Kvasny Prum. 1959; 5(9): 208-211 | DOI: 10.18832/kp1959026

Determination of beer bitter.Peer-reviewed article

M. KOTRLÁ-HAPALOVÁ

1. Various methods of spectral analysis used for determination of beer bitter have been compared and evaluated. It has been found that all the compared methods give with same sorts of beer identical results, providing the extracting procedure is the same. They fail to provide reliable informations on amount of active bitter matters and cannot serve for correct determination of bitter properties of beer. 2. Experiments with analytic determination of bitter matters in solutions before and after hydrolysis at which both balance and spectral methods were applied, indicate that the spectral analysis can disclose only a fraction of matter i.e. the complex of α-acid, whereas the balance analysis identifies all the matter present. 3. Spectrophotometric methods permit to determine all the bitter acids present before hydrolysis by ebullition and after it. Transition from hexacycle to  pentacycle is not reflected by any change of the spectrum wave lengths. Separation of the said modifications is possible by shaking only. 4. The spectral method is not very suitable for expressing the proportion of bitter matters in beer, since it indicates only a certain part (approximately 1/3) of bitter components, though during the brewing process reactions involving colloidal components of wort transfer into beer all soluble bitter matters. 5. Bitter matters belonging to the  α- complex are present in beer solutions in the first line in colloidal form. The  β - complex of bitter matters is to the contrary  represented chiefly by molecularly bound components. 6. The bitter index based upon the amount of α-bitter acid in the solution does not correspond with actual proportion of molecular to colloidal form of matter. 7. The colorimetric method of determination of the bitter matter contents, based upon the reaction of polyphenol with the Folin-Denis reagent cannot be used for classifying the bitter properties of beer since the α- complex gives under the same conditions three to four times more intensive colours than the β - complex. 8. Chromatographic tests with analogues of bitter matters disclose that the proportion of individual components is the same as in hops of given sort grown in certain district. Conclusuion can be made that all analogues are utilized brewing process in the same degree.1. Various methods of spectral analysis used for determination of beer bitter have been compared and evaluated. It has been found that all the compared methods give with same sorts of beer identical results, providing the extracting procedure is the same. They fail to provide reliable informations on amount of active bitter matters and cannot serve for correct determination of bitter properties of beer. 2. Experiments with analytic determination of bitter matters in solutions before and after hydrolysis at which both balance and spectral methods were applied, indicate that the spectral analysis can disclose only a fraction of matter i.e. the complex of α-acid, whereas the balance analysis identifies all the matter present. 3. Spectrophotometric methods permit to determine all the bitter acids present before hydrolysis by ebullition and after it. Transition from hexacycle to  pentacycle is not reflected by any change of the spectrum wave lengths. Separation of the said modifications is possible by shaking only. 4. The spectral method is not very suitable for expressing the proportion of bitter matters in beer, since it indicates only a certain part (approximately 1/3) of bitter components, though during the brewing process reactions involving colloidal components of wort transfer into beer all soluble bitter matters. 5. Bitter matters belonging to the  α- complex are present in beer solutions in the first line in colloidal form. The  β - complex of bitter matters is to the contrary  represented chiefly by molecularly bound components. 6. The bitter index based upon the amount of α-bitter acid in the solution does not correspond with actual proportion of molecular to colloidal form of matter. 7. The colorimetric method of determination of the bitter matter contents, based upon the reaction of polyphenol with the Folin-Denis reagent cannot be used for classifying the bitter properties of beer since the α- complex gives under the same conditions three to four times more intensive colours than the β - complex. 8. Chromatographic tests with analogues of bitter matters disclose that the proportion of individual components is the same as in hops of given sort grown in certain district. Conclusuion can be made that all analogues are utilized brewing process in the same degree.

Keywords: beer, bitterness, spectral analysis

Published: September 1, 1959