AbstractThe effects of continuous flow microwave treatment and conventional heating (using a plate heat exchanger) on the nutritional value of raw milk was estimated by measurement of the vitamin B1 retention. Microwave heating, without a holding phase, did not modify the vitamin B1 content of milk, whereas analogous treatment carried out with the plate heat exchanger led to a loss of this vitamin. A holding phase caused a similar loss of vitamin B1 in milk heated using either system. These results indicate that continuous flow microwave treatment of milk compares favourably with conventional heating because it produce less destruction of vitamin B1 in milk. This could be attributed to the shorter time taken to reach the final temperature and the lack of hot surfaces in contact with the milk in the case of the microwave system.