Preparation Of Micro/Nano Capsules Based On Plant Essential Oils And Study On The Preservation Effect Of Apricot

Fruits and vegetables storage during postharvest is of great significance in regulating their market supply,increasing added value and reducing post-harvest losses.Chemical preservatives commonly used in the preservation of fruits and vegetables are harmful to human health.Therefore,it is of valuble to develop preservative agents from natural sources.Plant essential oils are rich in aldehydes,phenols and terpenes,and can be used as effective bactericidal and insecticidal ingredients.These natural plant-derived ingredients have the advantages of broad-spectrum sterilization,biodegradation,safety and non-toxicity,and have been researched and applied in the field of food sterilization in recent years.However,plant essential oils are liquid,volatile and inconvenient to use,and a solution that can solve these problems is neccessary.In this study,the most effective antibacteral oregano oil was selected from wintergreen oil,trans-2-hexenal,clove oil,lemon essential oil,oregano essential oil and cinnamon essential oil.The oregano essential oil micro/nano capsules were prepared by complex coacervation method with gelatin and gum arabic as wall materials,and the preservation effects on apricot was studied.The main research results are as follows:The antibacterial effect of six plant essential oils against Botrytis cinerea and Penicillium were determined by filter paper method,minimum inhibitory concentration,minimum bactericidal concentration,direct contact in vitro method and in vitro fumigation method.The results showed that wintergreen oil,trans-2-hexenal,clove oil and cinnamon essential oil all had certain antibacterial effects against Botrytis cinerea and Penicillium;while lemon essential oil had no antibacterial effect against Botrytis cinerea and Penicillium.Oregano essential oil has the best antibacterial effect against Botrytis cinerea and Penicillium.Oregano essential oil microcapsules were successfully prepared by complex coacervation method using gelatin and gum arabic as wall materials.The preparation process was optimized by single factor test and orthogonal test.The optimal preparation process is as follows: wall material ratio is 1:1,p H value is 4.0,wall material concentration is 1%,core wall ratio is 1:1,reaction temperature is 45 ?,reaction time is 30 min,quality ratio of curing agent to gelatin is 1:4,curing time is 3 h.The encapsulation efficiency of oregano essential oil microcapsules prepared by this method is 83.65%,and the average particle size is 147 ?m,which has good thermal stability(thermogravimetric analysis)and storage stability(differential scanning calorimetry analysis).Oregano essential oil nanocapsules were successfully prepared by complex coacervation method using gelatin and gum arabic as wall materials.The preparation process was optimized by single factor test and orthogonal test.The optimal preparation process is as follows: p H value is 4.95,wall material concentration is 0.5%,core material concentration is 0.5%,emulsifier concentration is 0.6%,curing agent concentration is 0.2%,reaction temperature is 45 ?,reaction time is 20 min,curing time is 3 h.The encapsulation efficiency of oregano essential oil nanocapsules prepared by this method is 88.3%,and the average particle size is 135 nm,which has good thermal stability(thermogravimetric analysis)and storage stability(differential scanning calorimetry analysis).Oregano essential oil micro/nano capsules can reduce the decay rate,microbial quantity and polyphenol oxidase activity of apricot fruits stored at room temperature.It achieved the preservation effect on apricot by improving the activities of peroxidase,catalase,phenylalanine ammonia-lyase,beta-1,3-glucanase and chitinase.In addition,oregano essential oil nanocapsules have better preservation effect on apricot during storage at room temperature than that of oregano essential oil microcapsules.