Kinetic modelling of the heat stability of bovine lactoferrin in raw whole milk

Abstract

The thermal denaturation of the naturally occurring lactoferrin in raw bovine whole milk has been measured over a range of temperatures from 65 to 121 °C for holding times from 2 up to 300 s designed to mimic heating processes used in the food manufacturing industry. Data were generated by heat treatments of raw whole milk from two different sources, New Zealand (NZ) and China, and with lactoferrin at two different levels of naturally occurring iron saturation. Denaturation rates for lactoferrin in the Chinese-sourced milk samples were at least two-fold greater than lactoferrin in the NZ milk over the temperature range 65–80 °C. At 85 °C rates of denaturation were the same although more than 80-fold greater than at 65 °C whereas, at 95 °C, lactoferrin in the NZ milk denatured at twice the rate of that in the Chinese milk. The differences in denaturation rates up to 80 °C likely reflected the greater heat stability of the more iron-saturated NZ milk samples. From these data, a combined kinetic and Arrhenius-based model has been developed and validated that allows calculation of native lactoferrin retained after thermal processing at any temperature-time combination in the experimental range (65–95 °C). This model should have applicability in the evaluation of existing processes and for the design of processes to improve the retention of lactoferrin during food manufacture.