Iako klasična proizvodnja bijelih vina podrazumijeva fermentaciju mošta, suvremeni trendovi podrazumijevaju proizvodnju bijelih vina uz maceraciju, odnosno fermentaciju masulja. Cilj ovog rada bio je ...utvrditi utjecaj duge maceracije grožđa na kakvoću vina 'Graševina'. Istraživanje je provedeno tijekom 2021. godine u vinogradima i vinskom podrumu Veleučilišta u Požegi u vinogorju Kutjevo. Nakon berbe, kontrolni uzorak vina proizveden je klasičnim postupkom proizvodnje bijelih vina, te su provedena dva tretmana duge maceracije u periodu od 3 mjeseca - jedan uz sulfitiranje tijekom primarne prerade a drugi bez sulfita. U vinima su analizirani osnovni parametri kakvoće, koncentracija jabučne i mliječne kiseline, optička gustoća pri 280 nm, ukupni fenoli i antioksidativna aktivnost DPPH metodom. Statistički značajna razlika zabilježena je kod ukupnih fenola, kao i antioksidativnoj aktivnosti, s najvećim vrijednostima u maceriranom uzorku uz primjenu SO2. Organoleptičko ocjenjivanje uzoraka proveli su certificirani ocjenjivači, metodom 100 bodova. Najveću prosječnu ocjenu od 87 bodova dobilo je vino proizvedeno dugom mareracijom grožđa uz redovito sulfitiranje. Kontrolni tretman slabije je ocijenjen, sa 72 boda. Vino proizvedeno dugom maceracijom bez korištenja sulfita ocjenjeno je sa 66 boda uz napomenu pojedinih ocjenjivača o izraženoj oksidaciji.
Cilj: Utvrditi razliku u antioksidativnoj aktivnosti maslinovog, suncokretovog, bučinog i crnog ulja i njihovih tokoferolnih ekstrakata te proučiti kinetiku i mehanizam reakcije između slobodnih ...radikala i antioksidansa. Materijali i metode: Antioksidativna aktivnost ulja i tokoferolnih ekstrakata mjerena je spektrofotometrijski uz uporabu DPPH˙ (2,2-difenil-1-pikril-hidrazil), dok je Trolox ekvivalent poslužio kao referentni standard za kvantifikaciju rezultata dobivenih DPPH˙ testom. Pomoću kinetičkih monofaznih i bifaznih matematičkih modela procijenjena je i analizirana inhibicija signala DPPH˙. Rezultati: Vrijednost TEAC-a ukazuje da maslinovo i suncokretovo ulje (2,16 mmol/L) posjeduju jaču antioksidativnu aktivnost u odnosu na crno (1,85 mmol/L) i bučino ulje (1,68 mmol/L), a ujedno i intenzivniju inhibiciju DPPH˙ radikala. Tokoferolni ekstrakti imaju puno slabiji antioksidativni učinak od analiziranih biljnih ulja, pri čemu je najdjelotvorniji ekstrakt suncokretova ulja koji čini 22,1 % antioksidativne aktivnosti ulja, a najslabiji ekstrakt bučina ulja sa samo 13,9 %. Nestanak DPPH˙ radikala u uzorcima ulja odvija se u dva susljedna koraka, početnog eksponencijalnog koji se odvija unutar 7 min reakcije, ovisno o vrsti ulja, i drugog sporog, gdje su promjene proporcionalne s vremenom. Kod tokoferolnih ekstrakata brzi korak reakcije nije uočen, ukazujući time da se reakcija odvija mehanizmom kinetike prvog reda. Zaključak: Rezultati ukazuju da biljna ulja imaju jači učinak u inhibiciji radikala u odnosu na tokoferolne ekstrakte, pa se njihovom pravilnom konzumacijom potpomaže organizmu u „borbi“ protiv slobodnih radikala. Zapravo, najvažniji dio antioksidacijskog sustava obrane organizma od slobodnih radikala čini sinergističko djelovanje antioksidansa, odnosno antioksidansi u sinergiji imaju jači učinak nego sumarni učinak svih pojedinačnih antioksidansa.
Aim: To determine the difference in the antioxidant activity of the olive, sunflower, pumpkin and black oil and their tocopherol extracts as well as to examine the kinetics and mechanism of reactions between free radicals and antioxidants. Materials and Methods: Antioxidant activity of the oils and tocopherol extracts was measured spectrophotometrically using DPPH˙ (2,2-diphenyl-1-picrylhydrazil) while Trolox equivalent was used as a reference standard for the quantification of the results obtained by the DPPH˙ test. DPPH˙ signal inhibition was evaluated and analyzed by monophasic and biphasic kinetics mathematical models. Results: The TEAC values suggest that olive and sunflower oil (2.16 mmol/L) have a stronger antioxidant activity than black (1.85 mmol/L) and pumpkin oil (1.68 mmol/L) and they possess stronger inhibition of the DPPH˙ radical. Tocopherol extracts have a much weaker antioxidant effect than the analyzed vegetable oils, where the sunflower extract is most effective, making 22.1 % of the antioxidant oil activity, while the weakest extract is the pumpkin oil extract oil with only 13.9 %. DPPH˙ radical disappearance in oil samples takes place in two successive phases, the initial exponential which takes place within 7 min of the reaction, depending on the oil type, and the second slow phase where the changes are proportional to the time. The rapid reaction phase by tocopherol extracts was not noticed, indicating that the reaction takes places by the mechanism of the first order kinetics. Conclusion: The results indicate that vegetable oils have a stronger effect on the radical inhibition than the tocopherol extracts, and by their proper consumption they will support the organism in the “fight” against free radicals. In addition, the most important role of the antioxidant defense system against free radicals makes the synergic interactions among the different molecules present in the food, indicating that antioxidants in synergy have a stronger potential than the sum of all individual antioxidants.
The polyphenolic content and biological activities of dichloromethane, chloroform, ethyl acetate, and ethanol extracts of Cretan Salvia pomifera L. (Lamiaceae) were analysed. The ethyl acetate ...extract showed the highest content of total phenolics and total flavonoids. The ethanol extract exhibited the highest activity in the DPPH and FRAP assays, while the dichloromethane extract had the highest activity in the ABTS test. The ethyl acetate extract showed the highest activity in the β-carotene--linoleic acid system. The antioxidant activity of extracts was positively correlated with the total content of phenolics. Extracts demonstrated weak antibacterial activity. The ethyl acetate extract had the highest acethylcholinesterase inhibition at 50 μg/mL, while the ethanol and dichloromethane extracts showed the highest activity of tyrosinase inhibition at 25 μg/mL. In view of the significance of antioxidants in prevention and treatment of neurological diseases, the noticeable antioxidant and anti-neurodegenerative effects of the ethanol and ethyl acetate extracts recorded in this study make further research on S. pomifera seem promising
While there is a large number of scientific papers reporting chemical composition and biological activities of Aronia melanocarpa, there is a lack information regarding the commercially available ...bagged tea. In order to supply new information on the antioxidant activity of the Aronia melanocarpa tea infusions, the aim of this study was to evaluate individual phenolic compounds which could be responsible for antioxidant activities of these beverages.
Selected anthocyanins (cyanidin-3-O-galactoside, cyanidin-3-O-glucoside, cyanidin- 3-O-arabinoside, and cyanidin-3-O-xyloside), gallic acid, caffeic acid, rutin, morin, and protocatechuic acid were simultaneously detected from commercially available tea infusions using a High Performance Liquid Chromatographic (HPLC) method. The antioxidant activity was measured using five in vitro spectrophotometric methods: 1,1-diphenyl- 2-picrylhydrazyl radical scavenging activity (DPPH), 2,2'-azino-bis (3-ethylbenzthiazoline- 6-sulphonic acid) radical cation scavenging activity (ABTS), ferric reducing-antioxidant power (FRAP) and reduction power (RP)Fe(III) to Fe(II).
Obtained results showed that anthocyanins, predominantly of cyanidin-3-O-galactoside, are the major class of polyphenolic compounds in tea infusions. Among phenolic acids the most abundant is caffeic acid. A significant correlation between DPPH and ABTS and FRAP and RP suggested that antioxidant components in these beverages were capable scavenging free radicals and reducing oxidants.
Generally, these beverages had relatively high antioxidant capacities and could be important dietary sources of antioxidant phenolics for the prevention of diseases caused by oxidative stress.
U cilju dobijanja informacija o antioksidativnoj aktivnosti infuz čajeva ploda aronije (Aronia melanocarpa) određena je koncentracija pojedinačnih fenolnih jedinjenja za koje se smatra da su odgovorna za antioksidativnu aktivnost ispitivanih čajeva.
Sadržaj antocijana (cijanidin-3-O-galaktozid, cijanidin-3-O-glukozid, cijanidin-3-O-arabinozid, cijanidin- 3-O-ksilosid), galne kiseline, kafene kiseline, protokatehinske kiseline, rutina imorina određen je korišćenjem tečne hromatografije pod visokim pritiskom (HPLC) sa UV/Vis ifluorescentnim detektorom. Antioksidativna aktivnost je ispitana korišćenjem četiri in vitro spektrofotometrijske metode: metoda uklanjanja 2,2-difenil-1-pikrilhidrazil (DPPH) radikala, metoda vraćanja 2,2'-azino-bis (3-etilbenzotiazolin-6-sulfo katjon radikala) u svoj neutralni oblik (ABTS), redukcija gvožđe(III)-2,4,6-tripiridil-S-triazin kompleksa do gvožđe(II)-2,4,6-tripiridil-S-triazin kompleksa (FRAP) metoda redukcije Fe3+ do Fe2+jona (RP).
Na osnovu dobijenih rezultata može se zaključiti da su u ispitivanim infuz čajevima najviše zastupljeni antocijani, a zatim slede fenolne kiseline. Od antocijana najviše je zastupljen cijanidin-3-O-galaktozid, a od fenolnih kiselina kafena kiselina. Visok stepen korelacije između DPPH i ABTS metode i FRAP I RP metode ukazuje na to da su prisutna fenolna jedinjenja, kao redukujući agensi u ispitivanim uzorcima, dobri hvatači slobodnih radikala.
Generalno, dobijeni rezultati ukazuju da infuz čajevi od lista aronije pokazuju visok stepen antioksidativne aktivnosti i mogu biti dopuna svakodnevnoj ishrani u prevenciji bolesti izazvanih oksidativnim stresom.
Provider: - Institution: - Data provided by Europeana Collections- Antioxidative activity of flavonoids has been a subject of intensive experimental and theoretical investigation. Nevertheless, the ...research concerning antioxidative action of baicalein has been initiated only recently. Within this doctoral disertation the mechanisms of antioxidative action of baicalein: HAT (Hydrogen Atom Transfer), SET-PT (Sequential Electron Transfer – Proton Transfer), and SPLET (Sequential Proton Loss Electron Transfer) were examined. The investigation of antioxidative activity of baicalein was performed in correlation with the investigation of structural and electronic properties of baicalein. The results of the present doctoral disertation were obtained by using the DFT methods, as implemented in the Gaussian program package: M05-2X, B3LYP and RVE, combined with the 6-311+G(d,p) and 6-311+G(2df,p) basis sets. The calculations were performed for the gas phase and aqueous solution. To estimate the effects of water as solvent a continuum-based solvation model, CPCM, was used. The NBO (Natural Bond Orbital) analysis of all optimized geometries was performed, to reveal the effects that emanate from the electronic structure. Baicalein is a non-planar molecule, as documented with the experimental (9.0°) and calculated (24.5º) value for the dihedral angle between the V and S rings. In its most stable conformation baicalein has three hydrogen bonds with the stabilizing effect. The DH(H5--O4) hydrogen bond contributes most to the stabilization of the baicalein molecule. This finding was confirmed with the NBO analysis. The vibrational and UV/Vis spectra of baicalein were simulated, and compared to the corresponding experimental spectra. Excellent agreement between the experimentally obtained and simulated IR, Raman and UV spectra was achieved. Using the simulated spectra, a precise assignation of the vibrational modes in the IR and Raman spectra was accomplished. Some molecular orbitals of baicalein were distinguished. The electron transitions responsible for the UV spectrum occur among these orbitals. All radicals, anions, and radical cation of baicalein were examined, because they play a significant role in the antioxidative mechanisms of baicalein. The 6 site is most favorable for homolytic cleavage of the О–Н bond in the gas phase, whereas the 7 site is most favorable for heterolytic cleavage of the О–Н bond in the aqueous solution. The spin density distribution in the most stable О6R1 radical reveals that the unpaired electron is delocalized very well. This finding can explain the stability of this radical and antioxidative action of baicalein according to the НАТ mechanism. The charge distribution in the most stable anion О7А2 showed that there is delocalization of the negative charge in the А ring. This anion is strongly stabilized in the aqueous solution. Antioxidative action of baicalein according to the SPLET mechanism can be attributed to this fact. Our investigations predict a planar structure of the baicalein radical cation. An interesting feature of the radical cation in comparison to the baicalein molecule is that the H atom is transferred from О5 to О4. In this way delocalization of the unpaired electron is realized over the A ring, and, thus, the instability induced by the loss of an electron is reduced. Heterolytic dissociation of the radical cation yields three radicals. The structures of all three radicals were examined. It was found that the spin density delocalization is most pronounced in the thermodynamically most stable C6–O radical. BDE, PА, and IP values served to determine thermodynamically most favorable reaction pathway. The НАТ mechanism is most favorable reaction pathway for antioxidative action of baicalein in the gas phase. On the other hand, the SPLET mechanism is most favorable reaction pathway for antioxidative action of baicalein in the aqueous phase. SETPT is not favorable mechanism of antioxidative action of baicalein in either gas or aqueous phase. Mechanistic investigations of antioxidative action of baicalein have been commenced. A simulation of the reaction of baicalein with the hydroxyl radical confirmed that HAT is the dominant reaction pathway in the gas phase, and that the 6 position is most reactive. Due to the higher energies of the p orbitals of the hydroxide and methanthiolate anions in comparison to the energy of the SOMO of the radical cation, the radical cation does not conform to the SET-PT, but to the HAT mechanism in the gas phase. So far, our mechanistic investigations are in perfect accord with the results of theromodynamical research. Bearing in mind the findings of previous research regarding antioxidative activity of flavonoids, the results of this doctoral disertation provide a significant contribution to understanding the complex mechanisms through which antioxidative action of baicalein is realized. It should be emphasized that there are very few published results in this scientific field. It is expected that these results, by applying complementary approaches, will contribute to a better understanding of the structural and electronic properties of other polyphenols.- Iako je antioksidativna aktivnost flavonoida objekat veoma intezivnog eksperimentalnog i teorijskog istraživanja, antioksidativno delovanje bajkaleina se ispituje tek odnedavno. U okviru ove disertacije ispitivani su mehanizmi antioksidativnog delovanja bajkaleina, i to HAT (Hydrogen Atom Transfer), SET-PT (Sequential Electron Transfer – Proton Transfer) i SPLET (Sequential Proton Loss Electron Transfer). Ispitivanje antioksidativnih aktivnosti bajkaleina je izvedeno u korelaciji sa ispitivanjem strukturnih i elektronskih osobina bajkaleina. Rezultati ove doktorske disertacije dobijeni su pomoću metoda funkcionala gustine, koje su implementirane u programski paket Gaussian: M05-2X, B3LYP i RVE, u kombinaciji sa bazisnim skupovima 6-311+G(d,p) i 6-311+G(2df,p). Proračuni su izvedeni za gasovitu fazu i vodeni rastvor. Za procenu efekata vode kao rastvarača korišćen je solvatacioni model zasnovan na kontinumu – SRSM. Urađena je NBO (Natural Bond Orbital) analiza svih optimizovanih geometrija radi utvrđivanja efekata koji proističu iz elektronske strukture. Bajkalein je neplanaran molekul, što pokazuje eksperimentalna (9.0°) i izračunata (24.5º) vrednost za diedarski ugao između prstenova V i S. U najstabilnijoj konformaciji bajkalein ima tri vodonične veze koje imaju stabilizacioni efekat. Vodonična veza DH(H5--O4) daje najveći doprinos stabilizaciji molekula bajkaleina, što je potvrdila i NBO analiza. Izvršeno je simuliranje vibracionih i UV/Vis spektara bajkaleina i poređenje sa odgovarajućim eksperimentalnim spektrima. Postignuto je odlično slaganje između eksperimentalno dobijenih i simuliranih IR, Ramanskih i UV spektara. Uz pomoć simuliranih spektara izvršena je precizna asignacija vibracionih modova u IR i Ramanskom spektru. Određene su molekulske orbitale bajkaleina između kojih se vrše elektronski prelazi odgovorni za UV spektar. Ispitani su svi radikali, anjoni i radikal katjon bajkaleina, koji imaju važnu ulogu u antioksidativnim mehanizmima bajkaleina. Položaj 6 najpovoljniji je za homolitičko raskidanje O–N veze u gasovitoj fazi, dok je položaj 7 najpovoljniji za heterolitičko raskidanje O–N veze u vodenoj fazi. Raspodela spinske gustine u najstabilnijem O6R1 radikalu pokazuje da je nespareni elektron veoma dobro Izvršeno je simuliranje vibracionih i UV/Vis spektara bajkaleina i poređenje sa odgovarajućim eksperimentalnim spektrima. Postignuto je odlično slaganje između eksperimentalno dobijenih i simuliranih IR, Ramanskih i UV spektara. Uz pomoć simuliranih spektara izvršena je precizna asignacija vibracionih modova u IR i Ramanskom spektru. Određene su molekulske orbitale bajkaleina između kojih se vrše elektronski prelazi odgovorni za UV spektar. Ispitani su svi radikali, anjoni i radikal katjon bajkaleina, koji imaju važnu ulogu u antioksidativnim mehanizmima bajkaleina. Položaj 6 najpovoljniji je za homolitičko raskidanje O–N veze u gasovitoj fazi, dok je položaj 7 najpovoljniji za heterolitičko raskidanje O–N veze u vodenoj fazi. Raspodela spinske gustine u najstabilnijem O6R1 radikalu pokazuje da je nespareni elektron veoma dobro.- All metadata published by Europeana are available free of restriction under the Creative Commons CC0 1.0 Universal Public Domain Dedication. However, Europeana requests that you actively acknowledge and give attribution to all metadata sources including Europeana
The aim of this study was to assess the influence of cultivar and growth phase on the antioxidant activity (AOA) changes in common buckwheat (Fagopyrum esculentum Moench), as well as the its ...distribution in different plant parts. During 4 growth phases (GP) (buds formation - I, beginning of flowering - II, full flowering - III, full maturity - IV) stems, leaves, flowers, seeds were collected sequentially from 6 buckwheat cultivars - 'Pyra', 'Spacinska', 'Kasho', 'Jana C1', 'Hrusowska', 'Emka'. The highest values of AOA were measured in flowers (GP III) in 'Jana C1' (93.17%) and the lowest value in stems (GP I) in 'Spacinska' (46.09%). The highest increase of AOA was observed in GP IV in stems in 'Pyra'. Differences were compared for statistical significance at the level P < 0.05.
Ispitivano je uklanjanje radikala i antimikrobna aktivnost ekstrakata, tri kultivara Castanea Sativa Mill. Lišće i rese su ekstrahirane pod istim uvjetima 50%-tnim etanolom kao ekstragensom, a zatim ...su dobiveni suhi ekstrakti ispitivanih uzoraka. Nakon izvršene kisele hidrolize uzoraka ukupne fenolne tvari su ordređene HPLC-om. Radi određivanja efekta ekstrakata na stvaranje i transformiranje hidroksil (OH) radikala i (DPPH) radikala, ekstrakti su rastvoreni u destiliranoj vodi i dodani u Fenton-ov model sistem, do fi nalne koncentracije od 0,2 mg/ml. Visoka vrijednost antioksidativne aktivnosti (AA) u odnosu na hidroksil radikale određena je za resu Lovranskog kestena (59,09%). Najveća antiradikalna aktivnost u odnosu na DPPH radikale je utvrđena kod ekstrakta rese domaćeg pitomog kestena (37,50). Antimikrobni test je pokazao da etanolni ekstrakti rese i lista inhibiraju rast Gram pozitivnih bakterija.
Microgreens from common and tartary buckwheat genotypes were evaluated for total flavonoid content (rutin, quercetine and kaempferol separately), bound phenolic acids content, carotenoids and ...α-tocopherol content and antioxidant activity. The results have shown that in common and tartary buckwheat microgreens antioxidant activity was found. High level of flavonoids, carotenoids, and α-tocopherol was detected as well. Higher amount of flavonoids was found out in tartary buckwheat microgreens. No significant differences were detected between common and tartary buckwheat microgreens in content of phenolic acids. Microgreens of both common and tartary buckwheat represent potential nutritional sources for alternative vegetable in the Czech Republic.
Vsebnost celokupnih flavonoidov (posebej rutina, kvercetina in kempferola), vezanih fenolnih kislin, karotenoidov, α-tokoferola in antioksidantna aktivnost so bili raziskani pri mladih rastlinah navadne in tatarske ajde. Ugotovljena je antioksidativna aktivnost izvlečkov mladih rastlin navadne in tatarske ajde ter visoka vsebnost flavonoidov, karotenoidov in α-tokoferola. Posebej visoka vsebnost flavonoidov je bila ugotovljena pri tatarski ajdi, medtem ko glede na vsebnost fenolnih snovi ni bilo razlike med mladimi rastlinami navadne in tatarske ajde. Mlade rastline tako navadne kot tatarske ajde so možen alternativni vir zelenjave v Češki republiki
Obogaćivanje hrane je način da se smanji učestalost nedostataka mikronutrijenata u populaciji. Kus-kus je namirnica koja se u Alžiru konzumira u velikoj mjeri. Stoga je cilj ovog istraživanja bio ...dobiti obogaćeni kus-kus s poboljšanim terapeutskim potencijalom i dobrim fizikalno-kemijskim, tehnološkim i mikrobiološkim karakteristikama. Pšeničnom kus-kusu dodan je tradicionalni pripravak Issoufer (10, 20 i 30 %), te je smjesa uspoređena s kontrolnom čistom kus-kus krupicom. Znatno povećanje (p < 0,05) pepela, proteina, lipida, ugljikohidrata, fenolnih spojeva, flavonoida i anti-radikalne aktivnosti, zabilježeno je kod svih smjesa s dodanim Issoufer pripravkom. S druge strane, znatno (p < 0,05) su se smanjili udio vlage te pH-vrijednost. Studija akutne toksičnosti nije pokazala smrtonosne učinke i znakove toksičnosti pri ispitanim dozama ekstrakta Issoufera (100, 250, 500 i 750 mg kg–1) tijekom pet dana promatranja. Rezultati antibakterijske aktivnosti pokazali su da su promjeri zona inhibicije dosegli vrijednost od 29,90 ± 0,60 mm. Na temelju dobivenih rezultata, Issoufer prah može se smatrati dobrim sastojkom za razvoj funkcionalnog kus-kusa prirodno obogaćenog sekundarnim metabolitima te se može upotrebljavati za prevenciju više bolesti, ali i u prehrambenoj industriji.
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