Among vegetable foods peach (Prunus persica) has been recognized as a significant cause of allergy. The protein, which is considered to be the major peach allergen, has been named Pru p 1. Because peaches are consumed both as fresh fruits and after processing to obtain peach juice, nectar, jam, syrupy peach, etc., research was carried out to identify a technological process for production of hypo- or nonallergenic peach-based products. SDS-PAGE and immunoblotting analysis of extracts prepared from four commercial peach nectars showed that the Pru p 1 was not removed, and neither was its allergenic activity decreased by technological treatments carried out for nectar production. Some treatments oriented toward a removal of or, at least, a decrease in the allergenic power were assumed and verified at laboratory scale. A variable considered was heat treatment at 121 degrees C for 10 and 30 min: this treatment was not able to decrease the allergenicity of the Pru p 1 protein. Furthermore, the protein band was still present even after 60-min reaction with two different acidic proteases. The two technological treatments that were found to decrease the major allergen of peach were chemical lye peeling of fruits and ultrafiltration of juice through membranes with suitable cutoff. On the basis of the results obtained from this research, a processing flow sheet was defined to obtain hypoallergenic or probably nonallergenic limpid juices and nectars. These products may represent, besides finished foods, intermediates to obtain various products after addition of further ingredients such as pectins, sugars, and fiber.