| Abstract [eng] |
Hops are the flowers (cones) of hop plant Humulus lupulus L., a member of the Cannabaceae family of flowering plants. Hops are used primarily as a bittering, flavouring, and stabilizing agent in beer; they also valued in herbal medicine for their sedative, anti-inflammatory, antioxidant, antimicrobial, neuroprotective, antitumor, anticarcinogenic and other properties. The mentioned health-beneficial effects are attributed to the structural diversity of secondary metabolites present in hops [1-4]. The aim of this study was to compare chemical composition and aroma profile of hop cones (Lithuanian origin) and commercial pellets (German origin), and determine the total phenolic content (TPC) in EOs (essential oils) and WEs (water extracts). Before analysis cones (C) and pellets (P) were ground by an ultra-centrifugal mill ZM 200 using a 0.5 mm hole size sieve. The aroma compounds of hops C and P were collected by headspace solid phase microextraction and analysed by gas chromatography time-of-flight mass spectrometry (HS-SPMEGC- TOFMS). The EOs were hydrodistilled (HD) in Clevenger type apparatus and further analysed by GCTOFMS. Proximate composition was determined by the standard AOAC methods, total amount of phenolic compounds (TPC) was determined by Folin–Ciocalteu method. It was determined that C were characterized by higher moisture and lipid content, while P were of higher ash and dry matter content: C and P consist of moisture (9.9 and 8.2%), ash (6.6 and 7.7%), lipid (13.9 and 10.4%) and vitamin C (9.9 mg%), respectively. The yields of EO varied from 0.18 (C) to 0.41% (P). The residues after HD were separated to liquid and solid fractions by filtration. The liquid fractions were lyophilized resulting in WEs, yielding from 24.9% (C-WE) to 30.8% (P-WE), respectively. Solid residues yielded from 57.5% (P) to 59.8% (C) of the initial hop raw material subjected to HD. [...]. |
