Ultrastructural changes of myofibrillar protein gelled with 1,5-glucono-δ-lactone at chilled temperatures

Changes in the ultrastructure of myofibrillar protein as a result of 1,5-glucono-δ-lactone-induced gelation at chilled temperatures were investigated using transmission electron microscopy. The myofibril structure appeared to have completely disintegrated at pH 4.0 resulting in a granular, amorphous appearance. It was suggested that as the pH was lowered to about 4.5, partial extraction of the A-band proteins occurred. A composite system of a myosin gel network reinforced by the residual myofibrillar structure was proposed to have formed. As the pH was lowered further, complete depolymerisation of actomyosin was suggested to have resulted in the formation of a predominantly myosin gel. The inclusion of sodium chloride resulted in swelling of the myofibrillar protein and retention of the myofibrillar structure to pH 3.8.