TY - JOUR
T1 - Detection of walnut residues in foods using an enzyme-linked immunosorbent assay
AU - Niemann, Lynn
AU - Taylor, Steve L.
AU - Hefle, Susan L.
PY - 2009/8
Y1 - 2009/8
N2 - Tree nuts, including walnuts, can be responsible for allergic reactions. Food manufacturers have the responsibility to declare the presence of walnuts on packaged foods even when trace residues may be present from the use of shared equipment or the adventitious contamination of ingredients. The aim of this study was to develop a rapid, sensitive, and specific enzyme-linked immunosorbent assay (ELISA) method for the detection of walnut protein residues. Mixtures of raw and roasted English walnuts of several varieties were defatted, powdered, and used as separate antigens in sheep and New Zealand white rabbits. An ELISA was developed using the sheep antiroasted walnut serum as the capture reagent and rabbit antiroasted walnut serum as the detector reagent followed by addition of commercial goat anti-rabbit IgG antibody labeled with alkaline phosphatase and subsequent substrate addition. The performance of the ELISA was validated by testing known amounts of walnut (0 to 100 ppm) either spiked into or manufactured into milk chocolate, cookies, muffins, or ice cream. Recoveries of 1 to 100 ppm walnutin-chocolate ranged from 71.6% to 119% ± 7% to 16.5%. The walnut ELISA has a detection limit of 1 ppm (1 μg/g) walnut in several food matrices. Substantial cross-reactivity was observedwith pecan while minimal cross-reactivity was noted for hazelnut, mustard, mace, and poppy seed among almost 100 foods and food ingredients tested. This walnut ELISA can be used to detect undeclared walnut residues in foods and ingredients and as a tool to validate the effectiveness of allergen control programs for walnuts.
AB - Tree nuts, including walnuts, can be responsible for allergic reactions. Food manufacturers have the responsibility to declare the presence of walnuts on packaged foods even when trace residues may be present from the use of shared equipment or the adventitious contamination of ingredients. The aim of this study was to develop a rapid, sensitive, and specific enzyme-linked immunosorbent assay (ELISA) method for the detection of walnut protein residues. Mixtures of raw and roasted English walnuts of several varieties were defatted, powdered, and used as separate antigens in sheep and New Zealand white rabbits. An ELISA was developed using the sheep antiroasted walnut serum as the capture reagent and rabbit antiroasted walnut serum as the detector reagent followed by addition of commercial goat anti-rabbit IgG antibody labeled with alkaline phosphatase and subsequent substrate addition. The performance of the ELISA was validated by testing known amounts of walnut (0 to 100 ppm) either spiked into or manufactured into milk chocolate, cookies, muffins, or ice cream. Recoveries of 1 to 100 ppm walnutin-chocolate ranged from 71.6% to 119% ± 7% to 16.5%. The walnut ELISA has a detection limit of 1 ppm (1 μg/g) walnut in several food matrices. Substantial cross-reactivity was observedwith pecan while minimal cross-reactivity was noted for hazelnut, mustard, mace, and poppy seed among almost 100 foods and food ingredients tested. This walnut ELISA can be used to detect undeclared walnut residues in foods and ingredients and as a tool to validate the effectiveness of allergen control programs for walnuts.
KW - Allergy
KW - ELISA
KW - Immunoassay
KW - Walnut
UR - http://www.scopus.com/inward/record.url?scp=70350136016&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=70350136016&partnerID=8YFLogxK
U2 - 10.1111/j.1750-3841.2009.01214.x
DO - 10.1111/j.1750-3841.2009.01214.x
M3 - Article
C2 - 19723237
AN - SCOPUS:70350136016
SN - 0022-1147
VL - 74
SP - T51-T57
JO - Journal of food science
JF - Journal of food science
IS - 6
ER -