Soluble Salts in Processed Cheese Prepared with Citrate- and Phosphate-Based Calcium Sequestering Salts

Area of Science:

• Food Science
• Dairy Chemistry
• Protein Chemistry

Background:

• Processed cheese (PC) quality is influenced by protein and salt distribution.
• Calcium sequestering salts (CSS) play a critical role in processed cheese functionality.
• Understanding salt-protein interactions is key to optimizing processed cheese texture and stability.

Purpose of the Study:

• To determine the distribution of protein and mineral salts (Ca, P, Na, Mg) in processed cheese.
• To evaluate the impact of different calcium sequestering salts (disodium phosphate, disodium pyrophosphate, sodium hexametaphosphate, trisodium citrate) on salt and protein solubility.
• To assess the effectiveness of the water-soluble extract (WSE) method for analyzing salt distribution in processed cheese.

Main Methods:

• Preparation of processed cheese samples with varying levels (180 or 360 mEq/kg) of CSS.
• Extraction of a water-soluble fraction (WSE) from processed cheese.
• Ultracentrifugation of the WSE to separate soluble and particulate components.
• Analysis of salt (Ca, P, Na, Mg) and protein content in different fractions, including 10 kDa permeate.

Main Results:

• Processed cheese samples exhibited 45-46% moisture, 26-27% fat, 20-21% protein, and pH 5.2 or 5.7.
• Ultracentrifugation indicated most protein in the WSE was non-sedimentable.
• Higher WSE protein content was observed in processed cheese at pH 5.7 compared to pH 5.2 at equal CSS concentrations.
• For disodium pyrophosphate (DSPP) and sodium hexametaphosphate (SHMP), 55-85% of Ca and P in the WSE was 10 kDa-permeable, suggesting non-permeable Ca-polyphosphate-casein complexes.
• For trisodium citrate (TSC), >90% of Ca in the WSE was 10 kDa-permeable, indicating micellar disruption via sequestration of micellar Ca.

Conclusions:

• The water-soluble extract (WSE) method is suitable for studying salt distribution in processed cheese.
• The 10 kDa permeate of the ultracentrifugal supernatant of the WSE provides the most accurate assessment of soluble salts, excluding protein-associated salts.
• Different CSS exhibit distinct mechanisms in affecting salt and protein solubility and complex formation in processed cheese.