DETECTION OF BREAD WHEAT FARINA ADULTERANT IN DURUM-WHEAT SEMOLINA AND PASTA DRIED AT LOW, HIGH, AND ULTRA-HIGH TEMPERATURES

Methods were developed to detect adulteration in durum wheat pasta by bread wheat farina. Adulteration can be detected when sterol palmitate s (campesterol and beta-sitosterol) are found in farina but not in sem olina, as has been reported for wheats grown in the United States. A n ew method using reverse-phase high-performance liquid chromatography ( RP-HPLC) was developed to measure sterol palmitates. The sterol palmit ates in farina adulterant become chemically bound during pasta making. They are found in low amounts in petroleum ether extracts previously used to determine adulteration of semolina. Three polar solvents (chlo roform-methanol, chloroform-methanol-water [C-M-W], and water-saturate d n-butanol) extracted the bound sterol palmitates from pasta. Only th e extracts with C-M-W proved to be satisfactory for measuring sterol p almitates by gas chromatography (GC) or RP-HPLC. Adulterated pasta sam ples (0-100% farina), dried at low, high, and ultra-high temperatures, were prepared for testing the adulteration methods. Sterol palmitate content in the pasta samples was determined in C-M-W extracts using th e new RP-HPLC method and the GC method of Hsieh et al (1981). Adultera tion levels down to about 3% were detected in our pasta test samples m ade with U.S. wheat varieties. In farina from 97 bread wheat varieties , six soft cake wheat varieties currently grown in the U.S. and Canada , and two soft wheat varieties from Italy, sterol palmitate content va ried from 17 to 44 mg/100-g sample; that of farina from the Canadian v ariety Glenlea was 8.9 mg/100-g sample. In semolina from 40 durum whea t varieties (29 from the U.S. and Canada, five from Mexico, and six fr om Italy), sterol palmitate content varied from 0 to 0.7 mg/100g sampl e. Thus, our results confirm the observations of earlier workers that analysis for sterol palmitate content can be used to detect adulterati on in pasta made from U.S. wheats.