ANALYSIS OF VOLATILE COMPOUNDS FROM SUPERCRITICAL EXTRACTED SOYBEANS BY HEADSPACE GAS-CHROMATOGRAPHY AND THERMAL-DESORPTION OF A POLYMER ADSORBENT

Soybean flakes were extracted with supercritical carbon dioxide to produce a solvent-free, good-quality soybean oil. Volatile compounds from the supercritical fluid extracted (SFE) oil and from a hexane-extracted crude soybean oil were analyzed by dynamic headspace gas chromatographic methods to determine qualitative differences between the extraction methods. The major difference in the-volatile profiles was the higher concentration of hexane in the solvent-extracted oil. During the SFE process, volatile compounds were trapped on a porous polymer trap attached at the exhaust port of the SFE apparatus. The volatile profile obtained from the sorbent trap was found to be similar to the headspace profile from the SFE/soybean oil removed during the same extraction. In addition, crude soybean oil was heated in a stirred reactor and the volatiles, which were stripped by supercritical carbon dioxide in an attempt to improve oil properties, were collected on sorbent traps and analyzed by the above method for comparison. The described methodology permits the characterization of volatiles and semivolatiles in SFE soybean oil and can be used to monitor the extraction and quality of the resultant oil.