Influence of Extraction Methods on Polyphenol Profile and Antiradical Activity of Hops

Area of Science:

• Agricultural Chemistry
• Food Science
• Phytochemistry

Background:

• Hop polyphenols are vital for beer stability and offer biological activities.
• Limited data exists on how extraction conditions affect hop polyphenol recovery and antioxidant potential.

Purpose of the Study:

• To compare hot-water extraction with 80% aqueous acetone extraction for hop polyphenol analysis.
• To assess the impact of extraction solvent on polyphenol content and antiradical activity in Czech hop cultivars.

Main Methods:

• Extraction of four Czech hop cultivars using hot water and 80% aqueous acetone.
• Quantification of group-type polyphenols, total polyphenols, anthocyanogens, and flavonoids.
• UHPLC-HRMS analysis for detailed flavonoid profiling.
• DPPH assay to evaluate antiradical activity.

Main Results:

• Aqueous acetone extraction yielded significantly higher anthocyanogens and prenylflavonoids.
• Acetone extracts consistently demonstrated higher antiradical activity, especially in hops with high α-acid content.
• Hot-water extracts showed slightly higher total polyphenols but lower anthocyanogens and antioxidant capacity.
• Antiradical activity in water extracts correlated with polyphenol levels, while acetone extracts were influenced by polyphenols and bitter acids.

Conclusions:

• The choice of extraction solvent critically influences hop polyphenol profiles and antioxidant properties.
• Aqueous acetone is more effective for isolating bioactive polyphenol fractions with significant antiradical performance.
• Optimized extraction methods are essential for maximizing the recovery of beneficial hop compounds.