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Ekstrakcija hmeljnih komponent med hladnim hmeljenjem ležak piva
ID Medved, Zarja (Author), ID Žnidaršič Plazl, Polona (Mentor) More about this mentor... This link opens in a new window, ID Košir, Iztok Jože (Comentor)

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Abstract
Hladno hmeljenje je pivovarska tehnika, kjer se hmelj ali hmeljni proizvodi dodajo pivu med fermentacijo ali zorenjem. S to tehniko pivovarji dosežejo prenos hmeljnih komponent v pivo, ki spremenijo aromo in profil okusa piva. Proces hladnega hmeljenja se precej razlikuje od tradicionalnega hmeljenja med vretjem sladice in je v zadnjih letih vzbudilo veliko zanimanja. Tehnika je novost v proizvodnji piva, zato so določeni deli procesa še nepojasnjeni in potrebni proučitve. V tej študiji smo izvedli eksperimente hladnega hmeljenja na laboratorijski ravni, kjer smo uporabljali ležak pivo. Proučevali smo vpliv več različnih faktorjev, kot so vpliv trajanja procesa, vpliv sorte hmelja, temperature in mešanja na ekstrakcijo hmeljnih komponent v pivo. Proces smo vodili pri različnih temperaturah ter ga izvajali dinamično (z mešanjem) ali statično (brez mešanja). Osredotočili smo se na razumevanje ekstrakcije grenčičnih spojin med hladnim hmeljenjem. Te hmeljne spojine so: α-kisline, izo-α-kisline in polifenoli. Rezultati kažejo, da se koncentracija α-kislin in polifenolov med hladnim hmeljenjem poveča, medtem ko se koncentracija izo-α-kislin zmanjša. Ugotovili smo, da je ekstrakcija hmeljnih komponent odvisna od več dejavnikov, kot so sorta hmelja, temperatura in intenzivnost mešanja, pa tudi lastnosti osnovnega piva, kot sta pH in vsebnost alkohola. Spektrofotometrično smo določevali grenčico (angl. International Bitterness Units – IBU) hladno hmeljenega piva, s čimer smo dobili vpogled v ekstrakcijo manj proučenih grenčičnih komponent hmelja. Na osnovi rezultatov se pod vprašanje postavlja uporabnost te analitske metode za ocenjevanje grenčice v hladno hmeljenih pivih in izpostavlja potreba po izboljšanih analitičnih metodah za natančno kvantifikacijo kompleksnih sprememb v sestavi piva med procesom hladnega hmeljenja. Naše ugotovitve prispevajo k delnemu razumevanju spreminjanja vsebnosti hmeljnih komponent v pivu med hladnim hmeljenjem, kar daje pomembne informacije za pivovarje, ki imajo cilj optimizirati proizvodnjo hladno hmeljenega piva in njegovih grenčičnih profilov.

Language:Slovenian
Keywords:hladno hmeljenje, alfa kisline, izo-alfa kisline, polifenoli, grenčica
Work type:Master's thesis/paper
Typology:2.09 - Master's Thesis
Organization:FKKT - Faculty of Chemistry and Chemical Technology
Year:2023
PID:20.500.12556/RUL-150903 This link opens in a new window
COBISS.SI-ID:173197827 This link opens in a new window
Publication date in RUL:25.09.2023
Views:779
Downloads:71
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Secondary language

Language:English
Title:Extraction of hop components during dry hopping of lager beer
Abstract:
Dry hopping is a brewing technique where hops or hop products are added to the process during beer fermentation or maturation. This technique is used by brewers to impart hop characteristics to the beer, which in turn changes the aroma and flavour profile. The dry hopping process differs significantly from traditional kettle hopping during wort boiling and has gained substantial interest in recent years. However, due to its novelty, certain aspects of dry hopping remain unexplored and require further studies. In this study, we conducted dry hopping experiments at the laboratory scale using lager beer. We investigated the influence of various factors such as the duration of the process, different hop varieties, temperature, and agitation on the extraction of hop components into the beer. The process was conducted under varying conditions of temperature and agitation – dynamic (with mixing) and static (without mixing). Specifically, we focused on understanding the extraction of bittering compounds during dry hopping, which include α-acids, iso-α-acids, and polyphenols. Our results indicate that the concentration of α-acids and polyphenols increases during dry hopping, while the concentration of iso-α-acids decreases. We found that the extraction of hop components depends on factors like hop variety, temperature, agitation intensity, as well as the initial beer characteristics such as pH and alcohol content. Additionally, we evaluated the dry-hopped beers using spectrophotometric analysis to determine their bitterness, quantified as International Bitterness Units (IBU). This provided insights into the extraction of less studied bittering hop compounds. Our study raises questions about the suitability of this analytical method for assessing bitterness in dry-hopped beers and highlights the need for improved analytical techniques to accurately quantify the complex changes in beer composition during the dry hopping process. These findings contribute to a partial understanding of how hop components interact with beer matrices during cold hopping, offering valuable information for brewers aiming to optimize the production of dry-hopped beer and its bitterness profiles.

Keywords:dry hopping, alpha acids, iso-alpha acids, polyphenols, bitterness

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