Preparation Of Curdlan And Polyvinyl Alcohol Blending Films And Its Application In Chilled Meat Preservation

The degradable films are products that use biodegradable materials such as proteins,polysaccharides,lipids,and other macromolecules to produce molecular interactions through specific processing methods to obtain specific properties.The thickness of the film is between 0 and 10 ?m.However,compared with traditional petrochemical plastics,the degradable film has poor mechanical properties and limited application.Curdlan(CD)is an extracellular polysaccharide produced by microbial fermentation.It has excellent thermogelability and water holding capacity and is often used in the food industry.However,the purely curdlan film is bad in elongation at break and gas barrier properties.Polyvinyl alcohol(PVA)is a safe and non-toxic biodegradable polymer.Pure PVA film has good stretchability and gas barrier properties,but it is soluble in water due to its hydrophilicity.Therefore,in this paper,the curdlan and polyvinyl alcohol blend film can be prepared according to different blending ratios,and the mechanical properties,barrier properties and mechanism properties of the film can be determined.In order to obtain a film with good mechanical strength and barrier properties,the purpose of improving the deficiency of a single matrix film is achieved.In addition,thyme essential oil with antibacterial and anti-oxidant functions was added to the blend membrane to study its effects on the properties of the blending membrane.It is expected that the blending membrane can obtain antibacterial and anti-oxidation properties while improving the compatibility of the two.The blending film was applied to wrap cold meat and stored at 4? in order to increase the shelf life of the cold meat.The results of this experiment are as follows:1.The effect of blending ratio of curdlan and polyvinyl alcohol on the properties of blended membranes was studied.The optimum process conditions for the preparation of the blending membrane were finally determined as follows:the mother liquor of the curdlan was uniformly mixed with the mother liquor of polyvinyl alcohol in a ratio of 4:1,and the dry matter mass of the membrane was 20%,and the dry matter mass of the membrane was 20%.Tween 80,stir evenly and adjust the pH of the mixed membrane solution to 4.0 with lactic acid.Immediately after homogenization,it is placed in a PTFE mold with a size of 18 cm X 18 cm.The temperature is constant at RH 50%and 25?.The film was peeled off after wet drying for 24 h.After the preparation of the blending membrane,various physical and chemical indicators are analyzed,such as mechanical properties,barrier properties,water content,color,infrared spectrum,crystallinity and thermal stability analysis.The results showed that when the ratio of curdlan to polyvinyl alcohol was 4:1,good mechanical properties were obtained,the tensile strength was 11.81 MPa,the elongation at break reached 189.31%,and the water and gas barrier properties were well.The improvement of infrared spectrum scanning analysis shows that the intermolecular force changes,the hydrogen bond and the CH bond are shifted;the crystallinity of the blending film becomes high and the thermal stability increases.2.Define the improvement effect of thyme essential oil on the performance of blending filmThe thyme essential oils of 1.0%,1.5%,and 2.0%of the dry weight of the membrane liquid were separately added to prepare a blending film of the obtainable curdlan and the polyvinyl alcohol.The mechanical properties of the blending membrane,XRD,infrared spectrum and thermal stability were determined to determine the improvement effect of the thyme essential oil on the blending membrane.With the increase of the amount of thyme essential oil,the elongation at break of the blending film increased to 225.99%,and the barrier property was improved.By analyzing the infrared spectrum,XRD pattern and DSC pattern of the blending membrane,the crystallinity of the blending membrane was reduced and the heat was stabilized.The properties were slightly reduced,the C=O bond was enhanced and the components in the film were physically combined,and no chemical changes were produced,and no new chemical bonds were produced.It can be seen from the microstructure of the blending film that the surface of the thyme essential oil blending film is smoother and finer.3.Determine the fresh-keeping effect of the blending film on chilled meattThe blending film containing thyme essential oil was wrapped on the surface of chilled meat and stored at 4?.The results showed that the shelf life of the control group was 6 d,and the chilled meat wrapped with the blending film wrapped with 2%thyme essential oil was used.The TBARS and TVB-N values were not exceeded for 14 days,and the shelf life was 16 days,which was 10 days longer than the untreated group.