Curcumin Purification Via Complex-dissociation And Its Preparation Of Nanoemulsions

Turmeric Puree is the by-product of curcumin pigment extraction in the industrial process, which contains abundant curcumin pigment. There are also large numbers of impurities such as oil, gum, mucopolysaccharide and ester in turmeric puree, so it is difficult to be applied as colorants in food. Through analyzing the structure and physicochemical properties of curcumin molecular, we found there are keto groups on curcumin molecular chain, which can complex with transition metal ions. This study put forward the way of metal ions complex-dissociation purification methods to purify pigment from turmeric puree for the first time, and found out the factors relevant to pigment complexion to optimize the purification process. Since curcumin pigment is insoluble in water, biological utilization rate of which is very low, and also sensitive to the environmental conditions of light, metal ions and high temperature, storage is hardly possible under natural conditions. In order to solve this problem, this study prepared purified curcumin into nanoemulsions and explored the factors of its stability.Through the research of physical and chemical properties of the nanoemulsions, make it adapt to the application in food industry.Reaction solvent, complexing metal salt and dissociation agent are the key factors on influencing pigment purity. By single factor experiment, the yield and purity of curcumin was improved,when ethanol was chose as reaction solvent, zinc acetate as the complexing agent and citric acid as complexing agent solution. The best process of curcumin purification is: the material is extractum of curcumin, the ethanol solution of curcumin extractum is 4 g/100 m L, weight ratio of zinc acetate and extractum is 0.3:1.0, adjust the p H of solution to 9.5 for complexing, add 0.5g citric acid to adjust p H to 5.5 for disaggregation. Purity of sample was improved from 18% to 52%,Recovery was up to 85.6%. Color value is enhanced from E425nm(1% 1cm) 43 to over E425nm(1% 1cm) 126. The color of sample is similar to the sterling and has better ability of eliminating DPPH and antioxidation.Taking advantage of emulsibility of whey isolate, Curcumin nanoemulsions have better dispersibility and stability in water, higher absorptivity and accompanying bioavailability. Experimental results show that turmeric puree purified by two successive complexation reaction has higher purity which can reach to 76.34%, thus the sample got this way can be used as a core material for preparing the nanoemulsion. Since the solubility of pigment component in the moderate carbon chain fatty glyceride can reach to 7.56 mg/m L, it will be an ideal oil phase of the nanoemulsion. Therefore, curcumin nanoemulsions of oil-in-water is prepared using an ultrasonic homogenizer with whey isolate as emulsifier, moderate carbon chain fatty glycerideas as the oil phase. According to the particle size of the nanoemulsion, centrifugal stability constants, viscosity and turbidity index, the key process parameters are chosed as follows: 3 g/100 m L whey protein following hydrating for 4 h, 15% the oil phase volume fraction, 480 w ultrasonic power for 6 min. In this way, the nanoemulsion particle diameter is less than 216 nm, with a polydispersity index of 0.250. Homogeneous and stable nanoemulsion is observed under an atomic force microscope. After one month of storage at room temperature, the nanoemulsion particle size remains relatively stable, and curcumin retention rate is still as high as 70%.Two layers nanoemulsion is prepared by twice ultrasonic homogenization, with the addition of gum arabic to the nanoemulsion to improve its stability. When the amount of gum arabic is 3mg/100 m L at p H 6, zeta potential increases from-30.6 m V to-51.2 m V. Besides, the p H stability of the emulsion, the storage stability and high temperature stability are all best under this condition as indicated by the experimental results. In vitro digestion simulation, FFA release rate in the gastrointestinal fluid of single layer and two layers nanoemulsion system respectively reach up to 131.04% and 123.38% after 2 h, curcumin bioacceptability can reach to 28.38% and 23.14%. Above all, curcumin prepared this way can thoroughly exhibate its physiological function of pigment into food.