| الوصف: |
Oves je ena najbolj razširjenih žitaric, ki se primarno uporablja za krmo živali, vendar vse večji pomen pridobiva tudi v prehrani človeka. Razlog za povečanje zanimanja po ovsu je biološka vrednost surovega materiala, ki ima visoke vsebnosti proteinov, maščob, mineralov in vitaminov. Poleg tega vsebuje tudi fitokemikalije, ki naj bi bile vzrok za zmanjšanje tveganja nastanka kroničnih bolezni kot so koronarna arterijska bolezen, sladkorna bolezen tipa 2 in rak. Redno uživanje ovsa pa zmanjša tudi nivoje LDL holesterola in sistoličnega krvnega tlaka. Oves ljudje v večini uživamo v obliki kosmičev in kaše, kruh pa iz njega delamo redko, saj ne vsebuje glutena. Prav to oves naredi primernega za ljudi z intoleranco do glutena in za razne diete. V diplomski nalogi smo se osredotočili na določevanje fenolnih spojin in njihove antioksidativne lastnosti. Za izolacijo biološko aktivnih spojin smo uporabili Soxhletovo in superkritično ekstrakcijsko metodo. Spektrofotometrično smo ekstraktom določili vsebnost totalnih fenolov, antioksidativno aktivnost, totalne ogljikove hidrate in proteine. S tekočinsko kromatografijo z masno spektrometrijo (LC-MS) pa smo določili posamezne fenolne spojine in proste maščobne kisline (GC). V diplomskem delu smo ugotovili, da so boljša topila za ekstrakcijo raztopine organskih topil kot pa čista organska topila. Konkretno smo primerjali čisti etanol, 50 % etanol in 70 % etanol. Ekstrakt 50 % etanola je pokazal najboljše rezultate z največjo vsebnostjo totalnih fenolov (75,49 mg/100 g materiala), totalnih ogljikovih hidratov (15,45 mg/g materiala) in najmanjšim EC50 (10,00 mg/mL). Naša druga ugotovitev je, da s predhodno superkritično ekstrakcijo s CO2 vplivamo na rezultate nadaljnje Soxhletove ekstrakcije. Od fenolnih spojin je bilo v vseh ekstraktih prisotne največ kavne kisline. Pri določenih prostih maščobnih kislinah največji delež zavzemata oleinska in linolna kislina, kateri sta obe sta nenasičeni. Oats is one of most common cereal, primarily used for animal feed, but is also gaining importance in human diet. The reason for the increased interest in oats lies in the biological value of the raw biomaterial, which is high in protein, fat, minerals and vitamins. In addition, it contains phytochemicals that are thought to reduce the risk for chronic diseases such as coronary heart disease, type 2 diabetes and cancer. Regular consumption of oats also lowers LDL cholesterol level and systolic blood pressure. Oats are mostly eaten in form of cereal or porridge, as we rarely make bread out of it due to lack of gluten. The latter makes oats suitable for people with gluten intolerance and for various diets. In our research we focused on the determination of phenolic compounds and their antioxidant properties. Soxhlet and supercritical extraction were used to isolate biologically active compounds. We used spectrophotometric methods to determine total phenol content, antioxidant activity, total carbohydrates and proteins in extracts. Single phenolic compounds and free fatty acids were determined by liquid chromatography in tandem with mass spectrometry (LC-MS) and gas chromatography (GC), respectively. In our work we have found that solvents for extraction are better as a water solution rather than pure organic solvent. Specifically, pure ethanol, 50 % ethanol, and 70 % ethanol were compared. The 50 % ethanol extract showed the best results with the highest content of total phenols (75.49 mg/100 g of material), total carbohydrates (15.45 mg/g of material) and the lowest EC50 (10.00 mg/mL). Our second finding is that prior supercritical CO2 extraction influences the results of further Soxhlet extraction. Amongst all determined phenolic compounds, caffeic acid was present in the highest in concentration and was found in all extracts. Determined free fatty acids mostly appeared as oleic and linoleic acids, both of them are unsaturated. |
