Priprava in karakterizacija ekstraktov cianobakterij vrste Arthrospira platensis pred in po mlečnokislinski fermentaciji

Mrak, Aleksandra (author), Pogačnik, Lea (mentor)

V okviru naše raziskave smo optimizirali ekstrakcijo nefermentirane in fermentirane paste cianobakterij vrste A. platensis ter primerjali vsebnost skupnih fenolnih spojin (SF) in antioksidativno učinkovitost (AOU) vodnih in etanolnih ekstraktov nefermentirane paste z ekstrakti fermentirane paste. Pasta A. platensis je bila fermentirana z dvema različnima vrstama mlečnokislinskih bakterij rodu Lactobacillus (Lb. plantarum ali Lb. brevis), različno dolgo (24, 48 in 72 ur). Za najučinkovitejšo se je izkazala dvostopenjska ekstrakcija (dvakrat po pol ure) v vodni kopeli pri 40 °C z uporabo destilirane vode (dH2O) ali 96 % etanola kot ekstrakcijskima topiloma. SF smo določali po metodi Folin-Ciocalteu, rezultate pa izrazili kot ekvivalent galne kisline. AOU smo določali z metodo lovljenja prostega radikala DPPH· in rezultate podali kot ekvivalent troloksa. Najvišjo vsebnost SF in AOU smo izmerili v vodnih ekstraktih nefermentirane paste (4,38 mM SF in 1,40 mM AOU), najnižjo pa v etanolnih ekstraktih nefermentirane paste (0,66 mM SF in 0,46 mM AOU). Pri vodnih ekstraktih sta se vsebnost SF in AOU s fermentacijo zmanjšali, medtem ko smo v etanolnih ekstraktih določili višje vrednosti pri ekstraktih fermentirane paste A. platensis. V nadaljevanju smo ekstrakte še posušili in ponovno raztopili v manjši količini topila (vodne z dH2O na 50 mg suhe snovi/mL; etanolne z dimetil sulfoksidom na 100 mg suhe snovi/mL). Pri tem smo ohranili večino antioksidantov.

• Language: Slovenian
• Keywords: cianobakterije, Arthrospira platensis, ekstrakcija, antioksidanti, fenolne spojine, antioksidativna učinkovitost, vsebnost fenolnih spojin, Folin Ciocalteu, DPPH·
• Work type: Master's thesis/paper
• Typology: 2.09 - Master's Thesis
• Organization: BF - Biotechnical Faculty
• Publisher: [A. Mrak]
• Year: 2019
• PID: 20.500.12556/RUL-106370
• UDC: 582.232:66.061:66.094.3.097.8
• COBISS.SI-ID: 5026424
• Publication date in RUL: 20.02.2019

Secondary language

• Language: English
• Title: Preparation and characterisation of cianobacteria species arthrospira platensis extracts before and after the lactic acid fermentation

Abstract

The aim of our study was to optimize the extraction of unfermented and fermented paste of cyanobacteria species A. platensis and to compare the content of total phenolic compounds (TPC) and antioxidant capacity (AOC) of aqueous and ethanolic extracts of unfermented paste extracts with fermented paste extracts. The paste underwent lactic acid fermentation with two different lactic acid bacteria (Lb. plantarum and Lb. brevis) for 24, 48 and 72 hours. The most effective was two-phase extraction (twice for 30 minutes) in water bath at 40 °C using distilled water or 96 % ethanol as extraction solvents. TPC was determined by the Folin-Ciocalteu method and the results were expressed as gallic acid equivalent. AOC was determined by DPPH· radical scavenging method and the results were expressed the as trolox equivalent. The highest TPC and AOC content were determined in aqueous extracts of unfermented paste (4.38 mM TPC and 1.40 mM AOC). The lowest TPC and AOC content was obtained in ethanolic extracts of unfermented paste (0.66 mM TPC and 0.46 mM AOC). In the case of aqueous extracts, the content of TPC and AOC was reduced by fermentation, while the content of TPC and AOC increased in the ethanolic extracts of fermented A. platensis paste. Subsequently, the extracts were dried and re-dissolved in a smaller amount of solvent (aqueous extracts with distilled water to obtain 50 mg dry matter/mL, ethanol extracts with dimethyl sulfoxide to obtain 100 mg dry matter/mL). With this procedure we have managed to preserve most of the antioxidants.

• Keywords: cyanobacteria, Arthrospira platensis, extraction, antioxidants, phenolic compounds, antioxidant capacity, total phenolic compounds, Folin Ciocalteu, DPPH·