Fabrication,Characterization And Application Of Pickering Emulsion Stabilized By Tea Waste Microcrystalline Cellulose

Nowadays,application of Pickering emulsion in functional food has been the hot topic in whole food industry.Initially,emulsion was stabilized by inorganic,composite particles,such as silica,graphene oxide.But in order to meet the needs of natural,green,safety,developing food-grade Pickering particle stabilizers in functional food research becomes more important.In addition,China is a big tea producing country.During tea deep prosessing,there is a large amount of tea waste that is not properly utilized every year,which not only puts pressure on the environment,but also causes huge waste of resources.It was reported that tea waste contained 16-18%cellulose.As the important derivant of cellulose,Microcrystalline Cellulose（MCC）receives considerable attentions and has been applicated in Medical,Chemical,Food and Materials industries.In this study,Microcrystalline cellulose（MCC）was prepared from Oolong tea waste by acid hydrolysis.The hydrolysis conditions were optimized by an orthogonal L₉（3）⁴ experiment.Under optimal conditions,the chemical structure,thermostability and surface topography of tea waste MCC was characterized.Then,the Pickering emulsion stablized by tea waste MCC was studied like properties and storage stability.Finally,the potential applications of tea waste MCC Pickering emulsion in the encapsulation and delivery of lycopene was investigated.The main research contents and results are as follows:（1）Preparation of tea wasteDuring the acid hydrolysis,time,temperature,acid to materials ratio,HCl concentration have significant effect on DP and yield of MCC（p<0.05）.And with the increasing of time,temperature,acid to materials ratio,HCl concentration,the DP ad yield of tea waste MCC decreased.The orthogonal experiment was used to optimize conditions:acid to materials ratio 1:20,HCl concentration 1.5mol/L,65^oC,90min,and under these optimized conditions,while the yield and degree of polymerization（DP）were 86.7%and145,respectively.Four factors followed the order of hydrolysis temperature>HCl concentration>hydrolysis time>ratio of acid to materials.（2）Characterization of tea waste MCCFourier transform-infrared spectroscopy（FT-IR）,X-ray diffraction（XRD）analysis,Thermal analysis and Scanning electron microscopy（SEM）were used to characterized tea waste MCC.Characterization results showed that tea waste MCC had cellulosic structure and it was cellulose I type.MCC had shorter fibers with rough surface morphology and some holes on the surface from SEM results.Thermal analysis demonstrated that MCC had good thermal stability.（3）Properties of tea waste MCC Pickering emulsionThe diameter of emulsion increased with increasing of concentration of MCC,oil/water ratio and pH.High MCC concentration（1.00、2.00%）,pH,low oil/water ratio（1:9）and low NaCl concentration benefited in emulsion stability.The diameter of emulsion did not have significant change in 42d when it was in MCC concentration（1.00,2.00%）,pH 7,low oil/water ratio（1:9）and NaCl concentration 0 mmol/L.（4）Embedding of active material and digestion in virtroCompared by soybean oil,embeding by pickering emulsion increased stability of lycopene.Added,the higher the MCC concentration was,the higher stability of lycopene was.The low temperature and low light conditions are favorable for the embedding stability of lycopene in MCC emulsion.In vitro simulation of digestion,the contents of MCC Pickering emulsion containing lycopene were kept at over 90%in the stomach and small intestine,and the digestive stability was good.Lycopene was not released during stomach digestion,and the lycopene release rate reached 66.09%after digestion in the small intestine.