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Mandarin citrus (C reticulata) was grown in China and Japan on a large scale since the 16th century and it does not well suited for industrial processing of juice but segments canned in syrup can be found.China is the largest producer of mandarin processing and it account for more than 80％ of all processed citrus products.In mandarin canned citrus process using water throughout the entire process，resulting in a large number of organic-rich wastewater.If insufficiently treated，this effluent can seriously impact the environment.Mandarin canning process produces large amounts of acidic wastewater and alkaline wastewater，which are contain higher pectin.This study chooses the acidic wastewater and alkaline wastewater as raw materials that contain higher pectin that can be manufactured，the main conclusions were listed as follows:1.To know the quality of the discharged water from different processing steps of mandarin canning factoryIn this study to monitor and analysis color，turbidity，pH，suspended solids，odor,visible solid，acidity，alkalinity，total dissolved solids，COD of wastewater according to the Chinese Standard Methods for the Examination of Water and Wastewater and the microbial status.The results showed that the wastewater quality of physical and chemical index in every step were higher than the requirements of Chinese National Standard GB5749 except: the index of color，start from grading water，transport water and sterilize canned cooling water，12.65(HU)，10.85(HU)，11.25(HU)，index of turbidity for rinse water 3，grading water，transport water and sterilize canned cooling water 2.40(NTU)，2.10(NTU)，2.25(NTU)，2.00(NTU)，index ofpH in rinse water 1,rinse water 2，rinse water 3，grading water，transport water and sterilize canned cooling water，7.80，6.47，6.45，6.56，6.98 and total number of colony in every process.2.Obtaining of pectin from acidic wastewater and alkaline wastewater because of high content of pectin.Mandarin canning process produces large amounts of acidic wastewater and alkaline wastewater，which are contain higher pectin.The physicochemical properties of acidic wastewater and alkaline wastewater of mandarin canning process as follows:pH value was stable，the monosaccharide composition of acid and alkali pectin,results showed that the acid pectin contains highest amount of galacturonic acid (46.72 mol％)，while alkali pectin has most Arabinose (50.85 mol％).3.Replacement of fat in cookies by the pectin is investigated.The effect of pectin from acid and alkaline wastewater was studied as a fat replacer in cookies.For the application，cookies were enriched with pectin as a substitute of fat at levels of 10％，20％，30％，40％，and 50％ fat replacement basis.When pectin was incorporated into cookies formulations in place of shortening up to 30 ％ by the weight of shortening，the cookie spread diameter was reduced while the color had no significant difference with the control (redness).Surprisingly，the use of citrus pectin as a fat replacer in different percentage reduced the fat content significantly.Sensory data on a 9 point hedonic scale indicated that the panelists liked cookies (up to 20％ pectin replacement) because of the color，texture and appearance as same as control cookies.Thus，citrus pectin proved to be a promising alternative as a fat replacer in cookies production.4.Replacement of fat ice cream by the pectin is investigated.Another application of the obtained pectin is using it on ice cream.Physicochemical，rheological，texture analysis，and sensory evaluation of the ice creams containing different amount of pectin were performed.The results of organoleptic investigation and fuzzy mathematical analysis showed that comprehensive scores of the ice cream containing 0.15％ concentration pectin were similar with full-fat sample.Adding pectin in different concentrations has positive effect on the quality characteristics of ice cream (expansion rate and melting rate),both of expansion rate and melting resistance are increase，because of pectin as a hydrophilic colloid，with gelation and emulsion stability，so that the process of whipping gas is easy to combine with the ice cream，beside that pectin also has a strong water holding capacity