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The aim of the research was to determine the changes in the immunoreactivity of whey protein concentrate (WPC) modified by two enzymes: proteinase, Alcalase 2.4L FG (Novo Nordisk), and cross-linked transglutaminase (EC 2.3.2.13, Activa^TM P, m-TG, Ajinomoto). The new products were characterised by 2D electrophoresis, immunoblotting, and ELISA methods. The WPC hydrolysate obtained with Alcalase contained proteins and peptides characterised mostly by low molecular weight peptides (MW < 14.4 kDa) in the pH range of 3–10. Immunoblotting showed strong immunoreactive properties of the hydrolysate with &alpha;-la and &beta;-lg polyclonal rabbit antibodies. The 2D electrophoretic patterns of WPC and its modified product obtained with m-TG did no differ significantly. However, the immunoblot analysis demonstrated that WPC showed a stronger reactivity towards IgE of allergic patients as compared to WPC with m-TG. ELISA methods showed that two-step hydrolysis with Alcalase followed by m-TG significantly reduced the immunoreactive properties of whey proteins. No cross reactions were observed with α-la and only about 0.6% cross-reactivity with &beta;-lg.

RESUMENEfecto de los compuestos fenólícos extraídos de semillas de girasol sobre la actividad lipoxigenasa nativa.Se obtuvieron extractos de lipoxigenasa de semillas de girasol usando 12 mezclas de extracción diferentes, y se determinó la actividad lipoxigenasa y el contenido en compuestos fenólicos. Este último se llevó a cabo mediante medida de la relación de absorbancias a 320/280 nm. El análisis estadístico de los resultados para los extractos mostró una correlación entre la actividad lipoxigenasa y la relación OD32onm/OD28onm con T = 0,619. Sin embargo, después de la diáli-sis de los extractos, no se observó esta correlación. PALABRAS-CLAVE: Compuestos fenólicos -Girasol -Upoxigenasa (actividad). SUMMARYEffect oí phenolic compounds extracted from sunflower seeds on native lipoxygenase activity.Extracts of lipoxygenase were obtained from sunflower seeds using 12 different extraction mixtures, and lipoxygenase activity and content of phenolic compounds in the extracts were determined. The content of phenolic compounds was determined as the ratio of optical densities at 320/280nm. Statistical analysis of the results for the extracts showed a significant correlation between the lipoxygenase activity and the ODaaonm/ODasonm ratio with r = 0.619. However, after dialysis of the extracts, no correlation was found.

Polyethylene glycol (PEG) was conjugated with milk proteins to determine the changes of the immunoreactive properties of a-lactalbumin (a-la) and b-lactoglobulin (b-lg). The competitive ELISA method was applied to determine the antigenicity of modified protein, using rabbit polyclonal antibodies. The immunoreactivity decreased to 0.90 mg ml -1 a-la (which corresponded with 0.05%) and 0.14 mg ml -1 b-lg (which corresponded with 0.08% of the immunoreactivity observed in raw milk). The determination of allergenicity of modified whey proteins was carried out on a group of 10 allergic patients and it was insignificantly weaker than that of a control sample of milk allergens.