Whey proteins technological production processes

These results demonstrated the feasibility of EDBM for whey protein separation and the influence of the initial protein concentration on the purity and yield of the separated fraction. At 5% WPI initial concentration, this technology allowed the separation of 98% pure (3-lg fraction with a 44% recovery yield, while at 10% WPI initial concentration a (3-lg-enriched fraction was produced containing 97.3% of (3-lg and 2.7% a-la, for a 98% total protein purity. The 10% protein concentration seems to be the best level for electrodialytic parameters and protein recovery. Furthermore, EDBM of a 10% WPI solution, by precipitation of 53.4% of the (3-lg, allowed the production of an a-la-enriched fraction in the supernatant. Since the best pH to precipitate (3-lg was demonstrated to be pH 4.65 [21], and that the protein yield increases with an increase in initial protein concentration in the solution, it was expected that electroacidilication of a 20% WPI solution to pH 4.65 would allow the highest precipitation yield. However, the limiting factor of such a process at 20% was the low conductivity of the protein solution at pH 5.0. 

The application of ultrafiltration membranes, which are currently all of a polymeric nature, is more widespread because it is possible to separate smaller molecules such as sugars from larger molecules such as proteins. The main attraction for ultrafiltering cheese milk is the increased yield that results from the incorporation of whey protein into the cheese. In a traditional process these proteins remain in the waste liquid whey. The waste stream from a membrane unit still contains lactose (milk sugar) and this can be used for alcohol production, as an animal feed or as a feed to an anaerobic digester which will produce methane. The technology is being applied to both hard and soft cheese examples includes Cheddar and Camembert. 

Membrane Sep r tion. The separation of components ofhquid milk products can be accompHshed with semipermeable membranes by either ultrafiltration (qv) or hyperfiltration, also called reverse osmosis (qv) (30). With ultrafiltration (UF) the membrane selectively prevents the passage of large molecules such as protein. In reverse osmosis (RO) different small, low molecular weight molecules are separated. Both procedures require that pressure be maintained and that the energy needed is a cost item. The materials from which the membranes are made are similar for both processes and include cellulose acetate, poly(vinyl chloride), poly(vinyHdene diduoride), nylon, and polyamide (see AFembrane technology). Membranes are commonly used for the concentration of whey and milk for cheesemaking (31). For example, membranes with 100 and 200 p.m are used to obtain a 4 1 reduction of skimmed milk. 

Improvement of membrane separation technology has resulted in the isolation of MFGM-enriched material from commercially available products. A phospholipid-rich fraction can be extracted from whey (Boyd et al., 1999) and buttermilk (Sachedva and Buchheim, 1997) with a reported yield of 0.25 g of phospholipids/g of protein in buttermilk (Sachdeva and Buchheim, 1997). Microfiltration of whey derived from the Cheddar cheese process, using 0.2 pm ceramic filters results in a fraction containing two major phospholipids, phosphatidylcholine and phosphatidylethanolamine, and lesser amounts of phosphatidylinositol, phosphatidylserine, sphingomyelin and cerebrosides (Boyd et al., 1999). The phospholipid fraction separated from the total lipids contains a larger proportion of mono- and polyunsaturated fatty acids (mainly oleic, Cig i and linoleic, C ) compared to the total lipid and the neutral lipid fraction (Boyd et al., 1999). 

However, various technologies have been developed that utilise extractions from oilseed meals and pulses as the raw material for the production of flours, protein isolates and protein concentrates. These technologies are mainly used in the processing of soybeans and, to a lesser extent, in the processing of peanuts, cotton, lupine and other oilseed meals. Additional sources of protein are whey, fishmeal and others. The final products can be various mixtures rich in proteins (often enriched by minerals and vitamins), which are mainly used in less-developed countries. 

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