Thermoxidative stability of triacylglycerols from mutant sunflower seeds

Thermoxidative stability was evaluated in triaclyglycerols (TAG) from the oils of the mutant sunflower lines CAS-3, CAS-4, and CAS-8 (with a high percentage of stearic acid), CAS-5 (with a high percentage of palmitic acid), all from standard highlinoleic genetic backgrounds, and the mutant sunflower line CAS-12 (with a high percentage of palmitic acid), from a high-oleic genetic background. These oils contained unusually high contents of TAG molecular species with one or two saturated fatty acids at the sn-1,3 positions. Purified total TAG devoid of tocopherols were subjected to controlled thermoxidative treatment at 180°C. Polymerized TAG were determined at 2-h intervals for 10 h. After this time, total polar compounds, oxidized TAG monomers, TAG dimers, and TAG oligomers were determined. TAG from highly saturated sunflower oils with levels of linoleic acid similar to those found in conventional sunflower oils (40–50%) showed enhanced thermal stability. In these TAG, the amount of polar compounds formed during the thermoxidative treatment was similar to that formed in the high oleic acid line. Excellent results were obtained for the TAG of the CAS-12 oil, which had the highest thermal stability, producing half the amount of polar compounds as the conventional line and less than two-thirds that of the high-oleic line.     

Lipid composition ofHerrania andTheobroma seeds

The seeds of nineHerrania and nineTheobroma species were surveyed for fatty acid, sterol, tocopherol and tocotrienol compositions. Principal component and cluster analyses suggested that these analytes could be used collectively as chemotaxonomic criteria to differentiate theHerrania species from theTheobroma species, as well as to provide subgroup distinctions within each genus for comparison to the existing classification schemes.     

Determination of tocopherols and phytosterols in sunflower seeds by NIR spectrometry

The objective of this work was to develop a near‐infrared reflectance spectrometry (NIRS) calibration estimating the tocopherol and phytosterol contents in sunflower seeds. Approximately 1000 samples of grinded sunflower kernels were scanned by NIRS at 2‐nm intervals from 400 to 2500 nm. For each sample, standard measurements of tocopherol and phytosterol contents were performed. The total tocopherol content was obtained by high‐performance liquid chromatography coupled with a fluorescence detector, while the total phytosterol content was assessed by gas chromatography. For tocopherol, the calibration data set ranged from 175 to 1005 mg/kg oil (mean value around 510 ± 140 mg/kg oil), whereas for the phytosterol content, the calibration data set ranged from 180 to 470 mg/100 g oil (mean value of 320 ± 50 mg/100 g oil). The NIRS calibration showed a relatively good correlation (R² = 0.64) between predicted by NIRS and real values for the total tocopherol content but a poor correlation for the total phytosterol content (R² = 0.27). These results indicate that NIRS could be useful to classify samples with high and low tocopherol content. In contrast, the estimation of phytosterol contents by NIRS needs further investigation. Moreover, in this study, calibration was obtained by a modified partial least‐squares method; the use of other mathematical treatments can be suitable, particularly for total phytosterol content estimation.     

Validation of a method for the analysis of phytosterols in sunflower seeds

Phytosterols are natural compounds that contribute to lower serum cholesterol in humans. Sunflower seeds and oils are rich sources of phytosterols. Breeding for phytosterol content in sunflower has been scarce thus far, mainly because of the lack of analytical methods suitable for use in plant breeding. The objective of this research was to validate a method for the analysis of phytosterols in small seed samples of sunflower. Samples consisting of six seeds were analyzed for phytosterol content in a set of 87 inbred lines using a method adapted to small samples. The accuracy of the method was evaluated through the standard error of the analysis of replicates of ground samples, which was 72.12 mg/kg compared to average values of 1665.3 and 1887.2 mg/kg seed in the samples. Sunflower inbred lines showed ranges of variation from 1426.0 to 4710.0 mg/kg seed and from 2855.2 to 9752.0 mg/kg oil. The method correlated strongly with the conventional method based on the analysis of extracted oils (r = 0.85). The results indicated that analysis of phytosterols on samples consisting of sunflower seeds is an accurate approach for breeding and genetic studies, in which extraction of the seed oil is not feasible. Practical applications : Phytosterols are usually analyzed in extracted oils. However, studies in plant breeding and plant sciences often require a direct analysis of phytosterols in seeds, without previous oil extraction (e.g. large‐scale screening of germplasm in breeding programs or genetic studies). Our results will be useful for plant scientists interested in the analysis of phytosterols in small samples of plant tissues.     

Composition of organic and conventionally produced sunflower seed oil

The aim of the present study was to highlight the main differences between seed oils produced from conventionally cultivated crops and organically cultivated ones and processed using mild extraction procedures. The composition and the nutritional and health aspects of both types of sunflower seed oils were compared and were analytically tested to determine the macroscopic differences in proximate composition, the main differences in the minor components, the main quality parameters, the in vitro antioxidant activity, and the presence of trans-ethylene steroisomers in FA. No significant trends were found in the oil samples for TAG and FA composition, but remarkable differences were found in the composition of minor components and in the main chemical and analytical quality properties. The organically grown samples had a higher total antioxidant activity compared with the conventional samples. Trans FA were found only in the conventional oils.     

Lipid synthesis and acyl-CoA synthetase in developing rice seeds

Developing rice seeds rapidly accumulated storage lipids between 5 and 12 d after flowering. The contents of palmitic, oleic, and linoleic acids increased throughout seed development, while the alpha-linolenic acid content remained low. The activity of acyl-CoA synthetase varied coincidentally during the period of lipid accumulation, and rice seeds had a sufficient capacity to supply acyl-CoA substrates for TAG synthesis. Acyl-CoA synthetase showed a broad specificity for native FA of rice seeds except for stearic acid, and pi electrons of a delta9-delta11 double bond in the C16-C18 acyl chains were required for its maximal activity.     

Oxygenated fatty acids of oil from sunflower seeds after prolonged storage

Chemical analysis of a number of sunflower (Helianthus annuus) seed oil samples revealed a low and variable percentage of hydrogen bromide-reactive material. To characterize the compounds responsible for this reactivity, oil was extracted from selected introductions from Uruguay, Turkey, and Yugoslavia that had been subjected to prolonged storage. Two epoxy fatty acids and two conjugated dienolic acids were isolated from the methyl esters derived from these sunflower seed oils by using a combination of column chromatography and countercurrent distribution. The epoxy acids arecis-9,10-epoxystearic acid (0.5%) andcis-9,10-epoxy-cis-12-octadecenoic (coronaric) acid (2.2%). Characterization of the dienols revealed that they are 9-hydroxy-trans-10,cis-12-octadecadienoic acid (1.2%) and 13-hydroxy-cis-9,trans-11-octadecadienoic acid (1.3%). Fresher seed of some of these introductions contained less of the oxygenated components. Oil from recently produced seed of selected high-oil Russian sunflower varieties, including some currently grown in the United States, contained no more than trace amounts of oxygenated acids. Though the relative contributions of genetic and environmental factors toward genesis of oxygenated acids are not established, increase of those acids in some sunflower lines as a result of storage has been demonstrated. Presented at the AOCS-AACC Joint Meeting, Washington, D. C., April 1968. No. Utiliz. Res. Dev. Div., ARS, USDA.     

Aqueous processing of full-fat sunflower seeds: Yields of oil and protein

Undehulled sunflower seeds were comminuted and extracted with water containing 0.2% Na₂SO₃ at pH 10, which extracted from the fiber 86% of the oil and 85% of the protein. Isolate was prepared by addition of acid, with best yield achieved from pH 5 precipitation.     

A new twin-screw press design for oil extraction of dehulled sunflower seeds

Transport of material in a single-screw press depends mainly on friction between the material and the barrel’s inner surface and the screw surface during screw rotation. Thus, a solid core component, like seed hulls, is often necessary to produce the fraction. This sometimes causes excess frictional heat, large energy consumption and oil deterioration. Furthermore, if single-screw presses are not configured with breaker bars or other special equipment, they provide inadequate crushing and mixing. A twin-screw oil press can be expected to solve these problems because of the higher transportation force, similar to a gear pump, and better mixing and crushing at the twin-screw interface. A twin-screw press (screw diameter=136 mm, length/diameter=6.5, screw speed 15–100 rpm, feed rate=50–150 kg/h) was designed with partially intermeshing and counter-rotating screws and was tested on dehulled sunflower seed. The results were compared to a single-screw lab-scale press. Dehulled sun-flower seed (wt, 6.0%; oil, 58.6%) without pretreatments (crushing or cooking) gave 93.6% oil recovery with the twin-screw press, in contrast to 20% oil recovery with the single-screw press. The oil expressed with a twin-screw press had less foreign material than the oil from the single-screw press. Other properties of the oil were also good. Energy consumption of the twin-screw press was more efficient. All results suggested that oil production from dehulled sunflower seed with a twin-screw press is highly efficient.     

Lipid composition of millet (Pennisetum americanum) seeds

The composition of lipids extracted from a sample of millet seeds by each of 8 solvent systems is reported. Lipid components were separated by silicic acid column and thin layer chromatography (TLC) and quantitated by analysis of fatty acid methyl esters by gas liquid chromatography (GLC), with heptadecanoic acid as internal standard. Best results were obtained by extraction with hot water-saturated butanol. Lipids extracted amounted to 7.2% of the seed dry weight and consisted of 85% neutral lipids, 12% phospholipids and 3% glycolipids. Neutral lipids contained mostly (85%) triacylglycerols and small amounts of mono- and diacylglycerols, sterols and free fatty acids. Sterols consisted of campesterol, stigmasterol and 2 unidentified sterols, occurring in the same proportions in free and esterified forms. Ten glycolipid and 10 phospholipid components were separated and characterized. Contrary to previously published observations, lysophosphatidylcholine was the major phospholipid (42%) in millet seeds; smaller amounts of phosphatidylcholine (24%), lysophosphatidylethanolamine (21%) and trace amounts of phosphatidylglycerol, phosphatidic acid, phosphatidylserine and phosphatidylinositol also were present. The major glycolipids were esterified sterol glycoside, sterol glycoside, monogalactosyldiacylglycerol, digalactosyldiacylglycerol and cerebrosides (ceramide monohexosides).     

Experimental and modelling of supercritical oil extraction from rapeseeds and sunflower seeds

The supercritical oil extraction from oleaginous seeds (sunflower and rapeseeds) is presented here through experimental and modelling results. The experimental setup allows an accurate following of the mass of the oil extracted and to derive the experimental influences of pressure, temperature and supercritical CO₂ flowrate on the extraction curves. These parameters are very sensitive and highlight the necessity of precise optimisation of experimental conditions. In order to complete the behaviour of supercritical fluids extraction, an improved modelling is proposed. The modelling basic equations are based on others modelling published previously. In this work, the determination of several parameters comes from correlations and the other constants are fitted with all the experimental results. Thus the modelling is more representative and predictive as other ones. The modelling results present a good agreement with the experimental results, and hence it can be used for the dimensioning of some extraction autoclaves.     

Lipid changes during pre-germination and germination ofstriga asiatica seeds

Witchweed (Striga asiatica L. Kuntze) seeds were incubated at 28 C in a moist environment for a 14-day period, after which seeds germinated only when exposed to specific natural or synthetic germination stimulants. Changes in lipid composition were determined during germination of witchweed seeds and during early seedling growth. Witchweed seeds contained 37.5% (w/w) oil. Increased levels of monogalactosyl-diacylglycerol and phosphatidylglycerol suggested the enlargement or multiplication of plastids after witchweed seeds had germinated. In contrast to the usual course of events in seeds with high oil reserves, witchweed seeds did not hydrolyze triacylglycerol rapidly during or after germination. These findings indicated that triacylglycerol in germinating witchweed seeds was conserved for subsequent use during haustorial formation and host invasion.     

Lipid components of flax,perilla, and chia seeds

Composition of fatty acids, tocopherols, sterols, and TAGs in the lipids of flax, perilla, and chia seeds were investigated where lipid content was at 45, 40, and 35%, respectively. α‐Linolenic acid (ALA) dominated among fatty acids in all oils and accounted for 58.2, 60.9, and 59.8% in flax, perilla, and chia, correspondingly in these three oils trilinolenin was the main TAG found at 19.7, 22.6, and 21.3%. Triunsaturated TAGs accounted for 77.9, 77.5, and 74.5% of the total amounts in flax, perilla, and chia oils. Contents of tocopherol were at 747 in flax, 734 in perilla, and 446 mg/kg in chia seed lipids. γ‐Tocopherol was the dominating isomer contributing 72.7% in flax, 94.3% in perilla, and 94.4% in chia to the total amount of tocopherols. Flaxseed lipids contained 25.6% of plastochromanol‐8, derivative of γ‐tocotrienol with longer side chain; perilla and chia oils contained only 1.4% of it. Phytosterols were present at 4072, 4606, and 4132 mg/kg in those seeds, respectively. Among sterols, β‐sitosterol dominated and was found at 35.6, 73.3, and 49.8% of the total amounts of sterols in flax, perilla, and chia seed lipids. All of the investigated oilseeds have an excellent nutritional quality and can be a potential source of nutraceutical fats which can enrich diet in linolenic acid and other functional components.     

Oxidative stability of structured lipids produced from sunflower oil and caprylic acid

Traditional sunflower oil (SO), randomized lipid (RL) and specific structured lipid (SL), both produced from SO and tricaprylin/caprylic acid, respectively, were stored for up to 12 wk to compare their oxidative stabilities by chemical and sensory analyses. Furthermore, the effect of adding a commercial antioxidant blend Grindox 117 (propyl gallate/ citric acid/ascorbyl palmitate) or gallic acid to the SL was investigated. The lipid type affected the oxidative stability: SL was less stable than SO and RL. The reduced stability was most likely caused by both the structure of the lipid and differences in production/ purification, which caused lower tocopherol content and higher initial levels of primary and secondary oxidation products in SL compared with RL and SO. Grindox 117 and gallic acid did not exert a distinct antioxidative effect in the SL oil samples during storage.     

A new family of beta-hairpin mimetics based on a trypsin inhibitor from sunflower seeds

The ability of proteases to regulate many aspects of cell function and defense accounts for the considerable interest in the design of novel protease inhibitors. There are many naturally occurring proteinaceous serine protease inhibitors, one of which is a 14 amino acid cyclic peptide from sunflower seeds that shows both sequence and conformational similarity with the trypsin-reactive loop of the Bowman-Birk family of serine protease inhibitors. This inhibitor adopts a beta-hairpin conformation when bound at the active site of bovine beta-trypsin. We illustrate here an approach to inhibitor design in which the beta hairpin from the naturally occurring peptide is transplanted onto a hairpin-inducing template. Two mimetics with the sequences RC*TKSIPPIC*F (where C*C* is a disulfide) and TKSIPPI are studied, each mounted onto a D-Pro-L-Pro template. NMR studies revealed a well-defined beta-hairpin conformation for each mimetic in aqueous solution; this conformation is closely related to the trypsin-bound conformation of the natural inhibitor and includes a cis-Ile-Pro peptide bond. Both mimetics inhibit trypsin in the mid nanomolar range. An alanine scan revealed the importance for inhibitory activity of the specificity-determining Lys residue and of the first but not the second Pro residue in the IPPI motif. Since these hairpin mimetics can be prepared by parallel combinatorial synthesis, this family of molecules may be a useful starting point for the discovery of other biologically or medicinally useful serine protease inhibitors.     

Performance of sunflower oil with high levels of oleic and palmitic acids during industrial frying of almonds,peanuts, and sunflower seeds

High-oleic, high-palmitic sunflower oil (HOHPSO) is a seed oil from a new mutant sunflower line characterized by increased levels of both oleic acid (>50%) and palmitic acid (>25%) and a high oxidative stability. In this study, its performance at frying temperature was compared with that of palm olein in thermoxidative assays (4 h, 180°C). Also, industrial discontinuous frying of almonds, peanuts, and sunflower seeds (200 kg of each product) was carried out to define both the performance of HOHPSO and the main changes undergone by the foods. The evaluation of polar compounds and their distribution in the main groups, i.e., polymers, oxidized monomers, and DAG, as well as changes in tocopherols and oxidative stability, demonstrated the excellent behavior of HOHPSO during thermoxidation and frying. The increase in polar compounds and the loss of tocopherols and stability were much lower for HOHPSO than for palm olein under identical heating conditions. Only 1.3% polar compounds were formed during industrial discontiuous frying for 4 h and the oil stability increased, probably due to the formation of antioxidant compounds. As for the foods, the FA composition of the surface oil was clearly different from that corresponding to the internal oil, the former denoting the presence of HOHPSO in high concentration, particularly in fried sunflower seeds. Changes in oil stability of the foods attributable to the frying process clearly demonstrate the interest in using a highly stable oil such as HOHPSO to protect the surface against oxidation during food storage.     

Variation in composition of sunflower oil from composite samples and single seeds of varieties and inbred lines

The seed oil of eight sunflower varieties grown at 10 locations in 1964 and 14 locations in 1964 showed highly significant differences between varieties and between stations in mean values for percentage of stearic, oleic and linoleic acids but no significant difference for palmitic acid. The same observations held for oleic and linoleic acids in three varieties common to eight stations in the two years. The only significant interaction appearing in these studies was between years and stations. Varieties requiring the same time to mature differed significantly. Oil from composite samples of inbred lines showed large differences in composition, e.g., the ranges in 56 lines grown in one season at one location were: palmitic 4.7–8.2%; stearic 1.7–9.1%; oleic 13.9–40.3%; and linoleic 47.9–76.4%. Single seeds within inbred lines also showed striking variation. The greatest variation occurred in lines inbred for one to three generations and the least in lines inbred for eight to nine generations. Pairs of lines with identical or similar flowering date differed significantly in mean values of all four acids. Variation between seeds within varieties were relatively narrow in Armavirec and Advent, but wide in Peredovik where the range was: palmitic 4.5–9.4%; stearic 2.5–12.4%; oleic 14.8–46.4%; and linoleic 34.3–75.5%. The results show that genetic control of oil quality, independent of flowering or maturity date, exists in sunflowers. The wide range in composition suggests that altering oil quality in the crop by breeding is a practical objective. Contribution No. 73, Research Station, Research Branch, Canada Department of Agriculture, Morden, Manitoba and contribution No. 97, Analytical Chemistry Research Service, Ottawa. Presented at the AOCS Meeting, Chicago, October 1967.