Optimization of protein fractionation by skim milk microfiltration: Choice of ceramic membrane pore size and filtration temperature.
The objective of this study was to investigate how ceramic membrane pore size and filtration temperature influence the protein fractionation of skim milk by cross flow microfiltration (MF). Microfiltration was performed at a uniform transmembrane pressure with constant permeate flux to a volume concentration factor of 2.5. Three different membrane pore sizes, 0.05, 0.10, and 0.20µm, were used at a filtration temperature of 50°C. Furthermore, at pore size 0.10µm, 2 different filtration temperatures were investigated: 50 and 60°C. The transmission of proteins increased with increasing pore size, giving the permeate from MF with the 0.20-µm membrane a significantly higher concentration of native whey proteins compared with the permeates from the 0.05- and 0.10-µm membranes (0.50, 0.24, and 0.39%, respectively). Significant amounts of caseins permeated the 0.20-µm membrane (1.4%), giving a permeate with a whitish appearance and a casein distribution (αS2-CN: αS1-CN: κ-CN: β-CN) similar to that of skim milk. The 0.05- and 0.10-µm membranes were able to retain all caseins (only negligible amounts were detected). A permeate free from casein is beneficial in the production of native whey protein concentrates and in applications where transparency is an important functional characteristic. Microfiltration of skim milk at 50°C with the 0.10-µm membrane resulted in a permeate containing significantly more native whey proteins than the permeate from MF at 60°C. The more rapid increase in transmembrane pressure and the significantly lower concentration of caseins in the retentate at 60°C indicated that a higher concentration of caseins deposited on the membrane, and consequently reduced the native whey protein transmission. Optimal protein fractionation of skim milk into a casein-rich retentate and a permeate with native whey proteins were obtained by 0.10-µm MF at 50°C.
TINE SA, Centre for Research and Development, N-0902 Oslo, Norway; Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, N-1432 Ås, Norway. Electronic address: camilla.jorgensen@tine.no.
Camilla Elise
CE
Jørgensen
Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, N-1432 Ås, Norway.
Roger K
RK
Abrahamsen
Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, N-1432 Ås, Norway.
Elling-Olav
EO
Rukke
TINE SA, Centre for Research and Development, N-0902 Oslo, Norway; Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, N-1432 Ås, Norway.
Anne-Grethe
AG
Johansen
Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, N-1432 Ås, Norway.
Reidar B
RB
Schüller
Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, N-1432 Ås, Norway.
Siv B
SB
Skeie
D000818:Animals; D001798:Blood Proteins; D002364:Caseins / Q000032:analysis; D002516:Ceramics; D005591:Chemical Fractionation / Q000295:instrumentation / Q000379:methods; D005374:Filtration / Q000295:instrumentation / Q000379:methods*; D005511:Food Handling / Q000379:methods; D008567:Membranes, Artificial; D008892:Milk / Q000737:chemistry*; D008894:Milk Proteins / Q000032:analysis / Q000302:isolation & purification*; D011312:Pressure; D013696:Temperature; D000067816:Whey Proteins / Q000032:analysis / Q000302:isolation & purification
D001798:Blood Proteins; D002364:Caseins; D008567:Membranes, Artificial; D008894:Milk Proteins; D000067816:Whey Proteins
ceramic membrane pore size; constant flux; filtration temperature; protein fractionation; uniform transmembrane pressure