Extraction Technique And Properties Of Pectin From The Peel Of Jiangxi Navel Orange

Citrus Pericarp resource can be found, but it is serious waste and caused environmental pollution, so it is urgent to comprehensive utilizate. Pectin, which is greatly demanded of food producing and processing, could transformate most Citrus Pericarp resource to improve its added value.In this paper, peel of Navel orange from South Jiangxi as the material, we compared three methods of pectin extraction , as acid extraction method,oxalic acid extraction method and ion exchange resin extraction method, from pectin yield and economic cost perspective; then we analyzed and optimized ion exchange resins extraction by quadratic general revolving regression and response surface method. And Pretreatment of orange peel, decoloration of pectin and separation process were studied, further analyzed basic physicochemical property and rheological property of pectin, some conclusions were drawn as follows:1. The viscosity of pectin solution as index, this paper compared three methods as steam,boiling water blanching and high-temperature drying-out to killing enzyme. The results showed that the effect of killing enzyme of orange peel was the best and the viscosity number was eight times of the unprocessed sample, while it was steaming at 121°C for 8 minutes2.The yield rate of pectin extracted by ion exchange resin (IPE) was 4.9% more than it by acid extraction method (AP) ,and 0.3% more than it by oxalic acid extraction method. As processing one ton orange peel, the enhancive economic value of IEP and AOP were the same, but increased 3610 yuan than AP, and the ion exchange resin could be recycling and reusing in production process; The optimum extraction condition of IEP after optimizing and selecting was as follows: the weight of the ion exchange resin was 20% of weight of dry orange peel,pH1.87, extraction temperature 88°C, extraction time 110min. Under these conditions, the yield of IEP was 27.55%.3. The decolorizing effect of AB-8 macroporous adsorption resin was the best, because the appearance color of product was white, the solution was colorless transparent, the absorbance value was 0.011 and the loss rate of pectin was 3.8%; The optimum extraction condition of ethanol precipitation method was as follows: ethanol concentration 55%, solution temperature below 40°C, 20min. Under these conditions, the loss rate of pectin was only 0.5%.4. The quality indexes as galacturonic acid and ash of IEP were accord to national standard and FCC standard; The molecular weight of EEP was relatively large,it of about 1513.5kDa, and there was no larger impure peaks,so IEP has high purity; IEP contained rhamnose(0.151%), arabinose(0.209%), xylose(0.081%), mannose(0.201%) and galactose(0.392%), it also contained other neutral sugar to situation of peak, this could explain that the neutral sugar side chains were more in IEP molecular.5. The viscosity value of 0.5 % pectin solution decreased with increasing shear rate, so it was a typical non-Newtonian fluid; The viscosity of pectin solution was greater affected by pectin concentration, heat treatment temperature, treatment time, pH, sugar addition and calcium in water, the viscosity of solution was increased nearly 28 times while pectin concentration improved ten times; The viscosity of solution was unchanged and showed it was a non-Newtonian fluid when treated at 100°C for 10min; The viscosity of solution was increased nearly 7% when the sugar concentration was 16%; As the concentration of Ca²⁺ in water reached 400mg/g, the viscosity of solution was 1.6 times than blank solution; The magnesium ion and iron ion in water had little influence on the viscosity of pectin solution, and range of the viscosity was 0-2cp.