NMR structural elucidation of dehydrodimers resulting from oxidation of 5-O-caffeoylquinic acid in an apple juice model solution.

During apple juice and cider-making processes, phenolic compounds undergo enzymatic oxidation. 5-O-caffeoylquinic acid (CQA) is one of the major hydroxycinnamic acid derivatives and it is the preferential substrate for polyphenol oxidase (PPO) in apple juices. Consequently, CQA dehydrodimers (MW 706 Da) are among the main products resulting from CQA oxidation.

Preparative isolation of apple flavan-3-ols monomers and oligomers using pH-zone-refining centrifugal partition chromatography combined with reversed-phase liquid chromatography.

Flavan-3-ols (catechin monomers and procyanidins) are the main class of polyphenols in apples and are found in high concentrations in cider apple varieties. They are known to be involved in bitterness and astringency in apple-based beverages, and also contribute to polyphenol nutritional intake.Therefore, highly purified flavan-3-ol fractions isolated from raw materials are needed to study their various properties.

Interactions between polyphenol oxidation products and salivary proteins: Specific affinity of CQA dehydrodimers with cystatins and P-B peptide.

Throughout the apple juice and cider making process, polyphenols undergo enzymatic oxidation which generates a great variety of polyphenol oxidation products. Since 5'-O-Caffeoylquinic acid (CQA) is one of the major phenolic compounds and the preferential substrate for polyphenoloxidase in apple juice, its oxidation leads to the formation of newly formed molecules by which dehydrodimers (MW 706 Da) are included. Interactions of salivary proteins (SP) with native polyphenols is a well-known phenomenon, but their interactions with polyphenol oxidation products has not been studied yet.

Heat-unstable apple pathogenesis-related proteins alone or interacting with polyphenols contribute to haze formation in clear apple juice.

Physico-chemical instability is a damaging defect that can occur in clear bottled beverages leading to the formation of haze. In a previous study, we showed the presence of proteins in haze gathered from apple juices. For the first time, proteomics was used to sequence and identify four pathogenesis-related proteins (PRPs) from the haze of a commercial apple juice.

Preparative fractionation of 5'-O-caffeoylquinic acid oxidation products using centrifugal partition chromatography and their investigation by mass spectrometry.

When apples are processed into juices or ciders, a great variety of neoformed molecules are generated by enzymatic oxidation of polyphenols. These phenolic oxidation products could be responsible of specific organoleptic properties in apple juices and ciders. 5'-O-Caffeoylquinic acid (CQA) is the major hydroxycinnamic acid in apple and the preferential substrate of apple polyphenoloxidase (PPO).

Self-aggregation of oxidized procyanidins contributes to the formation of heat-reversible haze in apple-based liqueur wine.

The ability of tannins to self-associate or form complexes with other macromolecules has important nutritional implications but can also result in defects in beverages. In addition, oxidation may be involved in the aggregation properties of tannins. In order to assess the impact of tannin oxidation on their self-association, oligomeric procyanidins were oxidized in a model solution and their aggregation kinetics were studied using light scattering.

Haze in Apple-Based Beverages: Detailed Polyphenol, Polysaccharide, Protein, and Mineral Compositions.

Producers of apple-based beverages are confronted with colloidal instability. Haze is caused by interactions between molecules that lead to the formation of aggregates. Haze composition in three apple-based beverages, namely, French sparkling cider, apple juice, and pommeau, was studied.