Volatile retention in the formation and dehydration of food powders

This PhD thesis is concerned with improving the retention of volatiles in the manufacture of instant coffee powders. Two processes have been studied in depth: spray drying and spray freeze drying. Spray freeze drying consisted of a combined spraying and freezing operation, followed by sublimation in a fluidised bed under partial vacuum. The aroma quality was measured using headspace solid-phase micro-extraction (HS-SPME) technique followed by gas chromatography coupled with mass spectrometry (GC/MS). Experiments were also performed with maltodextrin as the encapsulating matrix for comparison. [Continues.]