Tocopherols: Chemical Structure, Bioactivity, and Variability in Croatian Virgin Olive Oils

Virgin olive oil (VOO) represents a rich source of natural antioxidants, with tocopherols as the most effective group of lipophilic, phenolic antioxidants. α-Tocopherol represents more than 95% of the total tocopherols in virgin olive oil, and it possesses the highest biological activity among members of the vitamin E family. Content and composition of the tocopherols of virgin olive oil depend on several agronomic factors, as well as olive processing and oil storage conditions

On-line DACC-HPLC analysis of polycyclic aromatic hydrocarbons in edible oils

In this work an HPLC method for determination of polycyclic aromatic hydrocarbons (PAH) in edible oils on a DACC (donor-acceptor complex chromatography) column coupled with an on-line HPLC system with fluorescent detection. Method was used to determine the content of individual PAHs in the refined sunflower oil, virgin olive oil, cold pressed pumpkin seed oil, dark sesame oil and pumpkin seed oil produced with roasting obtained from domestic market. Calibration and validation were conducted for 13 individual PAHs among which are all 8 PAHs that are listed as priorities for determination in food and environment by both European Commission and US Environmental Protection Agency (EPA). Correlation coefficients of calibration curves for all standards were above 0.999 in selected range and all validation parameters (limit of detection, limit of quantification, accuracy and precision) were within limits set by European regulation. Content of PAHs in cold pressed pumpkin seed oil, roasted pumpkin seed oil and especially dark sesame oil was several-fold higher than the recommendations set by different European oil research and production organizations even though for both pumpkin seed oils it was lower than limits set by official European legislation. High content of cancerogenous heavy fraction PAHs were found in dark sesame oil that advises to limitation of its consumption in human diet

Color Parameters and Total Anthocyanins of Sour Cherries (Prunus cerasus L.) During Ripening

Color is very important indicator of quality of fresh fruit. It also serves for estimating the stage of maturity of fruit. Plant pigments responsible for the color of some kind of fruits are anthocyanins. Anthocyanins are the flavonoids which are present in high amounts in sour cherries. The aim of this study was to determine total anthocyanins and color parameters of sour cherries ‘Cigančica’ and ‘Keleris’ collected in Osijek and Zadar (Croatia) in 2005 during ripening. Color parameters of skin and fl esh of sour cherries were determined with colorimetric CIE LAB method and total anthocyanins were determined by means of high performance liquid chromatography (HPLC) using UV/VIS PDA detector. Total anthocyanin was higher in sour cherries cv. Keleris grown in Zadar than in cv. Cigančica grown in Osijek during ripening although cv. Keleris is light colored genotype. Obtained results suggested that warm Mediterranean climate could have influence on high anthocyanin synthesis during ripening. Analysis of variance showed that stage of ripening did not influence total anthocyanin concentrations, but influenced almost all color parameters. Parameter H° was good indicator of color variation during ripening in both sour cherry cultivars

Fatty Acid Composition in Oil of Recent Rapeseed Hybrids and 00 Cultivars

Fatty acid composition in oil of seven new hybrids (‘Artus’, ‘Baldur’, ‘Exact’, ‘Executive’, ‘Extra’, ‘RG 9908’, ‘RG 9909’) and eight 00-cultivars (‘Aviso’, ‘Bristol’, ‘Canary’, ‘Dexter’, ‘Ella’, ‘Kosto’, ‘Navajo’, ‘Royal’) of rapeseed was investigated in the period 2003-2005. The experiments were placed in the experimental field of the Faculty of Agriculture in Zagreb. Fatty acid composition was determined by gas chromatography of their methyl esters, and the oil iodine number was calculated as well. The studied new rapeseed hybrids and 00 cultivars contained no erucic acid or it was present far below 2%. The average content of oleic acid was 61.88±2.64% in hybrids and 62.54±3.90% in 00-cultivars, the content of linoleic acid was 20.52±1.49% and 19.57±2.51%, the content of linolenic acid was 8.39±1.50% and 7.92±2.12%, the content of palmitic acid was 5.13±0.48% and 5.50±0.51%, and the content of stearic acid was 1.48±0.16% and 1.58±0.19%, respectively. Th is ratio of fatty acids confirms the high nutritive quality of rapeseed oil. The iodine value was 112±2 in oil from hybrids and 110±4 in oil from 00-cultivars. In both investigated groups there were no differences in fatty acid composition which could influence the quality and stability of rapeseed oil. The average values in oils obtained from hybrids as well as from 00-cultivars are inside the data prescribed in law regulations. Although, there were several samples in which oleic and palmitic acid contents were above and linoleic and linolenic acid contents (as well as the iodine values) below the limit values, what ought to be incorporated into the revision of present regulations on vegetable oils. Fatty acid composition in hybrids and in 00-cultivars was greatly influenced by weather conditions. In the year with higher mean monthly air temperatures and less precipitation during May and June compared to average long-term weather conditions for these months, oil contained more oleic and less linoleic and linolenic acid

Effect of Maturity and Geographical Region on Anthocyanin Content of Sour Cherries (Prunus cerasus var. marasca)

Istraživan je utjecaj različitih stupnjeva zrelosti na količinu antocijana i pokazatelje boje u tri ekotipa višnje maraske s dva geografska područja Dalmacije. Antocijani su određivani primjenom HPLC uz UV/VIS PDA detekciju, a boja je plodova određivana tristimulusnim kolorimetrom (sustav CIELAB). Najveća količina antocijana nađena je u svim ekotipovima maraske, i to cijanidin 3-glukozilrutinozid i cijanidin 3-rutinozid, za razliku od pelargonidin glikozida koji je bio u manjim koncentracijama. Tijekom zrenja količina se antocijana nije podjednako mjenjala, ali je u većini ekotipova određena u većim koncentracijama u posljednjem stupnju zrenja (3,18-19,75 g po kg suhe tvari). Stvaranje tamnocrvene, gotovo crne boje u zrelim višnjama maraske uvjetovalo je smanjenje vrijednosti crvene komponente boje (a*), svjetloće (L*) i intenziteta obojenja (C*). Rezultati analize varijance s dva faktora pokazuju da područje uzgoja bitno utječe na povećanje količine pojedinačnih antocijana u višnjama i promjenu vrijednosti parametra boje L* tijekom zrenja. Nadalje, količina ukupnih antocijana u višnjama osobito ovisi o ekotipu i međusobnom utjecaju ekotipa i područja uzgoja.The influence of different stages of maturity on the anthocyanin content and colour parameters in three sour cherry Marasca ecotypes grown in two Dalmatian geographical regions has been studied. Anthocyanins were determined by HPLC-UV/VIS PDA analysis and the colour of fruit flesh and skin was measured by tristimulus colourimeter (CIELAB system). The major anthocyanins in all ecotypes at all stages of maturity were cyanidin 3-glucosylrutinoside and cyanidin 3-rutinoside, whereas pelargonidin glycosides were determined in lower concentrations. During ripening, anthocyanins did not change uniformly, but in most ecotypes they were determined in higher concentrations at the last stage of maturity (3.18 to 19.75 g per kg of dry matter). The formation of dark red, almost black colour in ripe Marasca cherries decreased redness (a*), brightness (L*) and colour intensity (C*). The results of two-way ANOVA test indicated that the growing region significantly influenced the accumulation of individual anthocyanins and L* value during ripening, while ecotype and the interaction between the growing region and the ecotype significantly affected total anthocyanin content of sour cherry

Agroecological conditions of industrial hemp production in the western Pannonian agricultural subregion and fatty acids composition of hemp seed oil

Konoplja se uzgaja širom svijeta i prilagođena je širokom rasponu agroekoloških uvjeta. Međutim visina prinosa i kvaliteta ulja sjemena konoplje ovisi o varijabilnosti agroekoloških uvjeta, kao i o uzgajanom kultivaru i agrotehničkim mjerama uzgoja. Cilj ovoga istraživanja je utvrditi klimatske i pedološke uvjete uzgoja industrijske konoplje sorte Fedora 17 na dva OPG-a na području zapadno Panonske poljoprivredne podregije koja zauzima oko 18,5% od ukupne površine Hrvatske i gdje se nalazi 555.198 ha poljoprivrednog zemljišta. Određen je i sastav masnih kiselina u ulju sjemena konoplje tijekom vegetacijskih godina 2016. i 2017. Pedološke prilike su određene standardnim terenskim i laboratorijskim metodama, klimatske značajke temeljem analize 30 godišnjeg (1986-2015) niza klimatskih podataka, dok je sastav masnih kiselina u ulju određen plinskom kromatografijom nakon hladnog prešanja sjemena konoplje. Rezultati ukazuju na veliku heterogenost pedoloških prilika na istraživanim lokacijama, dok su se klimatski uvjeti tijekom vegetacijskog razdoblja konoplje značajno razlikovali samo u prosječnim temperaturama zraka. Heterogenost agroekoloških uvjeta, prvenstveno fizikalnih značajki tla, je utjecala na visinu prinosa sjemena konoplje, koji je ovisno o lokaciji i godini istraživanja varirao od 350-1200 kg/ha, ali nije utjecala na sastav masnih kiselina u ulju koje je bilo zadovoljavajuće kvalitete na obje lokacije u obje godine istraživanja.Hemp is cultivated worldwide and it is adapted to a wide range of agroecological conditions. However, the yield level and the hemp seed oil quality depend on their variability, as well as on cultivars and agrotechnical cultivation measures. The objective of this study was determined climatic and pedological conditions of industrial hemp production, cultivar Fedora 17, on two family farms in the area of the western Pannonian agricultural subregion, which occupies about 18.5% of the total area of the Republic of Croatia where 555,198 ha agricultural land is located. It was determined the composition of fatty acids in the hemp seed oil grown during the investigation years 2016 and 2017. Pedological conditions were determined by standard field and laboratory methods, climatic features based on 30-yr analysis (19862015) of climatic data while the composition of fatty acid in hemp seed oil is determined by gas chromatography after seeds cold pressing. Results indicate a great heterogeneity of the pedological conditions at the investigated locations, while climatic conditions during the hemp vegetation differed significantly only in average air temperatures. The heterogeneity of the agroecological conditions, primarily pedophysical characteristics, influenced on hemp seed yield which depending on the location and year in which the study was conducted ranged from 350-1,200 kg/ha, but not infuenced on fatty acids composition in the oil that was of satisfactory quality at both locations and in both years of investigations

Survey of phenolic compounds and sensorial profile of Dalmatian virgin olive oils

Fenolni spojevi su prirodni antioksidansi prisutni u djevičanskom maslinovom ulju (DMU) koji utječu na konačnu procjenu kvalitete pojedinog maslinovog ulja. To su bioaktivni spojevi koji imaju izraženu antioksidacijsku aktivnost i značajno utječu na oksidacijsku stabilnost DMU, ali i na njegova senzorska svojstva. U ovom radu ispitivan je sastav fenola u djevičanskim maslinovim uljima iz odabranih autohtonih hrvatskih sorta s nekoliko lokacija na području srednje Dalmacije. Trogodišnja istraživanja provedena su na sortnim uljima dobivenim istovjetnim tehnološkim postupkom prerade. Provedeno je i senzorsko ocjenjivanje sortnih DMU kojima su definirana specifična obilježja okusa i arome koja se pripisuju isključivo sorti. U preliminarnim istraživanjima određeni su osnovni parametri kvalitete prema propisima za ekstra djevičansko maslinovo ulje, kao i ukupni udjel fenolnih tvari te sastav pojedinačnih fenola za pojedino sortno ulje. Kod nekih sorti su pojedine grupe fenolnih spojeva (sekoiridoidi, flavoni, lignani) pokazale veću antioksidacijsku aktivnost nego ukupni fenoli. Kod ulja drugih sorti, oksidacijska stabilnost ovisi upravo o udjelu ukupnih fenola. Kod svih ispitivanih uzoraka u ovom istraživanju vrlo je dobar udjel fenola i različitih sastava pojedinačnih fenolnih spojeva, ovisno o sorti. Senzorske karakteristike razlikuju se kod uzoraka ulja ovisno o ishodnoj sorti i imaju određena svojstva za svako pojedino sortno ulje.Phenolic compounds are natural antioxidants present in virgin olive oil (VOO) that influence the final assessment of the quality of certain olive oil. These are the bioactive compounds that have a pronounced antioxidant activity and significantly affect the oxidative stability of the VOO, but also its sensorial properties. This paper examined the composition of phenolic compounds in VOO\u27s from selected indigenous Croatian varieties from several locations in central Dalmatia. A three-year study was conducted on varietal oils obtained by identical chemical processing procedure. Sensory evaluation of monovarietal VOO’s was also conducted and specific characteristics of taste and aroma due to the olive variety were defined. In preliminary research, the basic quality parameters were determined according to the regulations for the extra virgin olive oil, as well as the total phenol content and the composition of individual phenolic compounds for particular monovarietal oils. Some varieties showed that a particular group of phenols (secoiridoided, flavones, lignans) had higher antioxidant activity than total phenols. In oils from other olive varieties, oxidative stability depended on the proportion of total phenols. In all samples in this study very good total phenol content was detected as well as different composition of individual phenolic compounds, depending on the olive cultivar. Sensorial characteristics of the samples varied depending on the variety and had specific attributes for each monovarietal VOO

Influence of Conditioning Temperature on the Quality, Nutritional Properties and Volatile Profile of Virgin Rapeseed Oil

Zagrijavanje sjemena uljane repice, prije izdvajanja ulja, provodi se radi povećanja iskorištenja procesa proizvodnje ulja. Međutim, povišene temperature mogu uzrokovati promjene u sjemenu, a time i promjene u sastavu hlapljivih i nehlapljivih komponenata proizvedenoga nerafiniranog repičinog ulja. Svrha je ovog istraživanja bila odrediti utjecaj temperature kondicioniranja sjemena (60, 80 and 100 °C) na kakvoću, nutritivnu vrijednost, aromatski profil i senzorske karakteristike nerafiniranoga repičinog ulja. Upotrijebljene temperature kondicioniranja nisu utjecale na kakvoću, niti na glavne hranjive sastojke proizvedenog ulja (masne kiseline i tokoferole). Međutim, povećanje je temperature uzrokovalo eksponencijalan porast koncentracije kanolola i značajne razlike u aromatskom i senzorskom profilu proizvedenih ulja. Dominantni hlapljivi spojevi hladno prešanog i nerafiniranog repičinog ulja proizvedenog pri 60 °C bili su produkti enzimske razgradnje glukozinolata (izotiocijanati i epitionitrili), odgovorni za izražen okus i miris tih ulja po sjemenu uljane repice. Povećanje temperature uzrokuje deaktivaciju prisutnih enzima te toplinsku degradaciju komponenti sjemena a samim time i povećanje koncentracije nitrila, aldehida, pirazina i furana, nosioca okusa i mirisa po orašastim plodovima i po prženju. Rezultati ovog istraživanja mogu uvelike pomoći proizvođačima ulja u kreiranju nerafiniranoga repičinog ulja sa specifičnim i poželjnim senzorskim karakteristikama.Heating the rapeseed prior to the oil extraction is conducted to increase the oil yield but it can also induce changes of various components of the seed. These changes may affect the composition of the volatile and non-volatile compounds of produced virgin rapeseed oil. The aim of our study is to determine the impact of different conditioning temperatures (60, 80 and 100 °C) on the quality, nutritional value, aroma profile and sensory characteristics of virgin rapeseed oil. Conditioning the seeds at all three temperatures had no influence on the quality and major nutritional components (fatty acids and tocopherols) of the produced oil. However, temperature increase caused an exponential increase of canolol and significant changes in the aroma and sensory profile of the produced oil samples. The dominant volatile compounds of cold-pressed and virgin oil produced at 60 °C were enzymatic degradation products of glucosinolates (isothiocyanates and epithionitriles), responsible for pronounced seed-like flavour of these types of oil. Increasing production temperature deactivated enzymes and caused thermal decomposition of seed components and increment of nitriles, aldehydes, pyrazines and furanes, carriers of nutty and roasty flavour. These results can help producers to design virgin rapeseed oil with specific and desirable sensory characteristics