A real-time PCR method for quantifying mixed cashmere and wool based on hair mitochondrial DNA

Cashmere, a kind of luxury fiber obtained from cashmere goat, is characterized by its fineness, lightness, and softness. Products made of cashmere are much more expensive than those of sheep wool, so adulteration and false declaration occur quite often in the industrial chain. We here describe a method for quantifying cashmere and wool mixture based on mitochondrial DNA extracted from natural or processed animal hair. Two sets of TaqMan polymerase chain reaction (PCR) primers and probes that can react specifically to goat and sheep mitochondrial 12 S ribosomal (rRNA) genes were designed. The two systems exert almost the same amplification rate. Cashmere collected from different producing areas of China, and cashmere from individual goats of different age were employed to verify the method, and no significant difference was found between different cashmere samples, which proved that the copy number of mitochondrion has little impact on quantifying results. Thus, the method can be applied to quantify each component in a cashmere/wool mixture. The method will also be of great value in inspection of the quality of cashmere products on the world markets.