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1.
J Agric Food Chem ; 68(9): 2773-2782, 2020 Mar 04.
Artigo em Inglês | MEDLINE | ID: mdl-32013417

RESUMO

The influence of covalent protein modifications resulting from the Maillard reaction (glycation) of casein and lactose on the noncovalent association behavior of the protein was studied. Nonenzymatic cross-linking with methylglyoxal (MGO) and glutaraldehyde (GTA) as well as enzymatic cross-linking with microbial transglutaminase (mTG) was investigated in comparison. Molar mass, particle size, and conformational characteristics of nonmicellar casein associates as well as the extent of intraparticle protein cross-linking were examined utilizing size-exclusion chromatography (SEC) combined with UV detection and static and dynamic light scattering. Cross-linking resulted in the stabilization of a certain fraction of casein associates, with particle sizes of approximately 30 nm in radius of gyration (Rg), and promoted an incorporation of further casein molecules into those particles, yielding molar masses (Mw) of 1.0-1.2 × 106 g/mol. When caseins were additionally conjugated with lactose during the early Maillard reaction, a further growth of the associates up to approximately 50 nm in Rg with a Mw of 2.1 × 106 g/mol was observed. Furthermore, glycation reactions induced a transition from slightly elongated, random-coil structures toward more anisotropic conformations. Associates consisting of caseins cross-linked with GTA appeared to preserve the original particle conformation.


Assuntos
Caseínas/química , Cromatografia em Gel , Reagentes para Ligações Cruzadas/química , Difusão Dinâmica da Luz , Glutaral/química , Lactose/química , Reação de Maillard , Tamanho da Partícula , Aldeído Pirúvico/química
2.
J Agric Food Chem ; 68(6): 1714-1724, 2020 Feb 12.
Artigo em Inglês | MEDLINE | ID: mdl-31957424

RESUMO

(-)-Epigallocatechin gallate (EGCG) had a significant effect on Maillard reaction intermediate formation in the xylose/alanine model system. A trapping effect of EGCG on the reactive deoxyosones was observed to change the reaction pathways. The rate constant of Amadori rearrangement product (ARP) conversion to deoxyosones was decreased with EGCG addition, indicating an inhibition of ARP degradation. Dehydration improved the ARP formation during the thermal reaction and synergistically improved the yield of ARP with the EGCG trapping effect on the deoxyosones. Additionally, EGCG decreased the activation energy for the conversion of xylose/alanine to ARP (from 77.8 to 62.8 kJ/mol) and in turn accelerated the ARP formation. The effect of EGCG was further facilitated at the optimal conditions of 90 °C, at pH 7.5, and a molar ratio of xylose to alanine of 2:1, which improved the yield of ARP (N-(1-deoxy-d-xylulos-1-yl)alanine) from 2 to 95%.


Assuntos
Alanina/análogos & derivados , Catequina/análogos & derivados , Catequina/química , Produtos Finais de Glicação Avançada/química , Temperatura Alta , Concentração de Íons de Hidrogênio , Reação de Maillard , Xilose/química , Xilulose/química
3.
J Sci Food Agric ; 100(4): 1524-1531, 2020 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-31769029

RESUMO

BACKGROUND: In recent years, cold-pressed oils have become more and more popular with consumers. However, their oxidative stability is low. Improving the oxidative stability of cold-pressed oils will increase their shelf life. Maillard reaction products (MRPs) have been shown to promote the oxidative stability of lipids. In this study, products from the Maillard reaction of reducing sugars and sesame enzymatically hydrolyzed protein (SEHP) were added to cold-pressed sesame oils to improve their oxidative stability. RESULTS: Three types of MRPs from reducing sugars (xylose, fructose, and glucose) and SEHP were prepared. Xylose-SEHP MRPs prepared under optimum conditions had the highest antioxidant activities among the three. The optimum conditions for xylose-SEHP were as follows: reaction temperature, 130 °C; reaction time, 180 min; pH, 6.5; and sugar/protein ratio, 10:1. The addition of xylose-SEHP MRPs at a level of 20 g kg-1 could significantly improve the oxidative stability of cold-pressed sesame oil. Besides, the addition of MRPs reduced the loss of tocopherol. The interaction of MRPs with endogenous antioxidants in the sesame oil (sesamol and tocopherol) was proved by comparison with lard. There was a synergistic increase in antioxidant activity for the combination of MRPs and sesamol and the combination of MRPs and tocopherol. CONCLUSIONS: The results provide evidence that adding certain MRPs can improve the oxidative stability of cold-pressed sesame oil. © 2019 Society of Chemical Industry.


Assuntos
Manipulação de Alimentos/métodos , Frutose/química , Glucose/química , Produtos Finais de Glicação Avançada/química , Proteínas de Plantas/química , Óleo de Gergelim/química , Sesamum/química , Xilose/química , Aditivos Alimentares/química , Reação de Maillard , Oxirredução
4.
J Sci Food Agric ; 100(3): 1030-1037, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31646633

RESUMO

BACKGROUND: The objective of this work was to develop gummy jellies containing honey and propolis, keeping the natural antioxidant principles of the beehive ingredients and satisfying consumer requirements. RESULTS: A gummy jelly containing honey and propolis (HPGJ) was developed. A sensory study with consumers (n = 74) performed an intensity level evaluation test analyzing color, hardness, adhesiveness, gumminess, sweet taste and honey taste. A penalty analysis indicated that HPGJ was too hard. However, in the global acceptance study, more than 90% of consumers gave liking categories. Regarding the potential functional properties, the antioxidant capacity (AC) of HPGJ was 8.17 ± 0.55 mmol Trolox equivalent kg-1 , and up to 40% AC was retained after in vitro digestion. Additionally, AC of HPGJ was up to ten times higher than that of similar commercial products. A storage study at 25 °C showed that color and AC increased significantly over 90 days owing to the development of Maillard reaction. Storage under darkness allowed keeping low values of global color change for up to 45 days. Another positive facet was that the addition of propolis delayed fungal growth during storage. CONCLUSION: An organoleptically palatable gummy jelly was obtained. Among the positive features, it showed higher AC than similar commercial candies. Additionally, HPGJ offered a high bioaccesible AC input detected upon in vitro digestion. Overall, HPGJ could be considered an interesting, appetizing and healthier alternative to regular gummy jellies available in the market. Adequate packaging should be considered in order to extend HPGJ shelf life, reducing browning reactions. © 2019 Society of Chemical Industry.


Assuntos
Doces/análise , Mel/análise , Própole/análise , Antioxidantes/análise , Manipulação de Alimentos , Armazenamento de Alimentos , Géis/análise , Humanos , Reação de Maillard , Paladar
5.
J Agric Food Chem ; 68(1): 332-339, 2020 Jan 08.
Artigo em Inglês | MEDLINE | ID: mdl-31814399

RESUMO

Thermal treatment of food leads to the formation of melanoidins by reactions of carbohydrates with free amino acids or proteins in the late stage of Maillard reaction. The aim of this study was the identification of reaction mechanisms responsible for the formation of melanoidins involving active methylenes with the heterocyclic structure and the structural characterization of the resulting products. For this purpose, norfuraneol was incubated with the aldehydes pyrrole-2-aldehyde or furfural at 125 °C. With the help of high-resolution mass spectrometry, the structural composition of oligomers of up to fifteen C5-units could be described for the first time. Aldol and Michael reactions could be identified as crucial steps for the formation of new C-C-bonds. With increasing heating time, the elimination of water from the products was facilitated, and oxidation reactions of integrated reductone structures lead to the expansion of conjugated double-bond systems responsible for the color formation of the samples.


Assuntos
Aldeídos/química , Furanos/química , Compostos Heterocíclicos/química , Polímeros/química , Furaldeído/química , Reação de Maillard , Estrutura Molecular , Oxirredução
6.
Food Chem ; 302: 125326, 2020 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-31416003

RESUMO

Ruminant meat is considered an excellent source of proteins, dietary fatty acids and essential minerals. Grilling is a popular cooking method; however, the high temperatures employ could modify the grilled meat quality and safety. In this study, the effects of novel beer-based marinades infused with herbs and spices on the quality, safety, and sensory perception of grilled beef and moose meat is examined. Unmarinated meat showed high content of volatile lipid oxidation and Maillard reaction products compared to the marinated samples, which contained higher number and abundance of terpenes and sulfur based compounds. Strong relationships between Maillard products and heterocyclic amines formation, as well as between volatile terpenes and the lipophilic antioxidant activity, were observed in the grilled meats. The findings suggest the unfiltered beer-based marinades were effective in reducing lipid oxidation and Maillard reaction compounds formation, while improving the nutritional quality, safety and sensory preference of grilled ruminant meats.


Assuntos
Cerveja , Culinária/métodos , Carne , Ruminantes , Adolescente , Adulto , Aminas/análise , Aminas/química , Animais , Bovinos , Qualidade dos Alimentos , Cromatografia Gasosa-Espectrometria de Massas , Compostos Heterocíclicos/análise , Temperatura Alta , Humanos , Reação de Maillard , Carne/análise , Pessoa de Meia-Idade , Valor Nutritivo , Carne Vermelha , Especiarias , Paladar , Compostos Orgânicos Voláteis/análise
7.
Food Chem ; 309: 125501, 2020 Mar 30.
Artigo em Inglês | MEDLINE | ID: mdl-31677451

RESUMO

In this study, we selected two most commonly-available commercial pectin, i.e. citrus pectin and apple pectin as the grafting polysaccharides to prepare soy protein isolate-pectin conjugates. Despite the similar degrees of methoxylation and acetylation for two pectin samples, apple pectin showed much more complex structures compared to citrus pectin, with a 2.20-fold higher molecular weight and large numbers of side chains. The conjugates were prepared under controlled dry-heating conditions and achieved the degree of graft of 25.00% and 21.85% for citrus and apple pectin, respectively. Formation of the conjugates was further confirmed by SDS-PAGE gel electrophoresis and IR spectra. Attributed to the strong steric-hindrance effect of pectin, the fluorescence intensity and surface hydrophobicity of the soy protein isolate were significantly decreased after Maillard reaction. However, both solubility and emulsifying properties of the conjugates were significantly improved. Results indicated that both pectin samples played favorable roles in protein modification.


Assuntos
Citrus/química , Malus/química , Pectinas/química , Proteínas de Soja/química , Emulsões , Calefação , Interações Hidrofóbicas e Hidrofílicas , Reação de Maillard , Solubilidade
8.
Food Chem ; 303: 125310, 2020 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-31473456

RESUMO

Tyrosinase is a metalloenzyme involved in o-hydroxylation of monophenols and oxidation of o-diphenols to o-quinones, with formation of brown or black pigments (melanines). Tyrosinase inhibitors are of great interest in medicine and cosmetics (skin whitening compounds), but also in food and beverage industry (antibrowning agents). Here we report on the activity as mushroom tyrosinase inhibitors of a series of hydroxyphenyl thiosemicarbazones (1-5): one of them revealed an inhibitory activity stronger than kojic acid, used as reference. Enzymatic inhibition activity was confirmed by colorimetric measurements on small wheels of Fuji apples treated with the hydroxyphenyl thiosemicarbazones. The mechanism of action of compounds 1-5 was investigated by molecular modelling and by studying in solution their speciation with Cu(II) ions, the ions in the active site of the enzyme. Finally, compounds 1-5 were tested on human fibroblasts: they are not cytotoxic and they do not activate cells in a pro-inflammatory way.


Assuntos
Agaricales/enzimologia , Inibidores Enzimáticos/química , Inibidores Enzimáticos/farmacologia , Reação de Maillard/efeitos dos fármacos , Monofenol Mono-Oxigenase/antagonistas & inibidores , Tiossemicarbazonas/química , Tiossemicarbazonas/farmacologia , Domínio Catalítico , Humanos , Cinética , Monofenol Mono-Oxigenase/química , Monofenol Mono-Oxigenase/metabolismo , Oxirredução/efeitos dos fármacos
9.
Food Chem ; 306: 125560, 2020 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-31590002

RESUMO

To control the oxidation in chicken fat by immobilized lipoxygenase (LOX), Maillard reaction products (MRPs) with chicken flavor were prepared and analyzed for flavor mechanism. >50% activity of immobilized LOX was retained after repeated use for five times or five weeks. The oxidized chicken fats were prepared by thermal, free LOX, and immobilized LOX treatments. After addition of chicken fats, Maillard reaction produced more aliphatic aldehydes and alcohols (126.0-839.5 ng/g and 493.5-2332.4 ng/g, respectively) which resulted in noticeable enhanced reaction, but the content of sulfur compounds such as thiols and thiophenes decreased significantly (870.8-1233.9 ng/g and 1125.0-2880.3 ng/g, respectively), and the structure of sulfur compounds could easily form alkyl side chains. However, there was no significant difference in sensory and flavors between oxidized chicken after treatments, which may be related to oxidized degree. The mechanism was proposed or aromatic effects of oxidized chicken fat on flaxseed derived MRPs.


Assuntos
Galinhas , Gorduras/metabolismo , Aromatizantes/química , Linho/química , Lipoxigenase/metabolismo , Animais , Enzimas Imobilizadas/metabolismo , Gorduras/química , Produtos Finais de Glicação Avançada/análise , Reação de Maillard , Oxirredução , Soja/enzimologia , Paladar
10.
Food Chem ; 305: 125504, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-31606691

RESUMO

Glucosamine (GlcN) and GlcN-myoglobin reaction systems were incubated at 4 °C to verify that GlcN can go through non-enzymatic browning at this low temperature, and to test the hypothesis that certain reductones from GlcN non-enzymatic browning can promote the formation of deoxy- and oxymyoglobin from metmyoglobin reduction. Remarkably, alpha-dicarbonyls and self-condensation products, fructosazine and deoxyfructosazine, were produced at this relatively low temperature. The presence of myoglobin shifted GlcN non-enzymatic browning toward the formation of glucosone and fructosazine. When glucosone (250-2000 mg/L) was incubated with myoglobin it contributed to the formation of deoxymyoglobin, indicating its capacity to reduce metmyoglobin. This study opens the possibility of using GlcN in meat products to increase oxy- and deoxymyoglobin and enhance the color of meat.


Assuntos
Temperatura Baixa , Glucosamina/química , Cetoses/química , Reação de Maillard , Metamioglobina/química , Mioglobina/química , Animais , Cor , Oxirredução
11.
Food Chem ; 306: 125613, 2020 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-31610331

RESUMO

Reduction of bitter taste in protein hydrolysates is a challenging task. The aim of this study was to apply a simple two-step approach to prepare low bitter hydrolysates and investigate the influence of peptide modifications on taste characteristics. Protein hydrolysates were prepared from porcine muscle and plasma through simultaneous hydrolysis using endo- and exo-peptidases combined with peptide glycation by glucosamine (GlcN). Spectroscopic analysis and quantification of major alpha-dicarbonyl compounds (α-DCs) indicated the relatively low extent of Maillard reaction in GlcN-glycated protein hydrolysates. Thermal degradation of high MW peptides (>10 kDa) might play a major role in Maillard reaction, reflected by the formation of more Maillard reacted peptides (1-5 kDa), especially in plasma samples. Sensory evaluation indicated that glycation by GlcN can alter taste profiles of protein hydrolysates, which may be attributed to the formation of Maillard reacted peptides and peptide modifications revealed by LC-MS/MS analysis.


Assuntos
Exopeptidases/química , Músculo Esquelético/química , Paladar , Animais , Aspergillus oryzae/enzimologia , Exopeptidases/metabolismo , Glucosamina/química , Glucosamina/metabolismo , Glicosilação , Hidrólise , Reação de Maillard , Músculo Esquelético/metabolismo , Peptídeos/química , Peptídeos/metabolismo , Hidrolisados de Proteína/química , Suínos
12.
Food Chem ; 305: 125482, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-31518838

RESUMO

To understand the effect of lipid degradation on Maillard formation of meaty flavors, initial reaction intermediates in model systems of glucose-glutathione with hexanal, (E)-2-heptenal, or (E,E)-2,4-decadienal were identified by HPLC-MS and by NMR. Besides Amadori compounds, hemiacetals and thiazolidines via addition of sulfhydryl to carbonyl or to the conjugated olefinic bond were found. Concentrations of all intermediates increased with reaction time while degradation of the intermediates with a glutathione moiety helped formation of thiazolidines with cysteinylglycine. The unsaturated aldehydes (E)-2-heptenal and (E,E)-2,4-decadienal exhibited high reactivity against glucose for glutathione, yielding higher levels of intermediate compounds than from glucose. Heating prepared intermediates reversibly released the original aldehydes, which caused various compounds formed by retro-aldol, oxidation, etc. to react with H2S and NH3. Among them, formation pathways including 3-nonen-2-one, 2-hexanoylfuran, and six dialkylthiophenes (e.g., 2-ethyl-5-(1-methylbutyl)thiophene) were proposed for the first time.


Assuntos
Aldeídos/química , Glucose/química , Glutationa/química , Cromatografia Líquida de Alta Pressão , Espectroscopia de Ressonância Magnética , Reação de Maillard , Oxirredução , Espectrometria de Massas em Tandem
13.
Food Chem ; 305: 125459, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-31520919

RESUMO

In this study the elemental compositions of melanoidin formed at 160 °C from d-glucose (Glc) and l-alanine (Ala) as well as from fructosylalanine - the corresponding Amadori rearrangement product - were compared. Specific chemical bonds were probed by FTIR spectroscopy. This approach tackles the different chemical pathways for melanoidin formation via the Amadori rearrangement in contrast to the reaction from Glc/Ala. Melanoidins formed from fructosylalanine contain about twice as much nitrogen and therefore amino acid as compared to melanoidin from Glc/Ala and exhibit higher absorption in the UV/Vis. Consequently, melanoidins formed from Glc/Ala contain more sugar degradation products with lower absorption due to a smaller size of the conjugated double bond network.


Assuntos
Alanina/análogos & derivados , Alanina/química , Frutose/análogos & derivados , Frutose/química , Glucose/química , Polímeros/química , Frutose/síntese química , Espectroscopia de Ressonância Magnética , Reação de Maillard , Polímeros/metabolismo , Espectroscopia de Infravermelho com Transformada de Fourier , Análise Espectral Raman
14.
J Dairy Res ; 86(4): 477-482, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31823833

RESUMO

The work described in this Research Communication concerns the production of Dulce de leche (DL), that is a traditional product from South America obtained by concentration. Maillard reaction (MR) products are mainly responsible for the formation of color and flavor in this product. Lactose-hydrolyzed products have been developed to supply consumer demand, but this hydrolysis may affect the flavor, color, taste, texture and even some nutritional aspects of the product. We studied the influence of different levels of lactose-hydrolysis, sucrose addition and initial pH on the development of MR, appraised by the determination of 5-hydroxymethylfurfural (HMF). A process simulator with multi-monitoring system was used to produce 15 DL. Box-Behnken 33 experimental design was applied for the three factors: pH, lactose-hydrolysis level and sucrose concentration. Lipids, protein, ashes, carbohydrates, water activity, dissolved solids, colorimetric analysis and HMF (free and total) are among the physicochemical attributes and MR indicators analyzed in this work. The products showed significant differences in composition but all the values were in agreement with the literature. Moreover, higher levels of lactose hydrolysis and higher pH presented a direct relation with the development of MR, observed by an increase in coloration (lower luminosity) and more formation of HMF, both free and total. The present study expands the knowledge about DL spread made of lactose-hydrolyzed milk, allowing the food industries to produce a lactose free DL with nutritional and sensory characteristics closer to the traditional product.


Assuntos
Furaldeído/análogos & derivados , Lactose/química , Leite/química , Animais , Fenômenos Químicos , Cor , Manipulação de Alimentos/métodos , Furaldeído/química , Concentração de Íons de Hidrogênio , Hidrólise , Reação de Maillard , América do Sul , Sacarose/análise , Sacarose/química , Paladar
15.
J Agric Food Chem ; 67(50): 13986-13997, 2019 Dec 18.
Artigo em Inglês | MEDLINE | ID: mdl-31710220

RESUMO

Increasing the thiamine concentration in a respective process flavor yields a product with a significant higher kokumi activity. S-plot analysis of the mass spectrometric data revealed beside thiamine itself, 4-methyl-5-thiazoleethanol, (S)-((4-amino-2-methylpyrimidin-5-yl)methyl)-l-cysteine, N-((4-amino-2-methylpyrimidin-5-yl)methyl)formamide, 3-(((4-amino-2-methylpyrimidin-5-yl)methyl)thio)-5-hydroxypentan-2-one, and 2-methyl-5-(((2-methylfuran-3-yl)thio)methyl)pyrimidin-4-amine as marker molecules for a process flavor with higher thiamine concentration. Sensory-based targeted isolation revealed that (S)-((4-amino-2-methylpyrimidin-5-yl)methyl)-l-cysteine, 3-(((4-amino-2-methylpyrimidin-5-yl)methyl)thio)-5-hydroxypentan-2-one, and 2-methyl-5-(((2-methylfuran-3-yl)thio)methyl)pyrimidin-4-amine showed an influence on the kokumi taste activity with taste threshold concentrations between 35 and 120 µmol/L. An adapted mass spectrometric-based carbon module labeling experiment as well as quantitative studies clearly demonstrated thiamine as the only precursor and an intermolecular formation pathway for the compounds (S)-(((4-amino-2-methylpyrimidin-5-yl)methyl)thio)-5-hydroxypentan-2-one and 2-methyl-5-(((2-methylfuran-3-yl)thio)methyl)pyrimidin-4-amine. On the basis of the knowledge that several thiamine derivatives showed taste-modulating activity, selected thiamine-based binary model reactions and synthesis were carried out. This resulted in the isolation of further thiamine-derived taste modulators like (S)-((4-amino-2-methylpyrimidin-5-yl)methyl)-l-cysteinylglycine, (S)-3-((((4-amino-2-methylpyrimidin-5-yl)methyl)thio)methyl)piperazine-2,5-dione, 3-(((4-amino-2-methylpyrimidin-5-yl)methyl)thio)pentan-2-one, 5-(((furan-2-ylmethyl)thio)methyl)-2-methylpyrimidin-4-amine, and (4-amino-2-methylpyrimidin-5-yl)methanethiol, 2-methyl-5-((methylthio)methyl)pyrimidin-4-amine with taste thresholds ranging from 35 to 880 µmol/L.


Assuntos
Aromatizantes/química , Pirimidinas/química , Tiamina/química , Adulto , Feminino , Humanos , Reação de Maillard , Masculino , Espectrometria de Massas , Estrutura Molecular , Paladar , Adulto Jovem
16.
J Agric Food Chem ; 67(46): 12863-12874, 2019 Nov 20.
Artigo em Inglês | MEDLINE | ID: mdl-31670949

RESUMO

A comprehensive quantitative characterization of Maillard reaction products was carried out for conventional (CON) and lactose-hydrolyzed (LH) ultrahigh temperature (UHT) milk during storage at 20, 30, and 40 °C for 1 year. The accumulation of 3-deoxyglucosone (3-DG) and 3-deoxygalactosone (3-DGal) in LH-UHT milk ranged from 20-fold (at 20 °C) to 44-fold (at 40 °C) higher than that in CON-UHT milk. High temperature storage (40 °C) significantly accelerated the accumulation of 3-DG, 3-DGal, and 5-hydroxymethyl furfural but not the majority of the analyzed advanced glycation endproducts (AGEs). The concentrations of major AGEs including N-ε-carboxymethyllysine (CML), N-ε-carboxyethyllysine (CEL), methylglyoxal-hydroimidazolone isomers (MG-H1/H3), glyoxal-hydroimidazolone isomers (G-H1/H3), and G-H2 detected in CON milk during storage were in the range 12-700, 1-14, 8-45, 4-13, and 1-30 µM, respectively, while they were 30-570, 2-88, 17-150, 9-20, and 5-34 µM, respectively, in LH milk. Pyrraline, S-(carboxymethyl)cysteine (CMC), and glyoxal-lysine dimer were detected in lower levels, while MG-H2, methylglyoxal-lysine dimer, argpyrimidine, glyoxal-lysine-amide, glycolic acid-lysine-amide, and pentosidine were not detected in any of the milk samples. This work demonstrates for the first time that five of the analyzed AGEs (CML, CEL, MG-H1/H3, G-H1/H3, and G-H2) could be selected as markers for evaluation of the extent of the Maillard reaction in UHT milk. These results contribute to a better understanding of how Maillard reactions progress during storage of UHT milk and can be used to develop strategies to inhibit Maillard reactions in LH milk.


Assuntos
Produtos Finais de Glicação Avançada/análise , Lactose/química , Leite/química , Animais , Bovinos , Desoxiglucose/análogos & derivados , Desoxiglucose/análise , Armazenamento de Alimentos , Galactose/análogos & derivados , Galactose/análise , Isomerismo , Lisina/análogos & derivados , Lisina/análise , Reação de Maillard , Aldeído Pirúvico/análise , Temperatura Ambiente
17.
J Agric Food Chem ; 67(46): 12885-12894, 2019 Nov 20.
Artigo em Inglês | MEDLINE | ID: mdl-31675227

RESUMO

α-Dicarbonyl compounds (α-DCs) are a major class of intermediates generated during Maillard reactions. They can serve as chemical markers of thermal processing and storage of sugar-rich foods. To distinguish between naturally matured acacia honey (NMAH) and artificially heated acacia honey (AHAH), we purified 12 major α-DCs quinoxaline derivatives to investigate the effects of temperature during heat treatment and storage on their accumulation in acacia honey. Nine of the 12 α-dicarbonyl compounds were found in acacia honey samples, and their contents varied depending on processing and storage conditions. Among them, the contents of 3-deoxyglucosulose (3-DG), 1,4-dideoxyglucosone (1,4-DDG), and 1-deoxyglucosone (1-DG) increased commensurately with heat. 3-DG content ranged from 103.7 to 146.6 mg/kg in NMAH and 572.4-1371.2 mg/kg in AHAH. Given the abundance and stability of 3-DG following heat treatment and storage, this compound can potentially serve as a reliable marker for distinguishing between NMAH and AHAH.


Assuntos
Acacia/química , Mel/análise , Manipulação de Alimentos , Temperatura Alta , Reação de Maillard , Controle de Qualidade
18.
J Food Sci ; 84(12): 3584-3593, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31721210

RESUMO

Maillard reaction intermediate (MGX) generated from glutathione and xylose in aqueous medium was prepared via the Maillard reaction performed under a two-stage temperature increase process. The purified MGX was identified by Fourier-transform infrared spectroscopy, mass spectrometry, and nuclear magnetic resonance as N-(1-deoxy-d-xylulos-1-yl)-glutathione (Amadori compound, C15 H25 O10 N3 S) with five main isomers. The method of Maillard reaction performed under a two-stage temperature increase process was further verified by high-performance liquid chromatography. The optimal reaction time and temperature for the preparation of MGX was determined as 60 min at 90 °C. The yield of MGX was increased from 8.60% to 55.52% through thermal reaction coupled with vacuum dehydration. In addition, rapid and more Maillard-type volatile compounds were formed in MGX during thermal treatment than that in Maillard reaction products or glutathione-xylose mixture. Beside, MGX possessed more pleasing meat-like volatile profile compared with the Amadori compound of glutamic acid-xylose (AAX), cysteine-xylose (ACX), and glycine-xylose (AGX). Therefore, it suggested that the MGX had the potential to achieve a better flavor formation during thermal treatment. PRACTICAL APPLICATION: Maillard reaction intermediates, such as Amadori or Heyns rearrangement products (ARP or HRP), are important flavor precursors, which possess stable physicochemical properties, but tend to degrade into flavor compounds at high temperatures. Maillard reaction intermediate from glutathione and xylose acts as primary flavor enhancers to complete Maillard reaction to produce flavors in the subsequent thermal processing, which can significantly improve and stabilize the flavor quality of the meaty food, and deserves a very broad application prospects. The new developed method will be a significant theoretical basis on research preparation and properties of Maillard reaction intermediates in complex food systems.


Assuntos
Glutationa/química , Xilose/química , Cisteína/química , Aromatizantes/química , Ácido Glutâmico/química , Produtos Finais de Glicação Avançada/química , Glicina/química , Temperatura Alta , Reação de Maillard , Vácuo
19.
Metabolism ; 101: 153977, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31655089

RESUMO

BACKGROUND: Increasing adaptive thermogenesis in adipose tissue may be a potential therapeutic target for overcoming obesity and obesity-related disorders. Preadipocyte factor 1 (Pref-1), a preadipocyte secreted protein, plays an inhibitory role in adipogenic differentiation. However, the role of Pref-1 in adipose tissue browning remains unknown. We investigated whether Pref-1 regulates thermogenic program and beige fat biogenesis. METHODS: Pref-1 expression levels were examined in inguinal white adipose tissue (iWAT) and differentiated 3T3-L1 adipocytes in thermogenic conditions induced by cold exposure or a beta-adrenergic stimulus (CL316,243). Overexpression and knockdown studies were performed both in vivo and in vitro to clarify the role of Pref-1 in iWAT browning. RESULTS: Cold exposure or CL316,243 induced a thermogenic program in adipose tissue of C57BL/6N mice and in 3T3-L1 adipocytes. Notably, Pref-1 levels were down-regulated in iWAT and adipocytes under these conditions. Overexpressing Pref-1 showed reduced thermogenic gene expressions in response to CL316,243 treatment, whereas depletion of Pref-1 augmented thermogenic program in 3T3-L1 adipocytes. Correspondingly, treating C57BL/6N mice with Pref-1 resulted in reduced expression of thermogenic and beige fat markers, a reduced rate of oxygen consumption, blunting of UCP1 expression and beige fat formation in iWAT in response to cold exposure or CL316,243 injection compared to the untreated mice. The opposite phenotype was observed in mice with inducible fat-specific knock-out of Pref-1. Mechanistically, these effects were regulated by modulation of TNF-α-converting enzyme activity and Pref-1 cleavage. CONCLUSION: Our findings establish a novel role of Pref-1 that regulates adaptive thermogenesis. This offers a unique target for improving energy homeostasis and treating obesity.


Assuntos
Proteína ADAM17/metabolismo , Tecido Adiposo/química , Proteínas de Ligação ao Cálcio/fisiologia , Reação de Maillard , Proteínas de Membrana/fisiologia , Células 3T3-L1 , Adipócitos/citologia , Tecido Adiposo Marrom/metabolismo , Tecido Adiposo Branco/metabolismo , Animais , Temperatura Baixa , Camundongos , Camundongos Endogâmicos C57BL , Termogênese
20.
J Agric Food Chem ; 67(43): 12094-12104, 2019 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-31566978

RESUMO

A large portion of Maillard reaction products (MRPs) cannot be absorbed in the upper gut and therefore may be further decomposed and utilized by colonic microbiota (CM). This work reported the stability of UV-absorbent MRPs, fluorescent MRPs and peptide-bound N(ε)-(carboxymethyl)-lysine (CML) in high molecular weight (HMW, >10 kDa), medium molecular weight (MMW, 1-10 kDa), and low molecular weight (LMW, <1 kDa) gastrointestinal digests of glyoxal-glycated casein in the presence of CM. Fluorescent MRPs showed high stability, whereas UV-absorbent MRPs may be partially decomposed. A higher depletion rate of CML was found in the LMW fraction (38.7%) than in the MMW (21.7%) and HMW (9.6%) fractions. The 16S rRNA sequencing results revealed both beneficial and detrimental changes in CM composition induced by the glycated fractions. Generation of short-chain and branched-chain fatty acids in fermentation solutions with glycated fractions was significantly suppressed compared with that in fermentation solution with unglycated digests. This work revealed the possible interplay between peptide-bound MRPs and CM.


Assuntos
Caseínas/metabolismo , Colo/microbiologia , Microbioma Gastrointestinal , Produtos Finais de Glicação Avançada/metabolismo , Glioxal/metabolismo , Peptídeos/metabolismo , Adulto , Bactérias/classificação , Bactérias/genética , Bactérias/isolamento & purificação , Bactérias/metabolismo , Caseínas/química , Colo/metabolismo , Ácidos Graxos Voláteis/metabolismo , Feminino , Produtos Finais de Glicação Avançada/química , Glioxal/química , Humanos , Reação de Maillard , Masculino , Peptídeos/química , Adulto Jovem
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