Effect Of Instantaneous High Temperature Sterilization On Quality Of Ilex Kudingcha

Ilex kudingcha C.J.Tseng is an evergreen tree belonging to the Ilex family.It mainly contains triterpenes and their glycosides,flavonoids,caffeyl quinic acids,polysaccharides,and has various biological activities such as lowering blood lipid,lowering blood sugar and antioxidant.High Temperature Short Time is a sterilization technology that uses direct steam or heat exchanger to keep food and medicine at 150℃～180℃temperature for a few seconds or more than 10 seconds after heating and sterilization,and then cools rapidly so that bacteria cannot survive and grow.Kuding tea is a kind of health tea that is used both as medicine and food,and its tea leaves have potential fungal pollution in the process of growth,picking,processing,transportation and storage,which seriously harms the health of users.Therefore,it is particularly important to choose an appropriate and efficient sterilization method.In this study,the instantaneous high temperature sterilization technology was adopted to optimize the instantaneous high temperature sterilization process parameters of Ilex kudingcha by using the dried leaves of Ilex kudingcha as raw materials,combined with multiple indexes of orthogonal design.The effect of instantaneous high temperature sterilization on the three indexes was evaluated by visual and variance analysis results,with sterilization temperature,sterilization time and drug particle size as the investigation factors,and sterilization rate,DPPH·antioxidant activity IC₅₀value and polyphenolic compounds content as the investigation indexes.The results of single factor visual and variance analysis showed that the sterilization temperature had a significant effect on the sterilization rate（P<0.05）,and other factors had no effect on the sterilization rate（P>0.05）.The optimum conditions of sterilization process were determined as follows:sterilization temperature 160℃,sterilization time 10 seconds,particle size no more than 24 mesh.Three batches of samples were sterilized according to the optimized process,and the effect of sterilization treatment on the quality of Ilex kudingcha was investigated from four aspects:moisture content,polysaccharide content,antioxidant activity and polyphenol content.The microbiological limit of the sterilized samples was in accordance with the provisions of the pharmacopoeia.The water content of the samples after sterilization decreased by 0.23%on average compared with that before sterilization.The average polysaccharide content decreased by 0.07%;The IC₅₀value of DPPH·antioxidant activity decreased by 0.19 mg/m L on average;The absorbance value of reducing power of potassium ferricyanide increased by 0.008 on average;The IC₅₀value of PTIO·antioxidant activity decreased by 1.12 mg/m L on average;The total polyphenol content increased by0.14%on average.The data related to quality before and after sterilization were tested by t test,and the results showed no significant difference（P>0.05）.The fingerprint of samples before and after sterilization was established,and the similarity was>0.9.In conclusion,instantaneous high temperature sterilization has no effect on the quality of Ilex kudingcha,which provides experimental basis for the application of this technology in the sterilization of Ilex kudingcha.The HPLC fingerprint of polyphenols was constructed,and the principal component analysis was carried out by SPSS22.0 software.The antioxidant activity of Ilex kudingcha from different producing areas was determined.Bivariate correlation analysis and partial least squares regression analysis were used to analyze the spectral effect relationship between polyphenols and antioxidant activity.The results of principal component analysis showed that neochlorogenic acid,cryptochlorogenic acid and peak 9 played an important role in distinguishing samples from different habitats.Cluster analysis showed that the Ilex kudingcha samples from different areas showed regional clustering characteristics.Spectrum analysis results showed that neochlorogenic acid,chlorogenic acid,cryptochlorogenic acid and isochlorogenic acid B had good antioxidant activity.Through the integrated analysis of Holly fingerprint and antioxidant activity of Kudingcha,the contribution of antioxidant activity of each component was determined,which provided a basis for the formulation of quality control methods.Three heavy metal elements of lead,mercury and arsenic,and two pesticide residues of hexafluoride and DDT in samples before and after sterilization were investigated.The heavy metal and pesticide residues in the samples before and after sterilization were in line with the national standards.The t test was conducted on the data related to agricultural residues and heavy metals before and after sterilization,and the results showed no significant difference（P>0.05）,indicating that the quality of Ilex kudingcha in the market circulation and the quality of Ilex kudingcha after instantaneous high temperature sterilization was stable and safe.