Cereal Chem. 70:405- 411   |  VIEW ARTICLE

Detection of Bread Wheat Farina Adulterant in Durum Wheat Semolina and Pasta Dried at Low, High, and Ultra-High Temperatures.

M. Sarwar and C. E. McDonald. Copyright 1993 by the American Association of Cereal Chemists, Inc. 

Methods were developed to detect adulteration in durum wheat pasta by bread wheat farina. Adulteration can be detected when sterol palmitates (campesterol an beta-sitosterol) are found in farina but not in semolina, as has been reported for wheats grown in the United States. A new method using reverse-phase high-performance liquid chromatography (RP-HPLC) was developed to measure sterol palmitates. The sterol palmitates 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 (chloroform-methanol, chloroform-methanol-water [C-M-W], and water-saturated n-butanol) extracted the bound sterol palmitates from pasta. Only the extracts with C-M-W proved to be satisfactory for measuring sterol palmitates by gas chromatography (GC) or RP-HPLC. Adulterated pasta samples (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 the new RP-HPLC method and the GC method of Hsieh et al (1981). Adulteration levels down to about 3% were detected in our pasta test samples made 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 varied from 17 to 44 mg/100-g sample; that of farina from the Canadian variety Glenlea was 8.9 mg/100-g sample. In semolina from 40 durum wheat varieties (29 from the U.S. and Canada, five from Mexico, and six from Italy), sterol palmitate content varied from 0 to 0.7 mg/100-g sample. Thus, our results confirm the observations of earlier workers that analysis for sterol palmitate content can be used to detect adulteration in pasta made from U.S. wheats.