Alkaline pH-dependent thermal aggregation of chicken breast myosin: formation of soluble aggregates

Abstract

Soluble aggregates, instead of insoluble gel network, were formed on heat-treated chicken breast myosin through alkaline pH-induced electrostatic regulation. Heat treatment of myosin at pH 9.0 significantly increased solubility, decreased turbidity, and resulted in the highest content at 260 nm particle size compared with those at pH 7.0 and 8.0. Results indicated that soluble myosin aggregates were produced at pH 9.0. The surface hydrophobicity and reactive sulfhydryl (R-SH) of unheated sample revealed gradual increases with increased pH. This increase was related to the decreased α-helical, thereby suggesting myosin unfolding. After heating, treatment at pH 9.0 showed the lowest surface hydrophobicity and R-SH, which may contribute to the highest dispersibility. Moreover, heated myosin (pH 9.0) after reshifting pH still exhibited excellent stability, which indicated the irreversible soluble aggregates formation. The controlled production of aggregates may provide the possibility of using soluble aggregates as ingredients for expanded meat protein application in beverage products.Agregación térmica alcalina dependiente del pH de miosina de pechuga de pollo: formación de agregados solubles RESUMEN En el presente estudio se formaron agregados solubles -en vez de una red de gel insoluble-a partir de la miosina de pechuga de pollo tratada térmicamente mediante regulación electrostática alcalina inducida por el pH. En comparación con tratamientos a un nivel de pH de 7.0 y 8.0, el tratamiento térmico de miosina con un pH de 9.0 aumentó significativamente su solubilidad, disminuyó su turbidez y produjo el contenido más alto, obteniéndose partículas de un tamaño de 260 nm. Los resultados indican que se formaron agregados de miosina solubles a un nivel de pH de 9.0. En la muestra no sujeta a tratamiento térmico, la hidrofobicidad superficial y el sulfhidrilo reactivo (R-SH) mostraron incrementos graduales al elevarse el pH. Este aumento está relacionado con la α-helical disminuida, lo cual sugiere que tuvo lugar el desdoblamiento de la miosina. Tras el calentamiento, el tratamiento a un nivel de pH de 9.0 presentó hidrofobicidad superficial y R-SH más bajas, lo cual puede contribuir a la mayor dispersibilidad. Asimismo, después de variar el pH, la miosina calentada (pH 9.0) siguió exhibiendo una excelente estabilidad, lo que da cuenta de la formación irreversible de agregados solubles. La producción controlada de agregados puede dar pie al posible uso de agregados solubles como ingredientes para la aplicación de mayores cantidades de proteína cárnica en productos de bebidas.

Effect of Chickpea Dietary Fiber on the Emulsion Gel Properties of Pork Myofibrillar Protein

“…R-SH is a mercaptan group that is exposed to the protein surface [ 53 ]. Most of them are distributed in the head of myosin, and play an important role in maintaining the tertiary and quaternary structure of proteins [ 54 ]. When the structure of myosin changed, the free sulfhydryl groups in myosin were exposed and oxidized to form disulfide bonds.…”

An effect of the recipe composition on minced meat properties

“…Changes in the pH values demonstrate meat system stability and indicate the development of irreversible protein aggregates and the level of meat raw material ageing [25]. It was established that after slaughter the pH level dropped in broiler meat (drumsticks) from the initial value of 6.18 to the ultimate value of 5.96 at 24 hours after slaughter [26].…”

Effect of Static Magnetic Field on the Quality of Pork during Super-Chilling Storage

“…Similar findings of a decrease in total sulfhydryl content were observed by Jiang et al [57] during the freezing of grass carp. The reactive sulfhydryl groups are located on the protein surface and are exposed, which are important for maintaining the tertiary and quaternary structure of proteins [58]. Figure 8b shows the active sulfhydryl content during the storage.…”