Effects Of Thyme Essential Oil On Fresh-Cut Potatoes Preservation And Preparation Of Active Packaging

With the development of society,people had higher and higher requirements for food quality.The application of natural freshness preservatives in food had attracted more and more attention.In this paper,the fresh-keeping effect of five plant essential oils fumigation(thyme,cinnamon,basil,fennel and rosemary)on fresh-cut potatoes was studied.By further adding essential oil to packaging materials;slow-release active packaging suitable for fresh-cut potatoes was prepared.The specific research contents and results are as follows:(1)The results showed that the five kinds of plant essential oil fumigation had a certain fresh-keeping effect on fresh-cut potato.In a certain period of time,they maintained the stability of sensory properties,delayed the decrease of soluble solids and vitamin C,and inhibited the growth of microorganisms.In particular,the preservation effect of thyme essential oil and cinnamon essential oil was better,followed by Rosemary essential oil.After storage for 6 days,the sensory evaluation score,soluble solids,vitamin C and total bacterial count of potato treated with thymus oil and cinnamon essential oil were 12.8 and 12.5,5.10 and 5.13,10 and 8.5 mg/100 g,2.7 and 2.8 CFU/g respectively.In addition,considering the smell of thyme essential oil is closer to potato,it is more suitable for fresh-cut potatoes preservation.(2)Different volume(0,5,10,20,40,80 L)thyme essential oils was used to fumigation on fresh-cut potatoes in a specific packaging system(15*11*2 cm),the results showed that the preservation effect was very different.It was found that the treatment with 20-40 ?L thyme essential oil had the longest preservation time for fresh-cut potatoes.5 ?L essential oil fumigation treatments had no significant difference with the control group.The preservation time of 10?L low concentration thyme essential oil fumigation treatment group was not long,but the score was higher than other concentration groups several days before storage.High concentration of thyme oil fumigation is toxic to fresh-cut potatoes.It can accelerate the decrease of soluble solids and the decomposition of ascorbic acid.Essential oil and gas have a heavy smell and poor sensory evaluation.From the changes of soluble solids and vitamin C content in fresh-cut potatoes,it could be concluded that 40?L fumigation of essential oil might cause slight toxic damage to the tissue of fresh-cut potatoes.By using essential oil fumigation method to preserve fresh-cut potatoes,it was found that the longest preservation time was achieved by adding 20?L essential oil,which could maintain freshness for 6-8 days.(3)The active packaging film was prepared by adding the essential oil of PYME into PVA solution and coating on PE film.With the increase of thyme essential oil content,the thickness,water content and water solubility of the films decreased,and the hydrophobicity of the films increased.The addition of essential oil resulted in the decrease of mechanical strength,the darkening of color and the increase of opacity.The polyvinyl alcohol film prepared by us had good storage stability and humidity-sensitive release,andwas suitable for use as a carrier of fresh-keeping agent at high water activity.In the environment of high water activity,the release rate and final release rate of thin film essential oil containing low concentration of essential oil were higher than those containing high concentration of essential oil,and the release rate of high concentration of essential oil was higher than that of thin film containing high concentration of essential oil.(4)The addition of modified montmorillonite,kaolinite and diatomite slowed the release of essential oil from the active film.The addition of modified montmorillonite had a moderate slow-release effect on the film,and the final release of essential oilwas high.The diatomite film had the strongest slow-release effect,but the final release was low.The slow-release effect of adding 1% and 2% montmorillonite to essential oil was weaker than that of adding 4%,and the final equilibrium release percentage was higher than that of adding 4%.After adding 8% montmorillonite,the slow-release effect was relatively weakened;With the increase of montmorillonite content,the final equilibrium release percentage of essential oil decreased gradually.(5)Active packaging film could be prepared by adding 1-2% montmorillonite and 2% thyme essential oil to polyvinyl alcohol through dissolving and coating.It could meet the requirement of the preservation of thyme essential oil under the condition of setting the packaging.