| China,one of the places where citrus orignated,is rich in citrus varieties.The planting area and production of citrus in 2007 has come to 1910 thouand hectares and 20.59 million metric tons respectively,which were the first in the world.The biochemical meaterials in citrus fruits such as inositols,flavonoids,limonoides,carotenoids not only have effects of reducing blood sugar level, cholesterol-lowering,anti-cancer,prevention and treatment of circulatory and psychiatric disorders and so on,but also can be used as the markers of screening species initially and adulteration detection of orange juice.Untill now,A few researches on myo-inositol in citrus have been reported, while rarely on chiro-inositol and scyllo-inositol.Both the simultaneous determining method of inositols and carbohydrates in citrus juice and the contents in various of citrus are all lace of systematic research.The physical and chemical characters and contents of inositols of 67 varieties samples collected from Chinese citrus germplasm resource garden,Newhall navel orange from south of Jiangxi province and the Three Gorges Reservoir areas,preservation navel orange samples,processing orange juices samples and citrus fruit juices samples from market were analyzed.Based on the results,the classification function of main cultivated varieties,the relation among different varieties revealed by character of juice were disscussed.The main results of this paper were as follows:1.A sensitive method for simultaneous determination of Chiro-inositol,Scyllo-inositol,Myo-inositols and carbohydrates in citrus juice,including fructose,glucose and sucrose,by gas chromatography has been developed.Citrus juice samples,after being centrifuged and dried by air stream,sugar oxirnes were formed using hydroxylamine chloride in pyridine and heated at 50℃for 20 min.After reaction,samples were persilylated using hexamethyldisilazane(HMDS) and trifluoroacetic acid(TFA) at 60℃for 25 min.Gas chromatographic separation was carried out using a HP-1701 capillary column(30m×0.32mm i.d.×0.25μm) and programmed temperature then detected by FID dector.Quantification by using internal standard.The average recoveries of carbohydrates and inositols in citrus juice were 98.1%～106.9%and 100.2%～106.9%respectively; RSD were 0.55%～2.01%and 2.18%～6.12%respectively.The repeatabilities of carbohydrates and inositols were 1.56%～3.54%and 1.94%～3.35%(n=11) respectively.The detection limits of carbohydrates and inositols in citrus juice were 0.30 mg·L-1 and 0.29 mg·L-1 respectively.Those results indicated that this method is fast,convenient,sensitiveand accurate,which practical for carbohydrates and inositols analysis in citrus juice.2.According to the characters and inositols analysised results of 67 varieties from citrus germplasm resources of the country garden,It has shown that,the difference on TTS is not significant among Sweet Orang,Polemo,Tanglo and Tangor,while significant between Mandarin and Limon.Limon got the highest level of TA,4.34 g·100ml-1,which is 8.51 times of Polemo (0.51g·100ml-1).Both Polemo and Sweet Orange are rich in Vc,which is about 58.65 and 48.02 mg in per 100 ml juice respectively.The fructose and glucose level in Sweet Orange is 19.79 and 18.21 g·L-1,and sucrose level in Polemo is 48.37 g·L-1,which are all highest in citrus juice,while the fructose,glucose and sucrose level in Limon is 4.57,3.88 and 1.85 g·L-1 respectively,which are lowest in citrus juice.According to the analysis results,inositols level in pomelo was the highest,reaching 2.16 g·L-1, while much less in Limon and kumquat,1.77 g·L-1 and 1.72 g·L-1 in sweet orange and mandarin respectively,tanglo and tangor were among thoes species.The sequence of diverse inositols contents was shown:chiro-inositol＞myo-inositol＞scyllo-inositol in mandarin and tangor;myo-inositol＞chiro-inositol＞scyllo-inositol in other citrus varieties,respectively.3.With the total amount of inositols(Is) as the abscissa and myo=inositol(MI),chiro-inositol (CI) and scyllo-inositol(SI) as the y-axis of scatter graph,Limon and kumquat can be distinguished by SI/Is,while not on sweet orange,mandarin,tangor and pomelo;MI/Is is better than CI/Is on Limon,pomelo and kumquat separation,and CI/Is can also be used to separated the common sweet orange from naval orange in sweet orange,suggesting that MI/Is and CI/Is are meaningful to the classification of citrus varieties.4.Three principal component were got from nine indexes of physical and chemical character and inositol contents by variance analysis,and the PCA score of samples were calculated and used in the Scatter graphing,K-culster and Hierarchical Cluster analysis.The scatter graphing results turn out that the Limon,Mandarin and Sweet Orang could be well separated from other species respectively,but not tangelo and tangor.K-culster played a role in Common Sweet Orange and Navel Orange discrimination and Hierarchical Cluster did some help on C.unshiu(Mak.) Marc.and C.reticulata Blanco seperation.5.The characters and inositol contents of samples from different areas,different processing methods and storing have been analysed,and the results shown:there was a significant difference on the characters and inositol contents in Newhall orange samples from south of Jiangxi province and Three Gorges Reservoir Area of the Yangtze.Little difference between the FMC juice and hand-pressed juice,so the squeeze methods have nothing to do with the inositol contents.The characters and inositol contents is decreasing in storing orange samples.The inositol contents in fruit juice from concentrate is lower than straight-processed.The inositol in citrus juice is account for the juice content in orange juice initionly.
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