Further Studies on Factors Affecting the Efflux of Betacyanin from Beet Root: A Note on Thermal Effects

As judged by betacyanin efflux, beet root tissue differs in stability toward O₂ at low and high temperatures (45–60°C and 60–100°C respectively). The effect of temperature itself can he divided into a high activation energy (93 Kcal mol^?1) process in the lower temperature range and a low activation energy process (19 Kcal mor^?1) in the higher range (> 60°C). From these data it is suggested that initially, elevating temperatures bring about reversible conformational changes in the membrane. With continuing increase in temperature in the presence of O₂, membrane chemical groups susceptible to oxidation are exposed and, upon oxidation, render conformational changes irreversible.