Taste fraction measurement

To gain further insights into the chemical structure of the compound causing the sweet taste, fraction III-5 was separately collected and analyzed by RP-HPLC. Isolated fractions were analyzed using a diode array detector and a mass spectrometer. The compound exhibiting sweet taste activity upon degustation showed a molecular mass of 197 Da and exhibited two UV-Vis absoiption maxima at 251 and 328 nm when measured at pH 8.2, or a sole maximum at 298 nm when measured at pH 3.5. 

The bitter taste of beer is principally due to the iso alpha acids, the transformation products of the alpha-acids which arise during the boiling of the hopped wort. Although there are two major and a number of minor isomers of the alpha-acids, and the relative proportions do vary from variety to variety, it is not certain that these differences have a marked effect on bitterness quality. In general, therefore, the total alpha-acid content is a measure of the bittering potential of the hop. Since the other soft resin components do not themselves contribute to bitterness, there has not been much incentive for studying the non-alpha acid, or beta fraction, of the soft resin. 

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