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Journals and Conferences
Polyphenols (tannins) in the diet not only precipitate oral proteins, producing an astringent sensation, but also interact with dietary proteins and digestive enzymes in the gut, resulting in a variety of antinutritive and toxic effects. Salivary proline-rich proteins (PRPs), which are secreted into the oral cavity, form complexes with and precipitate… (More)
Polyphenols are largely responsible for the astringency and "mouthfeel" of tea and wine by their interactions with basic salivary proline-rich proteins. Astringency arises from precipitation of polyphenol/peptide complexes, which is an important protective mechanism in animals that consume polyphenols. This paper presents biophysical studies of the… (More)
The interaction between salivary proline-rich proteins and plant polyphenols (tannins) in the oral cavity and their subsequent precipitation influences the taste, texture and nutritional value of food; it is thought to be responsible for the astringency of many foods and beverages. To investigate the interaction, two-dimensional 1H-NMR studies have been… (More)
The protein IB5 has been purified from human parotid saliva. This protein contains several repeats of a short proline-rich sequence. Dissociation constants have been measured at several discrete binding sites using 1H-NMR for the hydrolysable tannins (polyphenols) beta-1,3,6-tri-O-galloyl-D-glucopyranose, beta-1,2,4,6-tetra-O-galloyl-D-glucopyranose and… (More)
The chemistry underlying the changes which occur during tea leaf fermentation is reviewed and used as a basis for proposals for the structure of thearubigins, the major pigments of black teas.
After the early encouragement from the outstanding contribution in the early 1900s of Emil Fischer to an understanding of vegetable tannins the work of the following half-century had simply exemplified the complexity of the problems they presented. It was generally recognised [Freudenberg, 1920. Die Chemie der Natürliche Gerbstoffe. Springer, Berlin] that… (More)
The esterase and depsidase activities of tannase have been examined by kinetic methods. Although the esterase/depsidase ratio of tannase may be varied by cultural methods and isolation procedures, evidence has been obtained to show that tannase, esterase and depsidase are enzymes with low specificities capable of hydrolysing both esters and depsides of… (More)
Recent, NMR and precipitation, studies of molecular recognition of proline-rich proteins and peptides by plant polyphenols are described and rationalized. The action of polysaccharides and caseins in the moderation of the astringent response, which is engendered by polyphenols present in foodstuffs and beverages, is described. The possible influence of… (More)
The association of some natural and synthetic polyphenols with beta-glucosidase was examined and some observations on the chemical nature of the complex were made.