Analysis of structural properties and immunochemical reactivity of heat treated ovoalbumin

RUMBO, M; CHIRDO, FERNANDO GABRIEL; AÑON, MARÍA CRISTINA; FOSSATI C.A.

JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY

AMER CHEMICAL SOC

Lugar: Washington; Año: 1996 vol. 44 p. 3793 - 3798

0021-8561

Protein detection to certify foodstuff composition is frequently accomplished by immunochemicalmethods. Product processing (heating, pH change, etc.) usually alters protein structure and canmodify immunochemical reactivity of the protein. We studied the structural changes caused byheating ovalbumin under different time and temperature conditions and the influence of heat onthe immunochemical reactivity of ovalbumin. Differential scanning calorimetry (DSC), exposedsulfhydryl groups, and surface hydrophobicity (Ho) were used to evaluate structural changes. Theimmunochemical reactivity was measured by an inhibition ELISA. By DSC we obtained an equationthat can predict the denatured fraction after a heat treatment. We found a great increase of exposedsulfhydryl groups and surface Ho after denaturing treatments, with a good correlation between thetheoretically calculated denaturation degree and the measured values. Using ELISA we observedthat only denaturing treatments have an influence on immunochemical reactivity. Heating up to65 °C does not introduce any change in reactivity. At higher temperatures, different behavior wasobserved. Mild denaturing treatments cause an important rise in reactivity, whereas a loss ofreactivity is produced by total denaturing treatments. Consequently, when dealing with heatprocessedsamples, immunochemical methods could lead to an over- or underestimation of the actualprotein level.