Analysis of Structural Properties and Immunochemical Reactivity of Heat-Treated Ovalbumin

Abstract

Protein detection to certify foodstuff composition is frequently accomplished by immunochemical methods. Product processing (heating, pH change, etc.) usually alters protein structure and can modify immunochemical reactivity of the protein. We studied the structural changes caused by heating ovalbumin under different time and temperature conditions and the influence of heat on the immunochemical reactivity of ovalbumin. Differential scanning calorimetry (DSC), exposed sulfhydryl groups, and surface hydrophobicity (H o) were used to evaluate structural changes. The immunochemical reactivity was measured by an inhibition ELISA. By DSC we obtained an equation that can predict the denatured fraction after a heat treatment. We found a great increase of exposed sulfhydryl groups and surface H o after denaturing treatments, with a good correlation between the theoretically calculated denaturation degree and the measured values. Using ELISA we observed that only denaturing treatments have an influence on immunochemical reactivity. Heating up to 65 °C does not introduce any change in reactivity. At higher temperatures, different behavior was observed. Mild denaturing treatments cause an important rise in reactivity, whereas a loss of reactivity is produced by total denaturing treatments. Consequently, when dealing with heat-processed samples, immunochemical methods could lead to an over- or underestimation of the actual protein level. Keywords: Ovalbumin; heat treatment; immunochemical reactivity; denaturation

Effect of heat-treatment on the physico-chemical properties of egg white proteins: A kinetic study

“…Heat-induced denaturation of ovalbumin results in exposure of these sulfhydryl groups (Beveridge & Arntfield, 1979;Rumbo et al, 1996). As shown in Fig.…”

“…Many studies have been conducted on the correlation between the structural properties of egg white proteins (mainly the abundant ovalbumin) and their functional properties. In these studies much attention was paid to the heat-induced changes in structural properties of proteins, leading to changes in the functional characteristics (Donovan, Mapes, Davis, & Garibaldi, 1975;Kato, Fujimoto, Matsudomi, & Kobayashi, 1986;Mine, Noutomi, & Haga, 1990;Mine, 1995;Rumbo, Chirdo, Fossati, & Anon, 1996). However, from these studies, little information can be deducted to describe these heat-induced changes in kinetic terms.…”

Estimating the quantity of egg white and whey protein concentrate in prepared crabstick using ELISA

“…Breton, Phan Thanh, and Paraf (1988) found that affinity purified antibodies raised against native ovalbumin had higher avidity against heat-denatured ovalbumin than against the native ovalbumin molecule. Rumbo, Chirdo, Fossati, and Anon (1996) found that avidity peaked and then began to decrease as heating time increased. This trend held true for samples tested between 70 and 100°C.…”

Deglycosylation of ovalbumin prohibits formation of a heat‐stable conformer

“…For human consumption excessive heat-treatment of ovalbumin is relevant in view of the reported antigenic and allergenic properties of the native protein (Johnson and Elsayed, 1990;Kahlert et al, 1992), compared to heattreated forms (Ikura et al, 1992;Rumbo et al, 1996). Moreover, heat-treatment causes the protein to aggregate and allows the development of a gel structure (Weijers et al, 2004), a desired functionality for a food texturizer.…”