Preparation Of Nano-TiO₂ Modified Bacteriostatic Film And Its Application To The Preservation Of Silver Carp

With the improvement of people’s life quality,more and more people begin to pay attention to the health and safety of food,and food safety affects everyone’s heart.Food safety is related to thousands of households,and food packaging is an important factor affecting food safety.In recent years,many people have carried on the thorough research to the new food preservation packing.The new food fresh-keeping packaging is to add additives with special properties to the packaging materials on the basis of the original packaging,which makes the packaging materials have certain antibacterial and fresh-keeping characteristics.In this study,fresh silver carp meat was used as the target packaging material,and the additives with antibacterial and fresh-keeping effect,nano-titanium dioxide was added to the packaging film substrate.The study found that:（1）After modification of nano-titanium dioxide（Nano-TiO₂）,mixed granulation was added to low density polyethylene（Low density polyethylene,LDPE,PE for short）resin according to different proportion,and the modified film was prepared by casting.Polyethylene terephthalate（Polyethylene terephthalate,PET）film was used as outer film to composite,and high barrier modified bacteriostatic film was finally obtained.The mechanical,antibacterial and optical properties of the films were tested.The results show that,with the increase of the proportion of Nano-TiO₂,the mechanical and antibacterial properties of the films increased,but the optical properties decreased.Among them,when Nano-TiO₂is added to the resin in the proportion of 2.5%,the tensile strength and haze of the films are higher,but the tensile rate and transmittance are small,but their gas resistance,water resistance and antibacterial effect are better,so they can be used in antibacterial packaging of food.（2）Compared with PET/PE composite films,the mechanical properties,barrier and antibacterial properties of the modified antibacterial films prepared by two different crystal forms of nano-titanium dioxide（anatase and rutile）are improved.This is due to the formation of molecular polar bonds between PE molecules and TiO₂molecules after melting at high temperature,through intermolecular force links,and the addition of nano-TiO₂fills the gap between PE molecules,so the mechanical properties and barrier properties of the films increase after adding to PE.Moreover,from the comparison of the fresh-keeping effect of the two kinds of antibacterial films on silver carp meat,it is found that the antibacterial effect of anatase nano-titanium dioxide modified film is better,which also shows that the anatase nano-titanium dioxide is more suitable for antibacterial film.Therefore,this film can be extended to the fresh-keeping packaging of freshwater fish,prolong the shelf life of fish meat,and facilitate consumers to buy and eat.（3）Nano-TiO₂antibacterial film（PET/T-PE）,fennel essential oil antibacterial film（PET/F-PE）,potassium sorbate antibacterial film（PET/S-PE）and ordinary composite film（PET/PE）were used to packaged the fresh silver carp meat and preserved at low temperature.The fresh-keeping effect of several films on silver carp meat was studied by comparative analysis.It was found that the antibacterial film could prolong the preservation period of silver carp compared with the ordinary composite film,and the nano-TiO₂antibacterial film（PET/T-PE）had the best effect on the preservation of fish meat.On the8th day of preservation at low temperature,the sensory score was 4,the p H value was7.13±0.64,the total colony number was 5.9±0.14log·CFU/g,the water loss rate was11.21±0.48%,the TVB-N value was 23.53±1.39mg/100g,and the TBA value was0.65±0.08mg MDA/100g.After studying the properties of nanometer titanium dioxide modified packaging film,it is found that nanometer titanium dioxide modified film has certain antibacterial properties.Compared with ordinary thin films,their mechanical properties and barrier properties are improved.When studying nanometer titanium dioxide modified films with different crystal types,it was found that under the same concentration of adding antibacterial agent,modified film has the best effect on the preservation of silver carp meat.Compared with other modified films:fennel oil modified film,potassium sorbate modified film.Under the same circumstance,the properties of nano titanium dioxide modified film are all better.It is found that the modified film of nano titanium dioxide can be used for the packaging of fresh silver carp.From the perspective of economic analysis,on the one hand,it can solve the problem of high cost in the process of selling silver carp;on the other hand,nano-TiO₂modified film has spectral antibacterial property,which can not only be used for fresh-water fish such as silver carp,but also can be used for food fresh-keeping packaging in daily life.The base material of packing material and antiseptic agent are cheap and suitable for mass production.