Separation And Characteristics Of Pectin From Premna Microphylla Turcz Leaves

Premna microphylla Turcz is a perennial deciduous shrub whose leaves contain pectin from10% to 30%.The pectin content and properties have diversities in different months and regions from Premna microphylla Turcz leaves,and the quality of "leaf jelly" is closely related to the pretreatment and pectin of leaves.Using Premna microphylla Turcz leaves as raw material from Jiangyou City,Sichuan Province,firstly,the staple components of leaves were determined in different months and regions.Secondly,the effects of different pretreatments on the physical and chemical properties of pectin were studied,and then the process optimization and comparative analyses for the acid extraction method and the ultrasonic assisted extraction method were carried out.Next,the characteristic divergence of pectin from different months were compared.Finally,the application of pectin in solidified fermented milk was explored.The main research results of this thesis were as follows:The basic nutrients of leaves in different months and regions were significantly different,and the leaves from Jiangyou area were rich in crude protein,pectin,flavonoids,Magnesium,Calcium and so on.The pectin yield rate(It was obtained by calculating the percentage of pectin product quality as powder quality of Premna microphylla Turcz leaves.)was ranged from 4.24% to 18.24%,the percentages from May to September were relatively higher and more than 15%,which were suitable for pectin extraction.The principal component analysis method was used to comprehensively evaluate the affects of different pretreatments on physicochemical properties of pectin from Premna microphylla Turcz leaves,the consequents manifested that steam and microwave pretreatment improved the yield,galacturonic acid content(The content was calculated by galacturonic acid after acid hydrolysis of pectin products)and color of pectin,but the gel properties were greatly reduced under the same conditions,and the comprehensive rating was non-treatment > microwaves > acid soaking > steam > blanching > freezing,which indicated the pretreatment couldn't effectively promote the quality of pectin.The outcomes of the two extraction methods demonstrated that the extraction rate and galacturonic acid content of pectin obtained by acid extraction method were higher than that of the ultrasonic assisted extraction method,and the other master components and properties were similar.So the acid extraction method was better and the optimum conditions were1:30 of solid-liquid ratio,88? of extraction temperature,2.2 h of extraction time,and 1.6 of p H value.Under above combined condition,the extraction rate of pectin was 10.57%.The principal component analysis method was applied to assess the features of pectin in different months(from May to October),and the order of the comprehensive score from high to low was September>July>August>Octo>June>May,which revealed the quality of pectin leaves was visible discrepancy in different months.The pectins from July to September were15.30%~18.24% of yield,15.30%~18.24% of the galacturonic acid content and favorable gel and emulsifying properties,in addition,the comprehensive score was evidently higher than other months,which were more adequate for the extraction and utilization of pectin.The application discussion of pectin in solidified fermented milk found that the fermented milk had good quality when the amount added of pectin from Premna microphylla Turcz leaves was 0.05%,and it was close to the fermented milk with 0.15% of pectin from orange peel.The event suggested that the pectin from Premna microphylla Turcz leaves had obvious stability to fermented milk and was superior to the common commercial pectin of orange peel,which owned great application value.