Heat-Induced Effect on Soluble Proteins in Meat Soup Stock

Abstract

The heat-induced gelatinization of collagen and the solubilization, of myofibrillar proteins in meat during the preparation of soup stock were investigated. The ratio of gelatin originating from collagen to the total soluble protein in soup stock was about 30% after heating for 6 hr. When the purified myofibrillar proteins were heated, most disappeared from the SDS-polyacrylamide gel electrophoretic pattern, and 40, 000-, 23, 000- and 10, 000-18, 000-dalton proteins appeared. The molecular weights of these proteins were similar to those of the proteins in soup stock. Furthermore, the content of heat-soluble protein from myofibrils increased gradually with incteasing heating time.
The content of soluble proteins was lower when a mixture of sarcoplasmic and myofibrillar proteins was heated than when they were heated individually. A mixture with a higher ratio of sarcoplasmic proteins to myofibrillar proteins gave a more intense protein band of 10, 000-18, 000 daltons by SDS-polyacrylamide gel electrophoresis, the content of this low molecular weight protein increasing with increasing heating time.
These results suggest that some proteins in soup stock originate from not only stroma proteins, but also from sarcoplasmic and myofibrillar proteins.