The Journal of Meat Research, Volume 33, 2019, published a paper by Wang Wei, Wang Yu, Chen Rixin, Li Peijun, and Chen Conggui from the School of Food and Biological Engineering of Hefei University of Technology and the Engineering Research Center of Agricultural Biochemical Engineering of Hefei University of Technology. The effect of sodium molecular weight on the properties of low-fat emulsified intestinal gel." The paper was funded by: Anhui Province Science and Technology Major Project (17030701026).
The fat content of emulsified meat products such as Frankfurt sausage and luncheon meat is usually as high as 20% to 30%, and the proportion of cholesterol and saturated fatty acids is also high. Excessive intake of animal fat by humans will increase the risk of obesity, hypertension, cardiovascular disease and coronary heart disease. On the other hand, animal fat can play a key role in the processing of emulsified meat products by stabilizing the emulsion state of meat emulsion. Sodium alginate (SA) is a water-soluble dietary fiber polymerized by glycosidic bonds. It can form an ionic acid gel with Ca2+ in the stomach to provide satiety, reduce blood sugar and insulin, reduce fat digestion and reduce body mass ; Adding SA to meat products can stabilize, emulsify and thicken.
Wang Wei, Wang Yu, Chen Rixin, Li Peijun and Chen Conggui from the School of Food and Bioengineering, Hefei University of Technology and Agricultural Biochemical Engineering Research Center of Hefei University of Technology, Ministry of Education, used low-fat (10%) emulsified intestines as the research object, ranging from 0% to 0.75 % Addition level, study the influence of three molecular masses (2 660, 3 890, 4 640 kDa) SA on its gel properties (water-binding capacity (WBC) and texture), and from the surface of meat protein Hydrophobicity, rheological properties of meat emulsion, and gel microstructure are used to explore the influence mechanism in order to provide a reference for the selection of polysaccharides in the processing of low-fat emulsified meat products.
The influence of SA molecular weight on low-fat emulsified bowel WBC
The effect of the three molecular mass SA on low-fat emulsified bowel WBC showed the same trend, and the increase of SA addition would significantly reduce CL and increase WHC (P<0.05). Under the addition level of 0.25% to 0.75%, the cooking loss rate of the H-SA group was significantly lower than that of the L-SA group (P<0.01), while the WHC was significantly higher (P<0.05); but at the 0.25% addition level The effect of low molecular weight L-SA on low-fat emulsified intestine WHC was not significant (P>0.05), while high molecular weight M-SA and H-SA had significant effect on improving WHC (P<0.05). This shows that as the molecular weight and addition level of SA increase, its effect on improving low-fat emulsified bowel WBC is significantly enhanced.
Influence of SA molecular weight on texture of low-fat emulsified intestine
At the addition level of 0.25%～0.50%, both L-SA and M-SA can significantly improve the hardness of low-fat emulsified intestines (P<0.05), but at the addition level of 0.75%, the two have no effect on the gel hardness. Significant (P>0.05); while the effect of H-SA on gel hardness is not significant, even at the addition level of 0.75%, the hardness of emulsified intestines is significantly reduced (P<0.05). The three molecular masses of SA had no significant effect on the elasticity, cohesion and chewiness of the low-fat emulsified bowel in general (P>0.05).
Influence of SA molecular weight on surface hydrophobicity of meat protein
At 0.25% and 0.50% addition levels, the three molecular masses of SA can significantly reduce (P<0.05) the surface hydrophobicity of myofibrillar protein in meat emulsion, and with the increase of SA molecular mass and addition amount, the protein surface The degree of hydrophobicity decreased significantly in turn (P<0.05). This decrease may be due to the electrostatic repulsion between SA and meat protein leading to the aggregation of protein molecules, embedding part of the surface hydrophobic residues; and as the mass of SA molecules increases, steric hindrance and electrostatic repulsion increase, resulting in meat The protein aggregation is intensified, thereby embedding more surface hydrophobic groups, which is manifested as a significant decrease in the hydrophobicity of the protein surface.
Effect of SA molecular weight on rheological properties of low-fat pork mince
Although the addition of SA has a significant effect on the change of the G'value of low-fat minced pork, the rheological curves of the addition of three molecular mass SA low-fat minced pork are relatively similar. The effect of meat protein denaturation on G'value can be divided into three parts: 20～45 ℃ part, with the increase of temperature, G’ slowly decreases; 45～56 ℃ part, the increase of temperature accelerates the rate of protein denaturation, Accelerate the decline of G'; in the part from 56 to 75 ℃, G'increases rapidly with the increase of temperature, reflecting that the semi-sol state meat emulsion is transformed into elastic gel during heating.
The tanδ value of each experimental group is less than 1, indicating that the elasticity of the meat emulsion is greater than the viscosity, and in the range of 20-52 ℃, the higher the molecular weight of SA, the greater the tanδ value of the meat emulsion, indicating that the added polymer mass SA can increase The viscosity of the large meat emulsion sol system. Although there is an interaction between SA and meat protein, the tanδ curves of the three molecular mass SA meat emulsions are similar, indicating that SA may only affect the viscoelasticity of the meat gel network in a certain physical way without chemical bonding.
Influence of SA molecular weight on microstructure of low-fat emulsified intestine
The three molecular mass polysaccharides L-SA, M-SA and H-SA can all promote the formation of continuous microstructures of protein gels and reduce fat aggregates), and as the molecular mass increases, electrostatic repulsion and steric hindrance increase Large, the interference effect on the meat protein is enhanced, and the micropores of the protein gel microstructure are enlarged. Compared with the L-SA group, the gel structure of the M-SA group is more uniform, dense, and continuous; but compared with the L-SA group and the M-SA group, the gel structure of the H-SA group becomes rough, which may It is because the added H-SA produces greater steric hindrance and electrostatic repulsion, which intensifies the aggregation of protein, thereby reducing the hardness of the low-fat emulsified intestine.
The addition of 3 kinds of molecular masses of SA can significantly improve the WBC of low-fat emulsified intestines (P<0.05), and the larger the molecular mass, the more significant the improvement effect (P<0.01); the molecular mass of SA and the amount of SA added to low-fat emulsification The texture properties of the intestine were not significantly affected (P>0.05). The high-molecular-weight H-SA molecule contains rich hydrophilic groups, which can bind a large amount of water, and can promote the aggregation of meat protein, reduce the surface hydrophobicity, and significantly increase the WBC of the low-fat emulsified intestine; at the same time, H- The steric hindrance of SA and the electrostatic repulsion generated in the gel structure promote the formation of loose porous gel microstructure and reduce the hardness of the low-fat emulsified intestine. The results of this study can provide theoretical support for the low-fat processing of emulsified meat products.