Interfering substances in the colorimetric quantitation of grape monoterpenes

• Published in: HortScience Vol. 29; no. 11; pp. 1335 - 1336
• Main Authors: Benoteau, G. (Ecole Superieure d'Agriculture d'Angers, Angers, France.), Reynolds, A.G
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Alexandria, VA American Society for Horticultural Science 01.11.1994
• Subjects: Agronomy. Soil science and plant productions; Biological and medical sciences; COLORIMETRIA; COLORIMETRIE; colorimetry; COMPOSE VOLATIL; COMPUESTO VOLATIL; cultivar identification; ENSAYO DE SEMILLAS; ESSAI DE SEMENCES; FRUITS; FRUTAS; Fundamental and applied biological sciences. Psychology; General agronomy. Plant production; Generalities. Agricultural and farming systems. Agricultural development; Generalities. Production, biomass, yield. Quality; MONOTERPENE; monoterpenoids; MONOTERPENOS; RAISIN DE CUVE; TERPENOIDE; TERPENOIDOS; UVAS PARA VINO; VARIEDADES; VARIETE; VITIS VINIFERA; volatile compounds; wine cultivars; Volatile compound; Color; Interference; Colorimetry; Aldehyde; Flavor; Vitis vinifera; Viticulture; Spectral data; Terpene; Absorbance; Fruit crop; Vitidaceae; Dicotyledones; Intercompound effect; Angiospermae; Monoterpene; Spermatophyta; Chemical concentration; Aroma; Vanillin; Quantitative analysis; Cultivar
• ISSN: 0018-5345; 2327-9834
• DOI: 10.21273/HORTSCI.29.11.1335

The potential for interference by specific C6 compounds in the colorimetric quantitation of grape (Vitis vinifera L.) monoterpenes was investigated in model solutions and muscat and neutral-flavored grape cultivars. The unsaturated C6 aldehyde 2-hexen-1-al (2HX) showed color absorption at 608 nm in distilled water after reaction with an acidified vanillin solution. Absorbance also increased significantly when 2HX was added to a series of linalool solutions; approximately 2.5 mg 2HX per liter of a 1-mg.liter-1 linalool solution increased the absorbance by 10%. Adding 2.5 mg 2HX per kilogram of 'Gewurztraminer' berry homogenate significantly increased apparent free volatile terpene (FVT) concentrations to 121% of unadulterated control treatments but did not affect potentially volatile terpenes (PVT). Adding 2HX also increased apparent FVT concentration in 'Perlette' and 'Flame Seedless'. Both neutral-flavored table grape cultivars contained some FVT and PVT as a consequence of their muscat ancestries. FVT and PVT quantitation by colorimetric methods may be subject to significant error if the concentration of 2HX and other unsaturated C6 compounds in grape berries or must are 5 mg liter-1. However, low concentrations of unsaturated C6 compounds (80 micrograms.liter-1) in British Columbia wines suggest that there is a low probability of significant interference with this method