Določanje pristnosti hmelja (Humulus lupulus L.) in analiza aromatičnih sestavin hmelja v pivu

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Podatki

Jezik:	Slovenski jezik
Leto izida:	2018
Tipologija:	2.08 - Doktorska disertacija
Organizacija:	UL BF - Biotehniška fakulteta
Založnik:	[M. Ocvirk]
UDK:	633.791:663.4:543.2/.9
COBISS:	4917112
Št. ogledov:	3
Št. prenosov:	0
Ocena:	0 (0 glasov)
Metapodatki:

Ostali podatki

Sekundarni jezik:	Angleški jezik
Sekundarni naslov:	Determination of hop (Humulus lupulus L.) authenticity and analysis of hop aroma compounds in beer
Sekundarni povzetek:	The aim of this study was to determine the botanical origin of hops (Humulus lupulus L.), from the results of analysis of the amount and contents of essential oil and contents of alpha- and beta-acids, which are genetically influenced. With the use of multivariant statistics, we have successfully distinguish between the five most common cultivars grown in Slovenia. For the determination of geographical origin, we have collected 77 samples of hop cones which are representative of the major hop-growing regions of the World. Isotopic ratios can act as fingerprints for different growing regions from around the world and we observe clustering of hop samples based on significant differences between growing regions based on δ15N and δ34S values. The δ13C values which are the least discriminative in determination of geographical origin, proved to be the most discriminative in determination of botanical origin of four Slovenian varieties. We made a clustering of beer samples on appropriate ones and ones with some minor deviations, based on the results of analysis of aroma profile and contents of higher alcohols and esters in combination with chemometrics. Our results show that these deviations in beer aroma are not a consequence of a permanent repeatable error in the brewing process, because the samples with deviations are not forming their own unique group, but are scattered around appropriate ones. The optimal time of hopping with intent to achieve high bitterness is no longer, than 100 min. Cooking longer leads to degradations of iso-alpha-acids. During wort boiling, great reductions of hop essential oil components are noticed, even to the bellow detection limit. We have shown that, even though hop extracts consist of around 70 % of alpha- and beta-acids, isomerization process of alpha-acids are not responsible for the observed thermal transitions.
Sekundarne ključne besede:	hop;Humulus lupulus L.;hop extract;alpha-acids;iso-alpha-acids;essential oil;beer;hopping;aroma;higher alcohols;esters;differential scanning calorimetry;HS-SPME;GC;MS;GC-FID;FTIR;HPLC;authenticity;geographical origin;botanical origin;stable isotope carbon ratio;stable isotope sulphur ratio;stable isotope nitrogen ratio;GC-C-IRMS;chemometrics;
Vrsta dela (COBISS):	Doktorsko delo/naloga
Študijski program:	0
Konec prepovedi (OpenAIRE):	1970-01-01
Komentar na gradivo:	Univ. v Ljubljani, Biotehniška fak.
Strani:	VIII, 88 f.
ID:	10937957