title: Phenolic composition of Tempranillo wines following early defoliation of the vines.
abstract: BACKGROUND
  Early defoliation is a viticultural practice aimed at crop control. So far, the impact of early leaf removal on the monomeric phenolic composition of wines has not been explored. This study examines the effects of early defoliation on the phenolic profile and content in Tempranillo wines. The influence of the defoliation method (manual vs mechanical) and the timing of leaf removal (pre-bloom vs fruit set) was investigated.
  
  
  RESULTS
  Over two consecutive seasons, 2007 and 2008, the monomeric phenolic composition in Tempranillo wines was studied by high-performance liquid chromatography with photodiode array detection, and 22 compounds were identified and quantified. Overall, early defoliation led to wines more intensely coloured, of higher alcohol content and with larger concentrations of hydroxycinnamic acids, flavonols and anthocyanins (in 2008 only for mechanical treatments). In the absence of fungal infection, resveratrol was found to increase in wines corresponding to early defoliation treatments. The method of leaf removal seemed to be more critical than the timing of intervention, and larger effects on wine phenolic composition were observed for mechanical treatments.
  
  
  CONCLUSIONS
  Early defoliation proved to be an effective technique for improving the phenolic composition of Tempranillo wines, by favouring the accumulation of hydroxycinnamics, flavonols and anthocyanins. This is an important achievement, as wine quality is often described by its colour and phenolic attributes.
authors.affiliation: Instituto de Ciencias de la Vid y del Vino (University of La Rioja, CSIC, Gobierno de La Rioja), Logroño, La Rioja, Spain. maria-paz.diago@aurea.unirioja.es
authors.forename: Maria P
authors.initials: MP
authors.lastname: Diago
authors.forename: Belén
authors.initials: B
authors.lastname: Ayestarán
authors.forename: Zenaida
authors.initials: Z
authors.lastname: Guadalupe
authors.forename: Álvaro
authors.initials: Á
authors.lastname: Garrido
authors.forename: Javier
authors.initials: J
authors.lastname: Tardaguila
mesh_terms: D000383:Agriculture / Q000379:methods*; D000872:Anthocyanins / Q000032:analysis / Q000737:chemistry; D002851:Chromatography, High Pressure Liquid; D003373:Coumaric Acids / Q000032:analysis; D000431:Ethanol / Q000032:analysis; D005285:Fermentation; D044948:Flavonols / Q000032:analysis / Q000737:chemistry; D005511:Food Handling; D005638:Fruit / Q000737:chemistry / Q000254:growth & development*; D006027:Glycosides / Q000032:analysis; D010636:Phenols / Q000032:analysis* / Q000737:chemistry; D010860:Pigments, Biological / Q000032:analysis; D011786:Quality Control; D000077185:Resveratrol; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D013030:Spain; D013267:Stilbenes / Q000032:analysis; D027843:Vitis / Q000737:chemistry / Q000254:growth & development*; D014920:Wine / Q000032:analysis* / Q000382:microbiology
chemical_list: D000872:Anthocyanins; D003373:Coumaric Acids; D044948:Flavonols; D006027:Glycosides; D010636:Phenols; D010860:Pigments, Biological; D013267:Stilbenes; D000431:Ethanol; D000077185:Resveratrol