Determinación del contenido en polifenoles en uva de mesa mediante tecnología NIRS.

Abstract

Phenolic compounds of red grape come from its skin. Polyfhenols are important for the physiology of grapes since they contribute to the resistance of insects and microorganisms and help to preserve grapes integrity due to their continue exposure to environment stresses including ultraviolet radiation and relatively high temperatures. Polyphenols are much related to the organoleptic properties of table grapes. In general, the techniques used to determine these compounds are usually destructive being the more commonly used the refractometer and colorimetry or the use of high performance liquid chromatography (HPLC). Near infrared (NIR) spectroscopy is a non-destructive method able to determine polyphenolic compounds. In this research, NIR spectroscopy was used to measure the polyphenol content in table grape of ‘Crimson’ variety produced in ‘Herdade Vale da Rosa’ from the Ferreira do Alentejo area located at the south of Portugal. These table grapes were harvested in September 2010 using HPLC as a reference method. In addition, their Brix content, colour and pulp and skin weight was determined. The data obtained was analysed with Unscrambled software in order to find a model capable of predicting the content of polyphenols, Brix, colour and skin. The different models obtained have allowed us predicting with a r value between 0.76 and 0.96.