A review article titled 'Recent applications of biopolymers derived from fish industrial waste in food packaging' was published in Polymers by Francesca Rionetto from the Department of Innovative Engineering, University of Salento, summarizing the Recent advances in the valorization of fish industry waste and the potential to reuse these by-products in a circular economy approach for the preparation of bioplastics for food packaging.
Muscle protein
Muscle proteins are divided into three main groups based on their solubility: myofibrillar proteins, sarcoplasmic proteins, and matrix proteins. Myofibrillar protein is the main component of skeletal muscle, accounting for about 65-75% of total muscle protein. Myofibrillar proteins include some contractile proteins such as myosin and actin, regulatory proteins such as tropomyosin and troponin, and other minor proteins. Due to their structure and localization, myofibrillar proteins require denaturing conditions such as high ionic strength solutions to be solubilized and extracted.
Proteins are one of the most commonly used biomaterials in the food industry due to their nutritional value, non-toxicity, biodegradability and ability to form gels. In recent years, fish matrix proteins and myofibrillar proteins have received great attention due to their ability to form biodegradable edible films with good barrier properties to gases, organic volatiles, and lipids that are insoluble in water , but can be dissolved by adjusting the pH of the solution. These films made from fish myofibrils or muscle protein have several advantages: (i) excellent UV barrier properties compared to commercial packaging films made from polyvinyl chloride. ; (ii) good oxygen and carbon dioxide barrier properties; (iii) slight transparency; (iv) potential to produce active packaging.
The main drawbacks limiting the widespread commercial application of these films are rigidity and low mechanical strength, which are further enhanced by disulfide bonds, hydrogen bonds and/or electrostatic interactions due to extensive protein-protein chain interactions in the film network. To overcome this problem, high levels of plasticizers (about 40-60%) can be added to biodegradable films to reduce brittleness and increase ductility and toughness by reducing protein-protein chain forces. Another limitation of fish myofibrillar protein membranes is the poor water vapor barrier, which is due to the high hydrophilicity of amino acids in the protein and the addition of large amounts of hydrophilic plasticizers such as glycerol and sorbitol to give the membrane sufficient flexibility. Chemical cross-linking, electron beam and gamma irradiation have been reported to be effective methods to obtain stronger and less permeable films.
