UTILISATION OF SOLID-PHASE MICROEXTRACTION IN HOP OIL ANALYSES
An analytical procedure based on headspace solid-phase microextraction (HS-SPME) has been used for isolation of hop oils from various hop matrices. Fibers coated by polydimethylsiloxane and polydimethylsiloxane/divinylbenzene were used for separation. To obtain results comparable with conventional steam-distillation method SPME separation step have to be performed at elevated temperature (40 50°C) for one hour at least. Sample weight in the range of 0.1 0.3 g (in 4 ml ambre vial) did not influence sorption significantly. The quantity of the sample required for analysis is less than the weight of one hop cone. Factors such as hop variety, age of hops and type of hop matrix have to be taken into account for choice of a suitable SPME fiber. The PDMS 30 μm fiber proved to be most suitable for isolation of hop oils from female hops, PDMS/DVB 65 m fiber is the best one for isolation of hop oils from male hops. Optimised sampling parameters include 0.2-0.3 g of sample weight, temperature 50°C and exposure period 1-2 hours. The composition of hop oils isolated by HS-SPME method showed good complience with conventional steam-distillation method. SPME method was applied for confirmation of purity various cultivars and for analysis of hop oils composition of male hops. Utilisation of SPME helped to confirm the presence of some sesquiterpenoids in bakery products if hops was added in the course of dough preparation. SPME was used for elucidation of changes in hop aroma quality caused by powdery mildew infestation. It was proved that composition of hop oils components in infested cones significantly differ from healthy ones.
Krofta, K. and Nesvadba, V. (2005). UTILISATION OF SOLID-PHASE MICROEXTRACTION IN HOP OIL ANALYSES. Acta Hortic. 668, 191-200
hops (Humulus lupulus), separation procedures, head-space SPME, gas chromatography, male hops, sesquiterpenes, powdery mildew