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Dissertation - University Access Only
Doctor of Philosophy (PhD)
Agricultural and Biosystems Engineering
Large quantities of whey are produced during the manufacture of cheese and casein. This co-product is traditionally processed into whey powder, whey protein concentrates and whey protein isolates using a combination of ultrafiltration and microfiltration processes. These total whey protein products are mixtures of several individual protein fractions such as a-Lactalbumin (a-La), P-Lactoglobulin (P-Lg), Bovine Serum Albumin (BSA), Lactoferrin (LF), Lactoperoxidase (LP), and Immunoglobulins (IgG). In order to realize the true functional, nutritional as well as economic value of these specialty whey protein fractions, it is essential to process the whey into pure/enriched protein products. Accordingly, in the present study it was proposed to develop a novel membrane based whey protein fractionation process using a combination of microfiltration and wide pore ultrafiltration processes. In addition to this, a study was conducted to develop a foam fractionation process for the recovery and enrichment of whey proteins.
During membrane processing of whey, the presence of residual fat, phospholipids, protein aggregates and casein fines in the whey cause severe fouling of the membranes. This problem is more severe in selective fractionation of a specific protein fraction, Because the fouling alters the selectivity of the membranes. In order to limit the influence of these macromolecules, a prepurified cheese whey feed was manufactured. The prepurified feed was manufactured by microfiltration experiments using a 0.2 p polyvinyledene fluoride membrane. The overall flux, combined yield and the combined transmission of a-La and ß-Lg were selected as the parameters indicative of the process efficiency. Based on the results from the experiments, optimum levels of transmembrane pressure andpH were selected. From the present study, it was found that transmembrane pressure of 76 kPa and pH of 6.3 turned out to be optimum operating conditions giving a combined yield of 69.85%, overall flux of 121.04 LMH and a combined transmission of 0.8.
Selective fractionation of a particular protein fraction needs a selection of a suitable membrane, its molecular weight cut off (MWCO) and an appropriate driving force. In the process of optimizing the membrane selection, its MWCO and the transmembrane pressure, experiments were conducted using two polyvinyledene fluoride andonepolyethersulfone membranes with MWCO of 50, 100and 300 kDa and transmembrane pressures of 110, 207 and 310 kPa. Overall flux, yield and purity of a-La and a-La/p-Lg ratio were used as the parameters indicative of the process efficiency. From the study it was found that polyvinyledene fluoride membrane with a molecular weight cut off of 50 kDa operated at a transmembrane pressure of 207 kPa pressure resulted in a-La yield of 21.27%, a-La/p-Lg ratio of 1.4 and overall flux of 49.46 liters per meter square hour. Cost analysis of the process was conducted to determine the manufacturing cost of a-La enriched WPC. The manufacturing cost estimation of the process for a hypothetical plant indicated that a-La enriched whey protein concentrate 80 (WPC 80) could be produced at $17.92/kg when the price of whey was considered as an input cost. But the manufacturing cost could be reduced to $16.46 when the price of whey was not considered as an input cost. The results of this study indicated that production of a commercially viable a-La enriched WPC is possible and the developed process can be used to meet the world demand for a-La enriched whey protein.
In addition to the above, with the objective of developing a relatively less investigated foam fractionation process for enrichment and recovery of whey proteins, experiments were conducted to study the influence of initial protein concentration and feed pH. The enrichment ratio and the yield of total whey proteins, a-La, and P-Lg were used as the parameters indicative of the effectiveness of the foam fractionation. Four levels of initial protein concentration and five levels offered pH were used in the study. The yield and the enrichment ratios were determined for total whey proteins as well as a- La and P-Lg. The yield of whey protein ranged from 51.58 to 90.92%while the enrichment ratios ranged from 1.2 to 5.Theyield of a-Laranged from 59 to 94% while the highest enrichment ratio for a-La of 8.45 was obtained for an initial protein concentration of 109mg/L and pH of 5.1. The yield of p-Lgranged from 54 to 96% while the highest enrichment ratio for P-Lg of 7.79 was obtained for an initial protein concentration of 109 mg/L and pH of 6.3. Selective enrichment of a-Laover p-Lg was obtained at pH of4.65 with the highest a-La/p-Lg ratio of 0.49 obtained for an initial protein concentration of 109 mg/L. From these results it is clear that a-La can be selectively enriched at pH of4.65 while P-Lg can be selectively enriched at a pH of 6.3.
Library of Congress Subject Headings
Includes bibliographical references (147-161)
Number of Pages
South Dakota State University
Copyright © 2009 Chenchaiah Marella. All rights reserved
Marella, Chenchaiah, "Whey Protein Fractionation Using Membrane Separation Technology" (2009). Electronic Theses and Dissertations. 627.