Modification of milk protein concentrate and applicability in high-protein nutrition bars

Milk protein concentrates are powdered ingredients that contain 42% to 85% protein. The nutritional and functional properties of milk protein concentrates can be used to enhance food products. However, the use of milk protein concentrates in high-protein nutrition bars contributes to crumbly texture and rapid hardening during storage. Milk protein concentrate with 80% protein was extruded or toasted to modify its molecular structure and resulting functional properties. Modified samples had reduced protein solubility and surface hydrophobicity whereas gelation was relatively unaffected. Extruded, and toasted milk protein concentrates were used to manufacture model high-protein nutrition bars at 30% protein. Hardness along with other textural parameters, water activity, and color were measured over 42 day storage at 22°C, 32°C, and 42°C. Protein subunit profiles suggested formation of disulfide bonds that possibly contributed to textural changes during storage. Extruded milk protein concentrates produced bars that hardened slower than toasted or the unmodified control.