The presence of hidden nut and tree nut allergens in foods can result in serious

health issues, necessitating a method capable of detecting and quantifying them at

trace levels using a single robust assay. To find specific peptide markers that can

be

used to determine the presence or absence of specific nuts in food, proteins unique

to

11 tree nuts (almond, pecan, cashew, walnut, hazelnut, pine nut, brazil nut,

macadamia nut, pine nut, chestnut, and coconut) and peanut were enzymatically

digested and analyzed using accurate

-

mass Q

-

TOF LC/MS. Each marker peptide was

selected by establish

ing its presence in raw and roasted nuts, processed and

unprocessed food, abundance (sensitivity), sequence size, and uniqueness to a

specific nut. The National Center for Biotechnology Information (NCBI) nr database

searches were performed to confirm pep

tide identities, and to ensure that the

marker peptides chosen were not present in other nuts or common food ingredients

such as barley, corn, rice, soy, and wheat. Two marker peptides were selected for

each tree nut, and four were selected for peanuts. An

alysis of peptide digests from

grains such as barley, corn, rice, quinoa, soy, and wheat did not present interfer

-

ences. The peptide markers were tested to determine if they could be used to

screen common foods for the presence of the 11 tree nuts and pea

nut at sub

-

ppm

levels. Foods containing nuts as listed on the label showed a response for the cor

-

rect nut. Foods processed using equipment also used to process other tree nuts or

peanuts were in certain cases found to contain these other nuts.