title: Changes in color and phenolic compounds during the raisining of grape cv. Pedro Ximenez.
abstract: Changes in color parameters and phenolic compounds during the sun-drying grape raisining of cv. Pedro Ximenez to obtain sweet wines are studied. Browning increases during the process as a result of the contribution to a greater extent of the low and medium molecular size polymers than the high molecular size polymers. Raisining decreases hue and lightness and increases chroma, all measured as CIELab parameters, indicating a color change to dark reddish hues that is also preferentially due to low and medium molecular size polymers. Most of the phenols studied increase in concentration during raisining, essentially through the concentration effect resulting from the loss of water in the grapes. The concentration changes, however, are comparatively small for hydroxycinnamic esters and flavan-3-ol derivatives, suggesting that these phenolic fractions undergo predominantly oxidative degradation reactions by enzymatic pathways, contributing strongly to the browning of grapes.
authors.affiliation: Department of Agricultural Chemistry, Faculty of Sciences, University of Cordoba, Edificio Marie Curie, Campus de Rabanales, E-14014 Cordoba, Spain.
authors.forename: María P
authors.initials: MP
authors.lastname: Serratosa
authors.forename: Azahara
authors.initials: A
authors.lastname: Lopez-Toledano
authors.forename: Julieta
authors.initials: J
authors.lastname: Merida
authors.forename: Manuel
authors.initials: M
authors.lastname: Medina
mesh_terms: D003116:Color; D003890:Desiccation; D005638:Fruit / Q000737:chemistry*; D015416:Maillard Reaction; D010636:Phenols / Q000032:analysis*; D011108:Polymers / Q000032:analysis; D013472:Sunlight; D027843:Vitis / Q000737:chemistry*; D014920:Wine
chemical_list: D010636:Phenols; D011108:Polymers