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.     

Lignan contents in sesame seeds and products

Sesame seed (Sesamum indicum L.) is a rich source of furofuran lignans with a wide range of potential biological activities. The major lignans in sesame seeds are the oil‐soluble sesamin and sesamolin, as well as glucosides of sesaminol and sesamolinol that reside in the defatted sesame flour. Upon refining of sesame oil, acid‐catalyzed transformation of sesamin to episesamin and of sesamolin to epimeric sesaminols takes place, making the profile of refined sesame oils different from that of virgin oils. In this study, the total lignan content of 14 sesame seeds ranged between 405 and 1178 mg/100 g and the total lignan content in 14 different products, including tahini, ranged between 11 and 763 mg/100 g. The content of sesamin and sesamolin in ten commercial virgin and roasted sesame oils was in the range of 444–1601 mg/100 g oil. In five refined sesame oils, sesamin ranged between 118 and 401 mg/100 g seed, episesamin between 12 and 206 mg/100 g seed, and the total contents of sesaminol epimers between 5 and 35 mg/100 g seed, and no sesamolin was found. Thus, there is a great variation in the types and amounts of lignans in sesame seeds, seed products and oils. This knowledge is important for nutritionists working on resolving the connection between diet and health. Since the consumption of sesame seed products is increasing steadily in Europe and USA, it is important to include sesame seed lignans in databases and studies pertinent to the nutritional significance of antioxidants and phytoestrogens. It is also important to differentiate between virgin, roasted and refined sesame oils.     

Participation of sesamol in stability of sesame oil

Sesame oil is known to be the most resistant to oxidative rancidity. Constituents of sesame oil such as sesamolin, sesamol and sesamol dimer (a possible intermediate of oxidative degradation of sesamol) were determined by high performance liquid chromatography using a reverse-phase column. Sesamol was specifically determined in an alternative way by use of hydrogen peroxide/horseradish peroxidase. Sesamolin was relatively stable but sesamol and sesamol dimer were unstable when irradiated in benzene, and the final degradation products were identical. Whereas sesamolin was inactive, sesamol and sesamol dimer showed significant antioxidant activity in several kinds of fat and oils. Stability of Japan Pharmacopoeia sesame oil free from sesamol was relatively low; antioxidant activity of sesamol incorporated in the oil was unexpectedly low and was rapidly lost in the oil activated by oxygen. Edible sesame oil with intrinsic sesamol was highly stable. Activation of the edible oil gradually increased the sesamol content with concomitant decrease of sesamolin. High stability of edible sesame oil could not be ascribed to sesamol, but it could be explained by another powerful antioxidant(s) which might stabilize both the oil and unstable sesamol.     

Analysis of Fatty Acid and Lignan Composition of Indian Germplasm of Sesame to Evaluate Their Nutritional Merits

An attempt was made to individually analyze a germplasm collection of 54 indigenous Indian sesame cultivars for fatty acid and lignan composition of their seed oil by gas chromatography and high performance liquid chromatography, respectively. The entries varied in their fatty acid and lignan composition. The mean percentage contents of palmitic, stearic, oleic, linoleic and α‐linolenic acids ranged between 10–22, 5–10, 38–50, 18–43 and less than 1 whereas sesamol, sesamin and sesamolin scored between 3–37, 27–67, 20–59 of the total percentage of lignan, respectively. The highest percentage of α‐linolenic acid (ALA) was obtained in Var‐9 (1.3 % of the total fatty acids). Among the lignans, high sesamin content is considered to be significant, particularly in terms of long shelf life and nutraceutical value of sesame seed oil. The study has broadened our understanding related to differential biochemical composition of the rich sesame germplasms, thereby providing us with a useful groundwork for identifying potential targets and suitable cultivars for genetic engineering approaches to be undertaken in order to improve the nutritional quality of sesame oil, which in turn would be beneficial towards human health.     

Optimization of industrial‐scale deodorization of high‐oleic sunflower oil via response surface methodology

Optimization of industrial‐scale deodorization of high‐oleic sunflower oil (HOSO) via response surface methodology is presented in this study. The results of an experimental program conducted on an industrial‐scale deodorizer were analyzed statistically. Predictive models were derived for each of the oil quality indicators (QI) in dependence on the studied variable deodorization process parameters. The deodorization behavior of some minor components was analyzed on a pilot‐scale deodorizer. For comparison, a similar experimental program was also performed on the laboratory‐scale. The results of this study demonstrate that optimization of the deodorization process requires a suitable compromise between often mutually opposing demands dictated by different oil QI. The production of HOSO with top‐quality organoleptic and nutritional values (high tocopherol and phytosterol contents and low free and trans fatty acid contents) and high oxidative stability demands deodorization temperatures in the range between 220 and 235 °C and a total sparge steam above 2.0% (wt/wt in oil). The response surface methodology provides the tools needed to identify the optimum deodorization process conditions. However, the laboratory‐scale experiments, while showing similar response characteristics of QI in dependence on the process parameters and thus helpful as a guide, are of limited value in the optimization of an industrial‐scale operation.     

Antioxidant activity of pilot‐plant alcoholic and supercritical carbon dioxide extracts of thyme

Leaves and flowering tops of thyme (Thymus vulgaris L.) were extracted with ethyl alcohol and supercritical carbon dioxide. Antioxidant activity was measured in sunflower oil at 0.3, 0.6 and 1% concentrations of extracts by oven test and Rancimat method. The activities of extracts were compared to those of butylated hydroxytoluene at 0.01 and 0.1% level. The ethanolic extract showed a slightly higher antioxidative effect than that obtained by supercritical fluid extraction. The effectiveness of both extracts added at 0.6% level were equal to that of 0.1% of butylated hydroxytoluene.     

Isolation of tocopherol and sterol concentrate from sunflower oil deodorizer distillate

The isolation of tocopherols and sterols together as a concentrate from sunflower oil deodorizer distillate was investigated. The sunflower oil deodorizer distillate was composed of 24.9% unsaponifiable matter with 4.8% tocopherols and 9.7% sterols, 28.8% free fatty acid (FFA) and 46.3% neutral glycerides. The isolation technology included process steps such as biohydrolysis, bioesterification and fractional distillation. The neutral glycerides of the deodorizer distillates were hydrolyzed byCandida cylindracea lipase. The total fatty acids (initial FFA plus FFA from neutral glycerides) were converted into butyl esters withMucor miehei lipase. The esterified product was then fractionally distilled in a Claisen-vigreux flask. The first fraction, which was collected at 180–230°C at 1.00 mm of Hg for 45 min, contained mainly butyl esters, hydrocarbons, oxidized products and some amount of free fatty acids. The fraction collected at 230–260°C at 1.00 mm Hg for 15 min was rich in tocopherols (about 30%) and sterols (about 36%). The overall recovery of tocopherols and sterols after hydrolysis, esterification and distillation were around 70% and 42%, respectively, of the original content in sunflower oil deodorizer distillate.     

Evaluation of the Antioxidant Properties of Micronutrients in Different Vegetable Oils

Micronutrients (tocols, sterols, and total phenolic) and antioxidant activities of 15 varieties of common vegetable oil samples obtained from different countries are investigated. All methanol extracts are assayed for total antioxidant ability and cellular antioxidant activity (CAA) using oxygen radical absorbance capacity (ORAC) method and CAA assay. CAA has been widely used in the evaluation of food antioxidants recently. It quantifies antioxidant capacity utilizing a HepG2 cell model, which is more biologically representative. Linseed and sesame oils show much higher CAA values than the others tested; however, levels of walnut, sunflower, and coconut oils are extremely low, which are hard to be quantified. A significant correlation between the ORAC and CAA values and total phenolic content (p < 0.05) is observed. High‐phenolic olive oil has the highest level of phenolics and the highest ORAC, while linseed oil has the highest CAA value. Based on this, choosing proper edible oil consumption may reduce oxidative damage of human body and promote the precision processing of edible oil such as retaining beneficial ingredients moderately. Practical Application: This study demonstrates the evaluation of the universality of vegetable oils by the cellular antioxidant model and provides a data reference for the selection of edible oils with excellent antioxidant properties.     

A Rapid Method for Simultaneous Analysis of Lignan and γ‐Tocopherol in Sesame Oil by Using Normal‐Phase Liquid Chromatography

A novel method for rapid and simultaneous analysis of three lignans and γ‐tocopherol in sesame oil has been established based on a one‐step solvent extraction followed by normal‐phase liquid chromatography. The briefness of the experimental procedure, use of 5 mL of n‐hexane/isopropanol (98:2, v/v) for extraction without any further cleanup process, short analysis time (10 min), and excellent sensitivity and selectivity demonstrated the advantages of this practical and efficient method. All the analytes exhibited satisfactory recoveries ranging from 95.4 to 103.4% at three spiked levels, with the relative SD ranging from 1.1 to 4.4%. The limits of quantitation of this method for four analytes were in the range of 0.3–1.0 μg g^?1. The validated method was successfully applied to the coinstantaneous determination of lignan and γ‐tocopherol in five real sesame oil samples. Furthermore, the results of this study were compared with previously reported method and standard method.     

Formation of 4‐Hydroxy‐2‐Trans‐Nonenal,a Toxic Aldehyde,in Thermally Treated Olive and Sunflower Oils

4‐Hydroxy‐2‐trans‐nonenal (HNE) is a toxic aldehyde produced mostly in oils containing polyunsaturated fatty acid due to heat‐induced lipid peroxidation. The present study examined the effects of the heating time, the degree of unsaturation, and the antioxidant potential on the formation of HNE in two light olive oils (LOO) and two sunflower oils (one high oleic and one regular) at frying temperature. HNE concentrations in these oil samples heated for 0, 1, 3, and 5 hours at 185 °C were measured using high‐performance liquid chromatography. The fatty‐acid distribution and the antioxidant capacity of these four oils were also analyzed. The results showed that all oils had very low HNE concentrations (<0.5 μg g^?1 oil) before heating. After 5 hours of heating at 185 °C, HNE concentrations were increased to 17.98, 25.00, 12.51, and 40.00 μg g^?1 in the two LOO, high‐oleic sunflower oil (HOSO), and regular sunflower oil (RSO), respectively. Extending the heating time increased HNE formation in all oils tested. It is related to their fatty‐acid distributions and antioxidant capacities. RSO, which contained high levels of linoleic acid (59.60%), a precursor for HNE, was more susceptible to degradation and HNE formation than HOSO and LOO, which contained only 6–8% linoleic acid.     

Oxidative stability of oils containing olive leaf extracts obtained by pressure,supercritical and solvent‐extraction

The effect of the addition of olive leaf (Olea europaea, cv. Arbequina) extracts, i.e. hydroalcoholic (ethanol–water 1:1; OHE), juice (OJ) and supercritical fluid‐CO₂ (OSFE) on the oxidative stability of vegetable oils with different unsaturation, such as soybean oil (SBO), canola oil (CO) and high oleic sunflower oil (HOSO), were studied at two concentrations (250 and 630 mg/kg oil, expressed as caffeic acid equivalent (CAE)). The extracts were characterized by the total phenolic content (Folin–Ciocalteau method), phenol chromatographic profiles (LC‐MS) and antioxidant activity (DPPH). OHE showed the highest phenol content (7.7 mg CAE/mL) while OJ and OSFE showed values of 5.4 and 2.2 mg CAE/mL, respectively. Oleuropein and its derivatives were the major phenolic compounds identified in OHE. The addition of 630 mg CAE/kg oil of OHE and OSFE to HOSO, SBO and CO showed an antioxidant effect, increasing significantly the induction time (IT) (p<0.05). That effect was highest when the system was more monounsaturated. In contrast, OJ showed a pro‐oxidant effect for all oils systems for both concentration studied. This behaviour could be attributed to the diphenol oxidase (PPO) activity.     

Antioxidant capacity of flaxseed lignans in two model systems

The flaxseed lignans secoisolariciresinol (SECO) and its diglucoside secoisolariciresinol diglucoside (SDG) are reported to have a number of health benefits associated with their consumption that have in part been attributed to their antioxidant properties. In this study the relative antioxidant capacity of the flaxseed lignans vs. BHT was determined in two model systems. First, an antioxidants stoichiometric value was determined for SECO and SDG in a liposomal system as a mimic of lipid peroxidation. Stoichiometric values for SECO (1.5) and SDG (1.2) vs. BHT (2.0) were measured from the lag time for the formation of conjugated dienes; all values were significantly different (P<0.01). Second, the ability of flaxseed lignans to prevent oxidative degradation of canola oil was determined. Samples were stored at room temperature and analyzed at 30-d intervals over 120 d using a Rancimat^™ analyzer. The lignans prevented degradation of canola oil, as measured by induction time, in a concentration-dependent manner. Although SECO demonstrated a trend for better protection than either SDG or polymer containing SDG, they were not significantly different (P>0.01). There was also no significant difference between SECO or SDG and BHT, suggesting flaxseed lignans may be good alternatives to minimize rancidity in oil-based food products.     

Stability of refined olive oil and olive‐pomace oil added by phenolic compounds from olive leaves

Refined olive oil and olive‐pomace oil were enriched with olive leaf phenolic compounds in order to enhance its quality and bring it closer to virgin olive oil. The changes that occurred in the concentrations of pure oleuropein, oleuropein aglycone, hydroxytyrosol acetyl and α‐tocopherol at 400 µg/kg of oil during the storage of refined olive oil and olive‐pomace oil under accelerated conditions (50 °C) were investigated. In a period of 4 months, α‐tocopherol decomposed by 75% whereas less than 40% of the phenols were lost. During storage, enzymatic olive leaf extract hydrolysate that contains two major compounds, hydroxytyrosol and oleuropein aglycone showed the highest antioxidant activity and the lowest detected stability, followed by oleuropein. The oleuropein in olive leaf extracts exhibited similar degradation profiles, reducing by 60–50% and 80% for the olive oil and olive‐pomace oil in 6 months, respectively. The acetylated extract, however, displayed a loss of 10 and 5% in olive oil and olive‐pomace oil, respectively. In the fatty acid composition, an increase in oleic acid and a decrease in linoleic acid were observed. The antiradical activities of the olive oil and olive‐pomace oil enriched with olive leaf phenolic compounds at 400 ppm showed that enzymatic hydrolysate extract had the highest protective effect against oil oxidation. Based on the Rancimat method, the oils with added leaf enzymatic hydrolysate extract had the lowest peroxide value and the highest stability. After 6 months of storage and at 120 °C, the oxidative resistance of refined olive oil and olive‐pomace oil reached 0.71 and 0.89 h, respectively, whereas that of the non‐enriched samples fell to zero.     

Application of short path distillation for recovery of polyphenols from deodorizer distillate

During physical refining of oil derived from ‘high temperature short time’ (HTST) pretreated rapeseeds, polyphenols are separated from the oil during deodorization and accumulate together with other high‐value minor compounds in the so‐called deodorizer distillate. For recovery of these compounds single‐stage and multistage short path distillations were carried out in a laboratory scale apparatus at evaporation temperatures between 110 and 170°C and pressures between 0.006 and 0.01 mbar. In addition, the removal of traces of pesticides from rapeseed deodorizer distillate was investigated. It was observed that these compounds can be separated from deodorizer distillate by means of short path distillation very effectively. On the basis of these experiments, a recovery process for polyphenols was proposed involving short path distillation, acid catalyzed esterification with methanol, solvent crystallization and solvent extraction processes. The final product was a polyphenol enriched extract containing about 14% of polyphenols. A polyphenol recovery of 50% is considered to be reachable and fractions rich in tocopherols and sterols may be obtained as by‐products.     

Variation of Oil,Sesamin, and Sesamolin Content in the Germplasm of the Ancient Oilseed Crop Sesamum indicum L.

Currently, genetic improvement in oil and lignan content is a major objective in sesame breeding. As a prerequisite to meet the objective, the diversity of these traits of sesame germplasm was examined. Solvent extraction of the harvested seeds demonstrated variation in oil content ranging from 39% to 49% across the sesame accessions tested. High performance liquid chromatography of oil samples showed sesamin and sesamolin as the only lignans present in the oil, with their amount in the range of 2.74–10.55 g L⁻¹ and 2.49–13.78 g L⁻¹, respectively. Coefficient of variation for oil content remained the highest in brown and black seeded accessions, whereas it remained at maximum for sesamin and sesamolin in white seeded ones. Pearson analysis showed a positive correlation between oil and lignan content. It was concluded that Indian sesame accessions exhibit considerable variation in oil and lignans content. The S. indicum varieties with a desirable composition of oil and/or lignans have been identified and recommended for incorporation in breeding programs, as well as for specific human use.     

Antioxidant Activity of Seaweed Extracts: In Vitro Assays,Evaluation in 5 % Fish Oil‐in‐Water Emulsions and Characterization

In this study the antioxidant activity of absolute ethanol, 50 % ethanol and water extracts of two species of seaweeds, namely Fucus serratus and Polysiphonia fucoides, were evaluated both in in vitro assays and in 5 % fish oil‐in‐water (o/w) emulsions. The 50 % ethanolic extracts of P. fucoides showed higher antioxidant activity both in in vitro assays and in 5 % oil‐in‐water emulsion in the presence or absence of iron. In spite of the higher phenolic content and very good antioxidant activity in some of the in vitro assays, the absolute ethanol extracts of both the species showed a pro‐oxidative tendency in 5 % fish oil‐in‐water emulsion in the presence or absence of iron. In order to investigate the reason for the higher antioxidant activity of 50 % ethanolic extracts of P. fucoides, these extracts were further fractionated into polyphenol‐rich, protein‐rich, polysaccharide‐rich and low‐molecular‐weight fractions. These fractions were tested both in in vitro and in 5 % oil‐in‐water emulsions. The results of the present study showed that the main effect was due to the phenolic compounds. In conclusion, the 50 % ethanolic extracts of P. fucoides can be a potential source of natural antioxidants as these extracts have antioxidant activities similar to those of synthetic antioxidants such as BHT.     

Structural Effect of Lignans and Sesamol on Polymerization of Soybean Oil at Frying Temperature

The antipolymerization activity of the lignans including nordihydroguaiaretic acid, (+)-pinoresinol, (−)-secoisolariciresinol, enterodiol, and two sesame lignans (sesamol and sesamin), and four model compounds (4-ethylcatechol, 2-methoxy-4-propylphenol, 4-methyl-2,6-dimethoxyphenol, and piperonyl alcohol) were investigated for soybean oil at frying temperature (180 °C). The heated samples were analyzed by gel-permeation chromatography for polymerized triacylglycerols and by ¹H NMR to monitor the decrease in peak intensities for bisallylic protons and olefinic protons. The heating test results were compared with ability to scavenge the radical 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) to understand the relationship between radical-scavenging ability at room temperature and antipolymerization activity at 180 °C. It was found that the antipolymerization activity of a lignan at frying temperature cannot be predicted solely from the radical-scavenging ability at room temperature. The lignans tested in this research had antipolymerization activity, but it was not as strong as that of 200 ppm tert-butylhydroquinone (TBHQ) with equivalent of phenolic moiety (0.0012 meq/g). At higher concentrations, however, sesamol, nordihydroguaiaretic acid, and (+)-pinoresinol had better antipolymerization activity than the legal limit set for TBHQ (200 ppm, 0.0012 meq/g). Therefore, this research showed that by using an appropriate concentration, these natural antioxidants can replace synthetic antioxidants and provide better antioxidation activity.     

Antioxidant Activity of Phytochemicals from Distillers Dried Grain Oil

A distillate was obtained by molecular distillation of oil extracted from distillers dried grains (DDG). The distillers dried grain oil distillate (DDGD) contained phytosterols, steryl ferulates, tocopherols, tocotrienols, and carotenoids. DDGD was tested for its impact on the oxidative stability index (OSI) at 110 °C of soybean, sunflower, and high-oleic sunflower oils, as well as the same oils that were stripped of their natural tocopherols and phytosterols. In addition, the impact of added DDGD on the stability of stripped sunflower oil during an accelerated storage study conducted at 60 °C was also determined. DDGD (0.5–1% w/w) had little impact on the OSI of soybean, sunflower, and high-oleic sunflower oil, but at levels of 0.1–1% it significantly increased the OSI for stripped soybean, sunflower, and high-oleic sunflower oil in a dose-dependent manner. DDGD also delayed peroxide value, conjugated diene, and hexanal formation during accelerated storage of stripped sunflower oil. The antioxidant activity is probably due to the combination of tocopherols, tocotrienols, and steryl ferulates.     

Discrimination of Origin of Sesame Oils Using Fatty Acid and Lignan Profiles in Combination with Canonical Discriminant Analysis

The aims of this study were to investigate total fatty acid composition and lignan contents of Korean, Chinese and Indian roasted sesame oils and to differentiate the geographic origins of the oils using analytical data in combination with canonical discriminant analysis. The analytical data were obtained from 84 oil samples that were prepared from 51 Korean, 19 Chinese, and 14 Indian white sesame seeds harvested during 2010 and 2011 and distributed in Korea during the same period. Six variables selected for the discriminant analysis were the contents of three fatty acids (linoleic, oleic, and palmitic) and three lignans (sesamin, sesamolin, and sesamol). A good discrimination between sesame oils from Korea, China, and India was achieved by applying two canonical discriminant functions, with 97.6 % of the samples correctly classified into the geographic origin. When the origins of five commercial oil samples (one was prepared from Korean sesame seeds and the other four were made from imported sesame seeds) were predicted using discriminant functions, the Korean sesame oil was accurately distinguished from the others.     

The Antioxidant Activity and Oxidative Stability of Cold-Pressed Oils

In our study, we characterized the antioxidant activity and oxidative stability of cold-pressed macadamia, avocado, sesame, safflower, pumpkin, rose hip, Linola, flaxseed, walnut, hempseed, poppy, and milk thistle oils. The radical scavenging activity of the non-fractionated fresh oil, as well as the lipophilic and hydrophilic fractions of the oil was determined using a 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay. The fatty acid composition of the fresh and stored oils was analyzed by gas chromatography. The acid value, peroxide value, p-anisidine value and conjugated diene and triene contents in the fresh oils, as well as in those stored throughout the whole period of their shelf life, were measured by CEN ISO methods. The antioxidant activity of the oils expressed as Trolox equivalent antioxidant capacity (TEAC), ranged from 0.17 to 2.32 mM. The lipophilic fractions of the oils were characterized by much higher antioxidant activity than the hydrophilic ones. There were no significant changes in fatty acid composition and only slight changes in the oxidative stability parameters of the oils during their shelf life. Through the assessment of the relationship between antiradical activity and the oxidative stability of oils, it is proposed that a DPPH assay predicts the formation of oxidation products in cold-pressed oils—however, the correlations differ in fractionated and nonfractionated oils.