Beer Foam is a Carrier of Aroma

Figures & data

Figure 1. Beers before and after foaming.

A can of beer (brand B) stored in a refrigerator (5° C) was removed at room temperature (20° C). Samples of 50 mL (1) or 65 mL (2) of beer were transferred to a measuring container and bubbled by ultrasonic waves for 2 min in an ultrasonic washing machine.

(I) Before foaming and (II) after foaming.

Figure 2. A proton-transfer-reaction time-of-flight mass spectrometer with a dynamic and reactive flavor-release monitoring system.

Figure 3. The behavior of orthonasal aroma components of 65 mL beer A sample before and after foaming.

(1) m/z 43.0542, (2) m/z 45.0355, (3) m/z 57.0699, (4) m/z 60.0525, (5) m/z 71.0855, (6) m/z 89.1050, (7) m/z 131.1067, (8) m/z 145.2139, (9) m/z 173.1536, (10) m/z 201.1848

Figure 4. The behavior of orthonasal aroma components of 65 mL beer B sample before and after foaming.

(1) m/z 43.0542, (2) m/z 45.0355, (3) m/z 57.0699, (4) m/z 60.0525, (5) m/z 71.0855, (6) m/z 89.1050, (7) m/z 131.1067, (8) m/z 145.2139, (9) m/z 173.1536, (10) m/z 201.1848

Table 1. Target compounds in beer.

m/z	Monoisotopic mass	Main components in beer
43.0542	42.0542	Propanol group (–H2O)
45.0355	44.0355	Acetaldehyde
57.0699	57.0699	Butanol group (–H2O)
60.0525	59.0525	Acetone 13 C (Isotope)
63.0190	62.019	Dimethyl sulfide
71.0855	70.0855	Amyl alcohol group (–H2O)
89.1050	88.105	Ethyl acetate
131.1070	130.107	Isoamyl acetate
145.1230	144.123	Ethyl hexanoate
173.1536	172.1536	Ethyl octanoate
201.1849	200.1849	Ethyl decanoate

Figure 5. Comparison of the amount of headspace aroma components in 65 mL beer A sample with and without foaming.

The integral values of the concentration of each aroma component from 100 to 300 s of measurement are shown.

(1) m/z 43.0542, (2) m/z 45.0355, (3) m/z 57.0699, (4) m/z 60.0525, (5) m/z 71.0855, (6) m/z 89.1050, (7) m/z 131.1067, (8) m/z 145.2139, (9) m/z 173.1536, (10) m/z 201.1848

Figure 6. Comparison of the amount of headspace aroma components in 65 mL beer B sample with and without foaming. The integral values of the concentration of each aroma component from 100 to 300 s of measurement are shown.

(1) m/z 43.0542, (2) m/z 45.0355, (3) m/z 57.0699, (4) m/z 60.0525, (5) m/z 71.0855, (6) m/z 89.1050, (7) m/z 131.1067, (8) m/z 145.2139, (9) m/z 173.1536, (10) m/z 201.1848

Figure 7. The behavior of headspace aroma component concentration ratio in 50 mL (1), 65 mL (2), and 75 mL (3) samples of beer A before and after foaming.

Figure 8. The behavior of headspace aroma component concentration ratio in 50 mL (1), 65 mL (2), and 75 mL (3) samples of beer B before and after foaming.

Figure 9. The headspace volume concentration ratio by foaming. Each value was calculated as I volume/II volume.

Figure 10. The behavior of the headspace aroma component content ratio in 50 mL (1), 65 mL (2), and 75 mL (3) samples of beer A before and after foaming.

Figure 11. The behavior of the headspace aroma component concentration ratio in 50 mL (1), 65 mL (2), and 75 mL (3) samples of beer B before and after foaming.

Figure 12. Relationship between the headspace aroma component concentration ratio of 65 mL beer A (1) or B (2) samples before and after foaming and the partition coefficient of the aroma component.

Figure 13. Diagram of the high distribution coefficient aroma components in the gas-liquid interface of beer foam. The figure was drawn with reference to the Summary of AIST press release on August 10, 2018^[9] and the report by Suzuki.^[6]

Harayama, K. Analytical Method of Beer Flavor (Japanese). J. Brew. Soc. Japan. 1995, 90, 919–922. DOI: 10.6013/jbrewsocjapan1988.90.919.

 Google Scholar

Suzuki, W. Beer Foam -Their Lives – (Japanese). J. Brew. Soc. Japan. 1996, 91, 8–14. DOI: 10.6013/jbrewsocjapan1988.91.8.

 Google Scholar