Analysis of the Effects of Heat Treatment on Gliadin Immunochemical Quantification Using a Panel of Anti-prolamin Antibodies

RUMBO M; CHIRDO F; FOSSATI CA; AÑON MC

JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY

AMER CHEMICAL SOC

Lugar: Washington; Año: 2001 vol. 49 p. 5719 - 5726

0021-8561

Two different systems were used to study the effects of heat treatment on gliadin immunochemical quantification. Purified gliadin fractions were heat treated in soluble phase at different time-temperature conditions, avoiding in this way the changes in the efficiency of extraction of gliadin from the food matrix caused by heating. The second system analysed was a model of dough (wheat flour + water) treated at different time-temperature conditions simulating a baking process. Samples were extracted using aqueous ethanol 70%. Protein content and composition of extracts was evaluated by acid-PAGE (A-PAGE) and capillary electrophoresis (CE). In all cases the effects of heating were evaluated by antigen labeled ? capture ELISA using four different anti-gliadin monoclonal antibodies and a rabbit anti-gliadin serum. The analysis of purified gliadin fractions heat-treated in soluble phase showed that there is no particularly heat stable fraction. Remarkably, -gliadin did not present a differential heat stability. Reactivity vary depending on the time-temperature conditions of the treatment, the antibody employed and the fraction analyzed. The studies on the dough samples showed an impairment of protein extraction after heat treatment. The strongest treatments (160°C 20 min) caused the most important losses in extractability. CE analysis showed an impairment in the efficiency of protein extraction, however each gliadin group is affected to different extent, being gliadin the less affected. Immunochemical quantification of these samples using either of the five antibodies showed a decreased level of detection in heat-treated samples, in concordance to the loss in extracted proteins. Among the different sources of error in gliadin immunochemical quantification, the impairment in extraction efficiency of gliadins after heat treatment appears as a major drawback to be overpassed.