Proteomic Analysis of Oil-Roasted Cashews Using a Customized Allergen-Focused Protein Database

Cashews are one of the most prevalent
causes of tree nut allergies. However, the cashew proteome is far
from complete, which limits the quality of peptide identification
in mass spectrometric analyses. In this study, bioinformatics tools
were utilized to construct a customized cashew protein database and
improve sequence quality for proteins of interest, based on a publicly
available cashew genome database. As a result, two additional isoforms
for cashew 2S albumins and five other isoforms for cashew 11S proteins
were identified, along with several other potential allergens. Using
the optimized protein database, the protein profiles of cashew nuts
subjected to different oil-roasting conditions (139 and 166 °C
for 2–10 min) were analyzed using discovery LC-MS/MS analysis.
The results showed that the cashew 2S protein is most heat-stable,
followed by 11S and 7S proteins, though protein isoforms might be
affected differently. Preliminary target peptide selection indicated
that out of the 29 potential targets, 18 peptides were derived from
the newly developed database. In the evaluation of thermal processing
effects on cashew proteins, several Maillard reaction adducts were
also identified. The cashew protein database developed in this study
allows for comprehensive analyses of cashew proteins and development
of high-quality allergen detection methods.