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.
Yan Lu,Jinxia Dai,Sen Zhang,Junqin Qiao,Hongzhen Lian,Li Mao
It is widely acknowledged that casein is an important allergenic protein in milk which may cause danger to customers. The identification and confirmation of caseins through mass spectrometry requires the selection of suitable characteristic peptides. In this study, by means of matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS), the three most representative specific peptides of caseins in cow milk were screened out with mass-to-charge ratios (m/z) of 830, 1195, and 1759, respectively. By comparing 2,5-dihydroxybenzoic acid (DHB) andα-cyano-4-hydroxycinnamic acid (CHCA) MALDI matrices, it was found that DHB was more suitable for peptide detection with the limits of detection (LODs) of 0.1 mg/L forα,β-casein. Furthermore, on the basis of verifying the characteristic peptides of casein from cow milk, this protocol was applied to goat milk authentication. Cow milk addition in goat milk was investigated by using the screened specific peptides. The results showed that the adulteration could be identified when the proportion of cow milk was 1% or more. When applied to inspect adulteration in five brands of commercial goat milk, specific peptides of bovine casein were detected in four of them. The method has the advantages of strong reliability, high throughput, simple preprocessing, and fast speed, which can provide powerful help for prewarning dairy allergen.Keywords:goat milk authentication;allergen;bovine casein;specific peptide;matrix-assisted laser desorption ionization time-of-flight mass spectrometry
危险品化学品经营许可证（带存储）