New progress in the extraction and identification of Mexican cochineal (Dactylopius coccus) in fresh dyed wool and dyed wool with artificially accelerated aging and color description

Abstract

The main purpose of this study was to determine if a method developed in the laboratory by HPLC‐ESI‐QToF was able to identify the characteristic compounds of the Mexican cochineal (Dactylopius coccus) in freshly dyed wool fiber and following an artificially accelerated aging process. Wool fibers were dyed with various formulations of popular interest (red‐orange, Mexican red, cochineal red, and purple). These formulations are currently used by indigenous communities in the south of Mexico. Some dyed wools were aged in an UV chamber, in order to simulate the deterioration that a fiber dyed in a previous time could have. Notable results were the identification of the main component, carminic acid, and the respective biomarkers of the Mexican cochineal (dcII, dcIV, and dcVII) with a small amount of sample and in a short time, in three of the four formulations before and after aging, thus providing a method that can probably be used for conservation purposes of cultural heritage. It was concluded that when alum is used as a mordant and as a carbonate pH fixer, the fixation of cochineal on the wool is not very strong. This is one of the few works where Mexican cochineal has been studied, simulating the deterioration due to the passage of time in wool samples of different colors with the same natural dye. As a way of describing the color more objectively, the color was measured with the CIE L*A*B* scale in the four formulations of interest, in recently dyed and artificially aged wool.