Abstract: The aim of this study is to explore the main causes of different xanthohumol contents in different breeds. Six different beer and similar color dilution black ink shading experiments were conducted to compare their effects on the photoisomerization of xanthohumol samples. The results showed that any kind of beer covered or mixed into the sample could inhibit the photoisomerization of xanthohumol, and the inhibition effect of dark beer was better than that of light beer. In addition, the use of diluted black ink can also inhibit the photoisomerization of xanthohumol samples. The effect is consistent with the black beer with similar chromaticity. When adding different kinds of beer to xanthohumol samples and covering them with the same thickness of black ink, all varieties of beer could inhibit the decreasing of OD370, but there was no significant difference between all kinds of beer. And it implied that the real reason for the difference of xanthohumol content in different beer is that different brewers have different light transmittance, rather than the small molecule inhibitors in beer. 

Key words: beer, xanthohumol, content difference, photoisomerism