Optimiranje uvjeta uzgoja tibicosa na saharozi

master's thesis

• Title (english): Optimization of tibicos cultivation on sucrose
• Author: Domagoj Kurtoić
• Mentor: Antonija Trontel (mentor)
• Committee member: Božidar Šantek (predsjednik povjerenstva)
• 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: 2020-09-29, Croatia
• Scientific / art field, discipline and subdiscipline: BIOTECHNICAL SCIENCES; Biotechnology

Abstract

Tibicos ili zrnca „kefirnog napitka“ sastoje se od združene kulture bakterija i kvasca te
polisaharida koje proizvode navedeni mikroorganizmi. Simbiotski odnos mikroorganizama omogućava
zajedničku fermentaciju i dobivanje konačnog proizvoda – „kefirnog napitka“. Zrnca korištena za uzgoj
su nabavljena iz privatnog kućnog uzgoja te je njihov točan mikrobiološki sastav nepoznat. U ovom
radu provedeno je optimiranje uvjeta uzgoja kefirnog napitka (temperatura, različita koncentracija
saharoze). Uzgoj je proveden u prethodno steriliziranim vodenim otopinama saharoze različitih
koncentracije (20 -100 g Lˉ¹) i pri različitim temperaturama uzgoja (20-40 °C). Naknadno je određen
utjecaj alternativnih supstrata šećernih alkohola (eritrola i ksilitola) te stevije na metaboličku aktivnost
zrna kefirnog napitka. Alternativni supstrati nisu metabolizirani što ih čini upotrebljivima kao dodana
sladila u konačnoj formulaciji proizvoda. Između testiranih vrijednosti za temperaturu fermentacije i
različitih koncentracija saharoze kao optimalni uvjeti određene su temperatura od 30 °C i koncentracija
saharoze od 40 g Lˉ¹. Dinamika rasta zrnaca „kefirnog napitka“ i proizvodnje produkata u optimalnim
uvjetima okarakterizirana je nekim osnovnim biokinetičkim parametrima (YEtOH/S = 0,012 g gˉ¹, PrEtOH = 0,016 g Lˉ¹ danˉ¹; YOctena kis./S = 0,013 g gˉ¹, PrOctena kis. = 0,018 g Lˉ¹ danˉ¹; YMliječna kis./S = 0,028 g gˉ¹, PrMliječna kis. = 0,038 g Lˉ¹ danˉ¹).

Abstract (english)

Tibicos or „water kefir“ grains consist of a mixed culture of bacteria and yeast and polysaccharides produced by these microorganisms. The symbiotic relationship of microorganisms enables balanced fermentation and obtaining the final product – „water kefir“. The grains used for cultivation was obtained from private home cultivation and their exact microbiological composition is unknown. In this paper, the optimization of cultivation conditions (temperature, different sucrose concentration) was performed. The cultivation was carried out in previously sterilized aqueous solutions of sucrose of different concentrations (20 - 100 g Lˉ¹) and at different growing temperatures (20 - 40°C). The influence of alternative substrates of sugar alcohols (erythritol and xylitol) and stevia on the metabolic activity of water kefir grains was also determined. Alternative substrates are not metabolized which makes them useful as added sweeteners in the final product formulation. Between the tested values for the fermentation temperature and different sucrose concentrations, a temperature of 30°C and a sucrose concentration of 40 g Lˉ¹ was determined as optimal conditions. The dynamics of „water kefir grain“ growth and product production under optimal conditions was characterized by some basic biokinetic parameters (YEtOH/S = 0.012 g gˉ¹, PrEtOH = 0.016 g Lˉ¹ dayˉ¹; YAceti acid./S = 0.013 g gˉ¹, PrAcetic acid. = 0.018 g Lˉ¹ dayˉ¹; YLactic acid./S = 0.028 g gˉ¹, PrLactic acid. = 0.038 g Lˉ¹ dayˉ¹).

• Keywords: tibicos; kefirni napitak; određivanje koncentracije metabolita; saharoza; eritrol; ksilitol; stevia
• Keywords (english): tibicos; water kefir; determination of metabolite concentration; erythritol; xylitol; stevia
• Language: croatian
• URN:NBN: urn:nbn:hr:159:049289
• Study programme: Title: Bioprocess Engineering; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra inženjer/inženjerka bioprocesnog inženjerstva (magistar/magistra inženjer/inženjerka bioprocesnog inženjerstva)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2021-01-20 11:54:12