| Purple sweet potato is an annual plant within Ipomoea of convolvulaceae and itcontents a large amount of natural pigment-anthocyanins. The anthocyanins of purplesweet potato is a kind of safe, high quality pigment with broad bioactivities such asantioxidative activity, antimutagenicity and anticancer effect and so on. Therefore, it isgreatly worth of developing. Currently, anthocyanins and the by-products were extractedfrom purple sweet potato by different ways, acidified organic solvents and acidified waterwere generally used to get anthocyanins in the extraction process. However, employingwater as extracting solvent has been rarely reported. High cost, strict requirements forproduction equipment, byproduct of starch destroy easily make the utilization of theextraction with acidified organic solvents and acidified water restricted.Ultrasound assisted extraction was used to extract anthocyanins from purple sweetpotato with water as extraction solvent. The clarification of extraction solution(clarification with ZTC1+1and enzymes) and purification of purple sweet potatoanthocyanins by macroporous resin were investigated in this paper, which aims to providesome theoretical basis for industrial production of purple sweet potato anthocyanins. Theresults showed as follows:1. The maximum absorption wavelength of purple sweet potato anthocyanins was528nm. The optimum clarification conditions for anthocyanins extraction solution from purplesweet potato using ZTC1+1as clarifying agent were as follows: the adding order wasclarifier B before clarifier A, the optimum dosage was0.1g/L for clarifier A and0.2g/Lfor clarifier B. After adding clarifier Aand B in75℃for30min, the clarity could improveabout40%and the content of anthocyanins was47.13mg/L. Papain and glucoamylasecould clarify the extraction solution of anthocyanins. The optimum conditions for papainclarification were as follows: the dosage was1100U/mL,1h,60℃, the original pH ofthe extraction solution. The clarity could reach to40.60%and the content of anthocyaninwas45.57mg/L under this condition. As to glucoamylase, the optimum conditions were asfollows: the dosage was40U/mL,2h,65℃, the original pH of the extractionsolution.The clarity could reach to36.20%and the content of anthocyanin was44.65mg/Lunder this condition. When papain and glucoamylase were used at the same time, theoptimum conditions were as follows: the dosage of papain was1100U/mL, the dosage ofglucoamylase was50U/mL,60℃,1.5h, the original pH of the extraction solution. Underthis condition, the clarity was higher than50%and the content of anthocyanin was morethan50mg/L. By comparing the results, the effect of clarification with ZTC1+1wascomparable to clarification with papain, while dealing with glucoamylase was lesseffective. Clarifying with composite enzyme (papain and glucoamylase) was obviously better than ZTC1+1and single enzyme. After clarifying with different methods, theingredients which affect the clarity were decreased, so it was benefit for anthocyaninspurification by macroporous resin.2. The static adsorption and desorption tests of AB-8, D101, X-5andNKA-Ⅱmacroporous resins showed that AB-8was the optimum resin. It had the strongestcapacity (1.81mg/g), and its adsorption process could be equilibriumed after3.5hourslater. The elution rate was74.57%and its desorption process could be equilibriumed in1.0hour. Adsorption isotherm indicated that the adsorption of AB-8resin was multilayeradsorption, which was fit to FreundLich adsorption model. When the sample concentrationwas20mg/L, the flow rate was1.5mL/min，it was best for adsorption of AB-8resin.When the concentration of eluent was70%, the desorption ability was better at pH=2.0and1mL/min. As a result, the color value of the purified anthocyanin from purple sweet potatowas23.57. |
PDF Full Text Request