Authors: Virginia GonzálezCaballero MaríaTeresa Sánchez Juan FernándezNovales MaríaIsabel López Dolores PérezMarín
Publish Date: 2012/03/14
Volume: 5, Issue: 6, Pages: 1377-1385
Abstract
This study evaluated the ability of nearinfrared NIR spectroscopy to characterise the behaviour of white and red grapes during onvine ripening as a function of grape position in the bunch high middle and low and bunch orientation north south east and west and to distinguish between different ripening stages with a view to optimising harvesting times depending on the grape variety and the type of wine to be made A total of 24 bunches of two winegrape varieties cv Pedro Ximénez and cv Cabernet Sauvignon were labelled and analysed directly on the vine using a commercially available handheld microelectromechanical system spectrophotometer 1600–2400 nm Principal component analysis was performed to study relationships between the various configurations grape position and bunch orientation ripening stages and spectral data Results for the whitegrape variety showed that grapes high on the bunch behaved differently during ripening from those in central or low positions and that eastfacing bunches behaved differently from the rest For both varieties analysis of bunch spectral characteristics enabled three stages of ripening to be distinguished early middle and late Subsequently the ability of NIR technology to classify wine grapes as a function of reducingsugar content with a view to optimising harvest timing was evaluated by partial least squares discriminant analysis 88 of white grapes and 88 of red grapes were correctly classified while over 79 of samples were correctly assigned to representative groups These results confirmed that NIR technology in the spectral range 1600–2400 nm is an appropriate technique for onvine monitoring of the ripening process enabling selective harvesting depending on the type of wine to be made
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