Effects of heat on meat proteins – Implications on structure and quality of meat products

Considerable research has been done to better understand the basis for gel formation by myofibrillar proteins (MPs) in effort to manufacture acceptable processed meats with lower cost and more desirable nutritional characteristics. Results from research available indicate that there is no substitute for the myofibrillar protein myosin in gel formation by proteins from a wide variety of animal and fish species. This report consolidates information on determinants of protein gel formation, examining types of muscles and fibers, the species influence, and interactions of the MPs actin and myosin with each other and with fat, gelatin, starch, hydrocolloids, some protein soy, whey, and nonprotein additives such as phosphates and acidifiers, and the influences of pH, ionic strength, rates of heating, and its absence, protein oxidation, as well as the use of transglutaminase and high hydrostatic pressure. It is of interest that myosin alone will form acceptable gels. Gel formation by MPs is optimized at pH 6, an ionic strength of 0.6 M, and at 60 to 70 °C. The observations that collagen-derived gelatin can reduce the rubbery texture of low-fat products and that solubilization of MPs is not always essential for gel formation, and the observation that good gels can be formed in the absence of salt, are exciting developments that should be considered as pressure mounts to continue to reduce fat and salt in the diet.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1541-4337.2010.00137.x

Factors Influencing Gel Formation by Myofibrillar Proteins in Muscle Foods

Publisher Summary This chapter describes the process of the gelation of proteins Gelation is a phenomenon; therefore, its definition and that of its product, a gel, is dependent on the perspective of the observer and the technique(s) used to observe it For example, gels may be defined by their ability to immobilize a liquid, their macromolecular structure, or their textural or rheological properties The chapter reviews a variety of protein gel systems with a broad perspective stressing similarities between them, yet not without mentioning the important differences that make each unique It describes the multicomponent protein gels The rheological and optical properties of thermally irreversible gels are the outcome of two events First, a change in protein structure is needed that permits protein–protein interactions The subsequent aggregation process, which is highly influenced by the solvent environment, may produce the gel microstructure, which is responsible for the optical and rheological properties The physical integrity of a gel is maintained by counterbalancing forces of attraction and repulsion among polymer molecules and between the polymer network and the surrounding solvent

The Gelation Of Proteins

Background Plant-based meat alternatives are developed to address consumer demands and sustainability of future food supply, and the market has grown exponentially in recent years. Although progresses have been made to construct plant protein-based fibers organoleptically comparable to a whole-muscle cut, it remains challenging to reproduce the hierarchical organization of muscle tissue known to contribute to the overall sensory profile. For now, the market strategies are largely focused on restructured or formed meat mimeticks. Scope and approaches Literature search and supermarket surveys are conducted to identify processing technologies, product formulations, and the chemistry and functionality of various additives applied in meat alternatives production. Comparisons are made between muscle and legume proteins to elucidate disparities in macroscopic aggregation properties that may be greatly diminished through fabrication and ingredient innovation. Due to the highly formulated and processed nature, the nutrition, health, and safety of plant-based meat alternatives are analyzed. Key findings and conclusion Thermoextrusion is found to be the principal reconstructuring technique for meat-like fiber synthesis from plant proteins. Soy and pea proteins, gluten, and polysaccharides are the major building blocks. Through physicochemical interactions, plant proteins are able to aggregate into particles and anisotropic fibrils to impart meat-like texture and mouthfeel. Vegetable oil blends and spices are used to modify the texture and flavor; pigments are added to impart color; vitamins, minerals, antioxidants, and antimicrobials are incorporated to boost nutrition and improve shelf-life. Opportunities exist to overcome technology obstacles and nutrition and safety challenges in further developing the alternatives market.

Plant protein-based alternatives of reconstructed meat: Science, technology, and challenges

Flesh proteins, in the context of this article, are taken to be the component proteins of the contractile muscle of animals used for food (i.e., meat, poultry, and fish). Attention is given to the similarities and differences between the proteins from these different sources and in particular to the effects on them of freezing and frozen storage. It is believed that myosin and action, the main contractile proteins, are largely responsible for the functional properties of flesh foods, and that on frozen storage, myosin, in particular, undergoes aggregation reactions which lead to toughening of the muscle and a loss in water‐holding capacity. Variation in stability of flesh of different species on frozen storage can be attributed to some extent to the intrinsic characteristics of the respective myosins. Myosin from fish is generally less stable than its mammalian or avian counterparts and this is reflected in the stability of the flesh on frozen storage. Cryoprotectants, usually in the form of low ...

The effects of freezing on flesh proteins

Recent advances in muscle biology concerning the discoveries of a large variety of proteins have been described in this review. The existence of polymorphism in several muscle proteins is now well established. Various isoforms of myosin not only account for the difference in physiological functions and biochemical activity of different fiber types or muscles, but also seem to differ in functional properties in food systems. The functionality of various muscle proteins, especially myosin and actin in the gelation process in modal systems which simulate structured meat products, is discussed at length. Besides, the role of different subunits and subfragments of myosin molecule in the gelation mechanism, and the various factors affecting heat-induced gelation of actomyosin in modal systems are also highlighted. Finally, the areas which need further investigation in this discipline have been suggested.

Functionality of muscle proteins in gelation mechanisms of structured meat products.

Physicochemical and functional properties of myosin from red (red-myosin) and white (white-myosin) muscles of broilers, grown at different planes of nutrition, were studied. The red- and white-myosin from well-nourished broilers exhibited characteristic difference in certain physico-chemical properties. The specific viscosity of red-myosin was lower and sedimentation coefficient ( S202o,w) was higher than that of white-myosin. The transition of monomer⇌filament phase of white-myosin seemed to occur in a narrower range of ionic strength than that of red-myosin. Under identical conditions (ionic strength, pH, protein concentration, temperature) of the model system, white-myosin always exhibited greater gel strength than that of red-myosin. Characteristic differences were also observed in the three-dimensional structure of red- and white-myosin gel.Heat-induced gel strength of red-myosin from under-fed broilers was about 50% less than that of control, whereas the gelling property of white-myosin was not infl...

Biochemical and Functional Characteristics of Myosin from Red and White Muscles of Chicken as Influenced by Nutritional Stress

Some physico-chemical and heat-induced gelling properties of myosin heavy chains (MHCs) from rabbit skeletal muscle were studied. MHCs were found to be almost devoid of ATPase activity, possibly because of the absence of myosin light chains. MHCs formed precipitates below and ionic strength of 0.3, and above this ionic strength MHCs became soluble. On heating to 65°C at low concentrations of the protein, MHCs lost their solubility and formed aggregates even at high ionic conditions. Partially irreversible change in the conformation of MHC (from helical to random coil) also occurred in heated MHCs.The heat-induced gel strength of MHCs was found to be almost equal to that of intact myosin molecules with identical protein concentrations. This suggests that the gelling potential of myosin is solely confined in MHC. Although myosin light chains do not seem to contribute to the gelling power of myosin, possibly they provide some stability to the gel if the pH is varied above the optimum value, i.e., 6.0. The ad...

Ali Asghar

Papers

Functionality of muscle proteins in gelation mechanisms of structured meat products.

Biochemical and Functional Characteristics of Myosin from Red and White Muscles of Chicken as Influenced by Nutritional Stress

Role of Myosin Heavy Chains from Rabbit Skeletal Muscle in the Heat-induced Gelation Mechanism