Preliminary observations on the effects of milk fortification and heating on microstructure and physical properties of stirred yogurt
2003
Remeuf, F. | Mohammed, S. | Sodini, I. | Tissier, J.P.
The aim of this work was to study how milk fortification and heating affect yogurt microstructure (micellar characteristics, protein network) and physical properties (viscosity, water-holding capacity (WHC), and graininess). Milk was fortified with skim milk powder (control), whey protein concentrate (WPC), caseinate, or a mixture of caseinate and whey protein. Two heat treatments were applied, giving average whey protein denaturation levels of 58% and 77%. For caseinate-enriched yogurts, the heating effect was negligible. When milk was enriched with WPC, heating led to a high level of cross-linking within the gel network. Heating increased yogurt viscosity and WHC, but also graininess. When milk was fortified with a blend of WPC and caseinate giving a whey protein-to-casein ratio of 0.20, the yogurt viscosity was greatly improved, while graininess was kept low. The results show a relationship between micelle solvation and yogurt microstructure, as well as micelle size in milk base and yogurt graininess.
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