Identification of dipyrrolone pigments and their precursors formed in the Maillard reaction of carnosine and pentose under weakly acidic conditions

2021 ◽  
Author(s):  
Yuri Nomi ◽  
Kento Yamazaki ◽  
Yuki Mori ◽  
Hitoshi Matsumoto ◽  
Shinji Sato
Keyword(s):  
Maillard Reaction ◽  
Free Amino ◽  
Absorption Maximum ◽  
Group Analysis ◽  
Amino Compound ◽  
Formation Pathway ◽  
Amadori Compound ◽  
Potential Formation ◽  
Acidic Conditions ◽  
Yellow Pigments

Abstract Colored compounds formed by the Maillard reaction of carnosine with xylose or glucose were investigated in this study. Yellow pigments showing an absorption maximum at 450 nm were found in a heated solution of carnosine with xylose at pH 5.0. These pigments were then isolated and identified as dicarnosyl-dipyrrolones A and B. The generation of dipyrrolones in the absence of lysine suggests that dipyrrolone pigments can be formed by pentose as well as every amino compound such as amino acids, peptides and proteins possessing a free amino group. Analysis of α-dicarbonyls using LC-MS/MS showed that pentosone, 1-deoxypentosone, 3-deoxypentosone (3-DP), and methylglyoxal were predominantly generated via degradation of Amadori compounds. Also, a potential formation pathway of dypyrrolones was established, indicating that an Amadori compound which could form 3-DP is likely to play a role as a main precursor for dipyrrolones.

scholarly journals Effect of free amino acids and peptide hydrolysates from sunflower seed protein on the formation of pyrazines under different heating conditions

RSC Advances ◽  
2021 ◽  
Vol 11 (45) ◽  
pp. 27772-27781
Author(s):  
Furong Wang ◽  
Hailiang Shen ◽  
Xi Yang ◽  
Ting Liu ◽  
Yali Yang ◽  
...  
Keyword(s):  
Amino Acids ◽  
Maillard Reaction ◽  
Free Amino Acids ◽  
Free Amino ◽  
Sunflower Seed ◽  
Seed Protein ◽  
Heating Temperature ◽  
Reaction Model

Exploring the effect of heating temperature and time on the formation of pyrazines; revealing the potential roles of FAAs and hydrolyzed sunflower seed peptides in the Maillard reaction model.

Synergistic reaction between SO2 and NO2 on mineraloxides: a potential formation pathway of sulfate aerosol

2012 ◽  
Vol 14 (5) ◽  
pp. 1668-1676 ◽  
Author(s):  
Chang Liu ◽  
Qingxin Ma ◽  
Yongchun Liu ◽  
Jinzhu Ma ◽  
Hong He
Keyword(s):  
Sulfate Aerosol ◽  
Formation Pathway ◽  
Potential Formation ◽  
Synergistic Reaction

Heterogeneous reaction of Cl2 and NO2 on γ-Al2O3: A potential formation pathway of secondary aerosols

2018 ◽  
Vol 188 ◽  
pp. 25-33 ◽  
Author(s):  
Siqun Tang ◽  
Lingling Ma ◽  
Min Luo ◽  
Zhaohui Zhang ◽  
Xingzhong Cao ◽  
...  
Keyword(s):  
Heterogeneous Reaction ◽  
Formation Pathway ◽  
Potential Formation ◽  
Secondary Aerosols

scholarly journals Mycotoxins during the Processes of Nixtamalization and Tortilla Production

Toxins ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 227 ◽  
Author(s):  
Sara Schaarschmidt ◽  
Carsten Fauhl-Hassek
Keyword(s):  
Current Knowledge ◽  
Global Level ◽  
Lower Toxicity ◽  
Tortilla Chips ◽  
The Matrix ◽  
Potential Formation ◽  
Acidic Conditions ◽  
The One ◽  
Maize Kernels ◽  
Modified Forms

Tortillas are a traditional staple food in Mesoamerican cuisine, which have also become popular on a global level, e.g., for wraps or as snacks (tortilla chips). Traditional tortilla production includes alkaline cooking (nixtamalization) of maize kernels. This article summarizes the current knowledge on mycotoxin changes during the nixtamalization of maize and tortilla production. Upon nixtamalization, mycotoxins can be affected in different ways. On the one hand, the toxins can be physically removed during steeping and washing. On the other hand, mycotoxins might be degraded, modified, or released/bound in the matrix by high pH and/or high temperature. This also applies to the subsequent baking of tortillas. Many studies have shown reduced mycotoxin levels in alkali-cooked maize and in tortillas. Most of the available data relate to aflatoxins and fumonisins. The reduction (and detoxification) of aflatoxins during nixtamalization might, however, be partially reversed in acidic conditions. The loss of fumonisin concentrations is to some extent accompanied by hydrolyzation and by lower toxicity. However, some studies have indicated the potential formation of toxicologically relevant modified forms and matrix-associated fumonisins. More data are required to assess the influence of alkaline cooking regarding such modified forms, as well as mycotoxins other than aflatoxins/fumonisins.

Pyrrolomorpholine Spiroketal Alkaloids Present in Roasted Beans of Yunnan Arabica Coffee

2021 ◽  
Vol 11 ◽  
Author(s):  
GuiLin Hu ◽  
DeFu Hong ◽  
XiaoYuan Wang ◽  
YanBing Wang ◽  
Lin Zhou ◽  
...  
Keyword(s):  
Maillard Reaction ◽  
Volatile Components ◽  
Maillard Reaction Products ◽  
Reaction Products ◽  
X Ray Diffraction ◽  
Arabica Coffee ◽  
Formation Pathway ◽  
Planar Structures ◽  
Coffee Beans ◽  
Huge Impact

Background: Coffee is one of the most commonly consumed drink around the world. During the coffee roasting process, sugars and amines undergo a violent Maillard reaction, resulting in a large number of volatile and non-volatile components . These ingredients have a huge impact on the formation of coffee flavor. In addition, many maillard products in coffee have also been proven to exert antioxidative , anti-inflammatory and other properties. Objective: The objective of this research is to discover non-volatile Maillard reaction products in roasted coffee beans Results and Methods: A pair of enantiomers pyrrolomorpholine spiroketal alkaloids 1a and 1b were isolated from roasted beans of Yunnan Coffea Arabica. Their planar structures were elucidated by extensive spectroscopic analysis, HRESIMS spectra and X-Ray diffraction. Conclusion: Two pyrrolomorpholine spiroketal alkaloids were isolated from roasted arabica coffee beans. And their formation pathway via Maillard reaction was deduced. Their influence on the formation of coffee bitterness and biological functions is worthy of further study.

Extent of Peptide Cross-Linking in the Peptidoglycan of Neisseria gonorrhoeae

1980 ◽  
Vol 28 (3) ◽  
pp. 867-875 ◽  
Author(s):  
R. S. Rosenthal ◽  
R. M. Wright ◽  
R. K. Sinha
Keyword(s):  
Neisseria Gonorrhoeae ◽  
Free Amino ◽  
Group Analysis ◽  
Gel Filtration ◽  
Prototype Strain ◽  
Enzymatic Digestion ◽  
Diaminopimelic Acid ◽  
Cross Linking ◽  
Multiple Drugs ◽  
High Degree

The extent of peptide cross-linking in peptidoglycan (PG) isolated from various strains of Neisseria gonorrhoeae was examined. Purified PG, specifically labeled in the peptide moiety with [ 3 H]diaminopimelic acid (DAP) and labeled in the glycan with [ 14 C]glucosamine and [ 14 C]muramic acid, was digested completely with Chalaropsis B muramidase. Gel filtration of the digest on connected columns of Sephadex G-50 and G-25 revealed four well-defined peaks corresponding to soluble PG fragments and containing a constant ratio of 3 H to 14 C. On the basis of (i) K D values, (ii) amino acid composition, (iii) free amino group analysis of [ 3 H]DAP residues, (iv) borohydride reduction, (v) the β-elimination reaction, (vi) high-voltage electrophoresis, and (vii) paper chromatography in various solvents, the PG fragments were identified as un-cross-linked disaccharide peptide monomer, typical of chemotype I PG, and the corresponding peptide cross-linked dimers, trimers, and tetramers. The percent cross-linking of PG basically reflects the percentage of DAP residues that are involved in peptide cross-linking bonds. This value was estimated from the distribution of labeled fragments that resulted from the enzymatic digestion of PG and was confirmed by the analysis of free amino groups in [ 3 H]DAP of intact PG. Although there were subtle, strain- and medium-dependent differences in percent cross-linking, these values varied only over a relatively narrow range (36 to 44%). The percent cross-linking of PG in the prototype strain, RD 5 , grown in a standard gonococcal medium (LGCB + ) was 41.0 ± 2.0%. This is a relatively high degree of peptide cross-linking for a gram-negative bacterium. We also confirmed previous observations that the extent of PG cross-linking among isogenic gonococci was higher in strains, e.g., FA140 and FA136, carrying loci that govern increased resistance to multiple drugs.

scholarly journals 361 Beef flavor chemistry and how it influences sensory perception

2020 ◽  
Vol 98 (Supplement_4) ◽  
pp. 97-97
Author(s):  
Jerrad F Legako
Keyword(s):  
Amino Acids ◽  
Maillard Reaction ◽  
Free Amino Acids ◽  
Free Amino ◽  
Consumer Satisfaction ◽  
Water Soluble ◽  
Eating Quality ◽  
Quality Trait ◽  
Beef Flavor ◽  
Flavor Chemistry

Abstract Flavor can be simply defined as the combination of taste and aroma. Taste refers to the five basic receptors: sweet, salty, sour, bitter, and umami. Flavor is the perception of chemical compounds reacting with receptors in the oral and nasal cavities (aroma) in combination with taste. For beef, flavor is considered a primary eating quality trait. Flavor is developed during cooking through a combination of numerous chemical reactions, principally the Maillard reaction and oxidation of lipids. Any factor which mediates precursor compounds to these reactions may influence flavor chemistry and final perceived flavor. For the Maillard reaction, water-soluble compounds, such as free-amino acids and sugars, are essential and allow for the development of characteristic beef flavors. Likewise, oxidation of lipids, to a degree, provides beef -species-specific flavor. However, too much oxidation contributes to off-flavor. Both pre- and post-harvest factors may influence beef flavor precursor content and composition prior to cooking. Beef finishing diet is well understood to influence fatty acid composition. Meanwhile, carcass grade and muscle type each influence fatty acids. During post-mortem aging, free-amino acids and other metabolites accumulate in response to proteolysis. Recent work indicates that packaging type and retail environment also influence flavor precursor compounds. Finally, the aforementioned flavor pathways, lipid oxidation and the Maillard reaction, are initiated and accelerated during cooking. Therefore, degree-of-doneness and cookery type greatly influence beef flavor chemistry. These examples briefly depict how beef flavor chemistry may be influenced by common production factors, retail settings, and consumer preparation of beef. The resulting beef flavor dictates consumer liking of beef. Therefore, understanding beef flavor chemistry is integral to maintaining or increasing consumer satisfaction with beef.

Ultraviolet Spectrophotometric Determination of Hydralazine Hydrochloride in Tablets Following Derivatization with Nitrite

1987 ◽  
Vol 70 (1) ◽  
pp. 42-46
Author(s):  
Barry Mopper
Keyword(s):  
Spectrophotometric Determination ◽  
Spectrophotometric Method ◽  
Absorption Maximum ◽  
Spectral Characteristics ◽  
Spectrophotometric Assay ◽  
Assay Method ◽  
Content Uniformity ◽  
Acidic Conditions ◽  
Hydralazine Hydrochloride

Abstract Routine use of the USP XXI spectrophotometric method for the content uniformity determination of hydralazine hydrochloride tablets has shown that tablet excipients can significantly alter the spectral characteristics of the drug and thus cause inaccurate assay values to be obtained. Because of this problem, a simple and reliable alternative spectrophotometric assay method, based on the conversion of hydralazine to tetrazolo [5,l-α]phthalazine with nitrite ions under acidic conditions, was developed. The derivative showed an absorption maximum at about 274 nm and obeyed Beer's law over the concentration range 4-40 μg/mL. Mean recoveries of hydralazine hydrochloride added to commercial coated and uncoated tablets were 101.0% (n = 10) and 100.8% (n = 8), respectively. The proposed method was found suitable for the assay not only of individual tablets but also of tablet composites

Sign in / Sign up

Export Citation Format

Share Document