Variability in spectrophotometric pyruvate analyses for predicting onion pungency and nutraceutical value.
Onion pyruvate concentration is used as a predictor of flavor intensity and nutraceutical value. The protocol of Schwimmer and Weston (SW) (1961) is the most widespread methodology for estimating onion pyruvate. Anthon and Barret (AB) (2003) proposed modifications to this procedure. Here, we compared these spectrophotometry-based procedures for pyruvate analysis using a diverse collection of onion cultivars. The SW method always led to over-estimation of pyruvate levels in colored, but not in white onions, by up to 65%. Identification of light-absorbance interfering compounds was performed by spectrophotometry and HPLC analysis. Interference by quercetin and anthocyanins, jointly, accounted for more than 90% of the over-estimation of pyruvate. Pyruvate determinations according to AB significantly reduced absorbance interference from compounds other than pyruvate. This study provides evidence about the mechanistic basis underlying differences between the SW and AB methods for indirect assessment of onion flavor and nutraceutical value.
Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Av. Rivadavia 1917, Buenos Aires C1033AAJ, Argentina. Electronic address: vanesaberetta@hotmail.com.
Vanesa H
VH
Beretta
Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Av. Rivadavia 1917, Buenos Aires C1033AAJ, Argentina. Electronic address: flonur@hotmail.com.
Florencia
F
Bannoud
Instituto Nacional de Tecnología Agropecuaria (INTA), Instituto de Biotecnología, CC77, Hurlingham, Buenos Aires, Argentina. Electronic address: insani.ester@inta.gob.ar.
Marina
M
Insani
Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Av. Rivadavia 1917, Buenos Aires C1033AAJ, Argentina; Facultad de Ciencias Agrarias, Universidad Nacional de Cuyo, Almirante Brown 500, Luján de Cuyo, Mendoza 5505, Argentina; Instituto Nacional de Tecnología Agropecuaria (INTA) - E.E.A. La Consulta, Ex Ruta 40, km 96, La Consulta CC8, San Carlos, Mendoza 5567, Argentina. Electronic address: galmarini.claudio@inta.gob.ar.
Claudio R
CR
Galmarini
Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Av. Rivadavia 1917, Buenos Aires C1033AAJ, Argentina; Facultad de Ciencias Agrarias, Universidad Nacional de Cuyo, Almirante Brown 500, Luján de Cuyo, Mendoza 5505, Argentina; Instituto Nacional de Tecnología Agropecuaria (INTA) - E.E.A. La Consulta, Ex Ruta 40, km 96, La Consulta CC8, San Carlos, Mendoza 5567, Argentina. Electronic address: pablocavagnaro@hotmail.com.
Pablo F
PF
Cavagnaro
D002851:Chromatography, High Pressure Liquid / Q000379:methods; D019697:Onions / Q000737:chemistry*; D019289:Pyruvic Acid / Q000032:analysis*; D015203:Reproducibility of Results; D013053:Spectrophotometry; D013649:Taste
D019289:Pyruvic Acid
Allium cepa; HPLC; Onion; Pungency; Pyruvate; Spectrophotometry