| At present,the research on edible antibacterial starch membranes mainly focuses on the basic properties of the membranes and the simple antibacterial properties.Some existing antibacterial agents often have problems such as poor safety,poor drug resistance,and poor processing performance.It is not clear how the process of migrating and releasing from the membrane exerts antibacterial action.It is necessary to study how to add safe and non-toxic natural antibacterial agents to the starch film and reveal the migration and release of these antibacterial agents from the film.In this paper,natural plant essential oil carvacrol was first prepared into?-cyclodextrin,and then added into corn starch as antibacterial to make slow-release antibacterial starch film.The basic properties of the film and the transfer and release of carvacrol from the film were studied.The film is applied to tomato preservation.The main research contents and conclusions are as follows:?1?Preparation and properties of?-CD-CAR-IC??-cyclodextrin-carvacrol inclusion complex?Using?-cyclodextrin and carvacrol as raw materials,the?-CD-CAR-IC was prepared by the saturated aqueous solution method.The results showed that when the inclusion temperature was 80°C,the inclusion time was 2 h,and the inclusion ratio was 1:7,the inclusion rate of the?-CD-CAR-IC obtained was up to 73.41%,and the yield of the inclusion product was up to 84.25%.Infrared spectroscopy showed that carvacrol and?-cyclodextrin formed a?-CD-CAR-IC;the morphology of?-cyclodextrin and carvacrol was significantly different after scanning electron microscopy,indicating that a new type of carotenoid was formed.Differential scanning calorimetry also showed that carvacrol and?-cyclodextrin formed a?-CD-CAR-IC,which also showed that the clathrate was thermally stable.The antibacterial test of?-CD-CAR-IC showed that the?-CD-CAR-IC had inhibitory effect on Penicillium.The substance is the?-CD-CAR-IC can control the release of carvacrol.With the increase of temperature,the release rate is accelerated,and its release law conforms to the first-order kinetic equation.?2?Preparation and properties of slow-release antibacterial starch filmsCorn starch was used as the base of film,sorbitol was used as plasticizer,?-CD-CAR-IC was used as antibacterial agent,and slow-release antibacterial starch film was prepared.The results showed that the starch solution,sorbitol/starch solution,and?-CD-CAR-IC solution belong to the shear-thinning pseudoplastic fluid.The addition of sorbitol and?-CD-CAR-IC affects the performance of the film.The results showed that the sustained-release antibacterial starch film was prepared under conditions of corn concentration 6.0%,sorbitol concentration 1.2%,and?-CD-CAR-IC concentration of 0.5%.The TS of the membrane was 5.385 MPa,and the corn starch concentration was 4.0%.The sustained-release antibacterial starch film was prepared under the conditions of 1.79%concentration and 0.41%of?-CD-CAR-IC.The E value of the film was higher,which was 107.92%.Infrared spectroscopy and scanning electron microscopy studies of slow-release antibacterial agents and common membranes have shown that?-CD-CAR-IC has been added to corn starch film,and there is an intermolecular hydrogen bond interaction between carvacrol and corn starch.there was good compatibility between the film,and there was no obvious delamination of the film.The antibacterial test was performed on the antibacterial film and the ordinary film.Compared with the control group,the antibacterial effect of the antibacterial film was obvious.?3?Study on the migration and release of carvacrol from slow-release antibacterial starch filmsA food simulation system was used to study the migration of carvacrol from the membrane under different external conditions?mainly temperature?and different formulation conditions.In the distilled water of the food simulation system,the migration rates of carvacrol at different temperatures over time were approximately the same,both in the initial period?0-72 h?,the migration rate increased rapidly,and after 72 h,the trend was gradual and finally reached balance at different times.In general,the higher the temperature is,the faster the migration will be,and the faster the balance is reached,the shorter the time will be.When the starch concentration increases,the equilibrium time for migration and release is increases.When the sorbitol concentration increases,the equilibrium time for migration and release is shortened.When the concentration of carvacrolates increases,the equilibrium time for migration and release increases.The migration kinetics of carvacrol from the film was investigated.The diffusion coefficients of carvacrol in the sustained-release antibacterial starch film were all in the order of 10-12 at different temperatures and different formulations,indicating that adding carvacrol to corn starch film has a better sustained release effect.?4?Study on Slow-Release Antibacterial Starch Films for Preservation of tomatoesThe use of slow-release antibacterial starch membranes and ordinary starch membranes for the treatment of cherry tomato,to study the antibacterial effect of preserved fruits.During the storage period,the sensory,weight loss rate,rotting rate,soluble solids,and Vc changes were observed.The results showed that the tomato preserved by the slow-release antibacterial starch film coating was better than the ordinary and non-film preserved cherry fruits.The results of the three treatment methods?antibacterial film,ordinary film,uncoated film?on the storage of tomatoes during the storage period were as follows:the sensory scores were 10-5 points,10-4points,and 10-2.5 points at room temperature,10-6 points,10-4.5 points,10-3.5 points at low temperature.The change of weightlessness rate were 0-8.8%,0-10.2%,0-12.1%at room temperature,and 0-6.2%,0-7.5%,and 0-9.1%at low temperature.The rotting rates were 0-44.5%,0-50%,and 0-61.1%at room temperature,and 0-33.3%,0-44.4%,and 0-50%at low temperatures,respectively.The changes of soluble solids were4.08-5.4%,4.08-5.67%,and 4.08-6.11%and 4.08-5.12%,4.08-5.32%,and 4.08-5.6%at low temperatures,respectively.The changes of Vc were 40.16-24.8 mg/100 g,40.16-18.3 mg/100 g,and 40.16-6.9 mg/100 g at room temperature,and 40.16-27.9mg/100 g,40.16-22.8 mg/100 g,and 40.16-12.5 mg/100 g at low temperature,respectively.The low temperature preservation better prolongs the shelf life of the tomato,which is the result of the release of carvacrol.At 4°C,carvacrol can stay in the membrane for a longer time,the effect is better,and the low temperature helps to inhibit or slow the microorganisms and the role of enzymes in preventing tomato corruption.This shows that the antibacterial film can maintain the freshness of the tomato and extend the shelf life. |
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