Preparation Of Essential Oil/MFC Aerogel And Application In Packaging

Natural plant essential oil has many advantages,such as green environmental protection,high safety,wide spectrum bacteriostasis and so on.The combination of volatile and antibacterial properties of essential oils with green renewable,biodegradable and biocompatible raw materials of cellulose aerogels has become one of the hot topics in the research of aerogels with the function of slow release of essential oils.In this paper,we used eucalyptus bleached kraft pulp as the raw material,through the 2,2,6,6-tetramethylpiperidine-1-oxide(TEMPO)oxidative pretreatment and enzyme pretreatment to obtain microfibrillated cellulose(MFC).The MFC and essential oil nanoemulsion was mixed to prepare the essential oil/MFC aerogel,which has the sustained release effect.The research contents include:gas chromatography-mass spectrometry(GC-MS)analysis of thyme essential oil components;preparation of essential oil nanoemulsion;preparation and characterization of pure MFC aerogel;preparation and characterization of Essential Oil/MFC aerogels;Essential Oil/MFC aerogels on the fresh-keeping effect of fresh beef.GC-MS analysis of thyme oil shows that the main antibacterial component of thyme oil is thymol with an absolute content of 0.12 mg/mL.The best preparation of essential oil nanoemulsion was thyme oil 10g,Twain 80 10g,distilled water content 500g and lecithin was 0.001g.The pure MFC aerogels(M-A)performance analysis showed that the larger the mass percentage of MFC,the more conducive to aerogels forming,and the MFC of 1.0wt%has the best appearance appearance.The specific surface area of TEMPO pure MFC aerogels is 7.2 times of the specific surface area of enzyme pretreated pure MFC aerogels;compared with the enzymatic pretreatment of MFC aerogels,crystallization of TEMPO pure MFC aerogel is improved by 13.0%;The thermal degradation temperature of TEMPO type MFC aerogels is lower 11.5 degrees to the enzyme pretreated MFC aerogels,which had a better thermal stability;SEM observation shows that the microstructures of the two types of pure MFC aerogels are three-dimensional porous structure.The maximum essential oil concentration of essential oil/MFC aerogel was 0.6%.For the same type of essential oil/MFC aerogel,the initial retention rate of 0.6%was 2 times as much as the corresponding initial retention rate of 0.1%.Under the same concentration of essential oil,the initial retention rate of essential oil in enzyme pretreated essential oil/MFC aerogel was 3-4 times of the initial retention rate of essential oil in TEMPO type essential oil/MFC aerogel.It can be seen from the release characteristics of thyme essential oil in the composite aerogels,both of the release rate of composite aerogels with TEMPO and enzyme processing mode showed a tendency of increasing first and then decreasing,which indicated that aerogels had slow-release effect.The average release rate of C(6u/g)-O(0.1%)/M-A?C(6u/g)-O(0.6%)/M-A?T-O(0.1%)/M-A?T-O(0.6%)/M-A was 5.2%?3.1%?2.8%?1.5%respectively.In the same essential oil concentration,enzyme pretreatment type oil/MFC aerogel release oil volume is 1.1 times the amount of essential oils release from the TEMPO type essential oil/MFC aerogels,so TEMPO oil/MFC aerogel had a better sustained release effect.Chilled beef was prepared by the composite aerogels with 0.3%and 0.6%essential oil concentration.The results showed that the release effect of TEMPO pretreatment type oil/MFC aerogels were better than enzyme pretreatment type oil/MFC aerogels.Compared with the control group,The slow release of thyme essential oil through oil/MFC aerogels can better maintain the sensory quality of fresh beef,reduce the pH increasing rate,inhibit the growth of microorganisms,delay the increase of volatile basic nitrogen and fat oxidation degree.By comparison,TEMPO-0.6%type essential oil/MFC aerogel has better preservation effect than the other three kinds of composite aerogels,and it can extend the shelf life of fresh beef from 4-5 days to 9 days.