Effect of extraction temperature on the gelling properties and identification of porcine gelatin

High-performance liquid chromatography (HPLC) and linear-ion trap (LTQ)/Orbitrap high-resolution mass spectrometry were used to identify porcine gelatins extracted at different temperatures. Moreover, shear stress rheological detection techniques and a texture analyzer were applied to evaluate the gelling properties of various porcine gelatins. The results showed that, with an increased in the extraction temperature, the gel strength, gelation point and melting point of the porcine gelatin gradually decreased, indicating that the temperature significantly affected the gelling properties of gelatin. HPLC- LTQ/Orbitrap high-resolution mass spectrometry indicated that porcine gelatins prepared at different extraction temperatures also showed internal uniqueness, namely, diverse marker peptides for gelatin identification. Compared with the established theoretical sequence fragment database of porcine gelatin and bovine gelatin, 64, 74 and 71 tryptic porcine peptides in gelatins were extracted at 55 °C, 65 °C and 75 °C, respectively. Notably, regardless of the extraction temperature, 47 common peptides were detected in the tryptic hydrolysates of porcine gelatins. Using these common tryptic peptides can effectively improve the accuracy of the porcine gelatin identification.