Factors affecting sample preparation in the gas chromatographic determination of plant sterols in whole wheat flour

A fractional factorial experimental design was applied to study factors aff ecting sample preparation prior to a gas chromatographic determination of t otal plant sterols in cereal samples. Whole wheat flour was chosen for the representative matrix. Altogether six factors were studied at two levels. T he most affecting factors were a type of hydrolysis (combined acid hydrolys is and alkaline hydrolysis over alkaline hydrolysis alone), extraction solv ent after saponification (chloroform over hexane-ether), and sample amount (1.0 g over 2.0 g). Also, it was shown that there is no need to perform tot al lipid extraction prior to hydrolysis. The use of acid hydrolysis prior t o alkaline saponification was found to be essential in a plant sterol analy sis of flour matrix. In a further method development, that procedure is to be optimized with various foods of plant origin in order to establish a gen eral method to determine plant sterols. Toivo et al., Factors in the determ ination of plant sterols (C) 1999 Elsevier Science Ltd. All rights reserved .