The invention pertains to a process for simultaneous producing an infant formula product and an acidic dairy product from defatted animal milk, comprising (a) processing the milk into a casein stream, a whey protein stream and a lactose stream, by: (i) subjecting the defatted animal milk to a filtration step over a microfiltration membrane capable of retaining bacteria and permeating milk proteins, to provide a debacterialized milk as permeate; (ii) subjecting the permeate originating from step (i) to a filtration step over a microfiltration membrane capable of retaining casein and permeating whey proteins, to provide a casein stream as retentate and a permeate comprising whey protein; (iii) fractionating the permeate originating from step (ii) into a whey protein stream and a lactose stream; (b) combining part of the casein stream, at least part of the whey protein stream originating from step (a) and a lactose source to obtain a recombined stream, wherein the lactose source comprises acid whey; (c) using the recombined stream originating from step (b) in the manufacture of the infant formula product; (d) using part of the casein stream originating from step (a) in the manufacture of the acidic dairy product. The invention further concerns the infant formula product obtainable by step (c) of the process according to the invention, and to the acidic dairy product obtainable by step (d) of the process according to the invention.