Effect of Pre-treatment of Cheese Milk on the Composition and Characteristics of Whey and Whey Products

OF DOCTORAL DISSERTATION HELSINKI UNIVERSITY OF TECHNOLOGY P.O. BOX 1000, FI-02015 TKK http://www.tkk.fi Author Marko Outinen Name of the dissertation Effect of pre-treatment of cheese milk on the composition and characteristics of whey and whey products Manuscript submitted 2.10.2009 Manuscript revised 24.11.2009 Date of the defence 20.1.2010 Monograph x Article dissertation (summary + original articles) Faculty Faculty of Chemistry and Material Sciences Department Department of Biotechnology and Chemical Technology Field of research Bioprocess Engineering Opponent(s) prof. Marianne Nyström Supervisor prof. Matti Leisola Instructor Ph.D. Matti Harju Abstract Cheese producers want to increase cheese yield. The yield is improved by enhanced transfer of milk proteins and fat to cheese. This requires modifications to the traditional cheese process. During high-temperature heat treatment (HH), whey proteins are partially denaturated and co-precipitated with the cheese matrix. Elevation of the protein concentration of milk enhances the formation of the protein network in which whey proteins and fat are enclosed. The protein concentration is usually increased by ultrafiltration (UF) or microfiltration (MF) membranes. UF concentrates all milk proteins in the cheese milk. With MF, the casein content of milk is increased, as part of the whey proteins are transferred to MF permeate. Often, HH treatment is used in combination with membrane processes. All these milk processing technologies have an effect on the quantity and quality of whey. Whey is processed into different products, such as demineralised whey powders (DWP), whey protein concentrates (WPC) or isolates (WPI). All of these are used in infant formulas as well as in numerous other applications in food industry. The changes in the cheese process may have an undesirable effect on the composition and functional characteristics of the whey product. In addition to stable functional properties, the nutritional content of the raw material of infant formulas and baby foods is expected to remain within the specification. In this work, the effects of HH, UF, combination of HH and UF (UFHH) and MF processes on the yield and nutritional quality of whey were studied. The focus was on proteins and amino acids, which are especially important to the infant formula industry. There were no significant differences in the protein and amino acid compositions of the whey products obtained by HH, UF and UFHH. The functional properties of DWP were not adversely affected by these treatments. However, the whey obtained by ceramic and polymeric MF was considered to be of limited use in infant formulas due to its inferior amino acid profile compared to the traditional whey. The applicability of MF cheese whey in other food industries is also questionable, as the gelling properties of whey proteins were adversely affected by the elevated concentration of caseinomacropeptides.