Comparison of 4-Mercapto-4-methylpentan-2-one Contents in Hop Cultivars from Different Growing Regions

Abstract

Contributions of hop-derived thiols were examined. Extremely strong fruity, black currant-like aromas were detected in beers hopped with some U.S. cultivars. 4-Mercapto-4-methylpentan-2-one (4MMP) was supposed to be the main contributor to the fruity aroma, and the contents between cultivars were investigated. In hop pellets, a negative correlation between 4MMP concentration and copper ion content in hops was observed. 4MMP was detected only in U.S., Australian, and New Zealand cultivars, but no European ones, which are treated with copper-containing fungicides (Bordeaux mixture) and therefore have a high content of copper ions. The 4MMP content was highest in Simcoe cultivars, followed by Summit, Apollo, Topaz, Cascade pellets, and also differed between crop years. It was indicated that most 4MMP exists freely in wort or in hop pellets with only small amounts formed from precursors and that the amounts increased during the fermentation process.

The Significance of Volatile Sulfur Compounds in Food Flavors

“…This organomercury compound has been applied to determine polyfunctional thiols in beer (10,11), hops (11,12), and cheese (13). Typically, the sodium salt of pHMB is used to directly extract thiols from aqueous samples, while pHMB is used to concentrate thiols from organic solvent extracts of flavor compounds.…”

“…Multidimensional gas chromatography, especially heart-cut bidimensional gas chromatography, now offers an elegant alternative approach for identifying trace odorants. This hyphenated technique, combined with olfactometry, has recently been used to identify sulfur flavors in wines (23) and beer (11), thus suggesting new solutions for trace analysis.…”

“…It is also a characteristic flavorant in Japanese green tea (sen-cha) (58), a main contributor to the "fruity" aroma in beer made with certain hops (11), and contributes significantly to the flavor of hand-squeezed grapefruit juice (59). Representative chemical structures for sulfur-containing character-impact compounds in fruits are shown in Figure 2.…”

Influence of growing area, plant age, and virus infection on the contents of hop secondary metabolites

“…He pointed out the considerable differences between German and all other Tettnanger samples. Kishimoto et al (2008) monitored the impact of the growing region on the amount of 4-mercapto-4-methylpentan-2-one (4MMP) in the hop cultivars Perle and Nugget (crops 2005 and 2006). According to their study, the hop samples from the plants grown in Germany contained no 4MMP in contrast to those grown in USA.…”

Profilling of czech hop varieties by means of analyses of α- and β-bitter acids, essential oils and polyphenols.

“…The main disadvantage of this method is that the contents of these substances depend on a number of external factors such as growing area [7], plant health [8] and processing method [9]. Therefore, all results of profiling not only must be confirmed by repeated analyses of samples from different years of harvest and different growing areas but also by statistical analyses.…”