Changes of Proteins in Intermediate Moisture Meats during the Processing of Products

Studies on Factors Related to the Properties of Intermediate Moisture Meats Part I

Abstract

Intermediate moisture meats were manufactured from porcine loin using commercial procedures and with varying levels (2%, 4%, 6%, 8%, 10%) of NaCl. To study the changes of proteins in intermediate moisture meats, water activity, moisture content, salt concentration and extractability of proteins were investigated during curing and smoking. During the process of curing, the salt concentration in meat increased while the moisture content and water activity decreased. These changes were very rapid in the first 3 days of curing. The product, which was cured for 9 days, has been subjected to smoking (15°-20°C). As a result the water activity decreased rapidly. The extractability of proteins has been observed at the same time. SDS-PAGE shows that changes in extractability of water soluble proteins are less noticeable while the extractability of structural proteins depended on curing and smoking period. SDS-PAGE shows that the extractability of myosin decreased with increasing curing and smoking period. Changes in extractability of actin, tropomyosin and α-actinin seem to be not much. Electron micrographic observations show thateven after 9 days of curing the typical ultrastructure of the myofibrils is clearly visible. But when cured meat is smoked for 4 days, the structure of the thick filament and Z-line appears to be under-going disorganization. After 8 days of smoking the structure of muscle has undergone a greater degree of disorganization. However, the actin filaments are still organized.