Precipitation of whey proteins concentrated by ultrafiltration
Mljekarstvo 32(10; 11): 291-312; 323-346
The 1st part of this excerpt from the author's thesis (Zagreb University, 1981) is devoted to a review of literature on all relevant aspects of the problem, illustrated by tables and graphs. The 2nd part describes laboratory-scale experiments on concentration of whey and precipitation of proteins for whey cheese. Sweet cheese whey from the 'Sirela' factory in Bjelovar (Yugoslavia) with TS content 5.12-6.55% was filtered, and concentrated in 20- or 40-l batches on DDS model 20-1.8 LAB ultrafiltration installation with 1.8 msuperscript 2 membrane area to 50, 25, 20, 10 or 5% of initial vol. The conc. whey proteins were precipitated by heating to 90-95 degrees C for 15-20 min with or without NaCl, acetic acid, CaCl2, singly or combined, the coagulum was left to stand for 30 min, cooled to 45 degrees C and drained through cheese cloth. The resultant whey cheese was analysed for DM, fat, protein and ash, titratable acidity and pH were determined and organoleptic assessment was carried out. Whey concentration to 20-10% of initial vol. was best, but there were no marked differences between the various methods of heat precipitation of proteins, heating as stated without addition giving the most consistent results. Cheese yield was approx. 2.3% of the initial whey and the fresh cheese was of good quality.