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1.
The changes occurring in two oil samples [EPG-00 soyate (transesterified soybean oil) and soy oil esterified propoxylated glycerol (EPG-08 soyate, a model, fat substitute compound)] were compared after heating at approximately 190 degrees C for 12 h/day. The EPG-00 soyate sample required 48 h of heating to attain a polymer content >20%, while the EPG-08 soyate required only 36 h. After 48 h of heating the EPG-00 soyate sample, the free fatty acid value (FFA) increased from 0.19 to 0.79, the acid value (AV) increased from 0.10 to 1.59, and the p-anisidine value (p-AV) increased from 1.6 to 195.4. In comparison, after only 36 h of heating, the EPG-08 soyate sample had FFA, AV, and p-AV increases from 0.19 to 0.71, from 0.26 to 1.36, and from 1.1 to 191.7, respectively. The triacylglycerol substrate degradation rate for EPG-00 soyate was k = 0.0126 +/- 0.0003 h(-)(1), while the rate for EPG-08 soyate was k = 0.0166 +/- 0.0017 h(-)(1). The results suggest that the EPG-00 soyate or transesterified soybean oil is slightly more stable than EPG-08 soyate.  相似文献   

2.
The volatile reaction products of aqueous mixtures comprising combinations of methionine, glucose, linoleic acid, and starch heated in a modified Likens-Nickerson apparatus were extracted and analyzed by gas chromatography-mass spectrometry (GC-MS). The majority of volatile compounds were formed from linoleic acid degradation, hexanal, 2,4-decadienal, and 2-pentylfuran being identified in the greatest amounts. Dimethyl disulfide and dimethyl trisulfide were detected in every system containing methionine. 3-(Methylthio)propanal (methional) and other sulfur compounds were detected when methionine was heated with another precursor. No binding of volatile compounds to starch was observed; rather, starch appeared to act as an additional source of reactive carbohydrate. Almost all the components identified have been identified among the aroma components of cooked potato. No pyrazines, pyridines, or thiazoles were identified, probably due to the relatively low temperature/high moisture conditions.  相似文献   

3.
Camellia oil is widely used in some parts of the world partly because of its high oxidative stability. The effect of heating a refined camellia oil for 1 h at 120 degrees C or 2 h at 170 degrees C with exogenous antioxidant, namely, caffeic acid and tyrosol, was studied. Parameters used to assess the effect of heating were peroxide and K values, volatile formation, and fatty acid profile. Of these, volatile formation was the most sensitive index of change as seen in the number of volatiles and the total area count of volatiles in gas chromatograms. Hexanal was generally the dominant volatile in treated and untreated samples with a concentration of 2.13 and 5.34 mg kg(-1) in untreated oils heated at 120 and 170 degrees C, respectively. The hexanal content was significantly reduced in heated oils to which tyrosol and/or caffeic acid had been added. Using volatile formation as an index of oxidation, tyrosol was the more effective antioxidant of these compounds. This is contradictory to generally accepted antioxidant structure-activity relationships. Changes in fatty acid profiles after heating for up to 24 h at 180 degrees C were not significant.  相似文献   

4.
Antioxidant properties of ferulic acid and its related compounds   总被引：13，自引：0，他引：13  
Antioxidant activity of 24 ferulic acid related compounds together with 6 gallic acid related compounds was evaluated using several different physical systems as well as their radical scavenging activity. The radical scavenging activity on 1,1-diphenyl-2-picrylhydrazyl (DPPH) decreased in the order caffeic acid > sinapic acid > ferulic acid > ferulic acid esters > p-coumaric acid. In bulk methyl linoleate, test hydroxycinnamic acids and ferulic acid esters showed antioxidant activity in parallel with their radical scavenging activity. In an ethanol-buffer solution of linoleic acid, the activity of test compounds was not always associated with their radical scavenging activity. Ferulic acid was most effective among the tested phenolic acids. Esterification of ferulic acid resulted in increasing activity. The activity of alkyl ferulates was somewhat influenced by the chain length of alcohol moiety. When the inhibitory effects of alkyl ferulates against oxidation of liposome induced by AAPH were tested, hexyl, octyl, and 2-ethyl-1-hexyl ferulates were more active than the other alkyl ferulates. Furthermore, lauryl gallate is most effective among the tested alkyl gallates. These results indicated that not only the radical scavenging activity of antioxidants, but also their affinity with lipid substrates, might be important factors in their activity.  相似文献   

5.
To determine sources of desirable deep-fried flavor in frying oils, degradation products from heated triolein and trilinolein with 5-31% polar compounds representing low to high deterioration were evaluated by purge-trap gas chromatography-mass spectrometry-olfactometry. (E,E)-2,4-Decadienal, 2-heptenal, 2-octenal, 2,4-nonadienal, and 2,4-octadienal produced deep-fried odor at moderate-strong intensities in heated trilinolein. However, unexpected aldehydes-2,4-decadienal, 2,4-undecadienal, 2,4-nonadienal, and 2-octenal (all <15 ppm)-were produced in triolein heated for 6 h. These dienals possibly were produced by hydroperoxidation and/or hydroxylation followed by dehydration of 2-alkenals. The 2-alkenals were produced from thermal decomposition of hydroperoxides, epoxides, and keto and dimeric compounds produced during the heating of triolein. These aldehydes produced low intensities of deep-fried odor in triolein. This information helps to explain sources of the deep-fried flavor that is characteristic of high linoleic frying oils but which is only at low intensity levels in high oleic frying oils.  相似文献   

6.
The reactions of asparagine with methyl linoleate ( 1), methyl 13-hydroperoxyoctadeca-9,11-dienoate ( 2), methyl 13-hydroxyoctadeca-9,11-dienoate ( 3), methyl 13-oxooctadeca-9,11-dienoate ( 4), methyl 9,10-epoxy-13-hydroxy-11-octadecenoate ( 5), methyl 9,10-epoxy-13-oxo-11-octadecenoate ( 6), 2,4-decadienal ( 7), 2-octenal ( 8), 4,5-epoxy-2-decenal ( 9), and benzaldehyde ( 10) were studied to determine the potential contribution of lipid derivatives to acrylamide formation in heated foodstuffs. Reaction mixtures were heated in sealed tubes for 10 min at 180 degrees C under nitrogen. The reactivity of the assayed compounds was 7 > 9 > 4 > 2 > 8 approximately 6 > 10 approximately 5. The presence of compounds 1 and 3 did not result in the formation of acrylamide. These results suggested that alpha,beta,gamma,delta-diunsaturated carbonyl compounds were the most reactive compounds for this reaction followed by lipid hydroperoxides, more likely as a consequence of the thermal decomposition of these last compounds to produce alpha,beta,gamma,delta-diunsaturated carbonyl compounds. However, in the presence of glucose this reactivity changed, and compound 1/glucose mixtures showed a positive synergism (synergism factor = 1.6), which was observed neither in methyl stearate/glucose mixtures nor in the presence of antioxidants. This synergism is proposed to be a consequence of the formation of free radicals during the asparagine/glucose Maillard reaction, which oxidized the lipid and facilitated its reaction with the amino acid. These results suggest that both unoxidized and oxidized lipids are able to contribute to the conversion of asparagine into acrylamide, but unoxidized lipids need to be oxidized as a preliminary step.  相似文献   

7.
Antioxidative compounds from the outer scales of onion   总被引：2，自引：0，他引：2  
Antioxidative compounds were isolated from the methanol extract of dry outer scales of onion (Allium cepa L.). Nine phenolic compounds (1-9) were finally obtained by reversed-phase high-performance liquid chromatography, and their structures were elucidated by NMR and mass spectrometry analyses. They were the six known compounds, protocatechuic acid (1), 2-(3,4-dihydroxybenzoyl)-2,4,6-trihydroxy-3(2H)-benzofuranone (2), quercetin 4'-O-beta-D-glucopyranoside (3), quercetin (5), 4'-O-beta-d-glucopyranoside of quercetin dimer (7), and quercetin dimer (8), and three novel compounds, condensation products of quercetin with protocatechuic acid (4), adduct of quercetin with quercetin 4'-O-beta-D-glucopyranoside (6), and quercetin trimer (9). These phenolic compounds were tested for their antioxidant properties using autoxidation of methyl linoleate in bulk phase or free radical initiated peroxidation of soybean phosphatidylcholine in liposomes. The flavonoid compounds having o-dihydroxy substituent in the B-ring were shown to be effective antioxidants against nonenzymic lipid peroxidation.  相似文献   

8.
The aroma-active compounds in two apple ciders were identified using gas chromatography-olfactometry (GC-O) and GC-mass spectrometry (MS) techniques. The volatile compounds were extracted using solvent-assisted flavor evaporation (SAFE) and headspace solid-phase microextraction (HS-SPME). On the basis of odor intensity, the most important aroma compounds in the two apple cider samples were 2-phenylethanol, butanoic acid, octanoic acid, 2-methylbutanoic acid, 2-phenylethyl acetate, ethyl 2-methylbutanoate, ethyl butanoate, ethyl hexanoate, 4-ethylguaiacol, eugenol, and 4-vinylphenol. Sulfur-containing compounds, terpene derivatives, and lactones were also detected in ciders. Although most of the aroma compounds were common in both ciders, the aroma intensities were different. Comparison of extraction techniques showed that the SAFE technique had a higher recovery for acids and hydroxy-containing compounds, whereas the HS-SPME technique had a higher recovery for esters and highly volatile compounds.  相似文献   

9.
Three continuous assays are described for lipoxygenase (LOX), hydroperoxide lyase (HPL) and alcohol dehydrogenase (ADH) in leek tissue. The catalytic activity of LOX showed significant difference (significance level 5%) between linolenic acid (9.43 x 10(-)(4) katals per kg protein) and linoleic acid (2.53 x 10(-)(4) katals per kg protein), and the pH-optimum of LOX was 4.5-5.5 against linoleic acid. The catalytic activity of HPL was statistically the same for 9-(S)-hydroperoxy-(10E,12Z)-octadecadienoic acid (1.01 x 10(-)(2) katals per kg protein) and 13-(S)-hydroperoxy-(9Z,11E)-octadecadienoic acid (7.69 x 10(-)(3) katals per kg protein). ADH showed a catalytic activity of 5.01 x 10(-)(4) katals/kg of protein toward hexanal. Model experiments with crude enzyme extract from leek mixed with linoleic acid or linolenic acid demonstrated differences in the amount of produced aroma compounds. Linoleic acid resulted in significantly most hexanal, heptanal, (E)-2-heptenal, (E)-2-octenal, (E,E)-2,4-decadienal, pentanol, and hexanol, whereas linolenic acid resulted in significantly most (E)-2-pentenal, (E)-2-hexenal, (E,Z)-2,4-heptadienal, (E,E)-2,4-heptadienal, and butanol. Leek LOX produced only the 13-hydroperoxide of linoleic acid and linolenic acid.  相似文献   

10.
Two nonvolatile flavor precursors occurring in Allium vegetables, S-propyl-L-cysteine and its sulfoxide, were heated in closed model systems at different temperatures (from 80 to 200 degrees C) in the presence of variable amounts of water (0-98%) for 1-60 min. It seems to be indisputable that thermally generated breakdown products of both S-propyl-L-cysteine and particularly S-propyl-L-cysteine sulfoxide can significantly participate in the aroma formation of culinary processed Alliumvegetables. Dipropyl disulfide, dipropyl trisulfide, propylthiol, and dipropyl thiosulfonate were identified as the predominant volatile compounds generated by thermal degradation of S-propylcysteine sulfoxide. Dipropyl disulfide and 2-(propylthio)ethylamine were the major breakdown products formed from S-propylcysteine. Substantial amounts of various alkyl- and alkylthio-substituted pyridines were also generated from both S-propylcysteine and its sulfoxide.  相似文献   

11.
Mechanism of volatile compound production during storage of sunflower Oil   总被引：2，自引：0，他引：2  
Volatile compounds formed in the course of the thermal decomposition of hydroperoxides during storage of sunflower oil were analyzed by headspace solid-phase microextraction sampling followed by gas chromatographic separation and mass spectral detection. The determining role of alkoxyl radicals in the process has been proven by electron spin resonance spectroscopic measurements. On the basis of analytical results, the reaction networks and mechanisms were constructed by computer modeling to describe the formation of volatile products of radical decomposition of hydroperoxides. We established that off-flavor aliphatic aldehydes are originated from only the alkoxyl radicals derived from trigliceride of linoleic acid. To find a specific additive, which redirects the formation of these radicals toward production of more stable species, is suggested.  相似文献   

12.
Six volatile compounds, ethylmethylbenzene (1), 1-isopentyl-2,4, 5-trimethylbenzene (2), 2-(hex-3-ene-2-one)phenylmethyl ketone (3), E and Z isomers of 3-butylidene-3H-isobenzofuran-1-one (4 and 5), and 2-penten-1-ylbenzoic acid (6), were isolated from the mosquitocidal hexane extract of Delphinium x cultorum cv. Magic Fountains flowers. In addition, the ethyl acetate extract, which displayed corn earworm antifeedant activity, yielded 4-hydroxybenzoic acid (7) and bis(4-hydroxyphenyl)methanol (8). However, compounds 7 and 8 were not biologically active.  相似文献   

13.
The volatile compounds of guava wine were isolated by continuous solvent extraction and analyzed by GC-FID and GC-MS. A total of 124 volatile constituents were detected, and 102 of them were positively identified. The composition of guava wine included 52 esters, 24 alcohols, 11 ketones, 7 acids, 6 aldehydes, 6 terpenes, 4 phenols and derivatives, 4 lactones, 4 sulfur-compounds, and 5 miscellaneous compounds. The aroma-active areas in the gas chromatogram were screened by application of the aroma extract dilution analysis and by odor activity values. Twelve odorants were considered as odor-active volatiles: (E)-β-damascenone, ethyl octanoate, ethyl 3-phenylpropanoate, ethyl hexanoate, 3-methylbutyl acetate, 2-methyltetrahydrothiophen-3-one, 2,5-dimethyl-4-methoxy-3(2H)-furanone, ethyl (E)-cinnamate, ethyl butanoate, (E)-cinnamyl acetate, 3-phenylpropyl acetate, and ethyl 2-methylpropanoate.  相似文献   

14.
A mixture of soybean oil and/or water, sugar and/or monosodium glutamate (MSG) was water-boiled or oil-heated at 100, 120, 140, 160, or 170 degrees C, respectively, and volatile compounds produced were isolated by solid-phase microextraction and then identified by GC and GC/MS. Oxidative thermal degradation products of fatty acids (OTDPFA) were the major volatile compounds detected for all water-boiled samples. When MSG and sugar were heated together, 2, 5-dimethyl pyrazine and methyl pyrazine were also detected at or after 160 min heating. Water added in soybean oil increased OTDPFA production. In oil-heated samples of soybean oil alone, soybean oil with MSG, and soybean oil with sugar, OTDPFA were also the major compounds found. The samples containing MSG also produced 2-pyrrolidone, and the samples containing sugar also produced furfural and 5-hydroxy methyl furfural. The samples containing soybean oil, sugar, and MSG produced 23 pyrazines, OTDPFA, and gamma-butyrolactone as the major volatile compounds. The contents of OTDPFA were lower in MSG plus sugar and MSG-added samples, and it is postulated that antioxidant activities were produced in cooking.  相似文献   

15.
Poppy seed oil (Oleum Papaveris Seminis) is used for culinary and pharmaceutical purposes, as well as for making soaps, paints, and varnishes. Astonishingly, hardly anything was yet known about the volatile compounds of this promising comestible. Likewise, there are no current published data about the triglyceride (TAG) composition of poppy seed oils available. In this investigation solid-phase microextraction (SPME) with DVB/Carboxen/PDMS Stable-Flex fiber was applied to the study of volatile compounds of several seed oil samples from Papaver somniferum L. (Papaveraceae). 1-Pentanol (3.3-4.9%), 1-hexanal (10.9-30.9%), 1-hexanol (5.3-33.7%), 2-pentylfuran (7.2-10.0%), and caproic acid (2.9-11.5%) could be identified as the main volatile compounds in all examined poppy seed oil samples. Furthermore, the TAG composition of these oils was analyzed by MALDI-ReTOF- and ESI-IT-MS/MS. The predominant TAG components were found to be composed of linoleic, oleic, and palmitic acid, comprising approximately 70% of the oils. TAG patterns of the different poppy varieties were found to be very homogeneous, showing also no significant differences in terms of the applied pressing method of the plant seeds.  相似文献   

16.
日光温室不同时段补光对番茄果实品质及挥发性物质影响   总被引：4，自引：4，他引：0  
为探明日光温室中提高番茄产量和品质的最佳补光时段,以"粉太郎"番茄为试材,从植株定植后第25天到第一穗果完全成熟时进行补光,利用LED灯设置3种补光时段:揭帘前补光5 h(T1)、盖帘后补光5 h(T2)、揭帘前盖帘后分别补光2.5h(T3),以不补光作为对照(CK),研究其对番茄产量、果实品质以及挥发性物质成分和含量的影响。结果表明:补光处理可提高番茄平均单株产量、果实可溶性糖含量、可溶性固形物含量、糖酸比、挥发性物质总数量和总质量分数,但会降低有机酸含量,T1处理效果最显著(P<0.05)。4个处理共检测出83种挥发性物质,包括12种酮类、22种醛类、22种醇类、6种酯类、6种烃类和15种其他类物质。各处理挥发性物质总数量和总质量分数由大到小为:T1(68种,3 107.98μg/kg)、T3(65种,2 610.74μg/kg)、T2(63种,2 438.96μg/kg)、CK(59种,2 086.03μg/kg)。每个处理醇类含量最多,烃类含量最低,并且含量最高的物质均是顺-3-己烯-1-醇。3种补光处理均可提高酮类、醛类、醇类和其他类物质含量,但显著降低烃类物质含量(P<0.05),酯类物质含量只在T1处理时有所提高。所有被检测出的挥发性物质包含11种番茄特征香气成分,主要分为花香、果香与青香3种类型,其中青香味物质含量最多。综上,对番茄进行补光尤其是揭帘前补光5 h可有效提高番茄产量、果实品质和风味,是当地日光温室越冬茬番茄栽培的较优补光时段。研究结果可为设施番茄种植的光环境调控技术提供科学依据。  相似文献   

17.
This paper compares the volatile constituents of model systems containing the important meat aroma precursors cysteine and ribose, with and without either methyl linoleate, an n-6 fatty acid, or methyl alpha-linolenate, an n-3 acid, both of which are present in meat. Many of the volatile compounds formed from the reaction between cysteine and ribose were not formed, or formed in lower amounts, when lipid was present. This may be due to the reaction between hydrogen sulfide, formed from the breakdown of cysteine, and lipid degradation products. In addition, cysteine and ribose modified lipid oxidation pathways, so that alcohols and alkylfurans were formed rather than saturated and unsaturated aldehydes. Several volatile compounds, which have been found at elevated levels in cooked meat from animals fed supplements high in n-3 acids, were formed when methyl alpha-linolenate reacted with cysteine and ribose. The possible effects of increasing the n-3 content of meat upon flavor formation during cooking are discussed.  相似文献   

18.
Lipid hydroperoxides are important factors in lipid oxidation due to their ability to decompose into free radicals. In oil-in-water emulsions, the physical location of lipid hydroperoxides could impact their ability to interact with prooxidants such as iron. Interfacial tension measurements show that linoleic acid, methyl linoleate, and trilinolein hydroperoxides are more surface-active than their non-peroxidized counterparts. In oil-in-water emulsion containing surfactant (Brij 76) micelles in the continuous phase, linoleic acid, methyl linoleate, and trilinolein hydroperoxides were solubilized out of the lipid droplets into the aqueous phase. Brij 76 solubilization of the different hydroperoxides was in the order of linoleic acid > trilinolein > or = methyl linoleate. Brij 76 micelles inhibited lipid oxidation of corn oil-in-water emulsions with greater inhibition of oxidation occurring in emulsions containing linoleic acid hydroperoxides. Surfactant solubilization of lipid hydroperoxides could be responsible for the ability of surfactant micelles to inhibit lipid oxidation in oil-in-water emulsions.  相似文献   

19.
Eight volatile products characterizing strawberry aroma, which is generated from the oxidative degradation of linoleic and linolenic acids by a lipoxygenase (LOX) pathway, were examined because of their antifungal activity against Colletotrichum acutatum, one of the causal agents of strawberry anthracnose. In this study, the effects of aldehydes, alcohols, and esters on mycelial growth and conidia development were evaluated. (E)-Hex-2-enal was found to be the best inhibitor of mycelial growth [MID (minimum inhibitory doses)=33.65 microL L(-1)] and of spore germination (MID=6.76 microL L(-1)), while hexyl acetate was the least effective of all volatile compounds tested (MID=6441.89 microL L(-1) for mycelial growth and MID=1351.35 microL L(-1) for spore germination). Furthermore, the antifungal activity of (E)-hex-2-enal on susceptibility of strawberry fruits to C. acutatum was also confirmed. The presence of these molecules in jars containing strawberry fruits inoculated with a suspension of spores inhibited the fungus growth and prevented the appearance of symptoms. Moreover, a study of the effects of (E)-hex-2-enal on conidial cells of C. acutatum was evaluated by transmission electron microscopy. This volatile compound altered the structures of the cell wall and plasma membrane, causing disorganization and lysis of organelles and, eventually, cell death.  相似文献   

20.
The bioassay-guided isolation and purification of the hexane extract of the cultured mycelia of Grifola frondosa led to the characterization of a fatty acid fraction and three compounds, ergosterol (1), ergostra-4,6,8(14),22-tetraen-3-one (2), and 1-oleoyl-2-linoleoyl-3-palmitoylglycerol (3). The composition of fatty acid fraction was confirmed as palmitic, oleic, and linoleic acids by GC-MS and by comparison with the retention values of authentic samples. The structures of compounds 1-3 were established by spectroscopic methods. The fatty acid fraction and compounds 1-3 showed cyclooxygenase (COX) enzyme inhibitory and antioxidant activities. The inhibition of COX-1 enzyme by the fatty acid fraction and compounds 1-3 at 250 microg/mL were 98, 37, 55, and 67%, respectively. Similarly, COX-2 enzyme activity was reduced by fatty acid fraction and compounds 1-3 at 250 microg/mL by 99, 37, 70, and 4%, respectively. The inhibitions of liposome peroxidation by the fatty acid fraction and compounds 1 and 2 at 100 microg/mL were 79, 48, and 42%, respectively. This is the first report of compounds 2 and 3 from the cultured mycelia of G. frondosa. The COX inhibitory activities of compounds 1-3 are reported here for the first time.  相似文献   

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