ABSTRACT
Whey proteins, not long ago a waste product of the dairy industry, have become an important ingredient for many food products because of their high nutritional value and easy digestibility (de Wit 1998). In the last few decades, technologies have been developed to concentrate, isolate, and fractionate whey proteins and make them available as food ingredients (Zadow 1992). Whey proteins are well known for their functional properties, including emulsication, stabilization, foaming, and gelation (Huffman 1996; Foegeding et al. 2002; Totosaus et al. 2002). They are often
10.1 Whey Proteins .................................................................................................................... 147 10.1.1 Pretreatment Step .................................................................................................. 149
10.1.1.1 Enzymatic Pretreatment ....................................................................... 149 10.1.1.2 Heat Pretreatment ................................................................................. 150 10.1.1.3 Microstructure of Aggregates and Gels ............................................... 153 10.1.1.4 Effect of Preheating in Cold Gelation .................................................. 154 10.1.1.5 Rheological Properties of Aggregated Whey Solutions ...................... 155
10.1.2 Thickening ............................................................................................................ 155 10.1.3 Gelation Step ......................................................................................................... 157
10.1.3.1 CaCl2 Cold Gelation ............................................................................. 157 10.1.3.2 NaCl Cold Gelation .............................................................................. 159 10.1.3.3 Calcium vs. Sodium Salts ..................................................................... 160 10.1.3.4 Cold Gelation With Other Salts ............................................................ 161 10.1.3.5 Acid Cold Gelation ............................................................................... 161
10.1.4 Interactions between Protein Aggregates ............................................................. 163 10.1.4.1 Interactions in Salt Cold Gelation ........................................................ 163 10.1.4.2 Interactions in Acid Cold Gelation ....................................................... 164
10.1.5 Gel Models ............................................................................................................ 166 10.1.6 Cold Gelation of Whey Protein Emulsions ........................................................... 167 10.1.7 Encapsulation With Cold-Set Gels ........................................................................ 169 10.1.8 Cold Gelation With Saccharides ........................................................................... 171
10.2 Soy Proteins ........................................................................................................................ 172 10.3 Ovalbumin and Egg White ................................................................................................. 173 10.4 Conclusions ......................................................................................................................... 174 References ...................................................................................................................................... 175
used to improve texture in various foods, such as sausages, dairy products, desserts, bakery products, cold sauces, surimi, mayonnaise, and gelatin-like deserts (Barbut 1995a; Elofsson et al. 1997; Britten and Giroux 2001), and they can mimic the role of fats in enhancing textural properties of foods (Clark 1992).
