Targeted LC-MS Approach to Study the Evolution over the Harvesting Season of Six Important Metabolites in Fruits from Different Avocado Cultivars

Abstract

Herewith, a longitudinal study where the metabolic evolution of six relevant metabolites (p-coumaric, ferulic, chlorogenic, pantothenic and abscisic acids, and epicatechin) in four commercially important avocado varieties collected at different times over their harvest season is presented with the aim of evaluating the metabolic changes that take place during fruit development and maturation. The selection of these metabolites was based on the fact that they have been previously identified as potential varietal and/or ripening markers of avocado fruits and are produced by the phenylpropanoid pathway. Avocado metabolic profiles can be highly variable within a system, showing variations even from day to day. Thus, a longitudinal study design was selected to overcome possible negative effects of this variability on the interpretation of data, considering multiple sampling over time. A powerful HPLC-ESI-IT MS method was optimized and fully validated, and subsequently, a very unique sample selection (composed by 172 avocado extracts) was analyzed and the selected metabolites quantified. The content of pantothenic, p-coumaric, and ferulic acids was quite similar in the four avocado varieties studied. However, epicatechin, chlorogenic, and abscisic acid concentrations showed significant differences; ‘Bacon’ was the cultivar with the highest content of chlorogenic acid, ‘Hass’ and ‘Bacon’ of epicatechin, and ‘Fuerte’ and ‘Reed’ were the richest in terms of abscisic acid.