Effect of Reaction Conditions on the Volatile Pyrazines Components of Defatted Flaxseed Meal in the Maillard Reaction System

The reaction of glyoxal with nucleophilic amino acids was monitored for β-casein as well as β-lactoglobulin. As predicted from previous experiments with hippuryl amino acids, a measurable decrease of arginine can be found in the thiol-free β-casein, while the lysine content remained almost unchanged. For β-lactoglobulin, the incubation with glyoxal led to a slight decrease in the lysine content, while the arginine residues remained unmodified. Here, in accordance with nucleophilicity, it is suggested, that mainly cystein residues react with glyoxal. In solutions containing β-casein with or without glutathione, the effects were less pronounced and regarding the lysine and arginine content, the influence of thiols could hardly be recorded on a significant level. However, comparing the CML levels in the different incubations, it becomes obvious, that glutathione is favouring CML formation in a concentration depended manner. Therefore, the use of CML as an indicator, e.g. for the Maillard reaction, must be related to the composition of the reaction system.

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Advances in Chemistry of Isothiocyanate-derived Colourants

Czech Journal of Food Sciences ◽

10.17221/1092-cjfs ◽

2009 ◽

Vol 27 (Special Issue 1) ◽

pp. S207-S210

Author(s):

K. Cejpek ◽

J. Velíšek

Keyword(s):

Amino Acids ◽

Essential Oils ◽

Maillard Reaction ◽

Heterogeneous Group ◽

Model Systems ◽

Alkaline Media ◽

Reaction Conditions ◽

Condensation Products ◽

Amino Compounds ◽

Methylene Group

This study is focused on the reactions of isothiocyanates (ITCs) in the presence of amino compounds leading to coloured structures <I>via</I> substituted 2-thiohydantoins. A series of complementary experiments has been done and appropriate reaction conditions and structural prerequisites have been defined. Low-molecular colourants isolated and characterised from the model systems can be sorted into three groups. Yellow to red diastereomeric dehydrodimers of 2-thiohydantoin derivatives that contain an acidic methylene group are formed in mixtures consisted of ITCs and amino acids with α-methylene group in mild acidic to mild alkaline systems. The condensation products of the 2-thiohydantoins with reactive aromatic or heterocyclic carbaldehydes from the Maillard reaction, essential oils etc. comprise a heterogeneous group of mostly yellow colourants. Blue compounds of two types are structurally more complicated structures that arise from <I>N</I>-substituted amino acids and ITCs in alkaline media.

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Antimutagenic Effect of Maillard Reaction Products Prepared from Glucose and Tryptophan

Journal of Food Protection ◽

10.4315/0362-028x-55.8.615 ◽

1992 ◽

Vol 55 (8) ◽

pp. 615-619 ◽

Cited By ~ 2

Author(s):

GOW-CHIN YEN ◽

JEN-DAN LII

Keyword(s):

Maillard Reaction ◽

Antioxidative Activity ◽

Reducing Power ◽

Molar Ratio ◽

Maillard Reaction Products ◽

Alkaline Ph ◽

Reaction Products ◽

Reaction Conditions ◽

Antimutagenic Effect ◽

Effect Of Glucose

The antimutagenicity of Maillard reaction products (MRPs) prepared by refluxing D-glucose and L-tryptophan under various reaction conditions was determined by means of the Ames test. The dose of MRPs with 5 mg per plate showed no toxicity, and mutagenicity to Salmonella typhimurium TA98 and TA100 was used for antimutagenic assay. The mutagenicity of 2-amino-3-methylimidazo (4,5-f) quinoline (IQ) and 2-amino-6-methyldipyrido (1,2-a:3′,2′-d) imidazole (Glu-P-1) toward TA98 was markedly reduced by the addition of glucose-tryptophan MRPs, whereas the mutagenicity of 4-nitroquinoline-N-oxide (NQNO) was not inhibited. The mutagenicity of IQ, Glu-P-1, and NQNO toward TA100 was also markedly reduced by glucose-tryptophan MRPs, but the mutagenicity of NQNO was only slightly inhibited. Greater antimutagenic effects of glucose-tryptophan MRPs were found when these materials were prepared at an alkaline pH. The optimum combinations of reaction conditions for obtaining antimutagenic MRPs to IQ were glucose-tryptophan molar ratio = 0.5:0.25 at pH 9.0 for 5 and 10 h, molar ratio = 0.5:0.5 at pH 11.0 for 10 h, and molar ratio = 1.0:0.25 at pH 7.0 for 15 h and at pH 11.0 for 15 h. The antimutagenic effect of glucose-tryptophan MRPs to IQ and Glu-P-1 was well correlated with their browning intensity, reducing power, and antioxidative activity. The antimutagenicity of glucose-tryptophan MRPs might be due to both desmutagenic and bio-antimutagenic effects.

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Catalytic Dehydration of Fructose to 5-Hydroxymethylfurfural (HMF) in Low-Boiling Solvent Hexafluoroisopropanol (HFIP)

Molecules ◽

10.3390/molecules23081866 ◽

2018 ◽

Vol 23 (8) ◽

pp. 1866 ◽

Cited By ~ 3

Author(s):

Sarah Tschirner ◽

Eric Weingart ◽

Linda Teevs ◽

Ulf Prüße

Keyword(s):

Ion Exchange ◽

Exchange Resin ◽

Reaction System ◽

Water System ◽

Catalyst Particle ◽

Ion Exchange Resin ◽

Ion Exchange Resins ◽

Reaction Conditions ◽

Water As Solvent ◽

Exchange Resins

A mixture of hexafluoroisopropanol (HFIP) and water was used as a new and unknown monophasic reaction solvent for fructose dehydration in order to produce HMF. HFIP is a low-boiling fluorous alcohol (b.p. 58 °C). Hence, HFIP can be recovered cost efficiently by distillation. Different ion-exchange resins were screened for the HFIP/water system in batch experiments. The best results were obtained for acidic macroporous ion-exchange resins, and high HMF yields up to 70% were achieved. The effects of various reaction conditions like initial fructose concentration, catalyst concentration, water content in HFIP, temperature and influence of the catalyst particle size were evaluated. Up to 76% HMF yield was attained at optimized reaction conditions for high initial fructose concentration of 0.5 M (90 g/L). The ion-exchange resin can simply be recovered by filtration and reused several times. This reaction system with HFIP/water as solvent and the ion-exchange resin Lewatit K2420 as catalyst shows excellent performance for HMF synthesis.

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