This technology relates to a process and associated apparatus for use in spray freeze drying a fluid substance such as fruit juice, pharmaceuticals, nutraceuticals, tea and coffee. The method includes the steps of: holding a chamber at a temperature and pressure below the triple-point of the liquid substance; injecting and/or atomizing the liquid substance into the chamber through at least one injection port to generate a frozen liquid substance portion having a predetermined particle size and a first evaporated liquid substance portion; collecting the FLS portion as a layer on a conveying surface; and exposing the collected layer of FLS portion to a heating means thereby inducing sublimation and generation of a second evaporated liquid substance portion and a product, wherein the conveying surface conveys the collected FLS portion at a rate which achieves substantially a monolayer thickness of the FLS portion to accumulate on the conveying surface.