Lipid composition of perilla seed

The composition of lipids and oil characteristics from perilla [Perilla frutescens (L.) Britt.] seed cultivars are reported. Total lipid contents of the five perilla seed cultivars ranged from 38.6 to 47.8% on a dry weight basis. The lipids consisted of 91.2–93.9% neutral lipids, 3.9–5.8% glycolipids and 2.0–3.0% phospholipids. Neutral lipids consisted mostly of triacylglycerols (88.1–91.0%) and small amounts of sterol esters, hydrocarbons, free fatty acids, free sterols and partial glycerides. Among the glycolipids, esterified sterylglycoside (48.9–53.2%) and sterylglycoside (22.1–25.4%) were the most abundant, while monogalactosyldiacylglycerol and digalactosyldiacylglycerol were present as minor components. Of the phospholipids, phosphatidylethanolamine (50.4–57.1%) and phosphatidylcholines (17.6–20.6%) were the major components, and phosphatidic acid, lysophosphatidylcholine, phosphatidylserine and phosphatidylinositol were present in small quantities. The major fatty acids of the perilla oil were linolenic (61.1–64.0%), linoleic (14.3–17.0%) and oleic acids (13.2–14.9%). Some of the physicochemical characteristics and the tocopherol composition of perilla oil were determined.     

The antioxidant effects of phospholipids on perilla oil

Antioxidant effect of phospholipids on the oxidation of refined perilla oil (PO;α-18:3, 54.5%; 16:0, 7.2%; 18:0, 2.6%; 18:1, 18.6%; 18:2, 15.5%), tocopherol-free (POF) and tocopherol-enriched (POR) perilla oil were investigated by measuring weight-gains and by the oven test at 37°C. The oxidative stability of PO was especially increased by additions of phosphatidylethanolamine (PE) and phosphatidylserine (PS), but phosphatidylcholine (PC) scarcely showed an antioxidant effect. The oxidative stability of POF was markedly low, and none of the phospholipids (PC, PE, PS) showed an antioxidant effect on the oxidation of POF. The stability of POR was lower than that of PO regardless of its higher tocopherol contents. However, the oxidation of POR was significantly suppressed by additions of PE and PS, as was observed with PO. PC showed a small antioxidant effect on the oxidation of POR. Therefore, it seems that the antioxidant effects of phospholipids, especially of PE and PS, was due to the presence of tocopherols in the perilla oil.     

Microwave roasting effects on the physico-chemical composition and oxidative stability of sunflower seed oil

The purpose of the present study was to explore the influences of microwave heating on the composition of sunflower seeds and to extend our knowledge concerning the changes in oxidative stability, distribution of FA, and contents of tocopherols of sunflower seed oil. Microwaved sunflower seeds (Helianthus annuus L.) of two varieties, KL-39 and FH-330, were extracted using n-hexane. Roasting decreased the oil content of the seeds significantly (P<0.05). The oilseed residue analysis revealed no changes in the contents of fiber, ash, and protein that were attributable to the roasting. Analysis of the extracted oils demonstrated a significant increase in FFA, p-anisidine, saponification, conjugated diene, conjugated triene, density, and color values for roasting periods of 10 and 15 min. The iodine values of the oils were remarkably decreased. A significant (P<0.05) decrease in the amounts of tocopherol constituents of the microwaved sunflower oils also was found. However, after 15 min of roasting, the amount of α-tocopherol homologs was still over 76 and 81% of the original levels for the KL-39 and FH-330 varieties, respectively. In the same time period, the level of σ-tocopherol fell to zero. Regarding the FA composition of the extracted oils, microwave heating increased oleic acid 16–42% and decreased linoleic acid 17–19%, but palmitic and stearic acid contents were not affected significantly (P<0.05).     

Optimizing headspace sampling temperature and time for analysis of volatile oxidation products in fish oil

Headspace-gas chromatography (HS-GC), based on adsorption to Tenax GR®, thermal desorption and GC, has been used for analysis of volatiles in fish oil. To optimize sampling conditions, the effect of heating the fish oil at various temperatures and times was evaluated from anisidine values (AV) and HS-GC. AV indicated sample degradations at 90°C but only small alterations between 60 and 75°C. HS-GC showed increasing response with temperature and time. Purging at 75°C for 45 min was selected as the preferred sampling condition for oxidized fish oil.     

The effect of glycine in the production of toxic volatile aldehydes from heated corn oil

The fatty aldehydes generated from heated corn oil and from several corn oil/glycine mixtures were collected by a dynamic headspace sampling method and subsequently reacted with cysteamine to yield corresponding thiazolidines. Derivatized aldehydes were analyzed by a capillary gas chromatograph with flame photometric detector. Six fatty aldehydes, including formaldehyde and acetaldehyde, decreased in concentration in relation to increasing amounts of glycine in the oil.     

Phenolic compounds and some quality parameters of pumpkin seed oil

Pumpkin seed oil has become a recognized source of phenolic compounds. The main aim of this paper was to evaluate the concentration of phenolic compounds and their extraction from pumpkin seed oil. The total phenolics content (TPC) measured in the pumpkin seed oil samples ranged from 24.71 to 50.93 mg GAE/kg of oil. The individual phenolics were tyrosol, vanillic acid, vanillin, luteolin and sinapic acid. Hexane and acetone were the best solvents for the washing step, and methanol for the elution of the phenolics in the solid‐phase extraction (diol‐SPE), whereas bleaching caused a significant increase in the TPC obtained (24.5–30.7%). Additionally, some other oil characteristics were evaluated. The mean oxidative stability of the oils (OSI) was around 4 h, with 5.43 h for the most stable oil. The maximum antioxidant capacity measured by the reduction of the DPPH radical was 62%, which was comparable to 0.16 mM Trolox equivalent. The color of the oil was expressed by L*a*b* coefficients and its hue and saturation. Whereas all samples had similar lightness, their rates of green, red, yellow and blue color were different. Moreover, TPC correlated negatively with lightness, b* and saturation (–0.49, –0.48, and –0.43), and positively with a* and hue (0.58 and 0.52).     

Analysis of volatile compounds in almond and plum kernel oils

Almond and plum kernel oils were analyzed for volatile flavor components by headspace sampling, gas chromatography and mass spectrometry. The most important volatiles at 37°C, from both fruit oils, are derivatives of benzene,n-alkanes, cycloalkanes, aromatics and furan compounds. The structures were established mainly by interpretation of mass spectral data in comparison with literature data.     

The effect of roasting on the chemical composition and oxidative stability of pumpkin oil

This study is concerned with the effect of the process of roasting of naked pumpkin seeds prior to their pressing on the chemical composition and oxidative stability of the extracted oil. Ground seeds were roasted at temperatures of 90, 110, and 130°C for 30 and 60 min, according to the traditional technology of production of roasted pumpkin oil. Depending on the roasting conditions of the seeds, this treatment resulted in a significant increase of the contents of phospholipids (from 0.005 to 0.463%), total phenolic compounds (from 4.63 to 19.60 mg/kg), and total tocopherols (from 265.79 to 350.98 mg/kg) in oil. Higher contents of these minor components enhanced the oxidative stability of the oil, i.e., increased the induction period (from 4.50 to 12.93 h). However, at the same time, the applied thermal treatment generated an increase in the primary and secondary oxidation products, resulting in higher Totox values that could lower the quality of the oil.     

Effect of roasting on the physico-chemical properties,fatty acids,polyphenols and mineral contents of tobacco (Nicotiana tabacum L.) seed and oils

The physico-chemical properties, phytochemicals, mineral contents of tobacco (Nicotiana tabacum L.) seeds grown at Samsun province in Turkey were evaluated. The oil contents of tobacco seeds ranged from 20.6% (control) to 29.0% (microwave-roasted). L*, a* and b* values of tobacco seeds ranged from 32.38 to 35.61; from 6.32 to 6.78; from 13.72 to 14.27, respectively. Total phenolic contents of tobacco seed extract and oils were reported between 31.02 (oven-roasted) and 34.42 mg GAE/100 g (microwave-roasted) to 4.60 (microwave-roasted) and 6.45 mg GAE/100 g (oven-roasted), respectively. Total flavonoid values of raw and roasted tobacco seed extract and oils were determined between 26.62 (oven) and 67.10 mg/100 g (control) to 21.57 (control) and 44.71 mg/100 g (microwave-roasted), respectively. Gallic acid, 3,4-dihydroxybenzoic acid and catechin are the predominant phenolic components of raw and roasted tobacco seed oils. The amounts of oleic and linoleic acid in raw and roasted tobacco seed oils ranged from 10.23% (oven-roasted) to 12.48% (control) and 73.72% (control) to 76.63% (oven-roasted), respectively. The abundant elements found in seeds were K, P, Ca, Mg, S and Fe. The mineral amounts of the roasted seeds were found higher than that of the control. The highest increase was detected in oven roasted tobacco seeds.     

Profiles of volatile compounds in milk containing fish oil analyzed by HS‐SPME‐GC/MS

Long‐chain polyunsaturated fatty acids (LC‐PUFA) have various positive biological effects. Fish oil represents a major source of LC‐PUFA; therefore it is extensively used to enrich food products as, for example, infant formulae, dairy products and fruit juices. However, in the presence of oxygen and metals, LC‐PUFA readily degrade, producing off‐flavors and decreasing the nutritional value of the product. The deterioration of sensory properties (taste and odor) can be easily perceived by the consumer, due to the formation of volatile compounds that are formed by decomposition of lipid hydroperoxides, also known as primary oxidation products. In this study, we used the headspace solid‐phase microextraction‐gas chromatography/mass spectrometry technique (HS‐SPME‐GC/MS) to characterize and quantify volatile compounds in a food matrix supplemented with fish oil. We demonstrated that the HS‐SPME‐GC/MS method is a valuable tool to monitor lipid oxidation at early stages. We identified t‐2‐hexenal and c‐4‐heptenal as possible oxidation markers during the storage of milk enriched with 5% of cod oil.     

葵花籽油酯交换研究

以葵花籽油为原料,KOH作催化剂,对葵花籽油与甲醇进行酯交换反应研究,寻求酯交换反应的最佳条件。     

The impact of processing on the profile of volatile compounds in sesame oil

The flavor of sesame oil significantly depends on the roasting conditions and the relative concentrations of volatiles. In the present study, volatile components from three varieties of sesame oil produced by roasting the seeds under different conditions were analyzed and profiled using GC–mass chromatography. The results showed that the roasting temperature had an obvious effect on the aroma of the oils since there was an increase in the concentration of the volatiles responsible for aroma such as pyrazines, furans, and sesamol as the temperature at which the seeds were roasted was increased. However, the concentration of some components such as alcohols and aldehydes, decreased with an increase in the roasting temperature. The roasting conditions have an important effect on the characteristic aroma of sesame oil. Other methods used to process sesame oil, such as solvent extraction, mechanical pressing and hot water flotation, were also investigated. Sesame oil produced using the Chinese traditional hot water flotation method had the most preferred flavor. There was good consistency between the principal components analysis (PCA) and sensory evaluation. The results of the present study suggested that production of sesame oil with the most acceptable aroma was dependent on the appropriate processing method.     

Retardation of volatile aldehyde formation in the exhaust of frying oil by heating under low oxygen atmospheres

Volatile aldehydes were generated in the exhaust of high-oleic safflower oil during heating at 180°C by spraying water into atmospheres with four levels of oxygen concentrations (2, 4, 10, and 20%). These aldehydes were quantitatively analyzed by HPLC after the conversion to 2,4-dinitrophenyl hydrazones. Ten alkanals (C₂ through C₁₀), eight 2-alkenals (C₃ through C₁₀) and three 2,4-alkadienals (C₇, C₉, and C₁₀) were found. These aldehyde levels were found to be positively correlated with both the heating time and the atmospheric oxygen concentration. The total amounts of aldehydes were the lowest in the oil heated in an atmosphere with 2% O₂, and corresponded to 1/10 of those in the atmosphere with 20% O₂. Acrolein was not found in oils heated in the atmosphere with 2% oxygen. These results suggest that frying in atmospheres with low oxygen levels can effectively decrease the generation of volatile aldehydes in the exhaust.     

Rubber seed oil: A multipurpose additive in NR and SBR compounds

Rubber seed oil was used as a multipurpose ingredient in natural rubber (NR) and styrene butadiene rubber (SBR) compounds. The study shows that the oil, when substituted for conventional plasticiser, imparts excellent mechanical properties to NR and SBR vulcanizates. Further, it also improves aging resistance, reduces cure time, increases abrasion resistance and flex resistance, and reduces blooming. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 487–492, 1999     

Influence of roasting conditions on fatty acids and oxidative changes of Robusta coffee oil

The aim of this study was to determine the influence of roasting conditions, including elevated humidity of air used in the process, on the properties of coffee oil. Beans of Robusta coffee were roasted in a laboratory convective roaster with a possibility of changing the temperature, humidity, and velocity of roasting air. Roasting temperatures from 190 to 216°C, air humidity from 0.07 to 1%, and air velocity of 0.5 and 1 m/s were used. Parameters analyzed in roasted beans were: oil content, fatty acids composition, including trans fatty acids using the GC/FID method and indicators of oxidation level, namely peroxide value and content of conjugated dienes and trienes. Also a thermal profile of oil with the use of the DSC method and finally the bean aroma were evaluated. For maintaining the maximal amount of PUFA, the most favorable roasting conditions were, either, roasting at relatively high temperature and short time, or roasting at low temperatures. Using moderately high temperature resulted in the highest oxidative changes, but on the other hand, the aroma of received beans presented the best sensory properties. For the best nutritional properties, the best roasting conditions were: temperature 210°C and 1% humidity content in roasting air at 1 m/s flow velocity. In such conditions roasted beans obtained a very high quality aroma, and the roasting time was relatively short. Practical applications: This research concerns the quality of oil obtained from roasted coffee beans. The composition of coffee oil changes slightly during roasting, but nevertheless it might be a source of peroxides and trans fatty acids in human diet. In industrial processing coffee oil is extracted from the remains left over from instant coffee production, and it is a popular agent for aromatizing food products. Thus, in this kind of processing, roasting conditions that limit the unfavorable changes of coffee oil should be used.     

Effect of roasting temperature and time on the chemical composition of rice germ oil

Compositional changes of rice germ oils prepared at different roasting temperatures (160–180°C) and times (5–15 min) from rice germ were evaluated and compared with those of unroasted rice germ oil. The color development and phosphorus content of oils increased significantly as roasting temperature and time increased, whereas the FA compositions of rice germ oils did not change with roasting temperature and time. Four phospholipid classes, i.e., PE, PI, PA and PC, were identified. PE had the lowest stability under roasting conditions. There were no significant differences in γ-oryzanol levels of rice germ oils prepared at different roasting temperatures and times. Four tocopherol isomers (α−, β−, γ−, and δ-tocopherol) and three tocotrienol isomers (α−, γ−, and δ-tocotrienol) were identified, but no β-tocotrienol was detectable. The content of α− and γ−tocopherol in rice germ oil gradually increased as roasting temperature and time increased.     

Detection of adulteration in camellia seed oil and sesame oil using an electronic nose

An electronic nose was used for the detection of maize oil adulteration in camellia seed oil and sesame oil. The results of multivariate analysis of variance showed that the sensor signals of different kinds of oil are significantly different from each other. Principal component analysis (PCA) cannot be used to discriminate the adulteration of camellia seed oil, but can be used in the discrimination of adulteration in sesame oil. Linear discriminant analysis (LDA) is more effective than PCA and can be used in adulteration discrimination for both camellia seed oil and sesame oil. In order to check the discriminative power of LDA, canonical discriminant analysis was performed as well. Acceptable results were also obtained: The accuracy of prediction was 83.6% for camellia seed oil and 94.5% for sesame oil. The artificial neural network (ANN) model was used to detect the percentage of adulteration in camellia seed oil and sesame oil. The results showed that, based on ANN as its pattern recognition technique, the electronic nose cannot predict the percentage of adulteration in camellia seed oil, but can be used in the quantitative determination of adulteration in sesame oil.     

Relationship between volatile compounds and sensory attributes of olive oils by the sensory wheel

Sixty-five volatile compounds and 103 sensory attributes were evaluated in 32 virgin olive oil samples from three different Mediterranean countries. Volatile compounds were analyzed with a dynamic headspace gas-chromatographic technique by using a thermal desorption cold-trap injector. The sensory analysis was conducted by six panels composed of assessors from the United Kingdom, Spain, the Netherlands, Greece and Italy. Principal-components analysis of sensory attributes was used to construct a statistical sensory wheel that represents the whole virgin olive oil flavor matrix. This wheel is composed of seven sectors that show the basic perceptions produced by the oil: green, bitter-pungent, undesirable, ripe olives, ripe fruit, fruity and sweet. The boundaries of each sector were calculated from the circular standard deviation of its sensory attributes. The relationship between sensory and instrumental analysis was determined by projecting volatiles onto the sensory wheel. Correlations of each volatile with the first two components of the principal-components analysis were taken as its coordinates (x, y) in the sensory wheel. Volatiles took up the most appropriate place within the sector that corresponded with their perception, and often close to the sensory attributes that explained their sensory properties. A gas-chromatographic/sniffing method was applied to virgin olive oil samples to assess the aroma notes that corresponded to olive oil volatile compounds and to verify the relationships found by the sensory wheel procedure. Most (89%) of the volatiles were well classified. Use of the statistical sensory wheel as an appropriate method to relate volatile and sensory data was clearly demonstrated.