Optimization of ultrasound-assisted extraction of bioactive compounds from Pelvetia canaliculata to sunflower oil

In this study, Pelvetia canaliculata L. macroalga, collected from the Atlantic Portuguese coast, was used as a source of bioactive compounds, mostly antioxidants, to incorporate them in sunflower oil with the aim of increasing its biological value and oxidative stability. The lyophilized alga was added to the oil, and ultrasound-assisted extraction (UAE) was performed. Algae concentration and UAE time varied following a central composite rotatable design (CCRD) to optimize extraction conditions. The following parameters were analyzed in the oils: oxidation products, acidity, color, chlorophyll pigments, carotenoids, flavonoids, total phenolic content, antioxidant activity by DPPH (2,2-diphenyl-1-picrylhydrazyl) and FRAP (ferric reducing antioxidant power) assays, and sensory analysis. Extraction conditions did not affect the acidity and the amount of oxidation products in the oil. Chlorophylls and carotenoid contents increased with algae concentration, while flavonoid extraction did not depend on algae content or UAE time. Total phenolics in the oil were highly related only to FRAP antioxidant activity. Storage experiments of supplemented oil (12.5% algae; 20 min UAE) were carried out under accelerated oxidation conditions at 60 C/12 days. Antioxidant activity (FRAP) of supplemented oil was 6-fold higher than the value of non-supplemented oil. Final samples retained 40% of their initial antioxidant activity. The presence of algae extracts contributed to the increased oxidative stability of sunflower oilinfo:eu-repo/semantics/publishedVersio

Ultrazvočna ekstrakcija bioaktivnih snovi iz alg vrste Pelvetia canaliculata iz Atlantskega oceana v sončnično olje

The aim of this master thesis was to test antioxidants from algae Pelvetia canaliculata L. that might offer healthier alternative to synthetic antioxidants. In this study, lyophilized P. canaliculata L. from the Portuguese coast was added directly to the antioxidant free sunflower oil. Ultrasound Assisted Extraction for extracting bioactive compounds from the algae into the oil included the following optimization parameters: algae concentration and mass and extraction time. After extraction, the following parameters were analysed in the oils: oxidation products, acidity, colour and determination of chromatic characteristics (chromatic coordinates (x,y), transparency, dominant wavelength and purity), chlorophyll pigments, carotenoids, flavonoids, total phenolic content, antioxidant activity by DPPH (2,2-diphenyl-1-picrylhydrazyl) and FRAP (Ferric Reducing Antioxidant Power) assays, and sensory analysis. Bioactive pigments were successfully extracted from P. canaliculata into the sunflower oil, which consequently increased oil’s antioxidant activity. The chlorophyll and carotenoid content in the supplemented sunflower oils increased as much as 330 and 8-times, respectively. However, the flavonoid and phenolic extractions were limited, with extraction yields up to only 9.40% and 3.10%, respectively. The addition of P. canaliculata did not affect the chemical quality parameters (acidity and oxidation products) of the oil, however it affected the physical and sensory characteristics (colour, smell). In this study, we confirmed that such oils can be beneficial for the food industry, as they have an increased shelf life due to the extracted natural compounds, which also present some health benefits.Namen magistrskega dela je bil preveriti učinkovitost antioksidantov iz alge Pelvetia canaliculata L., ki lahko predstvaljajo bolj zdravo alternativo sintetičnim antioksidantom, ki imajo lahko negativne učinke na zdravje. V tej študiji smo liofilizirane alge P. canaliculata s portugalske obale dodali neposredno sončničnemu olju, ki ni vsebovalo antioksidantov. Optimizirali smo dva parametra ultrazvočne ekstrakcije za ekstrakcijo bioaktivnih spojin iz alg v olje, in sicer koncentracijo (maso) alg in trajanje ekstrakcije. Po ekstrakciji smo v oljih analizirali naslednje parametre: oksidacijske produkte, kislost, barvo in značilnosti barve (kromatske koordinate (x,y), motnost, prevladujoča valovna dolžina in čistost), vsebnost klorofila, karotenoidov, flavonoidov, skupne fenole, antioksidantivno učinkovitost, določeno z DPPH (2,2-difenil-1-pikrilhidrazil) in FRAP (železo-reducirajoča antioksidativna učinkovitost) ter opravili senzorično analizo. Bioaktivni pigmenti so bili uspešno ekstrahirani iz alg v sončnično olje, kar je posledično povečalo antioksidativno učinkovitost olja. Vsebnost klorofila in karotenoidov se je po ekstrakciji alg v olju povečala za 330-krat oziroma 8-krat. Ekstrakcija flavonoidov in fenolov je bila majhna, 9,40 % oziroma 3,10 %. Dodatek P. canaliculata olju ne vpliva na kemijske parametre in kakovost olja (kislost, oksidacijski produkti), vendar vpliva na fizikalne in senzorične parametre (barva, vonj). Potrdili smo, da so takšna olja lahko koristna za živilsko industrijo, saj imajo podaljšan rok trajanja in imajo lahko zaradi ekstrahiranih naravnih spojin tudi nekatere koristi za zdravje