Increasing water holding capacity of muscle foods: Protein isolate effect
Protein isolates made from low quality muscle foods can be an efficient method to increase the water holding capacity of muscle foods. Increased water holding capacity may improve the sensory values of muscle foods after cooking. Protein isolates from various sources can be utilized to add value and increase water holding of muscle foods.
In this study we focused on the mechanism of increasing the water holding of muscle foods after the injection of protein isolate suspensions. Cook yields of muscle samples increased after the injection of these suspensions. Addition of buffering salts and increasing the amount of NaCl in the suspensions increased cook yields further more.
Injection material containing protein isolates increased the retention of injected material in the muscle when compared to the injection solutions that did not contain the protein isolate. To reach a certain level of injection, a larger amount of injection solution has to be injected as part of this solution may leak out of the muscle once the injection is complete. When the suspension containing protein isolate is injected into the muscle, retention of the injected material is greater than in the case without the isolate and the injected suspensions stay in the muscle after injection.
The increased retention may be due to the suspension having a consistency sufficiently high to resist the pressure of the muscle to force it out. Injected protein isolate suspensions form pockets inside the muscle by deforming the muscle structure and the deformed muscle does not go back to its initial form even after the suspension is removed from the pockets. The injected material flows along the muscle fibers but not through connective tissue. Cuts of muscles with all fibers oriented in parallel fashion will have a better distribution of the injected material than muscle cuts with complex fiber orientation.
The consistencies of protein isolate suspensions showed similarities with their solubilities. Both of these properties increased with increase of pH and stayed at a higher level when the pH decreased back to initial pH values from the alkaline side. Solubility and consistency of protein isolate suspensions increased over time.