Study On Packaging Technology Of Keeping Fresh And Packaging Material On Plant Protein (Soybean Milk)

The substrate of this research project is polyethylene(PE),which is made of sodium dehydroacetate and ethylparaben as antibacterial modifier,and high barrier resin to improve the barrier property to make the high-barrier antibacterial film.The method is to study the effect on substrate performance by increasing the antibacterial performance of the film and improving the barrier property of the film.Firstly,the effects of adding different content of ethylparaben on the optical properties,mechanical properties,thermogravimetric analysis,scanning electron microscope and antibacterial properties of the modified polyethylene film materials were studied,and then the high barrier resin PVDC was studied,the influence of the performance and characterization of the modified basic antibacterial film,especially the permeability and water vapor transmission rate performance of the barrier antibacterial film.Finally,studying the barrier bacteriostatic film on the effect of fresh-keeping package of fresh soybean milk on the market at room temperature(25°C).(1)Effects of different mass fractions of Ethylparaben(ELN)on the properties of modified Antibacterial LDPE FilmsFirstly,ELN with different mass fractions was added to the modified LDPE resin and LDPE resin,and finally the prepared ELN-modified LDPE antibacterial film was prepared through the process of twin screw extrusion granulation and single screw extrusion blow molding.The performance and characterization of the packaging film material were tested,such as the mechanical properties,optical properties,oxygen permeability,structural characterization,and antibacterial properties associated with the bacteriostatic film,to analyze the effect of the addition of the modifier on the properties of the packaging material substrate.The results showed that as the ELN mass fraction increased,the tensile strength of the film changed slightly,the elongation at break first increased and then decreased,and the haze and light transmission decreased,rate changed in the opposite direction.The thermal stabilityof the film also showed a tendency of rising first and then decreasing,and the change of the air permeability and moisture permeability of the film first decreased and then increased.ELN can significantly improve the antibacterial performance of the film.When the mass fraction of ELN added was more than 0.5%,the film had a significant effect on the inhibition of Escherichia coli and Staphylococcus aureus.The addition of ELN had an effective improvement on the comprehensive performance and antibacterial effect of the modified membranes.It is important for far-reaching significance to develop new packaging materials.(2)The effect of high-barrier resin with different mass fraction on the performance of bacteriostasis films.In order to further study the improvement of the barrier properties of bacteriostatic membranes,the effect of different mass fractions of barrier resins on the modified bacteriostatic films was added.The structure of the membranes was characterized by FT-IR and SEM,and the effect of different mass fraction of PVDC was added on the physical,optical,and microstructure properties of the film.The results showed that when increasing the amount of PVDC added,the optical performance of the film decreased,and the mechanical strength of the film increased first and then decreased,and the optimal amount of PVDC is 2~3%,The moisture permeability and permeability of the film were best,the moisture permeability and breathability of the film were reduced by 23.47% and 29.64% respectively;when the mass fraction of PVDC is less than 3%,the added barrier resin had a certain improvement effect on the characterization structure of the film.Such barrier films have good barrier properties and can be used as food packaging materials,which will have a certain application value for the preservation effect of foods.(3)The effect of different types of barrier bacteriostatic films on the preservation of fresh soybean milk.At room temperature,the antibacterial film will be used to keep the freshness of the freshly-purchased fresh soybean milk.The packaged soybean milk at the same time interval was tested the sensory evaluation,pH,soluble solids,fat content,total number of colonies,etc.The analysis was conducted to investigate the effect of different types of barrier bacteriostatic films on the preservation of fresh soybean milk.The results showed that at room temperature,the antibacterial effect of Group D modified antibacterial film was better than that of other groups,and the sensory and microbiological contents of soybean milk did not exceed the national standard on the9 th day.The microbiological content of the film increased significantly on the 12 th day and the index of soybean milk decreased.The better comprehensive preservation effect of the film is that the content of PVDC in the barrier bacteriostatic film is 2% or3%.With reference to the soybean milk and soy milk beverage standards for vegetable protein beverages,the shelf life of soybean milk packaged at room temperature at 25°C can be maintained for 5~7 days,which can prolong the shelf life of soybean milk.(4)Although the research topic of this thesis has a certain scientific reference value,there are still some shortcomings.For example,some crystalline phenomena in the film,the surface hydrophobicity of high-barrier antibacterial film may need further study.