The invention relates to a food product heat treatment apparatus for heat treatment of heat-sensitive fluid food products, such as whey protein concentrate, baby food and cheese milk, comprising an inlet (21) for supplying the food product, an outlet (22) for discharging the heat treated food product, a holding device (23) downstream the inlet (21) for holding the food product for a specific time at a specific temperature, and a back pressure device (24) downstream the holding device (23) wherein the holding device (23) is a positive displacement holding device and/or a self cleaning holding device. The invention also relates to a method for heat treating a heat-sensitive fluid food product, such as whey protein concentrate, baby food and cheese milk, comprising the following steps: (a) supplying the food product to an inlet (21), (b) heat treating the food product by holding the food product for a specific time at a specific temperature in a holding device (23), (c) providing a back pressure device (24) downstream the holding device (23), and (d) discharging the heat treated food product through an outlet (22), wherein the back pressure device (24) is or comprises a cooled valve and/or the food product is positively displaced through the holding device (23).
