In order to obtain carminic acid by new extraction techniques,
pressurised liquid extraction (PLE) and supercritical fluid extraction
(SFE) were tested. When using PLE and SFE, a red carminic acid
precipitate was directly obtained, which is an important advantage
from an industrial point of view, because this dye presents better
stability in the solid state. Carminic acid yields (related to cochineal
weight) were significantly higher in the pressurised liquid extraction
(42.4%) and supercritical fluid extraction (39.4%) compared
with conventional solid–liquid extraction yields studied previously
(18.5%). Fig. 10 shows the IR spectra of the solid extract obtained
from pressurised liquid extraction and supercritical fluid extraction
treatment of the cochineal samples studied compared with that obtained
for the carminic acid commercial standard. Both extracts of
carminic acid (in the solid state obtained) show the characteristic
peaks (Cañamares, García-ramos, Domingo, & Sanchez-Cortes,
2006) of the carminic acid commercial standard, summarised in
Table 1. Protein contents in solid extracts obtained from both techniques
were significantly low. The best SFE extraction results were
found for methanol/water and ethanol/water as solvents at 100 and
150 C respectively. Methanol (as modifier) was used for the SFE
extraction technique, giving similar carminic acid yields for all
extraction pressure levels studied.