ON THERMAL-STABILITY OF LACTOFERRIN IN BO VINE-MILK

The objective of this work was to investigate heat-induced denaturatio n of bovine lactoferrin in milk in its native form. This should lead t o a better understanding of the behaviour of lactoferrin during essent ial heat-processing of milk. Lactoferrin concentration was determined by HPLC, using a reversed-phase column (Nucleosil 300-5C4, 4 x 120 mm) , a two stage gradient-program and a detection at a wavelength of alph a = 280 nm. Native lactoferrin was added to raw bovine skim milk obtai ned from 60 cows, to give a final concentration of 3 mg/ml. Samples we re heated in glass capillary tubes within a temperature range from 60 degrees C to 75 degrees C, and a time interval between 16 seconds and 12.5 hours using a temperature-controlled water bath. According to the se results the usual pasteurization technique in milk technology, high -temperature short time processing, has no pronounced effect (approx. 5 % denaturation) on lactoferrin denaturation. Heat treatments using t emperatures above 63 degrees C and some minutes heating time show a mo re pronounced effect. Holder pasteurization (63 degrees C/30 min) redu ced the native lactoferrin content by about 40 %.