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

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

Advanced oxidation treatments of olive mill wastewater

New and innovative advanced oxidative processes for wastewater treatments are currently in the focus of scientific research and development for possible industrial implantation. The main aim of this study was to investigate the effect of cold plasma treatment, high intensity ultrasound and UV radiation with the addition of additives: H2O2, TiO2, FeCl3 x 6H2O on degradation and removal of complex organic compounds from olive mill wastewater (OMWW). Olive mill wastewater represents a potential ecological problem when it is raw disposed into the environment, because of its high organic load. OMWW samples (with and without additives) were treated by high-voltage plasma discharge at frequencies 60 Hz and 120 Hz in combination with pumped gases (nitrogen, air and oxygen) for 30 minutes, by UV radiation for 30 minutes and 10 minutes by high intensity ultrasound. Physico-chemical parameters of quality, chemical oxygen demand (COD), and total dissolved carbon (TOC) were determined. The results have shown the efficacy of plasma treatment in degradation of organic compounds as well as degradation and reduction of polyphenolic compounds. Reduction of colour and total dissolved carbon occurred in all treated samples, mostly with the addition of FeCl3 x 6H2O. Treatment with UV radiation and ultrasound proved to be the most efficient resulting in the 50% reduction of organic compounds after a 10-minute treatment

Utjecaj klimatskih uvjeta, sortnih karakteristika i postupaka proizvodnje na udjele tokoferola, plastokromanola-8 i pigmenta u lanenom ulju

The objective of this study is to compare the influence of genotype, environmental conditions and processing methods after maturation and harvesting of four varieties of flaxseed (Altess, Biltstar, Niagara and Oliwin) on the levels of tocochromanols, carotenoids and chlorophyll in flaxseed oil. Samples were produced by cold pressing of dry seeds and seeds heated for 30 min at 60 °C. Temperature, sunshine and rainfall were primary environmental conditions included. Grand mean of mass fraction of γ-tocopherol was (522±29), of plastochromanol-8 (305±2) and total tocochromanols (831±3) mg per kg of oil. The highest levels of these compounds and strongest antioxidant activity were found in cold-pressed oil of Biltstar variety. During seed maturation, levels of γ-tocopherol and plastochromanol-8 increased with average temperature and total sunshine and decreased with total rainfall. Fifth week after flowering was identified as the maturation period with best climate conditions to achieve optimal tocochromanol content. Grand mean of mass fraction of carotenoids expressed as β-carotene was (1.83±0.01) and of chlorophyll expressed as pheophytin a (0.43±0.10) mg per kg of oil. Altess variety had the highest levels of pigments. Antioxidant activity decreased with the increase of chlorophyll, while correlations with carotenoids were not determined. Generally, oil obtained by cold pressing had higher levels of tocochromanols and lower levels of pigments but similar antioxidant activity to the oil after seed conditioning. The results of this study contribute to identifying the flaxseed variety that is the best for oil production with the highest antioxidant activity and nutritive value, and provide better understanding of tocochromanol biosynthesis depending on different climate conditions.Svrha je ovoga rada bila ispitati utjecaj genotipa, uvjeta okoliša i različitih načina obrade nakon dozrijevanja i žetve četiri sorte lana (Altess, Biltstar, Niagara i Oliwin) na udjele tokokromanola, karotenoida i klorofila u ulju dobivenom od tih sorata. Uzorci su proizvedeni hladnim prešanjem i kondicioniranjem sjemenki lana tijekom 30 min na 60 °C. Praćeni su glavni okolišni čimbenici, i to temperatura, padaline i insolacija. Prosječni udjel γ-tokoferola u uzorcima bio je (522±29) mg/kg, plastokromanola-8 (305±2) mg/kg, a ukupnih tokokromanola (831±3) mg/kg. Hladno prešano ulje sorte Biltstar imalo je najveći udjel tih spojeva te najizraženiji antioksidacijski učinak. Udjeli γ-tokoferola i plastokromanola-8 povećavali su se s porastom prosječne temperature i trajanjem insolacije, a smanjivali s povećanjem količine oborina u periodu sazrijevanja sjemena. Utvrđeno je da su za postizanje optimalnog udjela tokokromanola u ulju najbolji klimatski uvjeti bili pet tjedana nakon cvatnje. Prosječni udjel karotenoida u svim uzorcima ulja, izražen kao β-karoten, bio je (1.83±0.01) mg/kg, a klorofila, izražen kao feofitin a, (0.43±0.10) mg/kg. Ulja dobivena od sorte Altess imala su najveće udjele pigmenata. Antioksidacijska aktivnost ulja smanjivala se s povećanjem udjela klorofila, dok udjel karotenoida nije imao bitan utjecaj. Hladno prešana ulja imala su veće udjele tokokromanola i manje udjele pigmenata od ulja dobivenih od kondicioniranih sjemenki, no slična antioksidacijska svojstva. Ovo je istraživanje omogućilo identifikaciju najbolje sorte lana za dobivanje ulja najveće antioksidacijske aktivnosti i hranjive vrijednosti, što pridonosi spoznajama o utjecaju klimatskih uvjeta na biosintezu tokokromanola

Olive leaf extract activity against Candida albicans and C. dubliniensis – the in vitro viability study

Olive leaf extract is characterized by a high content of polyphenols (oleuropein, hydroxytyrosol and their derivatives), which is associated with its therapeutic properties. The objective of the present research was to evaluate the antifungal activity of olive leaf aqueous extract against Candida albicans ATCC 10231 and C. dubliniensis CBS 7987 strains. Minimum inhibitory concentration (MIC) of the extract was determined by several in vitro assays. The extract showed a concentration dependent effects on the viability of C. albicans with MIC value of 46.875 mg mL–1 and C. dubliniensis with MIC value 62.5 mg mL–1. Most sensitive methods for testing the antifungal effect of the extract were the trypan blue exclusion method and fluorescent dye exclusion method while MIC could not be determined by the method according to the EUCAST recommendation suggesting that herbal preparations contain compounds that may interfere with this susceptibility testing. The fluorescent dye exclusion method was also used for the assessment of morphological changes in the nuclei of the treated cells. According to the obtained results, olive leaf extract is less effective against the tested strains than hydroxytyrosol, an olive plant constituent tested in our previous study

Influence of "Supreme" active earth on nonglyceride compounds in soybean oil

Sirovo sojino ulje treba rafinirati da bi se dobilo jestivo ulje. Jedan od važnih procesa rafinacije ulja je bijeljenje ulja koje ovisi o više čimbenika. U ovom radu praćen je utjecaj uvjeta bijeljenja na boju, udjel sterola i tokoferola u sojinom ulju. Uzorci ulja su bijeljeni uz dodatak 0,5%, 1% i 1,5% aktivne zemlje “Supreme” pri 95°C, 105°C, 115°C. Na uklanjanje klorofila i karotenoida u najvećoj mjeri utjecao je udjel aktivne zemlje dok odabrane temperature nisu imale značajan utjecaj. Na gubitak sterola veći utjecaj je imala temperatura procesa nego udjel dodane zemlje. Od tri dominantna sterola (kampesterol, stigmasterol i β-sitosterol) najstabilniji je bio stigmasterol. U sojinom ulju najzastupljeniji je γ-tokoferol. Tijekom bijeljenja došlo je do gubitka ukupnih tokoferola od oko 7-18%. Dobivene vrijednosti nisu korelirale ni s udjelom aktivne zemlje ni s temperaturom procesa.Crude soybean oil should be refined to obtain edible oil. Bleaching is one of the most important processes in oil refining and it depends on several factors. In this study the influence of bleaching on soybean oil colour, content of sterols and tocopherols has been investigated. Samples of oil were bleached with the addition of 0,5%, 1% and 1,5% of active earth “Supreme” at 95°C, 105°C, 115°C. The decrease of chlorophllys and carotenoids was influenced mainly by the content of bleaching earth, while selected temperatures didn’t show significant influence. Process temperature showed greater influence on the decrease of sterol content, then the share of bleaching earth. Amongst three dominant sterols (campesterol, stigmasterol and β-sitosterol) stigmasterol showed the best stability. γ-tocopherol was dominant tocopherol in soybean oil. Total tocopherols content was decreased by about 7-18% during the bleaching. Obtained values were not in correlation with the content of bleaching earth nor process temperature

Influence of "Supreme" active earth on nonglyceride compounds in soybean oil

Sirovo sojino ulje treba rafinirati da bi se dobilo jestivo ulje. Jedan od važnih procesa rafinacije ulja je bijeljenje ulja koje ovisi o više čimbenika. U ovom radu praćen je utjecaj uvjeta bijeljenja na boju, udjel sterola i tokoferola u sojinom ulju. Uzorci ulja su bijeljeni uz dodatak 0,5%, 1% i 1,5% aktivne zemlje “Supreme” pri 95°C, 105°C, 115°C. Na uklanjanje klorofila i karotenoida u najvećoj mjeri utjecao je udjel aktivne zemlje dok odabrane temperature nisu imale značajan utjecaj. Na gubitak sterola veći utjecaj je imala temperatura procesa nego udjel dodane zemlje. Od tri dominantna sterola (kampesterol, stigmasterol i β-sitosterol) najstabilniji je bio stigmasterol. U sojinom ulju najzastupljeniji je γ-tokoferol. Tijekom bijeljenja došlo je do gubitka ukupnih tokoferola od oko 7-18%. Dobivene vrijednosti nisu korelirale ni s udjelom aktivne zemlje ni s temperaturom procesa.Crude soybean oil should be refined to obtain edible oil. Bleaching is one of the most important processes in oil refining and it depends on several factors. In this study the influence of bleaching on soybean oil colour, content of sterols and tocopherols has been investigated. Samples of oil were bleached with the addition of 0,5%, 1% and 1,5% of active earth “Supreme” at 95°C, 105°C, 115°C. The decrease of chlorophllys and carotenoids was influenced mainly by the content of bleaching earth, while selected temperatures didn’t show significant influence. Process temperature showed greater influence on the decrease of sterol content, then the share of bleaching earth. Amongst three dominant sterols (campesterol, stigmasterol and β-sitosterol) stigmasterol showed the best stability. γ-tocopherol was dominant tocopherol in soybean oil. Total tocopherols content was decreased by about 7-18% during the bleaching. Obtained values were not in correlation with the content of bleaching earth nor process temperature

Influence of the production parameters on the characteristic of rapeseed oil from Croatia

Cilj ovog istraživanja bio je odrediti svojstva repičinoga ulja proizvedenoga iz kultivara koji se uzgajaju na području Republike Hrvatske, te odrediti utjecaj načina proizvodnje sirovoga ulja kao i procesa rafinacije na kvalitetu, sastav masnih kiselina, udio bioaktivnih komponenata te na oksidacijsku stabilnost repičinoga ulja. Rezultati su pokazali kako je udio dominantnih masnih kiselina, sastav i udio sterola, karotenoida i tokoferola odlika pojedinog kultivara, a klimatske prilike značajno utječu na varijaciju rezultata navedenih parametara. U početnoj fazi razvoja sjemena stresni uvjeti uzrokuju smanjenje udjela karotenoida i α-tokoferola, ali povećanu sintezu plastokromanola-8 i fenolnih spojeva. Način proizvodnje ulja značajno utječe na udio i sastav negliceridnih spojeva repičinoga ulja. Kondicioniranjem sjemena znatno se povećava udio sterola i pigmenata, γ-tokoferola i ukupnih tokoferola. Najzastupljeniji fenolni spoj je kanolol čiji se udio kondicioniranjem povećava do 56 puta. Ulja proizvedena ekstrakcijom organskim otapalom sadrže više sterola i α-tokoferola u odnosu na ulja proizvedena prešanjem. Rafinacijom repičinoga ulja smanjuje se udio sterola, tokoferola, a posebno fenola, dok kanolol u potpunosti nestaje. Međutim, tijekom rafinacije dolazi do sinteze fenilindana, specifičnog spoja rafiniranoga jestivoga repičinoga ulja koji se odlikuje snažnim antioksidacijskim djelovanjem.The aim of this study was to determine characteristics of the rapeseed oil produced from cultivars grown in Croatia, and also to determine the affect of production parameters on the quality, fatty acid composition, amount of bioactive compounds and oxidative stability of the oil. Results have shown that the composition of dominant fatty acids, content and composition of sterols, catotenoids and tocopherols is a characteristic of a cultivar but those parameters are additionaly affected by climate conditions. Stressful conditions for the plant in the early stages of seed development decrease amount of carotenoids and α-tocopherol, but cause increased synthesis of the plastochromanol-8 and polyphenolic components. Amount and composition of nongliceride compounds was significantly influenced by oil production parameters. Conditioning rapeseed significantly increased amounts of sterols, pigments, γ-tocopherol and total tocopherols. The dominant phenolic component is canolol and conditioning increased its amount up to 56-fold. Oils produced by extraction with solvent have higher amount of sterols and α-tocopherol than pressed oils. Refining reduces amount of sterols, tocopherols and especially polyphenols, while canolol disappears completely. However, during refining process phenylindane is synthesized, a specific component of refined edible rapeseed oil which is characterized with strong antioxidant activity

Influence of the production parameters on the characteristic of rapeseed oil from Croatia

Cilj ovog istraživanja bio je odrediti svojstva repičinoga ulja proizvedenoga iz kultivara koji se uzgajaju na području Republike Hrvatske, te odrediti utjecaj načina proizvodnje sirovoga ulja kao i procesa rafinacije na kvalitetu, sastav masnih kiselina, udio bioaktivnih komponenata te na oksidacijsku stabilnost repičinoga ulja. Rezultati su pokazali kako je udio dominantnih masnih kiselina, sastav i udio sterola, karotenoida i tokoferola odlika pojedinog kultivara, a klimatske prilike značajno utječu na varijaciju rezultata navedenih parametara. U početnoj fazi razvoja sjemena stresni uvjeti uzrokuju smanjenje udjela karotenoida i α-tokoferola, ali povećanu sintezu plastokromanola-8 i fenolnih spojeva. Način proizvodnje ulja značajno utječe na udio i sastav negliceridnih spojeva repičinoga ulja. Kondicioniranjem sjemena znatno se povećava udio sterola i pigmenata, γ-tokoferola i ukupnih tokoferola. Najzastupljeniji fenolni spoj je kanolol čiji se udio kondicioniranjem povećava do 56 puta. Ulja proizvedena ekstrakcijom organskim otapalom sadrže više sterola i α-tokoferola u odnosu na ulja proizvedena prešanjem. Rafinacijom repičinoga ulja smanjuje se udio sterola, tokoferola, a posebno fenola, dok kanolol u potpunosti nestaje. Međutim, tijekom rafinacije dolazi do sinteze fenilindana, specifičnog spoja rafiniranoga jestivoga repičinoga ulja koji se odlikuje snažnim antioksidacijskim djelovanjem.The aim of this study was to determine characteristics of the rapeseed oil produced from cultivars grown in Croatia, and also to determine the affect of production parameters on the quality, fatty acid composition, amount of bioactive compounds and oxidative stability of the oil. Results have shown that the composition of dominant fatty acids, content and composition of sterols, catotenoids and tocopherols is a characteristic of a cultivar but those parameters are additionaly affected by climate conditions. Stressful conditions for the plant in the early stages of seed development decrease amount of carotenoids and α-tocopherol, but cause increased synthesis of the plastochromanol-8 and polyphenolic components. Amount and composition of nongliceride compounds was significantly influenced by oil production parameters. Conditioning rapeseed significantly increased amounts of sterols, pigments, γ-tocopherol and total tocopherols. The dominant phenolic component is canolol and conditioning increased its amount up to 56-fold. Oils produced by extraction with solvent have higher amount of sterols and α-tocopherol than pressed oils. Refining reduces amount of sterols, tocopherols and especially polyphenols, while canolol disappears completely. However, during refining process phenylindane is synthesized, a specific component of refined edible rapeseed oil which is characterized with strong antioxidant activity