| In recent years,with the improvement of living standards,yogurt,as a member of dairy products,has been loved by people for its unique flavor and high nutritional and healthy value.Yogurt not only retains all the advantages of milk,but also makes use of the advantages and avoids the disadvantages in some aspects through production and processing to meet the needs of different consumer groups.In daily life,it is found that many packaged yogurt especially league cup of yogurt has a large amount of yogurt residue after drinking,which causes a lot of waste.The food harvesting-processing-logistics-market-consumption,in this chain,the amount of food waste caused by the end consumer link(consumption behavior)is amazing.In order to meet the needs of consumers,the main purpose of this experiment is to reduce the residual amount of the cup of yogurt after drinking thereby reduce waste.In this experiment,the main study were the packaging materials of the anti-adhesive yogurt cup and the verification method of anti-adhesive property and the quality of the yogurt after been packaged.There are varieties types of yogurt packaging on the market.Many packaged of yogurts have a large amount of yogurt residue after consumers drink them,which causes a lot of waste,this phenomenon is not only related to the way of drinking yogurt,but also to the packaging materials of yogurt.This experiment investigated the plastic packaging form of yogurt on the market and the residual amount of yogurt in the league cups,so as to compare with the yogurt packaged in the prepared film.The main research methods and processes are as follows: firstly,conducted market research,investigated and recorded the packaging materials of different brands of yogurt,so as to determine the substrate used in this experiment;then measured the residual amount of league cup of yogurt of different packaging materials;by exploring and consulting relevant literature,determined that using polypropylene as the substrate,polytetrafluoroethylene and silicone oil as modifiers,anti-adhesive films were prepared by blending-extrusion casting process;after the wanted films was obtained,the mechanical properties,optical properties,thermogravimetry,microscopic properties the Fourier transform spectrum and the most important property — anti-adhesive properties of the films were tested;once the anti-adhesive properties of the films prepared by the Stretch film machine,packaged the yogurt with the prepared films stored at 4 ° C for 1 d,7 d,14 d.Then theviscosity,sensory evaluation,p H value,the sanitary safety performance and whether new substances were produced were analyzed,the data were used to demonstrate the packaging effect of the modified polypropylene anti-adhesive films on yogurt.The main conclusions were as follows:(1)According to the market investigation on the packaging materials of league yogurt,the survey results showed that most of the packaging materials of league cups of yogurt are polypropylene,and polypropylene is one of the commonly used plastic packaging materials,so the substrate of this experiment was polypropylene.(2)After eating the different brands of yogurt purchased in the supermarket with normal drinking methods,tested the residues amount of the yogurt remaining on the wall of the cups,the results showed that the average residual quantity of Yi Li league cups was 13.71%,and the average residual quantity of Guang Ming was11.90%,because the original quality of even a cup of yogurt is only about 100 gram,from the above data,the residual amount of yogurt was very large.So it is one of the purposes of this experiment to solve the above phenomenon.(3)Polypropylene was used as the substrate,added the content of 3%?5% and7% of silicone oil and the content of 6%?8%?10% and 12% of polytetrafluoroethylene as modifiers,then prepared the anti-adhesive films by blending and casting.The results showed that the tensile strength of films with silicone oil content of 5% and 7% and PTFE content of 6% and 8% were better than that of pure polypropylene films;the change of the contact angle of the modified films was as follows: the contact angle increased with the increase of silicone oil concentration,increased from 87.88° to116.73°,the contact angle of the films modified by PTFE gradually increased in the processing when the addition amount was 6% and 8%,to content 8% of the contact angle was the largest,it was 103.54 °,while when PTFE content was 10% and 12%,the contact angle gradually decreased with the increase of addition amount,decreased from102.20° to 94.60°.Therefore,when the amount of silicone oil was 7% and the amount of PTFE was 8%,the surface tension of the films,that was,the performance of hydrophobic and anti-adhesion was the best;It can be seen from the infrared spectra of the modified films that the two modifiers can be compatible with polypropylene and produced no other substances.They can neutralize the crystallization zone of polypropylene and stabilize the properties of the films;In addition,safety experiments were performed on the modified films according to the national standard method,and the results proved that the modified films had no hidden dangers and can be used for packaging;In this experiment,the following results can be drawn by designing three anti-adhesive verification methods: from the test 1-sliding from different tilt angle,it can be seen that with the increase of the tilt angle,when the angle was 90 °,the residualamount of the film modified by silicone oil content 7% was 16.73%,compared to the residual amount of the original cup films 27.48% decreased by 10.75%,and the residues of the films modified by the content of 8% PTFE was 12.46%,which less than the original cup films by 15.02%;from the test 2-simulation of the free fall drop experiment,the results showed that the residual amount of the film with 7% silicone oil was 40.42%less than that of the original cup film,and the residual amount of the film with 8%PTFE was 39.73% less than that of the original cup film.Successfully verified that the modified film has the anti-blocking function.After the verification of method three,the best anti-adhesive film was 8% PTFE-modified polypropylene film,and its remaining amount of yogurt was 26.61%,followed by the polypropylene film modified by 7%silicone oil,the residual amount of it was 28.67%.(4)Compared the quality of yogurt packed with modified films,original league cup and pure Polypropylene film storage at 4? for 1d,7d and 14 d,the results showed that: It is obvious to see from the infrared spectrum of yogurt that the yogurt packaged with modified films was similar to that of the original cup yogurt,and there was no substrate reduction or generation;As can be seen from the figure of p H value change experiment,the p H value of yogurt packaged with 7% silicone oil and 8% PTFE was not much different from that of original cup yogurt,which proves that the modified films will not affect the p H value of yogurt;According to the test of the change of the viscosity of yogurt,the viscosity of yogurt packaged with modified films is similar to that of yogurt packaged with original cup film after the same days of storage,which indicated that the viscosity of yogurt packaged with modified films will not change due to the packaging;Through the sensory analysis of yogurt,the color,smell,taste and organizational structure of the yogurt packaged with modified films were not much different from that of the original yogurt.In conclusion,on the premise that the anti-adhesive property of the modified films was much better than that of the original cup film,the quality of the yogurt packaged with the modified films was not much different from that of the original cup yogurt stored under the same conditions,so this experimental study has application value. |
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