The Effect of Crop Conditions and Processing Variables on the Dewatering of Lucerne Protein Curd in a Pilot-scale Decanter Centrifuge

Lucerne protein concentrate was produced from freshly harvested lucerne under a range of processing conditions in pilot-scale equipment. The pilot-scale process involved pulping of the crop, expression of juice from this pulped crop, steam injection to heat precipitate the protein and recovery of the precipitate in a horizontal solid-bowl (decanter) centrifuge. Decanter centrifuge performance varied dramatically from day to day depending on the condition of the crop. Crop condition also had a large effect on precipitate particle size distribution and precipitate strength, and was the most important variable overall. Ageing of the green juice decreased decanter centrifuge performance (i.e. the dry matter content of the centrifuge solids decreased). Precipitation pH did not affect centrifuge performance significantly, but an increase in pH (from 6.0 t o 8.5) increased retention of pigments. Decanter centrifuge performance was improved by using a high precipitation temperature (e.g. 98{degree}C), and was better at a short holding time of 20s than at holding times of 2-6 minutes.