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1.
Food Chem ; 304: 125403, 2020 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-31479993

RESUMO

Current information on the links between the chemistry and hedonic liking of edible mushrooms is scarce. In this study, 84 consumers evaluated the appearance, odor, taste, texture and overall liking of samples of Nordic edible wild mushroom species. Subsequently, multivariate models on the effects of non-volatile compounds, odor-contributing volatile compounds, sensory attributes and hedonic likings were created. The non-volatile compounds were measured with quantitative NMR. The five studied mushroom species were different in their sugar and acid contents. Three consumer clusters were found with species*cluster interactions. Correlations with sensory attributes and chemical components were found, and the multivariate models indicated predictor attributes for each consumer cluster. The results indicate that the sensory properties could be correlated to both volatile and non-volatile compounds, there are consumer clusters with differing likings as regards mushrooms, and these clusters are heterogenic groups with no simple factors such as age explaining their liking scores.

2.
Lifestyle Genom ; : 1-8, 2019 Jun 24.
Artigo em Inglês | MEDLINE | ID: mdl-31234179

RESUMO

AIM: This observational follow-up study was designed to assess the long-term behavioural and clinical effects of receiving personal genetic risk information. The information disclosed was the carrier status of the apolipoprotein E (APOE)alleles, which differentially contribute to the genetic risk for cardiovascular disease (CVD) and Alzheimer's disease. METHODS: This study forms a continuum with a previous 1-year intervention (2010-2011) monitoring the effects of disclosing the carrier status of the APOE ε4risk allele. The follow-up measurements, performed 5.5 years post-intervention, included clinical measurements (blood values and anthropomorphic parameters) and questionnaires (psychological and behavioural factors). The participants were healthy adult volunteers, aged 26-73 years (n = 70) who had participated in the previous intervention, and received their APOE allele status either at the beginning (former test group) or the end of the intervention (former control group). RESULTS: Personal genetic risk information resulted in a moderate health-conscious change in diet and had a slight positive long-term effect on clinical factors, particularly the serum lipids. These improvements were subsequent to the disclosure of genetic information and occurred mainly in the APOE ε4-positive members of the former control group, that is, those who were at increased genetic risk for CVD but had not been informed of their status before the end of the intervention. In contrast, changes in the values and health behaviour of the APOE ε4-positive individuals in the former test group, who had already changed their health behaviour during the previous intervention as a result of being informed of their carrier status, varied more: some continued to improve, some remained at their previously improved level, and some relapsed slightly. Both groups had nonetheless displayed an improvement immediately subsequent to the disclosure of their personal genetic risk. CONCLUSION: Receiving information on increased personal genetic risk (carrier status of APOE ε4)for CVD provided the motivation for improvements in health behaviour. The resulting changes, while modest, in most cases remained visible even after a number of years.

3.
Food Chem ; 283: 566-578, 2019 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-30722913

RESUMO

Although Nordic wild edible mushrooms offer a wide range of different odors their scientific examination has been scarce. The aim of this study was to characterize the aroma compounds of four Finnish wild mushroom species with trained assessors using gas chromatography-olfactometry as well as gas chromatography-mass spectrometry. Headspace volatiles were extracted from sous vide cooked mushroom samples (Boletus edulis, Lactarius camphoratus, Cantharellus cibarius and Craterellus tubaeformis) using solid-phase microextraction. Odor-contributing compounds were measured with two columns of differing polarity using the detection frequency method. Compounds were identified based on reference compounds, linear retention indices, odor descriptions, and mass spectrometry. Both the volatile compound profiles and the aromagrams were distinct with characteristic compounds for each species. The results demonstrate that especially saturated and unsaturated aldehydes and ketones contribute to the odor of the studied wild mushrooms. This thorough comparison also indicates compounds linked to the sensory properties of mushrooms.


Assuntos
Agaricales/química , Cromatografia Gasosa/métodos , Cromatografia Gasosa-Espectrometria de Massas/métodos , Odorantes/análise , Compostos Orgânicos Voláteis/análise , Agaricales/metabolismo , Olfatometria , Análise de Componente Principal , Microextração em Fase Sólida , Compostos Orgânicos Voláteis/isolamento & purificação
4.
Food Chem ; 278: 56-66, 2019 Apr 25.
Artigo em Inglês | MEDLINE | ID: mdl-30583411

RESUMO

The effect of cooking on the taste compounds of five mushroom species Agaricus bisporus, Lactarius trivialis, Cantharellus cibarius, Cantharellus tubaeformis and Suillus variegatus were assessed with a special focus on the compounds responsible for the umami taste. Liquid chromatography was used to analyse free amino acids (FAAs) and 5'-nucleotides from fresh and sous vide (SV) cooked mushroom samples and cooking juice. The SV technique enabled analysis of entire mushrooms, including the liquid released during cooking. FAA content decreased when cooking temperature increased, indicating their further chemical reactions. S. variegatus contained highest concentrations of FAAs in analysed wild mushrooms. The umami-enhancing nucleotide 5'-GMP was detected only in cooked samples, concentration being likely dependent on enzymatic activity. The highest concentration of 5'-GMP was detected in cooked L. trivialis samples (17 mg/100 g fw). To our knowledge, the analysed taste compounds of L. trivialis and S. variegatus are documented for the first time.


Assuntos
Agaricales/metabolismo , Aminoácidos/análise , Culinária/métodos , Nucleotídeos/análise , Agaricales/química , Cromatografia Líquida de Alta Pressão , Limite de Detecção , Paladar , Temperatura Ambiente
5.
Food Sci Nutr ; 6(5): 1220-1228, 2018 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-30065823

RESUMO

The foodservice industry is a highly competitive branch where customer satisfaction and loyalty is dependent on the price and the quality of the food. To improve cost competitiveness, instead of fresh ingredients, more preprocessed items are used as components in dishes. This may impair the perceived product quality, and thus potentially decrease customer satisfaction. The effects of the component quality on a single dish were tested by serving fish soup in a consumer study (n = 205), and by serving the dish to an in-house panel (n = 17) using a modified check-all-that-apply method. The variable used for the quality of the fish and vegetable components was a previously unprocessed/fresh component being compared to a processed. This study showed that in a modular dish, each component had an effect on the perceived quality of the dish. When replacing a preprocessed component with a fresh one, the perceived pleasantness increased to a higher level. The fish as the main dish component had the largest effect on the quality. Fresh fish has the ability to enhance the taste of soup, even with frozen vegetables. The results from this study indicate that the effect of freshness can also be perceived in the cooked product.

6.
Food Res Int ; 109: 526-536, 2018 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-29803480

RESUMO

Edible mushrooms are a global food with a history of consumption spanning several millennia. However, studies utilizing modern sensory methods on mushrooms are still scarce. In this study, the sensory properties of Nordic edible mushrooms were analyzed by two methods. In the sensory profile, sous vide processed wild mushroom species Cantharellus cibarius, Craterellus tubaeformis, Boletus edulis, and Lactarius camphoratus were studied with cultivated Agaricus bisporus as a control species. The sensory profile consisted of 18 descriptors, and the 5 mushrooms differed from each other in all of them. Only B. edulis and A. bisporus were linked to typical mushroom-like odor. In projective mapping, consumers evaluated blanched wild C. cibarius, C. tubaeformis and Suillus variegatus as well as cultivated Lentinula edodes and both blanched and fresh A. bisporus based on odor and on flavor. The consumers intuitively grouped the samples into three groups: wild, fresh cultivated and processed cultivated mushrooms. Wild mushrooms had a high odor intensity and various odor descriptions but a low flavor intensity. Cultivated mushrooms had opposite descriptions. Both tests showed differences in the sensory descriptors between the cultivated and wild mushrooms with the former linked to typical 'mushroom', indicating the importance and need for descriptive profiles for different mushroom types.

7.
Food Chem ; 247: 23-28, 2018 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-29277224

RESUMO

Edible mushrooms are valued because of their umami taste and good nutritional values. Free amino acids, 5'-nucleotides and nucleosides were analyzed from four Nordic forest mushroom species (Lactarius camphoratus, Boletus edulis, Cantharellus cibarius, Craterellus tubaeformis) using high precision liquid chromatography analysis. To our knowledge, these taste components were studied for the first time from Craterellus tubaeformis and Lactarius camphoratus. The focus was on the umami amino acids and 5'-nucleotides. The free amino acid and 5'-nucleotide/nucleoside contents of studied species differed from each other. In all studied samples, umami amino acids were among five major free amino acids. The highest concentration of umami amino acids was on L. camphoratus whereas B. edulis had the highest content of sweet amino acids and C. cibarius had the highest content of bitter amino acids. The content of umami enhancing 5'-nucleotides were low in all studied species.


Assuntos
Agaricales/química , Aminoácidos/análise , Nucleosídeos/análise , Basidiomycota/química , Cromatografia Líquida , Finlândia , Análise de Alimentos , Florestas , Ácido Glutâmico/análise , Nucleotídeos/análise , Paladar
8.
Appetite ; 123: 101-107, 2018 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-29253668

RESUMO

Locally produced and sourced food products are gaining popularity among consumers. The effect of the expectations induced by the origin of the food was studied with 1491 consumers in two separate studies among different age groups. In order to test the consumer response to the product origin neutral, domestic, and local conditions were used. Consumers evaluated the product's pleasantness, their probability to choose it, the overall quality, and their willingness to pay. To gather information on whether the phenomenon was consistent, independent from the product category, three different types of products were tested (meat, bread, and vegetables). Our results show that a closer origin does not necessarily produce a positive response, but that there are several moderating factors such as gender, age, and product type. Female university students responded equally to domestic and local origins in the case of bread, but for meat products, only those of local origin induced a positive reaction. In this study population, the male respondents only reacted to a local origin in the case of bread, while domestic meat products provided similar results to local origins. Among young men consumers in the 7th-9th grades responded to the local origin of vegetables positively, while others among the youngest consumers, the origin did not induce a significant effect. The results indicate that even when the product is not appealing itself, locality can still increase the perceived quality.


Assuntos
Pão , Comportamento do Consumidor , Abastecimento de Alimentos , Produtos da Carne , Adolescente , Comportamento de Escolha , Feminino , Finlândia , Preferências Alimentares , Humanos , Masculino , Paladar , Verduras
9.
Foods ; 6(12)2017 Nov 27.
Artigo em Inglês | MEDLINE | ID: mdl-29186893

RESUMO

Reducing salt (NaCl) intake is an important public health target. The food industry and catering services are searching for means to reduce the salt content in their products. This review focuses on options for salt reduction in foods and the sensory evaluation of salt-reduced foods. Simple salt reduction, mineral salts and flavor enhancers/modifiers (e.g., umami compounds) are common options for salt reduction. In addition, the modification of food texture and odor-taste interactions may contribute to enhanced salty taste perception. Maintaining consumer acceptance of the products is a challenge, and recent examples of the consumer perception of salt-reduced foods are presented.

10.
Talanta ; 161: 245-252, 2016 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-27769403

RESUMO

A direct quantitative proton nuclear magnetic resonance spectroscopy method was developed for the measurement of saccharides, organic acids and amino acids in potato (Solanum tuberosum L.) tuber filaments, a complex gel-like food matrix. The method requires minimal sample preparation. It is thus a faster alternative compared to liquid sample matrices, as well as an extension to methods analyzing only selected metabolites in the sample. The samples in this study were either raw or steamed potato strips that were either measured as D2O extracts or directly without extraction or derivatization steps (in situ technique). A total of 22 compounds were identified in extracts and 18 in potato strips. Of these, 20 compounds were quantifiable in potato extracts and 13 compounds in potato strips. The effect of thermal processing was reflected in the profile of analyzed compounds. One example was fumaric acid, which was completely lost in steamed samples in both measurement techniques. Additionally, the content of γ-aminobutyric acid in steamed potato strips was lower. In potato extracts, the contents of additional 7 compounds were statistically different. The raw and steamed samples separated into two groups with multivariate models both in extracts and potato strips, and these groups were linked to changes in aforementioned compounds. These results demonstrated that the in situ quantitative 1H NMR technique is a useful tool to analyze potato metabolites. This technique could be further applied to any gel-like complex matrix, meaning that lengthy sample pretreatment could be skipped.


Assuntos
Culinária , Extratos Vegetais/química , Tubérculos/química , Solanum tuberosum/química , Ácidos Acíclicos/análise , Aminoácidos/análise , Frutose/análise , Glucose/análise , Espectroscopia de Prótons por Ressonância Magnética , Sacarose/análise
11.
J Food Sci ; 80(12): C2711-6, 2015 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-26524113

RESUMO

This study examined the concentrations of umami compounds in pork loins cooked at 3 different temperatures and 3 different lengths of cooking times. The pork loins were cooked with the sous vide technique. The free amino acids (FAAs), glutamic acid and aspartic acid; the 5'-nucleotides, inosine-5'-monophosphate (IMP) and adenosine-5'-monophosphate (AMP); and corresponding nucleoside inosine of the cooked meat and its released juice were determined by high-performance liquid chromatography. Under the experimental conditions used, the cooking temperature played a more important role than the cooking time in the concentration of the analyzed compounds. The amino acid concentrations in the meat did not remain constant under these experimental conditions. The most notable effect observed was that of the cooking temperature and the higher amino acid concentrations in the released juice of meat cooked at 80 °C compared with 60 and 70 °C. This is most likely due to the heat induced hydrolysis of proteins and peptides releasing water soluble FAAs from the meat into the cooking juice. In this experiment, the cooking time and temperature had no influence on the IMP concentrations observed. However, the AMP concentrations increased with the increasing temperature and time. This suggests that the choice of time and temperature in sous vide cooking affects the nucleotide concentration of pork meat. The Sous vide technique proved to be a good technique to preserve the cooking juice and the results presented here show that cooking juice is rich in umami compounds, which can be used to provide a savory or brothy taste.


Assuntos
Aminoácidos/análise , Culinária/métodos , Temperatura Alta , Nucleotídeos/análise , Carne Vermelha/análise , Paladar , Água/análise , Monofosfato de Adenosina/análise , Animais , Ácido Aspártico/análise , Ácido Glutâmico/análise , Humanos , Inosina Monofosfato/análise , Nucleosídeos/análise , Proteólise , Suínos , Temperatura Ambiente
12.
J Nutrigenet Nutrigenomics ; 7(3): 161-74, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-25720616

RESUMO

AIM: To assess the behavioral effects of receiving personal genetic information, using apoE genotypes as a tool for promoting lifestyle changes. apoE was chosen because it has a significant impact on lipid metabolism and cholesterol absorption, both factors in cardiovascular disease. METHODS: This study was a 1-year intervention study of healthy adults aged 20-67 years (n = 107). Their behavioral changes were measured by diet (e.g., fat quality, as well as consumption of vegetables, berries, fruits, and fatty and sugary foods), alcohol consumption, and exercise. Health and taste attitudes were assessed with the Health and Taste Attitude Scales (HTAS). The measurements were performed 4 times: at baseline (T0), as well as 10 weeks (T1), 6 months (T2), and 12 months after baseline (T3). These behavioral effects were assessed for three groups: a high-risk (Ɛ4+; n = 16), a low-risk (Ɛ4-; n = 35), and a control group (n = 56). RESULTS: Personal genetic information affected health behavior. Dietary fat quality improved more in the Ɛ4+ group than in the Ɛ4- and control groups after personal, genotype-based health advice. This change differed significantly between the Ɛ4+ and the control group (p < 0.05), but only for a short time. CONCLUSION: Personal genetic information, based on apoE, may affect dietary fat quality. More research is required to determine how to utilize genotype-based health information and how to efficiently achieve long-term changes in the prevention of lifestyle-related diseases.


Assuntos
Apolipoproteínas E/genética , Doenças Cardiovasculares/prevenção & controle , Aconselhamento/métodos , Comportamentos Relacionados com a Saúde , Atividade Motora , Medicina de Precisão/métodos , Adulto , Idoso , Doenças Cardiovasculares/genética , Feminino , Genótipo , Humanos , Masculino , Pessoa de Meia-Idade , Comportamento de Redução do Risco , Adulto Jovem
13.
J Agric Food Chem ; 56(21): 9875-83, 2008 Nov 12.
Artigo em Inglês | MEDLINE | ID: mdl-18841984

RESUMO

Autolysis of protein isolates from vascular bundle and inner tuber tissues of potato (Solanum tuberosum) enhanced the inhibition of the angiotensin converting enzyme I (ACE), a biochemical factor affecting blood pressure (hypertension). The physiological age of the tuber affected the strength of ACE inhibition, the rate of its increase during autolysis, and the tuber tissue where ACE inhibition was most pronounced. The highest inhibitory activities (50% reduction in ACE activity achieved following autolysis at a protein concentration of 0.36 mg mL (-1)) were measured in tubers after 5-6 months of storage prior to sprouting. The rate of ACE inhibition was positively correlated with protease activity in tuber tissues. Amendment of the autolysis reaction with protein substrates from which bioactive ACE-inhibitory peptides may be released, for example, a purified recombinant protein or a concentrate of total tuber proteins, also enhanced ACE inhibition. Many tuber proteins including aspartic protease inhibitors were degraded during autolysis. The data provide indications of differences in the enzymatic activities confined to different parts of the potato tuber at different physiological stages. Results suggest that native enzymes and substrate proteins of potato tubers can be utilized in search of dietary tools to manage elevated blood pressure.


Assuntos
Inibidores da Enzima Conversora de Angiotensina/metabolismo , Regulação para Baixo , Peptidil Dipeptidase A/metabolismo , Proteínas de Plantas/metabolismo , Tubérculos/fisiologia , Solanum tuberosum/fisiologia , Sequência de Aminoácidos , Inibidores da Enzima Conversora de Angiotensina/química , Dados de Sequência Molecular , Proteínas de Plantas/química , Tubérculos/química , Alinhamento de Sequência , Solanum tuberosum/química
14.
Chem Phys Lipids ; 154(2): 105-14, 2008 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-18534191

RESUMO

NMR data on lipid hydroperoxides is scarce. In this study, hydroperoxides were produced from methyl 9-cis,11-trans-octadecadienoate and from methyl 10-trans,12-cis-octadecadienoate by autoxidation in the presence of 20% of alpha-tocopherol. Ten different hydroperoxides were isolated from the autoxidation mixtures of the two conjugated linoleic acid (CLA) methyl esters by SPE and HPLC. The assignment of the 1H and 13C NMR spectra of these hydroperoxides was accomplished by 2D NMR experiments and by spectral simulations. Substitution of a hydroperoxyl group at the allylic position in CLA methyl esters induced a 53.93 ppm downfield shift on the hydroperoxyl-bearing carbon resonance. The effects on the olefinic alpha, beta, gamma, and delta carbon resonances were -3.45, +4.96, -1.22, and +4.42 ppm, respectively. Furthermore, the solvent effects of deuterochloroform, deuteroacetone, and deuterobenzene on the 13C resonances of the hydroperoxides suggest that deuterochloroform is the appropriate solvent for 13C NMR studies on mixtures of lipid hydroperoxides.


Assuntos
Ácidos Linoleicos Conjugados/química , Peróxidos Lipídicos/química , Estabilidade de Medicamentos , Ácidos Linoleicos Conjugados/isolamento & purificação , Peróxidos Lipídicos/isolamento & purificação , Ressonância Magnética Nuclear Biomolecular
15.
Lipids ; 43(7): 599-610, 2008 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-18546029

RESUMO

Autoxidation of conjugated linoleic acid (CLA) methyl ester follows at least partly Farmer's hydroperoxide theory. A mechanism for this hydroperoxide pathway has been proposed based on autoxidation of 9-cis,11-trans-CLA methyl ester. This investigation aims at confirming and further clarifying the mechanism by analyzing the hydroperoxides produced from 10-trans,12-cis-CLA methyl ester and by theoretical calculations. Five methyl hydroxyoctadecadienoates were isolated by HPLC and characterized by UV, GC-MS, and 1D- and 2D-NMR techniques. In addition, an HPLC method for the separation of the intact hydroperoxides was developed. The autoxidation of 10-trans,12-cis-CLA methyl ester in the presence of high amount of alpha-tocopherol (20%) was diastereoselective in favor of one geometric isomer, namely Me 9-OOH-10t,12c, and produced new positional isomers 10- and 14-hydroperoxides (Me 10-OOH-11t,13t; Me 14-OOH-10t,12c; and Me 14-OOH-10t,12t). Importantly, one of these new isomers, which was characterized as an intact hydroperoxide, had an unusual cis,trans geometry where the cis double bond is adjacent to the hydroperoxyl-bearing methine carbon. Further insight to the mechanism was provided by calculating the relative energies for different conformations of the precursor lipid, the allylic carbon-hydrogen bond dissociation enthalpies, and the spin distributions on the intermediate pentadienyl radicals. As a result, a better understanding of the isomeric distribution of the product hydroperoxides was achieved and a modified mechanism that accounts for these calculations is presented.


Assuntos
Peróxido de Hidrogênio/química , Ácidos Linoleicos/química , Teoria Quântica , alfa-Tocoferol/química , Cromatografia Líquida de Alta Pressão , Cromatografia Gasosa-Espectrometria de Massas , Espectroscopia de Ressonância Magnética , Estrutura Molecular , Oxirredução
16.
Eur J Nutr ; 45(8): 439-44, 2006 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-17039285

RESUMO

BACKGROUND: Sesamin, a major lignan from sesame seeds has been associated with cholesterol reduction in previous reports, but recent studies suggested differences in the response to sesamin intake depending on the model studied as well as the nature of the sesamin preparation used. AIM: The effect of pure sesamin epimer on serum lipids was studied in hypercholesterolemic LDL receptor-knockout mice under cholesterol fed condition. DESIGN: Animals were randomly assigned to 4 groups, fed an atherogenic diet containing stanol ester, sesamin, combination of stanol ester and sesamin or a control diet with no additions. RESULTS: The control group showed an almost 3-fold increase in serum cholesterol levels due to the atherogenic diet but no effect was seen for triglyceride levels. Stanol ester alone or together with sesamin significantly attenuated the elevation of the cholesterol levels. CONCLUSION: Sesamin alone did not affect the elevation of the diet-induced cholesterol level and it did not enhance the effect of stanol ester.


Assuntos
Anticolesterolemiantes/farmacologia , Colesterol/sangue , Dieta Aterogênica , Dioxóis/farmacologia , Lignanas/farmacologia , Triglicerídeos/sangue , Animais , Anticolesterolemiantes/administração & dosagem , LDL-Colesterol/sangue , Dioxóis/administração & dosagem , Feminino , Lignanas/administração & dosagem , Camundongos , Camundongos Endogâmicos , Distribuição Aleatória , Receptores de LDL/deficiência , Organismos Livres de Patógenos Específicos , Ganho de Peso/efeitos dos fármacos
17.
Lipids ; 37(6): 533-40, 2002 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-12120950

RESUMO

The initial steps in the autoxidation of CLA methyl ester are poorly understood. The aim of this study was to determine the stereochemistry of the hydroperoxides formed during autoxidation of CLA methyl ester in the presence of a good hydrogen atom donor. For this purpose, 9-cis,11-trans CLA methyl ester was autoxidized in the presence of alpha-tocopherol under atmospheric oxygen at 40 degrees C in the dark. The CLA methyl ester hydroperoxides were isolated, reduced to the corresponding hydroxy derivatives, and separated by HPLC. The stereochemistry of seven hydroxy-CLA methyl esters was investigated. The position of the hydroxy group was determined by GC-MS. The geometry as well as the position of the double bonds in the alkyl chain was determined by NMR. In addition, the 13C NMR spectra of six hydroxy-CLA methyl esters were assigned using COSY, gradient heteronuclear multiple bond correlation, gradient heteronuclear single quantum correlation, and total correlation spectroscopy experiments. The autoxidation of 9-cis,11-trans CLA methyl ester in the presence of a good hydrogen atom donor is stereoselective in favor of one geometric isomer, namely the 13-(R,S)-hydroperoxy-9-cis,11-trans-octadecadienoic acid methyl ester. Three types of conjugated diene hydroperoxides are formed as primary hydroperoxides: trans,trans hydroperoxides (12-OOH-8t,10t and 9-OOH-10t,12t), a cis,trans hydroperoxide with the trans double bond adjacent to the hydroperoxide-bearing carbon atom (13-OOH-9c,11t), and a new type of cis,trans lipid hydroperoxide with the cis double bond adjacent to the hydroperoxide-bearing carbon atom (8-OOH-9c,11t). In addition, three nonkinetic hydroperoxides (13-OOH-9t,11t, 8-OOH-9t,11t, and 9-OOH-10t,12c) are formed. This study supports the theory that CLA methyl ester autoxidizes at least partly through an autocatalytic free radical reaction. The complexity of the hydroperoxide mixture is due to formation of two different pentadienyl radicals. Moreover, the stereoselectivity in favor of one geometric isomer can be explained by the selectivity of the two previous steps: the preferential formation of a W-conformer of the pentadienyl radical over the Z-conformer, and regioselectivity of the oxygen addition to the pentadienyl radical.


Assuntos
Peróxido de Hidrogênio/química , Ácido Linoleico/química , alfa-Tocoferol/química , Cromatografia Líquida de Alta Pressão , Ésteres , Espectroscopia de Ressonância Magnética , Oxirredução , Estereoisomerismo
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