Study On Preparation And Preservation Effect Of Nano Composite Films Based On Pectin And LDHs

With the increase of people's environmental and food safety awareness,the requirements for food cling film are getting higher and higher.Therefore,the development of good preservation effect and non-toxic composite preservation film has become a research hotspot for scholars.Because of the poor antiseptic function of the common preservative film,some nano functional materials with antiseptic effect are often added to it.In this paper,pectin was used as matrix,hydrotalcite as preservative,glycerin as plasticizer,and beeswax as hydrophobic agent to synthesize composite film with good preservation effect and environmental protection.The defects of single component can be made up by composite film,which can improve the performance and the preservation effect of the composite film was studied.The main experimental results are as follows:?1?The dehydroacetic acid intercalated hydrotalcite?MgAl-DHA-LDHs?nano materials were prepared by ion exchange method.Pectin as the matrix was mixed with MgAl-DHA-LDHs,glycerin,beeswax,calcium chloride,surfactant and other materials to make the MgAl-DHA-LDHs/pectin nano composite preservation film.The structure was characterized by XRD,FT-IR and SEM.Then,single factor and orthogonal experiment were used to optimize the performance of the film,determine the optimal technology of the film and study its composite preservation film effect.The results showed that:pectin2%;beeswax 0.7%;10%glycerol 40mL;calcium chloride 4%had the best performance.The best process was used to prepare composite preservation film,meanwhile,the above four factors were quantitative,the amount of MgAl-DHA-LDHs was changed to examine the preservation effect of cling film containing different amount of MgAl-DHA-LDHs on carp.The results showed that the preservation effect of 0.2%MgAl-DHA-LDHs was the best.After 16 days of storage,the indexes were as follows:the total number of colonies was 6log₁₀cfu/g,TVB-N was 19.595mg/100g,TBARs was0.2751mg/kg,pH was 6.07,water holding capacity was 78.43%,sensory evaluation was 6.3 points and the shelf life could be extended for 5-6 days.?2?MgAI-SA-LDHs nano materials were prepared by coprecipitation method and blended with pectin to make the composite preservation film.The structure of MgAI-SA-LDHs and composite preservation film was characterized by XRD,FT-IR and SEM.Then,The concentration of various substances was changed in the composite films to study the effect of the six properties,such as tensile strength,elongation at break,water vapor transmission,light transmittance,water solubility and water content by single factor test.On the basis of single factor,the orthogonal experiment was constructed and the optimal combination of technology was determined.The results showed that,when the comprehensive performance of the membrane was the best,the composition of the membrane was 40mL of 10%glycerol,0.5%beeswax,2%pectin and 4%calcium chloride.The film containing different amount of MgAI-SA-LDHs was used for the preservation of grass carp,the best effect was 0.2%MgAI-SA-LDHs.After 16 days of storage,TVB-N was 24.58mg/100g,TBA was 0.3651mg/kg,pH was 6.2,the total number of colonies was 6.88 log₁₀cfu/g,water holding capacity was 82.89%,sensory evaluation was 6.2 points and the shelf life could be extended for 4-5 days.