Changes in physical properties and characteristic peptides in porcine gelatin-containing gummy candies at different storage stages during shelf-life

The physical properties and gelatin identification of gummy candies could be affected in the storage process by acid hydrolysis and glycation reaction. In this work, the physical properties including texture, color, appearance and molecular weight distribution were evaluated in the porcine gelatin-containing gummy candies that were stored under the accelerated model at different storage stages. In addition, the characteristic peptides of porcine gelatin were identified by high performance liquid chromatography and linear ion trap/Orbitrap MS/MS (HPLC-LTQ/Orbitrap MS/MS) to investigate their changes. The results showed that hydrolysis was the main reaction in the early stage of storage. The hardness, gumminess, chewiness and high molecular weight peptides content of gummy candies decreased greatly with the extension of storage time. Free amino groups were produced by gelatin hydrolysis to promote glycation and glycosidic bond. In the later stage of storage, glycation was dominant, which led to the decrease of low molecular weight peptides. Moreover, HPLC-MS/MS identified 275, 260, 243, 248 and 257 characteristic peptides of porcine gelatin from gummy candies treated by the accelerated model in 0, 14, 28, 42 and 56 days, respectively. Among them, 130 characteristic peptides were found to remain unchanged during the shelf-life of gummy candies. By further comparison with the identification under various food processing conditions, 6 stable characteristic peptides were reserved until the end. They could provide the basis for the subsequent traceability of porcine gelatin.