| Due to the gradual shortage of resources and the increasing awareness of environmental protection,the development and utilization of economic green renewable resources has become a hot spot in current research.As a by-product of corn production,corncob is an economical and cheap green renewable resource.The starch film is a degradable film,but the mechanical properties of the single starch film are poor.By adding corncob cellulose as a reinforcing material,the mechanical properties of the starch film can be improved.Adding cassia oil to the composite film to impart certain antibacterial properties to the film.This study explored the properties of starch-based corncob cellulose oleic oil composite membrane,and sealed the fresh-keeping of the green extract,and explored the application value of this kind of degradable green packaging film in the field of vegetable and fruit preservation.The main research contents and conclusions are as follows:(1)Using corncob as raw material,with the ultrasonic-assisted sulfuric acid hydrolysis method,the single-factor and response surface test were designed to obtain the best process:sulfuric acid volume fraction 55%,acid hydrolysis time 80 min,acid hydrolysis temperature 48?,ultrasound Power 160 W.It was observed by SEM that the cellulose distribution was uniform and varied in shape,and most of them were columnar,with a length of about 50 ?m and a diameter of about 10 ?m.By FT-IR,it is shown that the cellulose treated by the ultrasonic-assisted sulfuric acid hydrolysis method has a similar spectrum to that of the original cellulose,and still has the basic chemical structure of the initial cellulose.(2)Using starch as the substrate and corncob cellulose as the reinforcing material,the starch-based corncob cellulose composite membrane was prepared by solution blending casting method,and the physical properties of the composite membrane were studied.The addition of the pigment will reduce the moisture permeability and light transmittance of the composite membrane,and improve the mechanical properties.Considering the cellulose addition amount at 2%(w/v),the WVP value of the membrane reaches 5.5 mm·g/(m2·24h kPa),and the light transmittance amounts to 24%,tensile strength and elongation at break can reach 6.1 Mpa and 40%,and the composite membrane performance is good.In the starch and corncob cellulose,cassia oil was added to make composite membrane,and the physical properties of the composite membrane were studied.It was found that the addition of cassia oil would reduce the moisture permeability and tensile strength of the composite membrane,and make the light transmission and elongation at break increase first and then decrease.Comprehensively balancing various properties,when the amount of cinnamon oil added is 0.2%(v/v),the WVP value of the film reaches 4.6 mm g/(m2·24h ·kPa),the light transmittance is 32%,the tensile strength and elongation at break can reach 5.0 Mpa and 58%.The composite film performs well.The surface of the composite film was observed to be smooth and flat by SEM,and the components were uniformly mixed.FT-IR analysis showed that both cinnamon oil and corncob cellulose molecules have successfully entered the starch matrix,forming a uniform and stable starch-based corncob cellulose oleic oil composite film.Thermogravimetric analysis of the composite film showed that the quality loss of the cassia film reached 65%in the range of 150? to 350?.At 600?,the remaining mass percentage of the starch-based cellulose membrane was only 5.5%,while the remaining mass percentage of the starch-based cellulose oleic oil composite film was 24%.That is,the composite film with the addition of cassia oil was more thermally stable,indicating that the starch-based corncob cellulose laurel composite had good heat resistance.(3)The fresh-keeping grape was sealed and preserved,and the changes of its physiological indexes were studied to explore the preservation effect of the two composite membranes.The experimental results show that the indexes of the green grape after sealing treatment are better than the blank group,and the fresh-keeping effect of the composite film rich in cassia oil is better than that of the starch-based corncob cellulose composite film.On the 10th day,and the decay rate of the green grape is only 29%,the decay index is 11%,the soluble solids is 15%,and the titratable acid content is 0.4%.The main reason is that cinnamaldehyde in cassia oil has antibacterial properties.The research shows that the starch-based eorncob cellulose guinea oil composite membrane is a composite membrane with good performance and certain antibacterial and fresh-keeping functions. |
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