Fermentacija i fizikalno-kemijsko vrednovanje vodenog kefira s potencijalnim zdravstvenim učincima

undergraduate thesis

• Title (english): Fermentation and physicochemical evaluation of water kefir with potential health effects
• Author: Lucija Mataga
• 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: 2024-07-10, Croatia
• Scientific / art field, discipline and subdiscipline: BIOTECHNICAL SCIENCES; Biotechnology

Abstract

Vodeni kefir je tradicionalan fermentiran napitak, a zahvaljujući svojim probiotičkim i prebiotičkim svojstvima, odlična je zamjena za mliječni kefir u veganskoj prehrani ili kod osoba koje su netolerantne na laktozu. U ovome radu istraživana su fiziološka, kemijska i antimikrobna svojstva vodenog kefira tijekom 10 dana fermentacije u negaziranoj vodenoj otopini različitih koncentracija saharoze (50, 80, 120 i 150 g/L). Tijekom fermentacije praćena je potrošnja supstrata i sinteza metabolita (organske kiseline i etanol). Glavni metaboliti fermentacije su bili mliječna i octena kiselina, uz niske koncentracije glukonske kiseline i etanola koji je biooksidacijom preveden u octenu kiselinu. Praćenjem prinosa vodenih kefirnih zrnaca i konačnim koeficijentom konverzije supstrata u biomasu, uočeno je da su pri koncentraciji od 50 g/L saharoze postignuti najbolji rezultati. Antimikrobna aktivnost testirana je na bakterijama Salmonella typhimurium, Pseudomonas aeruginosa i Staphylococcus aureus te kvascu Candida albicans. Primijećeno je izvrsno antimikrobno djelovanje na S. typhimurium i P. aeruginosa, te slabije na kvasac C. albicans i bakteriju S. aureus.

Abstract (english)

Water kefir is a traditional fermented drink, and thanks to its probiotic and prebiotic properties, it is an excellent substitute for milk kefir on a vegan diet or for people who are lactose intolerant. This paper investigated the physiological, chemical and antimicrobial properties of water kefir during 10 days of fermentation in a non-carbonated water solution with different concentrations of sucrose (50, 80, 120, and 150 g/L). Substrate consumption and metabolite synthesis (organic acids and ethanol) were monitored during fermentation. The primary fermentation metabolites were lactic and acetic acid, with low gluconic acid and ethanol concentrations converted into acetic acid by bio-oxidation. By monitoring the yield of water kefir grains and the final conversion coefficient of the substrate into biomass, it was observed that the best results were achieved at a concentration of 50 g/L of sucrose. Antimicrobial activity was tested on Salmonella typhimurium, Pseudomonas aeruginosa, Staphylococcus aureus, and the yeast Candida albicans. Excellent antimicrobial activity was observed against
S. typhimurium and P. aeruginosa, and weaker against the yeast C. albicans and the bacterium S. aureus.

• Keywords: vodeni kefir; organske kiseline; antimikrobna aktivnost
• Keywords (english): water kefir; organic acids; antimicrobial activity
• Language: croatian
• URN:NBN: urn:nbn:hr:159:952623
• 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: 2024-11-12 14:41:54