White phenolic compound

Bisphenol A is a solid material in the form of white flakes, insoluble in water but soluble in alcohols. As a phenolic compound, it reacts with strong alkaline solutions. Bisphenol A is an important monomer for producing epoxy resins, polycarbonates, and polysulfones. It is produced by the condensation reaction of acetone and phenol in the presence of HCI. (See Chapter 10, p. 273)... 

In Table 15 are recorded the dissociation constants of certain phenolic compounds. From these data it becomes obvious that the introduction of aldehyde groups, or other substituents, changes the dissociation constant of phenolic hydroxyls by over one-hundred fold. Moreover, oxidation studies carried out in this laboratory have shown that the native lignins from bagasse, white Scots pine and birch contain... 

Maatta K, Kamal-Eldin A and Torronen R. 2001. Phenolic compounds in berries of black, red, green, and white currants (Ribes sp.). Antioxid Redox Signal 3(6) 981-993. 

Matus-Cadiz MA, Daskalchuk TE, Verma B, Puttick D, Chibbar RN, Gray GR, Perron CE, Tyler RT and Hucl P. 2008. Phenolic compounds contribute to dark bran pigmentation in hard white wheat. J Agric Food Chem 56(5)1644-1653. 

Lee, C.Y. and Jaworski, A. 1987. Phenolic compounds in white grapes grown in New York. Am. 

A reversed-phase liquid chromatographic method was developed for simultaneous determination of carboxylic acids, phenolic compounds, and SA in white wines (84). The diluted samples are injected into a Spherisorb ODS-2 column with a gradient of sulphuric acid (pH 2.5)/methanol as mobile phase. A diode array detector is used, set at 210 nm for carboxylic acids and altered to 278 nm, during the run, for phenolics and SA. The identification of compounds is based on retention time and UV spectra. Some cleanup methods (Sep-Pak C18 and an ion-exchange column) were tested and did not improve the results. The analysis was considered simple, with no sample preparation. Application of this method was illustrated by analyses of Brazilian Welchriesling wines (84). 

MT Benassi, HM Cecchi. Method development for the simultaneous determination of carboxylic acids, phenolic compounds, and sorbic acid in white wines. J Liquid Chromatogr Related Technol 21 491-501, 1998. 

CY Lee, A Jaworski. Major phenolic compounds in ripening white grapes. Am J Enol Vitic 40 43-46, 1989. 

Many of the recent studies on the BAs in wines are from the research group of Busto. In 1994 this group developed a method suitable for the determination of 19 BAs in wine (48) that involves the removal of phenolic compounds with polyvinylpirrolidone (PVP), derivatization with DNS, SPE extraction with C18 cartridges, concentration, and HPLC-UV analysis reaching DLs between 50 and 150 /rg/L. The method was applied to five different red and white wines from Catalonia. 

Neohesperidin dihydrochalcone (NeoDHC) is a phenolic compound prepared from the bitter citrus flavanones naringin and neohesperidin (Horowitz Gentili, 1985). NeoDHC is a white solid with solubility in water of 0.5 g/1, which increases with temperature, but as use level is low, sufficient for most applications. 

Whiting DA. 2001. Natural phenolic compounds 1900-2000 A bird s eye view of a century s chemistry. Nat Prod Rep 18 583-606. 

Ortega, A. F., Lopez-Toledano, A., Mayen, M., Merida, J., and Medina, M. (2003). Changes in color and phenolic compounds during oxidative aging of sherry white wines. /. Food Sci. 68, 2461-2468. 

Due to the long maceration on skin, red wines are particularly rich in phenolic compounds, having higher antioxidant capacity and also higher resveratrol content than white wines. Of the high number of studies on this field, only a few focused on the botrytized white wines. 

The content of phenolic compounds found in the Madeira wine samples assayed is represented in Table 7.4. As can be easily observed, the phenolics analyzed are about six times more abundant in red than in white wines. The fact that polyphenols content is higher in red wines was widely described before in the literature (Kuroda and Hara, 1999). 

The intense reddish-brown color of the acetylacetone titanium complexes impart a yellow discoloration to white inks. This discoloration is accentuated when the inks are used to print substrates that contain phenol-based antioxidants. The phenolic compounds react with the organic titanate to form a highly colored titanium phenolate. Replacement of 0.25 to 0.75 moles of acetylacetone with a malonic acid dialkyl ester, such as diethyl malonate, gives a titanium complex that maintains the performance advantages of the acetyl acetone titanium complexes, but which is only slighdy yellow in color (505). These complexes still form highly colored titanium phenolates. 

Duarte-Vazquez MA, Ortega-Tovar M, Garcia-Almendarez B et al (2003) Removal of aqueous phenolic compounds from a model system by oxidative polymerization with turnip (Brassica napus L. var purple top white globe) peroxidase. J Chem Technol Biotechnol 78 42 17... 

The GC analysis (Fig. 7.7) shows a commercial white thyme with a high percentage of the phenols thymol (55.8%) and carvacrol (2.07%). This contrasts with that of sweet thyme (Fig. 7.8) with no phenolic compounds present and alcohols terpineol-4 (13%), a-terpineol (12.37%) and bomeol (5.95%) making up a total of 31.34% for this particular sample. 

Whilst sulfate appears to be fundamental to haze formation, other wine components such as phenolic compounds remain as candidate haze modulators. One possibility is that white wine phenolic compounds affect the particle size of denatured aggregated proteins, possibly through crosslinking. Several researchers (Oh et al. 1980 Siebert et al. 1996b) have suggested a hydrophobic mechanism for the interaction between phenolic compounds and proteins, in which the protein has a fixed number of phenolic binding sites. More of these sites are exposed when the protein is denatured. 

MPs are constituted by 90% of mannose, protein and phosphoric acids and represent the 35% of total polysaccharides in wine (Vidal et al. 2003). MPs combined with phenolic compounds have shown an indirect effect on astringency, although their stabilizing effect on protein precipitation in white wine and tartrate crystallization in both red and white wines are their main function (Ribereau-Gayon et al. 2006). Glucomannoproteinshscve been also detected in wines in lower amount than MPs (Ribereau-Gayon et al. 2006). 

Grape phenolics compounds are important to wine colour, flavour, astringency and bitterness, with red wines generally containing 1200-1800 mg gallic acid equiv-alents/L of total phenolics, six- to ninefold more than present in white wines (Kennedy et al. 2006). Hydroxycinnamic acids (non-flavonoid phenolics) are major phenolic compounds of white wines and are responsible for their colour. Other non-flavonoid phenolics contribute flavour, such as vanillin, vinyl phenols and gallic acid. Vinyl and ethyl phenols, which can be present to variable extents, elicit phenolics, medical, Bandaid , barnyard and spicy characters in wine, which are generally... 

Pozo-Bayon, M. A., Hernandez, M. T, Martin-Alvarez, P. J., Polo, M. C. (2003). Study of low molecular weight phenolic compounds during the aging of sparkling wines manufactured with red and white grape varieties. J. Agric. Food Chem., 51, 2089-2095. 

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