Development of a Mass Spectrometry-Based Method for Quantification of Total Cashew Protein in Roasting Oil.

Background: Food allergen cross-contact during food preparation and production is one of the causes of unintentional allergen presence in packaged foods. However, little is known about allergen cross-contact in shared frying or roasting oil, which prevents the establishment of effective allergen controls and may put allergic individuals at risk. To better understand the quantity of allergen transferred to frying oil and subsequent products, an analytical method is needed for quantifying protein in oil that has been exposed to frying/roasting conditions.

Objective: The goal of this study was to develop a parallel reaction monitoring LC-MS/MS method to quantify the amount of cashew protein in shared roasting oil.

Methods: The sample preparation method was evaluated to improve protein extractability and peptide performance. Four quantitative peptides representing cashew 2S and 11S proteins were selected as targets based on their sensitivity, heat stability, and specificity. A calibration strategy was developed to quantify the amount of total cashew protein in oil. Method performance was evaluated using a heated cashew-in-oil model system.

Results: The method showed high recovery in oil samples spiked with 100 or 10 parts per million (ppm) total cashew protein heated at 138 or 166°C for 2-30 min. Samples (100 ppm total cashew protein) heated for 30 min had more than 90% recovery when treated at 138°C and more than 50% when heated at 166°C.

Conclusion: The method is fit-for-purpose for the analysis of cashew allergen cross-contact in oil.

Highlights: A novel MS-based method was developed that can accurately quantify the amount of cashew protein present in heated oil.