Emulsion Properties And Application Of Pork Myofibrillar Protein In The Condition Of Partial Substituting NaCl With KCl And MgCl₂

As one of the most important substances in humans for existence, salt could maintain cell osmotic pressure and adjust acid-base balance. And chloride participates in synthesize gastric acid. However, researches also show that excess salt has been correlated with the incidence of strokes, hypertension and coronary heart diseases. Therefore, various studies on low-salt food have been launched. Salt is one of the most commonly ingredients in processed meat products, whose addition is 2%-4%. Reducing the salt content in meat products is possible, but it's difficult to achieve. Sodium makes products salty, chloride can modify the salty taste and solubilize myofibrillar proteins so as to display its processing properties. Emulsion-type meat products also need specific content of NaCl to ensure the quality. Decreasing the content simply has a negative effect on sensory, gel texture properties, water-holding capacity, fat-binding and shelf life. Thereby, it has been a urgent problem in emulsion-type meat production that how to reduce NaCl content while guarante the quality. The purpose of this study was to clarify the emulsion properties and conformation of pork myofibrillar protein in the condition of salt substitutes and explore a feasible formula of low-sodium & low-fat emulsion-type sausage. Not only it will provide in-depth understanding for the emulsion science of meat products, but also it will support the product development of low-cost and better nutrition emulsified meat with lower salt content.1 Effect of partial substituting NaCl with KCl and MgCl2 on emulsion properties of pork myofibrillar proteinThe aim of this work was to evaluate the emulsification and emulsion gel properties of pork myofibrillar protein prepared with blends of KCl and MgCl2 as partial substitutes for NaCl and soybean oil as substitutes for pork backfat. The results showed that, in contrast with comparison group, KCl added could significantly enhance (P?0.05) the myofibrillar protein solubility, viscosity, emulsion stability and emulsifying capacity of myofibrillar protein, improve the viscoelasticity of emulsified gel and significantly reduce (P<0.05) the juice loss of emulsified gel.The improvement of solubility, viscosity, emulsion stability, and emulsifying ability on the myofibrillar protein which was partially replaced of NaCl with MgCl2 was not obvious, but MgCl2 added could improve the viscoelasticity and significantly reduce (P<0.05) the juice loss of the emulsified gel.2 Effect of partial substituting NaCl with KCI and MgCl2 on conformation of pork myofibrillar proteinThe aim of this work was to determine the interactions, secondary structure (amide conformation domain) and the micro environment (tryptophan, tyrosine) of pork myofibrillar protein in the condition of partial substituting NaCl with KCI and MgCl2 through Raman spectroscopy. The results showed that, in the emulsions before heating, hydrogen bonds and hydrophobic interactions of nomal sodium group and potassium replacement group significantly increased (P<0.05) and low sodium group & magnesium replacement group and nomal sodium group & potassium replacement group had no significant difference (P?0.05). Results revealed that metal ions like K+, Na+ and Mg2+ led to the changes of hydrogen bonds and hydrophobic, which involved in the formation of emulsion. In the emulsion gel after heating, the change of hydrogen bonds was as same as emulsions, but hydrophobic had no significant difference (P>0.05). Results revealed different types of ions leaded to the change of hydrogen bonding, but there was no effect on the hydrophobic interaction. Raman spectroscopic results showed that there were no significant differences (,P>0.05) in the secondary structure of myofibrillar protein, which revealed that the secondary structure of myofibrillar protein didn't involve in the formation of emulsion. Compared with the magnesium replacement emulsion group before heating, the intensity of a band near 760cm-1 region decreased significantly (P?0.05) and 1850/1830 index significantly increased (P?0.05), which revealed that metal ions like K+, Na+ and Mg2+ led to the exposing of tryptophan and tyrosine residues, which involved in the formation of emulsion. In the emulsion gel after heating, the intensity of a band near 760cm-1 region had no significant difference (P>0.05), but the change of 1850/1830 index was as same as emulsions. The change of the intensity of a band near 760cm-1 region was due to the fully exposed hydrophobic groups.3 Effect of sodium replacement and pre-emulsifying oil on properties of low-Sodium& low-fat emulsion-type sausagesKCl and MgCl2 were used to replace one-third of NaCl to reduce the dosage of salt. And pre-emulsifying soybean oil was used to substitute pork backfat (50%) to reduce the fat content. The effects of sodium replacement and pre-emulsifying oil replacement on textural property, cooking loss, pressing loss, color and sensory quality of emulsion-type sausage were studied, aiming to find a new healthy formulation of low-salt & low-fat emulsion-type sausage. The results showed that compared with the normal sodium positive control and low sodium negative control, hardness, elasticity, cohesiveness, chewiness and resilience of potassium and pre-emulsifying oil mixed substitution and magnesium and pre-emulsifying oil mixed substitution increased significantly(P<0.05); cooking loss and total expressible fluid decreased significantly at different degrees(P?0.05); L*, b* value increased significantly at different degrees (P?0.05), a* value decreased significantly (P<0.05); sensory quality improved. Because of bitter taste, the magnesium substitution had lower acceptable level.