Effects of salts on ultrasonic extraction of protein from porcine myocardium

The porcine myocardium is a valuable protein source. However, it is generally not utilized owing to inefficient processing methods, e.g., protein extraction requires a complicated process and a high concentration of salt (>0.2 M NaCl). In the present study, the extraction method was improved by simplifying the pre-treatment process and reducing the amount of salt used. The effects of three salts used as food additives (NaCl, sodium phosphate, and sodium pyrophosphate) on the protein extraction efficiency were compared. The extraction yield was the greatest for sodium pyrophosphate, followed by sodium phosphate and NaCl. An extraction yield of 91.5% w/w was achieved only with 5 mM pyrophosphate and 80 min of ultrasonication. The physiological properties of extracted proteins were assessed by measuring Na²⁺- and Ca²⁺-ATPase activities, and digestion properties were examined using pepsin. Ultrasonic treatment in sodium pyrophosphate enhanced the extraction of proteins and digestibility by promoting the structural collapse of the myocardium. Accordingly, the developed extraction method can be used to recover proteins from the porcine myocardium and may contribute for the posterior application of this meat by-product in a nutritional supplement.