Assessment of amino acids and total soluble solids in intact grape berries using contactless Vis and NIR spectroscopy during ripening

• Published in: Talanta (Oxford) 2019-07, Vol.199, p.244-253
• Main Authors: Fernández-Novales, Juan, Garde-Cerdán, Teresa, Tardáguila, Javier, Gutiérrez-Gamboa, Gastón, Pérez-Álvarez, Eva Pilar, Diago, María Paz
• Format: Article
• Language: English
• Subjects: Amino acids; Grape; HPLC; NIR spectroscopy; Nitrogen; Partial least squares; Total soluble solids
• ISSN: 0039-9140; 1873-3573
• DOI: 10.1016/j.talanta.2019.02.037

The amino acid concentration assessment along grape ripening would provide valuable information regarding harvest scheduling, wine aroma potential and must nitrogen supplement addition. In this work the use of Visible (Vis) and near-infrared (NIR) spectroscopy to estimate the grape amino acid content along maturation on intact berries was investigated. Spectral data on two ranges (570–1000 and 1100–2100 nm) were acquired contactless from intact Grenache berries. A total of 22 free amino acids in 128 grape clusters were quantified by HPLC. Partial least squares was used to build calibration, cross validation and prediction models. The best performances (R2P ~ 0.60) were found for asparagine (SEP: 0.45 mg N/l), tyrosine (SEP: 0.33 mg N/l) and proline (SEP: 17.5 mg N/l) in the 570–1000 nm range, and for lysine (SEP: 0.44 mg N/l), tyrosine (SEP: 0.26 mg N/l), and proline (SEP: 15.54 mg N/l) in the 1100–2100 nm range. Remarkable models (R2P~0.90, SEP~1.60 ºBrix, and RPD~3.79) were built for total soluble solids in both spectral ranges. Contactless, non-destructive spectroscopy could be an alternative to provide information about grape amino acids composition. [Display omitted] •Contactless Vis-NIR spectroscopy to assess the amino acids and TSS in grape berries.•Comparison of the applicability of two different proximal spectroscopy sensors.•Sufficient predictive capacity to classify grape berries along the ripening process.