Reversed-phase high-performance liquid chromatography applied to the determination of soybean proteins in commercial heat-processed meat products

A reversed-phase chromatographic method has been developed and optimised in order to detect and quantitate soybean proteins in commercial heat-processed meat products. The optimised conditions consisted of a linear binary gradient tetrahydrofurane–water–0.05% trifluoroacetic acid at a flow rate of 1 mL/min. Meat products were defatted with acetone and soybean proteins were extracted with a buffered solution at pH 9.60. The injection of this extract into the chromatographic system enabled the detection of soybean proteins in heat-processed meat products in about 12 min. The method enabled the detection and quantitation of additions of 0.38% (w/w) and 0.63% (w/w), respectively, of soybean proteins (related to 10 g of initial product). The method has been proven to be precise with relative standard deviations (R.S.D.) for repeatability, intermediate precision, and internal reproducibility lower to 7.0%. Recoveries obtained for spiked meat products were close to 100% and no matrix interferences were observed. The application of the method to commercial heat-processed meat products in whose formulation soybean proteins were present yielded soybean protein contents ranging from 0.90% to 1.54%, below the maximum levels established by regulations.