Production and characterization of rabbit polyclonal antibodies to almond (Prunus dulcis L.) major storage protein.

Rabbits were immunized with purified almond major protein (AMP), the primary storage protein in almonds. Rabbit anti-AMP polyclonal antibodies (PA) could detect AMP when as little as 1-10 ng/mL were used to coat microtiter plates in a noncompetitive enzyme linked-immunosorbent assay (ELISA). Competitive inhibition ELISA assays detected the AMP down to 300 ng/mL. PA recognized the AMP in protein extracts from all U.S. major marketing cultivars of almonds (Mission, Neplus, Peerless, Carmel, and Nonpareil) with specific reactivity of 52.6-75% as compared to that of the AMP alone. Immunoreactivity of protein extracts prepared from commercial samples of blanched almonds, roasted almonds, and almond paste was respectively reduced by 50.0%, 56.6%, and 68.4% (noncompetitive ELISA) when compared to the immunoreactivity of the AMP. Moist heat (121 degrees C, 15 min) pretreatment of the AMP reduced the PA reactivity by 87% (noncompetitive ELISA). Exposing AMP to pH extremes (12.5 and 1.5-2.5) caused a 53% and 57% reduction in PA reactivity, respectively (noncompetitive ELISA). PA showed some cross-reactivity with the cashew major globulin, and to a lesser extent, the Tepary and Great Northern bean major storage protein (7S or phaseolin). The presence of almonds in a commercial food was detected using PA in a competitive ELISA.