Abstract
Micellar calcium phosphate (MCP) was prepared as a complex with phosphopeptide (CPP) from rennet casein using the following procedures. Rennet casein was suspended in water, hydrolyzed by trypsin, and the resulting suspension was heated to stop the enzymatic reaction. The pH was adjusted to 4.6, and the suspension was centrifuged. The supernatant was adjusted to pH 9.0, concentrated by ultrafiltration with a membrane (cut off 30 kDa), and then lyophilized. The dried MCP-CPP complex was easily dissolved in water and contained 63.1% peptide, 9.2% calcium, 3.5% inorganic phosphorus and 1.8% organic phosphorus based on the dry basis. The X-ray diffraction pattern revealed the absence of hydroxyapatite in the MCP-CPP complex. It was confirmed by gel permeation HPLC that MCP cross-linked CPP in the solution of the MCP-CPP complex as that in the casein micelles. Although ion exchange HPLC showed that the prepared MCP-CPP complex contained peptides other than CPP, almost no bitter taste was detectable. Five kilograms of rennet casein was suspended in 80 L of water and then treated by a method similar to the one above, to prepare 1.12 kg of the MCP-CPP complex. Although the MCP-CPP complex prepared in the present study contained somewhat less calcium and CPP than those in the previous one, it was prepared without the use of ethanol, suggesting that it can be prepared at a lower cost.
