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

Juan Fernández-Novales; Teresa Garde-Cerdán; Javier Tardáguila; Gastón Gutiérrez-Gamboa; Eva Pilar Pérez-Álvarez; María Paz Diago

doi:10.1016/j.talanta.2019.02.037

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

Talanta. 2019 Jul 1:199:244-253. doi: 10.1016/j.talanta.2019.02.037. Epub 2019 Feb 8.

Authors

Juan Fernández-Novales¹, Teresa Garde-Cerdán², Javier Tardáguila³, Gastón Gutiérrez-Gamboa⁴, Eva Pilar Pérez-Álvarez⁵, María Paz Diago³

Affiliations

¹ University of La Rioja, Department of Agriculture and Food Science, Madre de Dios, 53, 26006 Logroño, La Rioja, Spain; Instituto de Ciencias de la Vid y del Vino (CSIC, Universidad de La Rioja, Gobierno de La Rioja), Carretera de Burgos Km. 6, 26007 Logroño, La Rioja, Spain. Electronic address: juan.fernandezn@unirioja.es.
² Instituto de Ciencias de la Vid y del Vino (CSIC, Universidad de La Rioja, Gobierno de La Rioja), Carretera de Burgos Km. 6, 26007 Logroño, La Rioja, Spain. Electronic address: teresa.garde@icvv.es.
³ University of La Rioja, Department of Agriculture and Food Science, Madre de Dios, 53, 26006 Logroño, La Rioja, Spain; Instituto de Ciencias de la Vid y del Vino (CSIC, Universidad de La Rioja, Gobierno de La Rioja), Carretera de Burgos Km. 6, 26007 Logroño, La Rioja, Spain.
⁴ Instituto de Ciencias de la Vid y del Vino (CSIC, Universidad de La Rioja, Gobierno de La Rioja), Carretera de Burgos Km. 6, 26007 Logroño, La Rioja, Spain.
⁵ Centro de Edafología y Biología Aplicada del Segura (CEBAS), Campus Universitario Espinardo Ed. 25, 30100 Murcia, Spain.

PMID: 30952253
DOI: 10.1016/j.talanta.2019.02.037

Abstract

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 (R²_P ~ 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 (R²_P~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.

Keywords: Amino acids; Grape; HPLC; NIR spectroscopy; Nitrogen; Partial least squares; Total soluble solids.