Interactions among lactose, β-lactoglobulin and starch in co-lyophilized mixtures as determined by Fourier Transform Infrared Spectroscopy.

Processing and storage change food powders containing a large quantity of lactose due to lactose crystallization and interactions among components. Model food systems were prepared by co-lyophilization of lactose, β-lactoglobulin (BLG), and gelatinized starch. A mixture design was used to define the percentage of each mixture component to simulate a wide range of food powders. Interactions among lactose, BLG and starch were studied using Fourier Transform Infrared (FT-IR) at different relative humidities (RH), before and after 3 months storage. Results showed the presence of hydrogen bonds among these components. Moreover, interactions or formation of hydrogen bonds among lactose, starch and BLG preserved BLG against freezing and freeze-drying shocks. Lactose crystallization could be identified by comparing infrared spectra of amorphous and crystallized lactose at O - H and C - H stretching vibration bands.