager 1.77 1.40 1.63
Stout 0.57 0.63 1.27*
Lager 1.27 0.53 1.13*
Malt Liquor 2.30 1.93 2.60*
Low carb beer 1.90 1.60 1.60
Pale Ale 1.51 1.67 1.60
* = p < 0.01 ,** = p < 0.05, ‡ = p < 0.10

11. Dr. Laurence Bishop suggested in 1977
that kilning and roasting reactions lead
to protein-polysaccharide complexes
that are particularly foam-enhancing.
We started this project in order to confirm
this and isolate these materials, BUT …

12. … we found that there are foam
NEGATIVE substances that can be
produced when grain is strongly heated!

13. ASBC Mash Method to extract
grains
50 g fine grind cereal
200 mL H2O
45°C for 30 minutes
100 mL H2O
70°C for 60 minutes
Gravity filtration
Foam test within 24
hours

14. 0
5
10
15
20
25
30
35
Foam
Height
(mm)
Cereal
Single-Cereal Mash Foam Stabilities

15. 0.0
2.0
4.0
6.0
8.0
10.0
12.0
14.0
16.0
0.000 1.000 2.000 3.000 4.000
Foam
Height
(mm)
Wort Protein Content (% of malt, db)
2-Row Serial Dilution Foam Stabilities
0.0
5.0
10.0
15.0
20.0
25.0
30.0
0.000 1.000 2.000 3.000 4.000 5.000
Foam
Height
(mm)
Wort Protein Content (% of malt, db)
2-Row (Boiled Wort) Serial Dilution
Foam Stabilities
2-Row malt
as is
boiled

16. 0.0
2.0
4.0
6.0
8.0
10.0
12.0
14.0
16.0
0.000 1.000 2.000 3.000 4.000
Foam
Height
(mm)
Wort Protein Content (% of malt, db)
2-Row Serial Dilution Foam Stabilities
0.0
2.0
4.0
6.0
8.0
10.0
12.0
14.0
16.0
18.0
0.000 1.000 2.000 3.000 4.000 5.000
Foam
Height
(mm)
Wort Protein Content (% of malt, db)
2-Row (De-fatted Malt) Serial Dilution
Foam Stabilities
2-Row malt
as is
de-fatted

17. 0.0
0.5
1.0
1.5
2.0
2.5
3.0
0.000 1.000 2.000 3.000 4.000
Foam
Height
(mm)
Wort Protein Content (% of malt, db)
Crystal 75L Serial Dilution Foam
Stabilities
0.0
2.0
4.0
6.0
8.0
10.0
12.0
14.0
16.0
18.0
0.000 2.000 4.000 6.000 8.000
Foam
Height
(mm)
Wort Protein Content (% of malt, db)
Crystal 75L (Boiled Wort) Serial
Dilution Foam Stabilities
Crystal 75L
malt
as is
boiled

18. Crystal 75L
malt
as is
de-fatted
0.0
0.5
1.0
1.5
2.0
2.5
3.0
0.000 1.000 2.000 3.000 4.000
Foam
Height
(mm)
Wort Protein Content (% of malt, db)
Crystal 75L Serial Dilution Foam
Stabilities
0.0
2.0
4.0
6.0
8.0
10.0
12.0
0.000 1.000 2.000 3.000 4.000
Foam
Height
(mm)
Wort Protein Content (% of malt, db)
Crystal 75L (De-fatted Malt) Serial
Dilution Foam Stabilities

19. 0.0
5.0
10.0
15.0
20.0
25.0
30.0
35.0
40.0
0.000 2.000 4.000 6.000 8.000 10.000
Foam
Height
(mm)
Wort Protein Content (% of malt, db)
Black Patent Serial Dilution Foam
Stabilities Black Patent
malt
as is
boiled
0.0
5.0
10.0
15.0
20.0
25.0
30.0
35.0
40.0
45.0
0.000 2.000 4.000 6.000 8.000 10.000
Foam
Height
(mm)
Wort Protein Content (% of malt, db)
Black Patent (Boiled Wort) Serial
Dilution Foam Stabilities

20. 0.0
5.0
10.0
15.0
20.0
25.0
30.0
35.0
40.0
0.000 2.000 4.000 6.000 8.000 10.000
Foam
Height
(mm)
Wort Protein Content (% of malt, db)
Black Patent Serial Dilution Foam
Stabilities
0.0
5.0
10.0
15.0
20.0
25.0
30.0
35.0
40.0
45.0
50.0
0.000 2.000 4.000 6.000 8.000 10.000
Foam
Height
(mm)
Wort Protein Content (% of malt, db)
Black Patent (De-fatted Malt) Serial
Dilution Foam Stabilities
Black Patent
malt
as is
de-fatted

21. Ultrafiltration
90-mm static
ultrafiltration cell
1,000 nominal MW
membrane to
separate low and high
MW fractions
Shake test “as is” and
with varying additions
of egg albumin

22. Ultrafiltered extract of 2-row
malt
0.0
5.0
10.0
15.0
20.0
25.0
30.0
0 0.5 1 1.5
Foam
Height
(mm)
CEWA Protein Concentration
(mg/mL)
Ultrafiltered 2-Row Foam
Stabilities
Retentate Permeate
Control H2O Control Wort

23. Ultrafiltered extract of Crystal
75L
0.0
5.0
10.0
15.0
20.0
25.0
30.0
0 0.5 1 1.5
Foam
Height
(mm)
CEWA Protein Concentration
(mg/mL)
Ultrafiltered Crystal 75L
Foam Stabilities
Retentate Permeate
Control H2O Control Wort

24. 0.0
5.0
10.0
15.0
20.0
25.0
30.0
35.0
0 0.5 1 1.5
Foam
Height
(mm)
CEWA Protein Concentration
(mg/mL)
Ultrafiltered Black Patent
Foam Stabilities
Retentate Permeate
Control H2O Control Wort
Ultrafiltered extract of Black
Patent

25. 80.0
85.0
90.0
95.0
100.0
105.0
110.0
Rudin
Half-life
(s)
Rudin Values of Pilot Brews
Aggie's Ale (100% Pale malt) Aggie's Ale (20% Crystal 75L malt)
Aggie's Ale (20% Crystal 120L malt)

26. Foam Inhibition
Model Beer
– 0.1M Acetic Acid pH 4.5
– 31.7g/kg Ethanol
– 75µg/mL albumin extract from
barley
– 20mg/m3 iso-α-acid
Linoleic acid used as
positive control
Freeze dried C75 tested
as foam inhibitor

27. Foam Inhibition of Linoleic Acid and Crystal 75
0
1
2
3
4
5
6
7
8
9
10
0 0.1 0.25 0.5 1 2.5 5
Foam
Height
(mm)
Linoleic Acid Concentration (ug/mL)
Linoleic Acid
FD C75
Freeze Dried Crystal 75 Concentration (mg/mL)
0.25 2.5
0 0.5 1 5

28. Thin Layer Chromatography
Worts produced using ASBC
extract method
Extraction of lipids though Folch
method
– 1:3 wort:Folch reagent (1:1
chloroform:methanol)
Lipid extracts dried down under N2
Dried lipids re-suspended in
chloroform and plated on Silica
plates
Plates developed for ~20 minutes in
80:20:1 Petroleum ether: Ether:
Acetic Acid

29. TLC Lipid Class Reference Plate
NP-Nonpolar lipids
TG-Triglyceride
FFA-Free Fatty Acid
DG-Diglyceride
MG-Monoglyceride
PL-Phospholipid

30. TLC of Single Malt Worts
NP
FAME
TG
FFA
DG
NP
FAME
TG
FFA
DG

31. Hydroperoxy Lipids in Wort
NP
TG
FFA
DG
MG

32. Lipids Profiles of Malt
CE
TG
FFA
DG
MG

33. Foam Stabilities of Specialty Worts
0
2
4
6
8
10
12
14
Foam
Height
(mm)
Specialty Malt

34. Lipid Profiles of Specialty Worts
NP
TG
FFA
DG
MG
PL

35. Lipid Profiles of Specialty Worts
CE
TG
FFA
DG
MG
PL

36. TLC plates were
developed
A portion of the plate
was heated and
visualized
Corresponding areas
were scraped off
Lipids eluted with ether
Solution was evaporated
under nitrogen
Lipids retaken in ethanol
and dosed into model
beer
Recovery of Lipids from Plates

37. Foam Stabilities of Recovered Lipids
C75 Ox LA
NP
TG
Ox FA
Hydroperoxy
Origin
Ox LA
LA
Unknown
0
2
4
6
8
10
12
Foam
Height
(mm)
Position of Scraped Bands

38. cwbamforth@ucdavis.edu