Application of a hop by-product in brewing: reduction in the level of haze-active prolamines and improved antioxidant properties of the beer

Abstract

After supercritical CO 2 extraction of hops or formation of lupulin-enriched pellets (type 45), polyphenol-rich by-products remain. These have some industrial and agricultural applications (preparation of polyphenol extracts and in the production of low-bitterness beers). In this work, both materials were used in pilot-scale brewing experiments for the production of beer enriched with polyphenols. Samples of beer made from these residues underwent analyses for haze-active prolamines, total polyphenols, phenolic monomers, antioxidant capacity, bitterness and colour. An almost identical decrease in the content (from hopped wort to final beer) of the prolamines of approximately 30% was detected in standard beer as well as in the beer prepared from the hop residue (HR 1) after supercritical CO 2 extraction. In contrast, the level of prolamines was reduced by more than 50% in the beer following addition of the hop residue (HR 2) after production of lupulin enriched pellets. Both hop materials contributed to an increase in the antioxidant capacity of the final beer by 21.5 and 11.9%, respectively. Another part of this work was aimed at the investigation of colour and bitterness changes in beers made using hop by-products. Addition of the material HR 2 into the wort caused an increase in colour and in bitterness of the matured beer by 20 and 11% rel., respectively.

Beer metabolomics: molecular details of the brewing process and the differential effects of late and dry hopping on yeast purine metabolism

“…Ferulate originates from malt, and is released during the mash most effectively at 45 °C , which was the mash‐in temperature used in this study. Ferulate has been characterized in hop extracts ; however, analysis of the aqueous fraction of hop extracts in this study revealed no measurable ferulate (data not shown) at the micromolar detection limit of NMR. Myrcene is one of most abundant molecules found in hop oil and was the only hop aroma compound that was able to be identified in this work.…”

Hop tannin extract: a promising tool for acceleration of lautering

“…Polyphenolic pellets (residue after manufacturing of Saaz hop) contain technologically promising phenolics (flavan‐3‐ols, flavonols, phenolic acids etc. ), but also a relatively large amount of sensory active compounds, particularly resins and essential oils . Furthermore, polyphenolic pellets also contain technologically inert compounds (e.g.…”

“…The hot water extract for analyses of total polyphenols and analyses of total oils were performed according to Jelínek et al . .…”

“…Analyses of moisture, αand β-bitter acids and total polyphenols were performed according to EBC Analytica methods 7.2, 7.7 and 9.11 respectively (12). The hot water extract for analyses of total polyphenols and analyses of total oils were performed according to Jelínek et al (4).…”

“…Another property of hop polyphenols that is applicable in brewing is precipitation of haze active proteins. Jelínek and colleagues used spent hop material rich in polyphenols for the preparation of hopped wort and reported a rapid decline in the concentration of haze active malt prolamines during fermentation and maturation of the beers with high levels of flavan‐3‐ols. Similar results have been reported by Pöschl et al .…”