POSSIBILITIES AND LIMITATIONS OF SFE IN THE EXTRACTION OF AFLATOXIN-B1 FROM FOOD MATRICES

Extraction studies of aflatoxin B1 from animal feed demonstrate the advantages and limits of present-day equipment for supercritical fluid extraction (SFE). With pure carbon dioxide it is possible to remove the lipid constituents at low densities and extract the more polar aflatoxin at higher pressures. Densities above 1.072 g/mL or pressures above 820 atm (at 40°C) are required to extract aflatoxin at reasonable yields. The addition of methanol as modifier can help to circumvent this problem, but will decrease the selectivity of the extraction. Problems caused by plugging and cracking of restrictors, resulting in bad reproducibility, are described. Means to circumvent these problems are discussed. The limitations of SFE of aflatoxin stem from its low solubility in CO2, adsorption on the matrix constituents, and slow diffusion out of the matrix, due to the low swelling properties of CO2. The latter problem can be partially solved by macerating the matrix in solvents used for classical extraction. After evaporation of these solvents, the extraction yield of aflatoxins is improved considerably. This method combines the solvation power of liquid solvents with the extraction selectivity of SFE. © 1993 OUP Publishing Ltd.