Improved ovalbumin accurate quantitative performance in processed foods by full-length isotope-labeled protein.

Ovalbumin (OVA) is a high-risk allergen with complex tertiary structure in food samples. Here, we developed an accurate UPLC-MS/MS-based assay to improve OVA quantitative performance in processed foods. Full-length isotope-labeled OVA proteins (OVA-I) were synthesized using stable isotope labeling by amino acids in cell culture (SILAC) technique and employed as functional internal standards to ensure similar cleavage sites between internal standards and analytes. Subsequently, OVA and OVA-I fully expose their key cleavage sites by using 10 mol/L urea denaturation to correct errors caused by structural variations in different food matrices, the possible denaturation mechanism was also explored. Three quantitative peptides were selected for OVA detection, achieving 88 %-117 % recoveries with RSDs <9.36 % across three different spiking levels. The LOQs were set as 5 μg/g. OVA risk assessment in Chinese general population exhibited high exposure risks with intake level of most processed foods ranged from 0.35 to 215.66 mg.