Reaction Of Polyphenols Research Articles

Change in nutrients of Citri Reticulatae ‘Chachi’ in relation to browning during aging

Citri Reticulatae ‘Chachi,’ also called “Guang Chen pi” (GCP), is a geoherb of Citri reticulatae pericarpium(CRP), mainly produced in Xinhui, Guangdong, China. It has been a food and traditional medicine for thousands of years. GCPs are popular green food, and can be divided into three picking times and different aging periods according to edible quality. Despite many pharmaceutical studies, there is little information on edible differences among GCP types. The dynamic changes in dietary value for different aging and picking times were investigated through quantifying polyphenols, soluble proteins, ascorbic acid, reducing sugars, polysaccharides, and β-carotene. The browning index (BI) and pH were also measured. Comprehensive analysis results showed that nutrient contents in brownish and reddish peels were close, and higher than in green peel. With aging time, ascorbic acid and β-carotene decreased, while dissolution of polysaccharides, polyphenols, and proteins increased, likely contributing to the aroma change. At the same time, pH of the system gradually decreased, but BI increased. Mathematical path analysis of related substrates and BI showed the greatest correlation of polyphenols with BI. The browning mechanism likely started with ascorbic acid degradation that caused reduced antioxidation, contributing to further reaction of polyphenols with other compounds to produce browning.

SURFACE ROUGHNESS IMPROVEMENT OF POLYAMIDE RESIN DENTURE AFTER SOAKING IN 50% CINNAMON (Cinnamon burmanii) SOLUTION

Polyamide resin is widely used in dentistry as a denture base material. Cinnamon burmanii has been proven to have antibacterial and antifungal substances. Therefore, it is the potential to be used as a nature denture cleanser. This study aimed to examine the effect of soaking 50% cinnamon extract solution on the surface roughness of polyamide resin. This study used 16 polyamide resin samples soaked in 50% cinnamon extract solution and 16 samples soaked in distilled water as the control group. It examined the surface roughness before and after immersion for four days and seven days. Data were analyzed using paired T-test and independent T-test. The results showed a significant difference in the surface roughness of polyamide resin before and after immersion in cinnamon solution for four days and seven days. The surface roughness change is due to the polyphenol's reaction on the polyamide resin surface, which has destroyed the polymer chain of polyamide resin.

Reactions of polyphenols in pomegranate peel with nitrite under simulated stomach conditions.

Punicalagin and ellagic acid are the major polyphenols present in pomegranate peels. The contents of α‐punicalagin, β‐punicalagin, and ellagic acid in the pomegranate peels were approximately 75, 72, and 20 µM, respectively. The reactions of polyphenols in pomegranate peels with sodium nitrite under simulated stomach conditions were studied. The reactions decreased the polyphenolic contents of the pomegranate peels and accompanied the formation of nitroso compounds. The oxidation rates followed the order ellagic acid ＜α‐punicalagin ≈ β‐punicalagin. The results suggested that the reactions can occur in the stomach after a meal, while the pH changes from 2 to 4.5.

Reactions of polyphenols in masticated apple fruit with nitrite under stomach simulating conditions: Formation of nitroso compounds and thiocyanate conjugates

By the ingestion of fresh apple fruit, it is masticated squeezing apple juice into the oral cavity and the juice is mixed with saliva. The mixture of saliva and apple juice is swallowed into the stomach where the pH is around 2. This paper deals with the reactions of polyphenols in the juice obtained by mastication of apple fruit with salivary nitrite under acidic conditions. The concentrations of catechins, procyanidins, and chlorogenic acid in the apple juice were approximately 55, 55, and 170μM, respectively, and the polyphenols were oxidized by salivary nitrite under conditions of the stomach. Rates of the oxidation increased in order chlorogenic acid<catechins<procyanidins. The oxidation of catechins and procyanidins resulted in the formation of the nitroso compounds, and the oxidation of chlorogenic acid resulted in the formation of the thiocyanate conjugate. The production of dinitroso compounds is proposed to be due to the addition of nitric oxide (NO) to radicals of catechins and procyanidins. As the mechanism of thiocyanate conjugate formation, reaction of o-quinone of chlorogenic acid with a salivary component thiocyanate is proposed, and the formation of the thiocyanate conjugate is discussed from the point of detoxification of chlorogenic acid quinone.

Review of Oxidative Processes in Wine and Value of Reduction Potentials in Enology

The reduction potential of wines has been thought to indicate their level of oxidation or reduction, but how that relates to wine composition has remained vague. Reduction potentials are generated by redox couples, which are at equilibrium and both adsorbed on the measuring electrode, the magnitude of the potential for any couple being determined by the relative proportion of the oxidized and reduced component. However, redox couples associated with polyphenols, which are most likely to determine reduction potentials, are not at equilibrium in wine due to the instability of quinones. Reduction potentials are highly dependent on oxygen concentration and it is proposed that they are generated by the oxidation of ethanol coupled to the reduction of protons or of oxygen. While the so-called reduction potential is therefore of little value for wine, cyclic voltammetry has proved very useful in determining the reduction potential of wine constituents and estimating the concentration of the most readily reduced polyphenols. The reduction potentials of proposed redox couples involved in the reduction of oxygen and oxidation of polyphenols, ethanol, and sulfite are useful in determining the thermodynamic feasibility of possible interactions. The reaction of polyphenols with oxygen is mediated by iron, which redox cycles between them assisted by copper. Catechol-quinone and oxygen-hydrogen peroxide couples have similar reduction potentials. Consequently, the oxidation of catechols such as (+)-catechin cannot proceed to completion and is accelerated by substances that react with quinones, such as sulfite, which reduces them back to polyphenols. Sulfite, therefore, has multiple antioxidant activities. It accelerates oxygen consumption, prevents loss of polyphenols by regenerating them, and intercepts hydrogen peroxide, thus preventing ethanol oxidation.

Chemistry of Secondary Polyphenols Produced during Processing of Tea and Selected Foods

This review will discuss recent progress in the chemistry of secondary polyphenols produced during food processing. The production mechanism of the secondary polyphenols in black tea, whisky, cinnamon, and persimmon fruits will be introduced. In the process of black tea production, tea leaf catechins are enzymatically oxidized to yield a complex mixture of oxidation products, including theaflavins and thearubigins. Despite the importance of the beverage, most of the chemical constituents have not yet been confirmed due to the complexity of the mixture. However, the reaction mechanisms at the initial stages of catechin oxidation are explained by simple quinone–phenol coupling reactions. In vitro model experiments indicated the presence of interesting regio- and stereoselective reactions. Recent results on the reaction mechanisms will be introduced. During the aging of whisky in oak wood barrels, ellagitannins originating from oak wood are oxidized and react with ethanol to give characteristic secondary ellagitannins. The major part of the cinnamon procyanidins is polymerized by copolymerization with cinnamaldehyde. In addition, anthocyanidin structural units are generated in the polymer molecules by oxidation which accounts for the reddish coloration of the cinnamon extract. This reaction is related to the insolubilization of proanthocyanidins in persimmon fruits by condensation with acetaldehyde. In addition to oxidation, the reaction of polyphenols with aldehydes may be important in food processing.

Chain-breaking antioxidant activity of natural polyphenols as determined during the chain oxidation of methyl linoleate in Triton X-100 micelles

Natural polyphenols (PP) are known as potent antioxidants, which are believed to prevent many degenerative diseases, including cancer and atherosclerosis. Much attention in the literature has been given to the antioxidant activity of PP-containing products; however, information on the antioxidative properties of individual PP is rather poor and controversial. In this work, the chain-breaking antioxidant activities of several natural PP and their synthetic analogs were determined during the chain oxidation of methyl linoleate in an aqueous buffered, pH 7.40, micellar solution of Triton X-100, induced by 2,2 ′-azobis(2-amidinopropan) dihydrochloride at 37 °C. Use of the mode of the controlled chain reaction allowed separate determination of the rate constant for the reaction of PP with the lipid peroxy radical and the stoichiometric factor of inhibition ( f), which shows how many kinetic chains can be terminated by one molecule of PP. All the PP studied display a pronounced antioxidant activity. A significant difference in f value between catechol derivatives and pyrogallol derivatives was found. While with pyrogallol derivatives (gallic acid, epigallocatechin, propyl gallate, myricetin), f was found to be around 2, the theoretically expected value, f, for catechol derivatives (catechol, catechin, epicatechin, quercetin, rutin, caffeic acid) was found to be within the range 3.6–6.3. The elevated antioxidant capacity of catechol derivatives may be explained by the contribution of products of PP oxidative transformation, most likely by dimers, to inhibition. With catechin, epicatechin, and quercetin, the reactivity of products exceeds that of original PP. A real chain-breaking antioxidant activity of PP is likely determined not so much by the reactivity of the original PP as by the probability of the formation of active products and their antioxidant activities. The above findings were applied to explain some features of the antioxidant activity of teas and red wines.

Color changes during storage of honeys in relation to their composition and initial color

The causes of darkening in honey have been attributed to Maillard reaction, fructose caramelization and reactions of polyphenols, however, no systematic studies exist on this subject. The influence of composition and initial color on the rate of darkening of several Argentine honeys submitted to storage at 37°C during 90 days was evaluated through spectrocolorimetric measurements. The most suitable color functions to evaluate darkening of honeys [lightness (L ab*), browning index (BI), metric chroma (C ab*), metric hue (H ab*) and 1/Z] increased linearly as storage time increased, after an initial induction period of very low browning development. The slope of the linear browning development zone with time was an index of browning rate, and it was analyzed in relation to the initial color and the composition of honeys (moisture content, total nitrogen, total lipids and polyunsaturated fatty acids, fructose and glucose content). Of the analyzed variables, the initial color was the parameter which better defined the rate of darkening of honeys.

Reaction of polyphenols with formaldehyde

AbstractThe reaction of wattle and mangrove polyphenols with formaldehyde was studied at various pH and under different conditions of temperature and time. The reactivity was greater at pH 8 than at pH 1 and least at pH 4–5. The initial fast stage in the reaction was followed by a slow stage. The formaldehyde uptake at pH 8 and 100° in 3 h. was determined for several polyphenols; it gave a better indication of the efficiency of a polyphenol as an adhesive than did the determination of Stiasny polyphenols. The reasons for the different behaviour of polyphenols as adhesives are discussed.

Reaction of polyphenols with formaldehyde

Reaction of polyphenols with formaldehyde