Antioksidacijska svojstva i stabilnost boje tijekom ubrzanog i prirodnog starenja piva tamnih piva

undergraduate thesis

• Title (english): Antioxidative properties and color stability in forced and naturally aged beers
• Author: Filip Herceg
• Mentor: Sunčica Beluhan (mentor)
• Granter: University of Zagreb; Faculty of Food Technology and Biotechnology; (Department of Biochemical Engineering); (Laboratory for Biochemical Engineering, Industrial Microbiology and Malting and Brewing Technology); Zagreb
• Defense date and country: 2015-09-09, Croatia
• Scientific / art field, discipline and subdiscipline: BIOTECHNICAL SCIENCES; Biotechnology; Engineering

Abstract

Pivo je piće dobiveno alkoholnom fermentacijom sladovine, većinom pripravljene samo od ječmenog slada, no mogu se dodati i neslađene žitarice, kao što su kukuruz, pšenica ili riža. Smatra se dobrim izborom polifenola kojima je izvorište u ječmenom sladu i hmelju. U ovom je radu određivan oksidacijski profil dva različita tipa hrvatskih tamnih piva podvrgnutih ubrzanom postupku starenja (6 dana pri 42 oC) i prirodnom starenju (4 mjeseca pri sobnoj temperaturi). U uzorcima su određivani udjel ukupnih polifenola, sposobnost vezanja slobodnih radikala (DPPH), redukcijska snaga i stabilnosti boje piva tijekom istraživanja. Rezultati ubrzanog starenja piva su pokazali da se nije dogodila promjena u udjelu ukupnih polifenola i antioksidacijskog kapaciteta. Piva koja su prirodno starila imala su smanjeni udjel polifenola, smanjenu reducirajuću snagu i antioksidacijski kapacitet. Za smanjenje moguće nestabilnosti boje piva preporučeno je skladištenje piva bez prisustva kisika pri niskim temperaturama.

Abstract (english)

Beer is a beverage obtained through alcoholic fermentation of malt wort, usually made of barley, which could be added of other cereals, such as corn, wheat or rice. It can be considered a good source of polyphenols derived from barley malt and hops. This study evaluated the oxidative profile of two different types of Croatian dark beer submitted to a forced aging process (6 days at 42 oC) and natural aging (4 months at room temperature). The applied tests were: total polyphenol content, free radical scavenging ability (DPPH), reducing power and beer color stability. Results showed no changes in total polyphenol content or antioxidant capacity during forced aging. Beers aged naturally showed a decrease in their polyphenol content, reducing power and antioxidant capacity. Beer storage in the absence of oxygen and at low temperature is recommended so as to minimize beer color instability.

• Keywords: tamno pivo; polifenoli; antioksidacijski kapacitet; starenje; skladištenje
• Keywords (english): dark beer; polyphenols; antioxidant capacity; aging; storage
• Language: croatian
• URN:NBN: urn:nbn:hr:159:570136
• Study programme: Title: Biotechnology; Study programme type: university; Study level: undergraduate; Academic / professional title: sveučilišni/a prvostupnik/prvostupnica (baccalaureus/baccalaurea) inženjer/inženjerka biotehnologije (sveučilišni/a prvostupnik/prvostupnica (baccalaureus/baccalaurea) inženjer/inženjerka biotehnologije)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2015-12-15 11:23:43