Gekoppelte LC-GC für die Analyse von Olivenölen

Coupled LC-GC for the Analysis of Olive Oils The analysis of the so-called sterol fraction of fats and oils can be strongly improved by the application of on-line coupled LC-GC. LC replaces saponification, the (difficult) extraction of the non-saponifiable and the clean-up by preparative thin layer chromatography. The proposed method eliminates most of the manual sample preparation work, is more accurate, and provides more information at the same time, since the free and esterified components are analyzed separately. Analyzing olive oils, mostly small admixtures of other oils can be detected. For the determination of solvent extracted oil in “extra virgin” or “pure” olive oils, the method is more suitable than the conventional determination of the triterpenedialcohols erythrodiol and uvaol. Finally pressed oil of first quality (“extra virgin”) can be distinguished from that of second quality (“pure” olive oil). Oils of second quality are usually the result of pression with an excessive delay after harvesting the olives.     

Effect of processing on the oxidative stability of low erucic acid turnip rapeseed (Brassica rapa) oil

The effect of various processing conditions on the composition and the oxidative stability of mechanically pressed (90–95°C) rapeseed oil was investigated. The five different rapeseed oils included crude (nondegummed), superdegummed, steam stripped (at 140°C for 4h, nondegummed), physically refined (degummed, bleached and deodorized at 240°C), and cold pressed (40°C) oils. Oils were autoxidized in the dark at 60°C and under light at 25°C. Oxidation was followed by measuring changes in the peroxide values (PV) and the consumption of tocopherol and carotenoid was measured. In the dark the oils reached PVs of 10 meq/kg in the order: cold pressed > superdegummed > steam stripped ≅ crude > refined. However, under light conditions the order changed as follows: cold pressed > crude ≅ steam stripped > superdegummed > refined. Processing had no effect on fatty acid composition nor α-tocopherol content of the oils. Superdegumming and steam stripping decreased the carotenoid content of the oils while cold pressing and refining reduced also chlorophyll, γ-tocopherol and phosphorus content of the oils.     

Analysis of carotenoids and vitamin E in selected oilseeds,press cakes and oils

Carotenoids and vitamin E in oils from the market – 6 rapeseed and 6 sunflower oils, half of each cold pressed and refined – and in the oils of rape, sunflower, flax and safflower as well as the respective seeds and press cakes from a local oil mill were quantified by HPLC. Furthermore, a photometric determination of carotenoid content was tested and checked against the chromatographic method. In the cold pressed oils minor amounts of xanthophylls (all‐E)‐lutein and (all‐E)‐zeaxanthin were determined. With exception of traces of (all‐E)‐β‐carotene in cold‐pressed rapeseed oil this provitamin A active compound did not occur. Cold pressed rapeseed oils contained 0.5–1.5 mg total carotenoids/100 g which was manifold the content of the further oils. Vitamin E was found in all vegetable oils at plant‐typic tocopherol patterns. The photometric determination of carotenoids resulted in significantly higher concentrations compared to the HPLC. This overestimation bases on the carotenoid pattern which was validated by comparison with known high‐carotenoid materials, i.e. maize flour with an abundant amount of xanthophylls and carrots with an abundant amount of carotenes.     

The Contents of Lignans in Sesame Seeds and Commercial Sesame Oils of China

In this study, the concentrations of three lignans in 100 sesame seeds and 56 sesame oils were determined using a newly developed method based on high‐performance liquid chromatography coupled with a UV/Vis detector. Total lignan contents in sesame seed and oil samples ranged from 2.52 to 12.76 and 3.38 to 11.53 mg/g, respectively. Black sesame seeds showed higher sesamin content (range 1.98–9.41 mg/g, mean 4.34 mg/g) and sesamolin content (range 1.06–3.35 mg/g, mean 1.92 mg/g) than the other three varieties of sesame seeds. Black sesame oils had higher contents of lignans than the white sesame oils, although remarkable differences were not observed. Hot pressed and small mill sesame oils expressed higher contents of sesamol, sesamin, and total lignans than the cold pressed and refined sesame oils. The results revealed that there is extensive variability in lignan concentration in sesame oils and seeds.     

Optimization of Deodorization Design for Four Different Kinds of Vegetable Oil in Industrial Trial to Reduce Thermal Deterioration of Product

Trans fatty acids (TFA) have been shown to be associated with various health disorders. Due to thermal stress, one major source of dietary TFA is high-temperature deodorization of vegetable oils. In this study, precision minimal deodorization was proposed to obtain healthier “zero-TFA” vegetable oils (TFA ≤0.3%). By optimizing temperatures for different deodorizers, dual columns with dual temperatures (DCDT) deodorizers were proposed, transformed, and industrially implemented among dozens of plants. The deodorization temperatures were optimized and customized, respectively, for four kinds of vegetable oil (soybean oil and rapeseed oil: tray column 205 °C and packed column 225 °C, maize oil and sunflower seed oil: tray column 210 °C and packed column 230 °C). Industrial trials showed that all four kinds of oils can achieve “zero-TFA” by DCDT deodorization at the customized mild temperatures, and meanwhile oil physicochemical qualities and shelf-life stabilities were compared with corresponding conventional refining oils. The initial free fatty acid and color were a little higher than that of conventional refining oils, but no significant differences were shown in change trends of these physicochemical indexes during the shelf life, which indicated a good and stable oil quality of “zero-TFA” oils for future industrial productions and sales.     

Detection of pressed hazelnut oil in admixtures with virgin olive oil by analysis of polar components

Analysis of the polar fraction from virgin olive oil and pressed hazelnut oil by high-performance liquid chromatography showed marked differences in the chromatograms of the polar components in the two oils. Six commercial samples of pressed hazelnut oil and 12 samples of virgin olive oil (or blended olive oil including virgin olive oil) were analyzed. The phenolic content of the pressed hazelnut oil samples was 161±6 mg·kg⁻¹. Inspection of the chromatograms showed that the pressed hazelnut oil extracts contained a component that eluted in a region of the chromatogram that was clear in the olive oil samples, and consequently this component could be used to detect adulteration of virgin olive oil by pressed hazelnut oil. The component had a relative retention time of 0.9 relative to 4-hydroxybenzoic acid added to the oil as an internal standard. The ultraviolet spectrum of the component showed a maximum at 293.8 nm, but the component could not be identified. Analysis of blends of oils showed that adulteration of virgin olive oil by commercial pressed hazelnut oil could be detected at a level of about 2.5%.     

Sensory and Physico‐Chemical Properties of Cold Press‐Produced Tomato (Lycopersicon esculentum L.) Seed Oils

In this study, roasted and unroasted (control) tomato seeds were cold pressed and the seeds, oils, and seed presscakes (meals) were analyzed. Some physicochemical properties, total phenolic content and antioxidant capacity, thermal properties, mineral contents, fatty acids, sterols and tocopherols compositions, volatile compounds and sensory evaluation of the tomato seed oils were determined. The tomato seeds contained 3.3 % of ash, 17.3 % of oil and 27.2 % of protein. The cold press oil recovery rate was 7.2 and 10.28 % for control and roasted seeds, respectively. There were eight sensory terms defining the oils together with 34 different aromatic compounds quantified. The volatile compounds furfural, hexanal, benzaldehyde and 2‐isobutylthiazole were found with the highest frequency in the samples. Roasted, green and tomato were defined as characteristic sensory terms for tomato seeds oils. Fifteen different minerals, melting and crystallization temperatures and enthalpies of the oil samples were also quantified. This study provides important data for the tomato seed oils, and proves that pre‐roasted tomato seed oils are high quality, nutritious and aromatics oils with higher levels of consumer acceptability.     

What we know and what we should know about virgin oils – a general introduction

On international scale the Codex Alimentarius Standard for Named Vegetable Oils differentiates between virgin oils and cold‐pressed oils, while in Germany virgin, non‐refined and refined oils are available. Here cold‐pressed is an additional quality feature. The paper explains and comments the various definitions for vegetable oils other than olive oil obtained by mechanical extraction only, because they are partly contradictory. Resulting from gentle processing virgin oils are often appreciated by the consumers as the better oils. The answer of the present paper to the question which type of oil is better is that there is no better or worse oil, but only a better or worse suitability of an oil for application in food processing or the kitchen. Finally, the paper picks up the upcoming debate on the potential ’?new' contaminant, 3‐MCPD‐fatty acid esters, which were found in refined oils.     

A Survey of the Amounts of Oxidized Triglycerides and Triglyceride Dimers in Virgin and “Lampante” Olive Oils

The aim of this work was to ascertain the amount of oxidized triglycerides and triglyceride dimers in virgin and “lampante” olive oils: to this effect, 38 samples were collected from different oil-mills. No data on the above compound classes in ?lampante”? olive oils have ever appeared in literature up to now. However, fat autoxidation is known to imply polymerization reactions; so, low amounts of oligopolymers may be formed in oil at a given state of oxidation. This aspect also applies to virgin olive oils because the very few data reported in literature are mainly related to extra virgin olive oils which are classified as high quality oils. Column chromatography and high-performance size exclusion chromatography were used for oil analysis in this work. Triglyceride dimers were either absent or present in traces in virgin olive oils, but were found in ?lampante”? oils with a mean value of 0.07%. Oxidized triglyceride percentages in ?lampante”? oils were more than twice as high as those present in virgin oils. The data obtained suggest the following consideration: the presence of dimers in vegetable oils reveals a rather high oxidation level and is confirmed by the higher oxidized triglyceride values. This is a reliable index of oxidative degradation in oil.     

Trans fatty acid composition and tocopherol content in vegetable oils produced in Mexico

The purpose of this study was to evaluate the trans fatty acid (TFA) composition and the tocopherol content in vegetable oils produced in Mexico. Sample oils were obtained from 18 different oil refining factories, which represent 72% of the total refineries in Mexico. Fatty acids and TFA isomers were determined by gas chromatography using a 100-m fused-silica capillary column (SP-2560). Tocopherol content was quantified by normal-phase high-performance liquid chromatography using an ultraviolet detector and a LiChrosorb Si60 column (25 cm). Results showed that 83% of the samples corresponded to soybean oil. Seventy-two percent of the oils analyzed showed TFA content higher than 1%. Upon comparing the tocopherol contents in some crude oils to their corresponding deodorized samples, a loss of 40–56% was found. The processing conditions should be carefully evaluated in order to reduce the loss of tocopherols and the formation of TFA during refining.     

Machines for olive paste preparation producing quality virgin olive oil

Polyphenolic substances enhance the resistance to oxidation of virgin olive oils, but an excess of polyphenols determines a marked bitter, somewhat tannic taste of the oil, similar to the taste of unripe olives. Tests have been carried out on drupes of different cultivars in industrial productions to evaluate the effect of the machines used to prepare olive pastes on the contents of polyphenols in the oils. Notably greater amounts of polyphenols were found in the oils extracted from hammer-crushed pastes than in the oils extracted from milled pastes. The kneading process which follows, especially if it is long, often reduces the amounts of total polyphenols. Therefore, in order to obtain the best organoleptic and chemical quality in extra virgin olive oils, two systems are suggested for the processing procedures. For olives of certain cultivars (Coratina) and for not-blackened or slightly blackened drupes yielding oils with a very high content of total polyphenols, it is most expedient to use the stone-mill together with a kneader system. But it is more suitable to utilize the hammercrusher together with a kneader system in processing olives (such as the Ogiiarola Salentina or Leccino cultivars) yielding normally “sweet” oils with a low content of total polyphenols.     

Effects of frying on the trans‐fatty acid formation in soybean oils

To evaluate the effects of repeated deep‐frying on the trans‐fatty acid (TFA) formation in soybean oils, simultaneous frying experiments were carried out. French fries were prepared using three different types of soybean oil (pressed soybean oil, PSBO; first‐grade solvent extracted soybean oil, FG‐SESBO; and third‐grade solvent extracted soybean oil, TG‐SESBO). French fries were fried intermittently at 180–185°C for a total frying time of 32 h and at an interval time of 30 min. It was found that the initial amount of total TFAs was 0.29 g/100 g, 0.31 g/100 g, and 0.90 g/100 g in PSBO, TG‐SESBO, and FG‐SESBO, respectively. Before the frying started, the C18:1,t‐9, trans‐linoleic acid (TLA), trans‐linolenic acid (TLNA), and total TFA content of the PSBO and TG‐SESBO were significantly lower than in the FG‐SESBO (p<0.05). However, in the frying oil samples, the final concentration of total TFA in the PSBO, TG‐SESBO, and FG‐SESBO were 1.79 ± 0.17 g/100 g, 1.12 ± 0.10 g/100 g, and 1.70 ± 0.07 g/100 g, which was 6.17‐, 3.61‐, and 1.89‐fold higher that in fresh oil, respectively. The highest increasing slopes of C18:1,t‐9, TLA, TLNA, and total TFA were observed in the PSBO. Practical applications : A high intake of TFAs has been shown to lead to an increased risk of coronary heart disease. Plant oils, particularly soybean oil, have been widely used in the food industry in China. Frying is one of the most common methods to cook food. The formation of TFAs during frying has been shown to be closely related to the temperature and duration of the frying process. However, the effects of frying on the formation of TFAs in different soybean oils have not been well studied. In the present study, we demonstrated that increasing the number of frying cycles can cause an intensive increase in the concentration of TFAs in different types of soybean oil, but especially in PSBO.     

Stability of Cold-Pressed Oil from Commercial Indian Niger (Guizotia abyssinica (L.f.) Cass.) Seed as affected by Blending and Interesterification

Blending and interesterification of cold‐pressed oil from commercially available niger (Guizotia abyssinica (L.f.) Cass.) seeds was performed to improve its stability. The fatty acid composition of cold‐pressed niger seed oil (NSO) revealed that it contained a huge amount of polyunsaturated linoleic acid (69.2 %). NSO being rich in polyunsaturated fatty acids (PUFA) was susceptible to oxidation and hence was blended with saturated fatty acid (SFA) rich coconut oil (CNO) and monounsaturated fatty acid (MUFA) rich olive–pomace oil (OO) to enhance its stability. CNO contained a total of 91.3 % of SFA, while OO had oleic acid, C18:1 (74.3 %) as MUFA. Two blends of NSO with CNO and OO, i.e. NSO + CNO(B) and NSO + OO(B), were prepared in the ratio of 1:1. The blends were further interesterified using the lipase enzyme from Rhizomucor meihei and interesterified oils, i.e. NSO + CNO(I) and NSO + OO(I), were obtained. The oxidative stability of the oils was evaluated by incubating them at 37 °C and 55 % relative humidity (RH) for a period of 45 days. The peroxide values of NSO + CNO(B), NSO + OO(B), NSO + CNO(I) and NSO + OO(I) showed a reduction by 53.3, 42.6, 65.3 and 55.4 %, respectively, while the conjugated diene values showed a reduction by 75.0, 66.9, 76.7 and 75.3 %, respectively, as compared to NSO during the incubation period. This is probably the first report on the stability improvement of niger seed oil through blending and interesterification.     

不同植物油脂对冷制皂入皂特性的影响

选用椰子油、棕榈油、橄榄油、山茶油、乳木果油、甜杏仁油、美藤果油和霍霍巴油8种植物油脂为原料,采用冷制工艺制作成3组不同含油量的植物油脂手工皂,研究了不同植物油脂对冷制皂入皂特性的影响,并对植物油脂复配制作的冷制皂进行肤感感官评价。结果表明,植物油脂的种类和含量对冷制皂的p H值影响不大,对其他入皂特性均有影响。椰子油冷制皂硬度高、起泡性强且泡沫丰富、Trace time短,与不饱和植物油脂复配入皂有助于缩短制作冷制皂的Trace time,提高冷制皂的硬度和起泡能力;山茶油、甜杏仁油和橄榄油入皂有助于起泡;橄榄油入皂有助于提高冷制皂的泡沫稳定性;乳木果油和霍霍巴油入皂起泡能力较差;美藤果油入皂滋润度高、泡沫细腻、洗感舒适、肤感评价最佳。     

Detection of Adulteration in Iranian Olive Oils Using Instrumental (GC,NMR, DSC) Methods

This paper describes an investigation into the usefulness of some instrumental methods (GC, NMR, and DSC) in the detection of adulteration of olive oil with soybean, sunflower, and canola oils (that are relatively cheap oils mixed as adulterants with olive oil). These seed oils were compared with genuine and commercial olive oils, two of which appeared to have been adulterated. It was observed that from among physical and chemical indices, the iodine value and the refractive index in the two olive oil samples (named A and B) were significantly higher (P < 0.01) than in the reference (genuine) olive oil, both values being above standard limits established for olive oil. On the other hand, fatty acid (FA) profiles in these two samples exhibited higher amounts of linolenic and linoleic acids (5.34 and 39.92%, 6.38 and 54.42%, 0.79 and 12.88% for A, B and genuine olive oils respectively) but significantly lower amounts of oleic acid (30.07, 21.72 and 67.86%, respectively). The number and intensity of signals observed using ¹H NMR indicated that the peaks numbered 2 and 7 were useful in the determination of olive oil purity. Because of higher linolenic and linoleic acid contents in samples A and B, the intensity and integrated areas for these two signals were higher than those for other olive oil samples in which signal 2 was not observed and signal 7 had a very low intensity. Satisfactory results were achieved from quantitation of DSC parameters. The results show that due to increased unsaturated FAs in samples A and B and the consequent changes in triacylglycerol profiles, offset crystallization temperature and onset melting temperature in these two olive oils differed from those of the reference and clearly shifted to lower values. Crystallization and melting curves were similar to the corresponding curves observed for soybean and sunflower oils in terms of shape and number of peaks.     

Bioactive Compounds of Portuguese Virgin Olive Oils Discriminate Cultivar and Ripening Stage

The presence of different bioactive compounds in virgin olive oil affects its nutritional, oxidative and sensorial properties. Phenolic compounds are olive endogenous bioactive compounds highly susceptible to degradation. Olive endogenous oxidoreductases, mainly polyphenol oxidases (PPO) and peroxidases (POD), may play an important role on the profile of bioactive compounds in olive oil by promoting oxidation of phenolic compounds. The aim of this study was to evaluate if changes on PPO and POD activities in olive fruits from two Portuguese cultivars (Olea europaea, cv ‘Cobrançosa’ and cv ‘Galega Vulgar’) are related with the composition of their olive oils, especially phenolic compounds. Pattern recognition techniques [principal component analysis (PCA), cluster analysis (CA), and discriminant analysis (DA)] were used for multivariate data analysis. Olive oils characterized by their FA composition were grouped by cultivar. When olive oils were characterized by their phenolic composition, green pigments, and enzymatic activities in fruits, they could be discriminated by olive ripening stage. Along ripening, PPO activity was only detected in the fruit mesocarp of both cultivars and POD activity was mainly detected in the seeds. The POD activity, as well as vanillin and gamma‐tocopherol contents in olive oil increased with the ripening index. Conversely, higher PPO activity in fruits at early ripening stages together with higher levels of total phenols, green pigments, beta‐tocopherol, hydroxytyrosol and p‐coumaric acid in olive oils were observed. The ripening stage of fruits showed to be a key factor on the amount and profile of bioactive compounds of olive oil.     

Zur lebensmittelrechtlichen Beurteilung hervorhebender Hinweise bei Fetten und fetthaltigen Zubereitungen

Legal Food Estimation of Remarks Concerning the Quality of Fats and Fat Containing Preparations For legal food estimation of commercial fats and oils as well as of preparations, industrially produced of fats and oils, the general regulations of the food and requisite law of 15. 8. 1974 in context with definitions e. g. in the rules of the German foodbook or in guiding principles of the food management are to notice concerning accentuating quality hints as “fine”, “first class”, “good”, “pure”, “natural” or similar. The relations are explained on butter or pure butter fat and butter pastry, on lard, lard pastry, on native and refined sunflower oils as on hardened marine animal oil and preparations produced of these ingredients.     

Design and Characteristics of Novel Sensory and Nutritionally Oriented Olive,Seed, and Nut Virgin Oils’ Blendings

Virgin olive oil is considered a key component of the Mediterranean Diet, while nut and seed “cold-pressed” oils stand out as an interesting ingredient due to the growing consumer demand toward so-called gourmet and healthy oils. The main objective of this work is the development and characterization of novel virgin vegetal oils based on blendings of virgin olive oil with virgin oils obtained from seeds (sesame and flaxseed) and nuts (hazelnut and pistachio) of interest due to their peculiar nutritional and organoleptic characteristics. Oil formulations elaborated with 5% of sesame oils achieve a high content in vitamin E (842 mg kg⁻¹, 11.8 mg per standard 14 g oil dose, corresponding to an 80% of the recommended daily intake) and with 10% of flaxseed a high level in essential α-linolenic acid (6.4%, 0.90 mg per dose corresponding to a 66% of the recommended daily intake). In addition, sensory analysis shows that blends enriched with both 50% hazelnut oil and 75% pistachio oil not only maintain the typical aroma of virgin olive oil, but incorporate the characteristic nutty, roasty, seed-like, and sweet sensory attributes of nuts, providing an added value to the consumers.     

Effect of physical refining on selected minor components in vegetable oils

The final quality of vegetable oils is largely determined by the deodorization process. From an organoleptic point of view, oils should be light in color with a bland taste and a good cold and/or oxidative stability. Today, however, more and more attention is paid to the real nutritional quality. Oils should contain low trans fatty acid levels, low polymeric triglycerides, and secondary oxidation products and at the same time being rich in natural antioxidants. In order to comply to these new quality requirements, the deodorization technology has been modified substantially. Mathematical models were established describing the influence of different process parameters (time, temperature, steam, and pressure) on trans fatty acid formation, tocopherol stripping, and production of oxidized and polymeric triacylglycerides during physical refining of soybean oil. Trans fatty acid (TFA) formation was influenced only by time and temperature. No significant influence of pressure or sparging steam could be observed. Models expressing the relative degree of cis/trans-isomerization of linoleic (DI_18:2) and α-linolenic acid (DI_18:3) could be extrapolated to other oils and deodorizer designs. Tocopherol removal was mainly influenced by process temperature and sparging steam. Additionally, tocopherol retention seemed to be dependent on the deodorizer design (steam injection geometry and sparging steam distribution). During physical refining, oxidized and polymerized triacylglycerols were not significantly influenced by any of the investigated process parameters. Industrially, process conditions are adapted to minimize trans fatty acid formation and maximize tocopherol retention. These goals can be achieved in a so-called DUAL TEMP^copy; deodorizer.