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1.
G. P. Savage D. L. McNeil P. C. Dutta 《Journal of the American Oil Chemists' Society》1997,74(6):755-759
Hazelnut (Corylus avellana L.) samples were collected from six different cultivars of trees grown in an experimental orchard at Lincoln University.
Three U.S. commercial cultivars (Butler, Ennis, and Barcelona), two European commerical cultivars (Tonda di Giffoni and Campanica),
and one New Zealand selection (Whiteheart) were evaluated. The total oil, stability to oxidation of the oil, and fatty acid,
tocopherol, and sterol composition were determined on samples of freshly extracted hazelnut oil. The total oil content of
the seeds ranged from 54.6 to 63.2% while the stability of the oil, as measured by the Rancimat test ranged from 15.6 to 25.3
h. The content of the monounsaturated oleic acid in the oils ranged from 73.8 to 80.1% of the total fatty acids, while the
tocopherol content ranged from 225.8 to 552.0 mg/g freshly extracted oil. The major desmethylsterols were sitosterol, ranging
from 1416 to 1693 μg/g, campesterol, ranging from 78 to 114 μg/g, and Δ5-avenasterol, ranging from 110 to 170 μg/g. The oil
extracted from the cultivar Whiteheart was more stable (measured by Rancimat) than the oil from all other cultivars grown
at the same location and under the same conditions. Whiteheart contained higher levels of total and γ-tocopherol when compared
to the other cultivars. The higher levels of tocopherol in Whiteheart help to explain the greater stability of the oil during
the oxidative stress test. These results suggest that nuts from the cultivar Whiteheart could be stored longer than the other
nuts tested.
Presented as a poster at the 87th AOCS Annual Meeting, Indianapolis, Indiana, April 28–May 1, 1996. 相似文献
2.
Walnut (Juglans regia L.) oil was extracted with compressed carbon dioxide (CO2) in the temperature range of 308 to 321 K and in the pressure range of 18 to 23.4 MPa. The influence of particle size was
also studied at a superficial velocity of 0.068 cm/s, within a tubular extractor of 0.2 L capacity (cross-sectional area of
16.4 cm2). FFA, sterol, TAG, and tocopherol compositions were not different from those of oil obtained with n-hexane. The main FA was linoleic acid (56.5%), followed by oleic acid (21.2%) and linolenic acid (13.2%). The main TAG was
LLL (linoleic, linoleic, linoleic) (24.4%), followed by OLL (oleic, linoleic, linoleic) (19.6%) and LLLn (linoleic, linoleic,
linolenic) (18.4%). The main component of sterols was β-sitosterol (85.16%), followed by campesterol (5.06%). The amount of
cholesterol was low (0.31 and 0.16% for oils extracted by n-hexane and supercritical fluid extraction, respectively. The CO2-extracted oil presented a larger amount of tocopherols (405.7 μg/g oil) when compared with 303.2 μg/g oil obtained with n-hexane. Oxidative stability determined by PV and the Rancimat method revealed that walnut oil was readily oxidized. Oil extracted
by supercritical CO2 was clearer than that extracted by n-hexane, showing some refining. A central composite, nonfactorial design was used to optimize the extraction conditions using
the software Statistica, Version 5. The best results were found at 22 MPa, 308 K, and particle diameter (Dp) −0.1 mm. 相似文献
3.
The effect of roasting on the oxidative stability of oil from walnut (Juglans sinensis Dode) was investigated by observing changes in the characteristics of oils from unroasted and roasted kernels during storage in the dark at 60°C. Walnut kernels were roasted at 160°C for 15 min prior to oil extraction with the solvent, hexane. Roasting of kernels increased the peroxide value (POV) and conjugated dienoic acid (CDA) value of the oil. The rate of increase in the POV was significantly lower in roasted than in the unroasted walnut oil during storage at 60°C (1.90 vs. 1.06 and 4.45 vs. 3.55 meq/kg/day during induction period (IP) and post‐IP, respectively). Roasting of kernels significantly increased the IP of walnut oil from 0.89 to 3.39 days during storage. The total tocopherol content in roasted walnut oil was lower as compared to that in unroasted one (277.77 vs. 314.88 µg/g). However, the rate of degradation of total tocopherol during storage was lower in roasted walnut oil compared to unroasted one (1.18 vs. 2.17%/day), which showed that the tocopherol retention was higher in roasted walnut oil. These results indicate that roasting of kernels increased the oxidative and tocopherol stability of oil during storage in the dark. 相似文献
4.
Abdalbasit Mariod Bertrand Matthäus K. Eichner Ismail H. Hussein 《Journal of the American Oil Chemists' Society》2006,83(6):529-538
The behavior of crude Sclerocarya birrea kernel oil (SCO) and Sorghum bug (Agonoscelis pubescens) oil (SBO) during deep-frying of par-fried potatoes was studied with regard to chemical, physical, and sensory parameters,
such as content of FFA, tocopherols, polar compounds, oligomer TG, volatile compounds, oxidative stability, and total oxidation
(TOTOX) value. Palm olein was used for comparison. Whereas potatoes fried in SCO that had been used for 24 h of deep-frying
at 175°C were still suitable for human consumption, potatoes prepared in SBO that had been used for 6 to 12 h were not, considering
the sensory evaluation. In looking at the chemical and physical parameters, SBO exceeded the limits, after no later than 18
h of use, for the amount of polar compounds, oligomer TG, and FFA recommended by the German Society of Fat Sciences (DGF)
as criteria for the rejection of used frying oils. In contrast to SBO, SCO oil did not exceed the limits for the content of
polar compounds and oligomer TG during the frying experiment. Only the amount of FFA was exceeded; this was because the amount
of FFA at the beginning of the experiment was higher than for refined oils. The results showed that both oils were suitable
for deep-frying of potatoes, but remarkable differences in the time during which both oils produced palatable products were
found. 相似文献
5.
Varietal and crop year effects on lipid composition of walnut (Juglans regia) genotypes 总被引:1,自引:0,他引:1
Marcela L. Martínez Miguel A. Mattea Damián M. Maestri 《Journal of the American Oil Chemists' Society》2006,83(9):791-796
The FA, unsaponifiable, and volatile constituents of oil from three walnut varieties from two consecutive crop years were
studied. The walnut oils (WO) were rich in PUFA and low in saturated FA. The tocopherol fraction consisted mainly of γ-tocopherol.
High contents of β-sitosterol were found, together with campesterol and Δ5-avenasterol in similar amounts. Methylsterols present in WO were identified as cycloartenol, cyclolaudenol, cycloeucalenol,
and 24-methylenecycloartanol. The hydrocarbon fraction was characterized by the predominance of C14–C20
n-alkanes. The major volatiles were aldehydes produced through the linoleic acid oxidative pathway. FA, methylsterols, and
some hydrocarbons presented statistically significant differences among varieties. Most of this variation was due to the genotype.
The Franquette variety was noteworthy by its higher oil and oleic acid contents. In contrast, tocopherols and volatile compounds
showed minor differences among varieties; they were strongly influenced by the crop year. Chemical data were subjected to
principal component analysis. The parameters that gave the greatest discrimination between the walnut varieties were oleic
and linolenic acids, tetradecane, eicosane, tetracosane, cycloartenol, and 24-methylenecycloartanol. These components presented
the major varietal influences and could be useful to determine the identity of walnut genotypes. 相似文献
6.
Supercritical carbon dioxide (SC-CO2) was used to partially defat walnuts, and the oxidative stability of the extracted walnut oils was assessed. The SC-CO2-extracted oils were less stable during accelerated storage in the dark than was pressed walnut oil, as determined by PV,
headspace analysis by solid-phase microextraction, and sensory methods. The SC-CO2-extracted oils, however, exhibited greater photo-oxidative stability than did pressed walnut oil by all of these methods,
possibly because of the presence of chlorophyll in the pressed oil. Oxidative stability indices and tocopherol contents were
significantly lower in the SC-CO2-extracted oils than in pressed oil. 相似文献
7.
J. A. Zygadlo R. E. Morero R. E. Abburra C. A. Guzman 《Journal of the American Oil Chemists' Society》1994,71(8):915-916
The seeds ofOenothera picensis, O. indecora, Ludwigia longifolia andL. peruviana (Onagraceae) contained 18.3, 16.4, 13.9 and 10.1% oil, respectively. Chromatographic analyses showed high levels of linoleic
acid (>71.5%) in the seed oils. 相似文献
8.
9.
Casimir C. Akoh 《Journal of the American Oil Chemists' Society》1994,71(2):211-216
Oxidative Stability Index (OSI) of carbohydrate fatty acid polyesters, fat substitutes and vegetable oils were measured with
the Omnion Oxidative Stability Instrument according to the new AOCS Standard Method Cd 12 B-92 (The Official Methods and Recommended Practices of the American Oil Chemists' Society, edited by D. Firestone, AOCS, Champaign, 1991). The stability of crude and refined, bleached and deodorized (RBD) vegetable
oils (soybean, hydrogenated soybean and peanut) were determined at 110°C. In addition, OSI times for sucrose polyesters of
soybean oil, butterfat, oleate:stearate and methyl glucoside polyester of soybean oil were determined in the absence and in
the presence of 0.02 wt% antioxidants, [Tenox TBHQ (tertiary butylhydroquinone, Tenox GT-2 (from Eastman Chemical Products
(Kingsport, TN); and vitamin E (from BASF, Wyandotte, MI)], and the results were compared with those of vegetable oils. Crude
oils were most stable (20.4–25.9 h), followed by RBD oils (9.3–10.4 h) for soybean and peanut oils, respectively, and fat
substitutes (3.8–6.8 h). Overall, Tenox TBHQ was the best antioxidant for improving the oxidative stability of both vegetable
oils and fat substitutes. The sucrose polyester made with oleic and stearic acid was more stable than fat substitutes containing
more polyunsaturated fatty acids, such as those from soybean oil, or from short-chain fatty acids, such as from butterfat.
Antioxidants enhanced the stability of RBD oils (222% increase) and synthetic fat substitutes (421–424% increase) more than
that of crude oils (33% increase). The shapes of the induction curves, not the actual OSI times for fat substitutes and vegetable
oils, were similar and sharply defined. 相似文献
10.
Nuo Shen Walter Fehr Lawrence Johnson Pamela White 《Journal of the American Oil Chemists' Society》1997,74(3):299-302
Oils from soybean lines, developed to contain different amounts of palmitate (16:0) and linolenate (18:3), were evaluated
for oxidative stability. Oils were extracted in the laboratory from the soybean seeds and refined, bleached, and deodorized.
Two replications, separated at the point of conditioning, were evaluated for each genotype, including Hardin 91 (normal beans),
P9322 (10.6% 16:0 and <2.6% 18:3), A91-282036 (26.3% 16:0 and 9.8% 18:3), and HPLL (23.2% 16:0 and 3.5 % 18:3). Elevating
16:0 and/or lowering 18:3 increased the oxidative stability of soybean oils as measured by peroxide values. Soybean oils with
elevated 16:0 had higher solidification temperatures than did oils with normal 16:0 content, and soybean oils with low 18:3
content had higher solidification temperatures than did oils with normal 18:3 contents. 相似文献
11.
Afaf Kamal‐Eldin 《European Journal of Lipid Science and Technology》2006,108(12):1051-1061
The oxidative stability of vegetable oils is determined by their fatty acid composition and antioxidants, mainly tocopherols but also other non‐saponifiable constituents. The effect of fatty acids on stability depends mainly on their degree of unsaturation and, to a lesser degree, on the position of the unsaturated functions within the triacylglycerol molecule. Vegetable oils contain tocopherols and tocotrienols, especially α‐ and γ‐tocopherols, as their main antioxidants. The antioxidant behavior of tocopherols represents a complex phenomenon as they are efficient antioxidants at low concentrations but they gradually lose efficacy as their concentrations in the vegetable oils increase. The “loss of efficacy” of tocopherols, sometimes referred to as a “pro‐oxidant effect”, is witnessed by an increase in the rate of oxidation during the induction period, despite elongation of this phase. The phenomenon is much obvious for α‐tocopherol, but is also evident for other tocopherols. In agreement with nature's wisdom, the tocopherol levels in vegetable oils seem to be close to the optimal levels needed for the stabilization of these oils. The presence of other antioxidants in the oils, e.g. carotenoids, phenolic compounds, and Maillard reaction products, may synergize with tocopherols and minimize this loss of efficacy. 相似文献
12.
The qualitative and quantitative composition of the acid fraction of wood extractives from three SpanishPinus pinaster Ait. subspecies (Atlantic, mountain Mediterranean and plain Mediterranean) were studied. Seven samples of each subspecies
were prepared according to Technical Association of Pulp and Paper Standards, extracted with petroleum ether (b.p. 40–60°C)
in a Soxhlet apparatus and saponified with ethanolic 0.4N potassium hydroxide. The acid fraction was methylated with diazomethane
and studied by combined gas chromatography/mass spectrometry. The major constituents found were palmitic, oleic and linoleic
among the fatty acids and pimaric, sandaracopimaric, levopimaric, isopimaric, abietic and dehydroabietic among the resin acids.
Neoabietic and palustric acids were not found. Variations in the quantitative composition of the acid fraction enable us to
distinguish the three subspecies. Main quantitative differences are found between the Atlantic subspecies and the two Mediterranean
subspecies. 相似文献
13.
Robert L. Wolff Corinne C. Bayard 《Journal of the American Oil Chemists' Society》1995,72(9):1043-1046
The fatty acid composition of seeds from seven species of the genusPinus (P. pinaster, P. griffithii, P. pinea, P. koraiensis, P. sylvestris, P. mughus, andP. nigra) was established. Pine seeds are rich in oil (31–68% by weight) and contain several unusual polymethylene-interrupted unsaturated
fatty acids with acis-5 ethylenic bond. These are thecis-5,cis-9 18:2,cis-5,cis-9,cis-12 18:3,cis-5,cis-11 20:2, andcis-5,cis-11,cis-14 20:3 acids, with a trace ofcis-5,cis-9,cis-12,cis-15 18:4 acid. Their percentage relative to total fatty acids varies from a low of 3.1% (P. pinea) to a high of 30.3% (P. sylvestris), depending on the species. The majorcis-5 double bond-containing acid is generally thecis-5,cis-9,cis-12 18:3 acid (pinolenic acid). In all species, linoleic acid represents approximately one-half the total fatty acids, whereas
the content of oleic acid varies in the range 14–36% inversely to the sum of fatty acids containing acis-5 ethylenic bond. The easily available seeds fromP. koraiensis appear to be a good source of pinolenic acid: their oil content isca. 65%, and pinolenic represents about 15% of total fatty acids. These values appear to be rather constant.Pinus pinaster, which is grown on several thousand acres in the southwest of France, is an interesting source ofcis-5,cis-11,cis-14 20:3 acid (7% in the oil, which isca. 35% of the dehulled seed weight), an acid sharing in common three double bonds with arachidonic acid. Apparently,P. sylvestris seed oil contains the highest level ofcis-5 double bond-containing acids among pine seed oils that have ever been analyzed. 相似文献
14.
Lars Ovesen Torben Leth Kirsten Hansen 《Journal of the American Oil Chemists' Society》1998,75(12):1079-1083
This study examined trans monounsaturated fatty acid contents in all margarines and shortenings marketed in Denmark, and in frying fats used by the
fast-food restaurants Burger King and McDonald’s. Trans C18:1 content was 4.1±3.8% (g per 100 g fatty acids) in hard margarines, significantly higher than the content in soft margarines
of 0.4±0.8%. Shortenings had an even higher content of trans C18:1, 6.7±2.3%, than the hard margarines. Margarines and shortenings with high contents of long-chain fatty acids had about 20%
total trans monoenoic of which close to 50% were made up of trans long-chain fatty acids. Both fast-food frying fats contained large amounts of trans C18:1, 21.9±2.9% in Burger King and 16.6±0.4% in McDonald’s. In Denmark the per capita supply of trans C18:1 from margarines and shortenings and frying fats has decreased steadily during recent years. The supply of trans C18:1 from margarines and shortenings in the Danish diet is now 1.1 g per day. 相似文献
15.
The relationships between FA and the volatile profiles of olive and walnut oils from Argentina were studied using GC and solid-phase
microextraction coupled with GC-MS. The major volatiles were aldehydes and hydrocarbons, produced mainly through the oxidative
pathways. n-Pentane, nonanal, and 2,4-decadienal were predominant in walnut oils, whereas nonanal, 2-decenal, and 2-undecenal were the
most abundant components in olive oils. A multivariate analysis applied to the chemical data emphasized the differences between
the oils and allowed us to see a pattern of covariation among the FA and the volatile compounds. The main differences between
walnut and olive oils were the presence of larger amounts of short-chain (C5–C6) saturated hydrocarbons and aldehydes in the former and the greater quantities of medium-chain (C7–C11) compounds in olive oil. This can be explained by their different origins, mainly from the linoleic acid in walnut oil or
almost exclusively from the oleic acid in olive oil. 相似文献
16.
Lars Ovesen Torben Leth Kirsten Hansen 《Journal of the American Oil Chemists' Society》1998,75(9):1079-1083
This study examined trans monounsaturated fatty acid contents in all margarines and shortenings marketed in Denmark, and in frying fats used by the
fast-food restaurants Burger King and McDonald’s. Trans C18:1 content was 4.1±3.8% (g per 100 g fatty acids) in hard margarines, significantly higher than the content in soft margarines
of 0.4±0.8%. Shortenings had an even higher content of trans C18:1, 6.7±2.3%, than the hard margarines. Margarines and shortenings with high contents of long-chain fatty acids had about 20%
total trans monoenoic of which close to 50% were made up of trans long-chain fatty acids. Both fast-food frying fats contained large amounts of trans C18:1, 21.9±2.9% in Burger King and 16.6±0.4% in McDonald’s. In Denmark the per capita supply of trans C18:1 from margarines and shortenings and frying fats has decreased steadily during recent years. The supply of trans C18:1 from margarines and shortenings in the Danish diet is now 1.1 g per day. 相似文献
17.
Fatty acid compositions of crude melon seed oil from two different sources were compared. Melon seeds fromCitrullus vulgaris (syn.C. lanatus) contained phosphatidylcholine (PC), lysophosphatidylcholine (LPC) and phosphatidylserine (PS), whereas melon seeds fromCitrullus colocynthis contained only PC and LPC, but not PS. Analysis of the total lipids revealed that the major fatty acid of the oils was 18:2n-6.Citrullus vulgaris seed oil contained 71.3% andC. colocynthis contained 63.4% of 18:2n-6. The predominant fatty acids in theC. vulgaris PC were 18:2n-6 (32.2%), 18:1n-9 (26.4%) and 16:0 (22.2%), whereas theC. colocynthis PC contained 44.6% of 18:1n-9 as the major fatty acid. The level of monoenes in theC. colocynthis variety (46.2%) was different from theC. vulgaris (27.3%). The major fatty acid in the LPC was 18:1n-9 for both varieties. Notably, theC. colocynthis variety did not contain any PS. The major fatty acids in theC. vulgaris PS were 18:1n-9 (37.9%) and 18:2n-6 (33.7%). Of all the phospholipids, LPC contained the greatest amount of monoenes, 48.6–52.4%. 相似文献
18.
Y. F. Lozano C. Dhuique Mayer C. Bannon E. M. Gaydou 《Journal of the American Oil Chemists' Society》1993,70(6):561-565
Four varieties (Zutano, Bacon, Fuerte, Lula) of avocado (Persea americana) have been investigated for their unsaponifiable matter (UM) in mature and immature fruits. The UM content in crude oil was
always higher in immature fruits (15–40%vs. 4–9%). The UM was fractionated by high-performance liquid chromatography for the determination of total sterols and tocopherol.
The sterol content in the oil was always higher in immature (1.1–6.2%) than in mature (0.8–2.0%) fruits. The tocopherol content
differed with the varieties (10.2–25.0 mg/100 g UM), and the levels in the oil were higher in immature (20.1–45.6 mg/100 g
oil) than in mature (5.7–10.3 mg/100 g oil) fruits. 相似文献
19.
Effects of microwave and conventional baking on the oxidative stability and fatty acid composition of puff pastry 总被引:1,自引:0,他引:1
Orhan Daglioglu Murat Tasan Baris Tuncel 《Journal of the American Oil Chemists' Society》2000,77(5):543-545
The effects of microwave and conventional baking on the fatty acid and trans fatty acid compositions of puff pastries, which contain high amounts of hydrogenated fat, were investigated. In addition,
free fatty acids, peroxide value, and induction time for oxidative stability by the Rancimat method have been compared for
microwave- and conventionally baked puff pastries. The data indicate there were considerable changes in acidity, peroxide
value, and Rancimat induction time in both microwave- and conventionally baked samples. Although the content of saturated
fatty acid such as palmitic and stearic and the ratio of saturated to unsaturated fatty acids did not change significantly,
an apparent increase was determined in trans oleic acid levels by both baking methods. In addition, a significant decrease in linoleic acid content of the samples was
found by microwave baking. 相似文献
20.
Lipid oxidation is a major factor affecting flavor quality and shelf life of vegetable oils. Oxidative stability is therefore
an important criterion by which oils are judged for usefulness in various food applications. In this study a method based
on headspace analysis was developed to evaluate relative oxidative stability of canola oils. The method does not require the
use of chemicals, involves minimal sample preparation, and can be performed on a relatively small sample size in comparison
with traditional wet chemical methods. Canola oils freshly extracted in the laboratory from different seed samples were subjected
to accelerated oxidation and analyzed for PV by standard methods and headspace volatiles by solid phase microextraction/GC-MS.
Forward stepwise regression analysis of the data revealed a relationship between PV and headspace concentration of the volatile
lipid oxidation products hexanal and trans,trans-2,4-heptadienal. The PV calculated using this formula correlated (R
2=0.73) with those measured by conventional methods.
Presented in part at the 96th Annual Meeting of the AOCS, 1–4 May 2005, Salt Lake City, UT. 相似文献