magistrsko delo
Nik Mahnič (Author), Bojana Bogovič Matijašić (Reviewer), Polona Jamnik (Mentor)

Abstract

Arthrospira platensis (spirulina) je mikroalga, ki jo ljudje že tisočletja uživamo predvsem zaradi visoke vsebnosti visokokakovostnih beljakovin, vitaminov, mineralov in drugih bioaktivnih spojin. Zaradi znanih ugodnih vplivov mlečnokislinske fermentacije na obstojnost, funkcionalnost in senzorične lastnosti živil, smo svežo biomaso mikroalge A. platensis podvrgli mlečnokislinski fermentaciji z dvema vrstama mlečnokislinskih bakterij – Lactobacillus plantarum in Lactobacillus brevis. S spreminjanjem velikosti inokuluma (1 %, 5 % (v/v)), dodanih hranil (dH2O, raztopina glukoze in kvasnega ekstrakta, ter 0,9 in 3 % (m/v) NaCl) in časa fermentacije (24, 48, 72 h) smo iskali optimalne razmere fermentacije glede na merjene parametre (vrednost pH, koncentracija mlečnokislinskih bakterij in koncentracija mlečne kisline). Mlečnokislinska fermentacija je najbolj učinkovito potekla z 1 % inokulumom in dodatkom fiziološke raztopine kot tekočine. Zaradi nespremenjenih vrednosti v času med 24 in 72 h smo se odločili, da je optimalen čas fermentacije 24h. Ugotovili smo tudi, da so v mikroalgni biomasi že prisotne nativne mlečnokislinske bakterije, ki do neke mere samostojno izpeljejo fermentacijo, a večjega prispevka ob uporabi starterske kulture ne dajo. Preizkusili smo tudi antioksidativno učinkovitost vodnih in etanolnih ekstraktov nefermentirane in fermentirane mikroalgne paste na celicah kvasovk Saccharomyces cerevisiae. V primerjavi z nefermentirano pasto se je po fermentaciji antioksidativna učinkovitost etanolnih ekstraktov paste povečala, pri vodnih ekstraktih pa se ni spremenila oz. se je zmanjšala, kar pa je bilo odvisno od koncentracije ekstrakta in uporabljene starterske kulture. Mikroalga A. platensis se je izkazala kot dober samostojni substrat za mlečnokislinsko fermentacijo, pri čemer so se spremenile tudi antioksidativne lastnosti, ki smo jih preverili na celičnem modelu.

Keywords

mikroalge;cianobakterije;Arthrospira platensis;spirulina;mlečnokislinska fermentacija;Lactobacillus plantarum;Lactobacillus brevis;optimizacija;antioksidativna učinkovitost;Saccharomyces cerevisiae;

Data

Language: Slovenian
Year of publishing:
Typology: 2.09 - Master's Thesis
Organization: UL BF - Biotechnical Faculty
Publisher: [N. Mahnič]
UDC: 582.232:602.42+604.4:577.1
COBISS: 5107832 Link will open in a new window
Views: 872
Downloads: 313
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Other data

Secondary language: English
Secondary title: Optimization of lactic acid fermentation of cianobacteria species Arthrospira platensis
Secondary abstract: Arthrospira platensis (spirulina) belongs to microalgae and has been consumed by humans for millennia mainly because of its high content of high quality proteins, vitamins, minerals and other bioactive compounds. Due to the known beneficial effects of lactic acid fermentation on the shelf life, functionality and sensory properties, fresh biomass of A. platensis microalgae was subjected to lactic acid fermentation by two lactic acid bacteria species - Lactobacillus plantarum and Lactobacillus brevis. By varying inoculum size (1 %, 5 % (v / v)), nutrients added (dH2O, solution of glucose and yeast extract, 0.9 and 3 % (w/v) NaCl) and fermentation time (24, 48, 72 h) the optimal fermentation conditions according to the measured parameters (pH, lactic acid bacteria concentration and lactic acid concentration) were selected. Lactic acid fermentation proceeded optimal with 1 % inoculum and addition of 0,9 % (w/v) NaCl as a liquid. Due to the constant values between 24 and 72 h, 24 h was selected as the optimal fermentation time. We also found that native lactic acid bacteria are already present in the microalgal biomass, which independently perform the fermentation to some extent, but they do not make a major contribution when using starter culture. Furthermore, the antioxidant activity of water and ethanol extracts of non-fermented and fermented microalgae paste using yeast Saccharomyces cerevisiae was tested. Compared to non-fermented paste, the antioxidant activity of ethanol paste extracts increased after fermentation, but decreased or did not change in water extracts, depending on the concentration of the extract and the starter culture used. The A. platensis microalgae proved to be a good sole substrate for lactic acid fermentation where their antioxidative properties tested on the cell model also changed.
Secondary keywords: microalgae;cyanobacteria;Arthrospira platensis;spirulina;actic acid fermentation;Lactobacillus plantarum;Lactobacillus brevis;optimization;antioxidant activity;Saccharomyces cerevisiae;
Type (COBISS): Master's thesis/paper
Study programme: 0
Embargo end date (OpenAIRE): 1970-01-01
Thesis comment: Univ. v Ljubljani, Biotehniška fak., Oddelek za živilstvo
Pages: XII, 44 f., [8] f. pril.
ID: 11238862