Study On The Separation And Purification And Properties Of Purple Sweet Potato Anthocyanins

Purple sweet potato，as a new variety of sweet potato，is rich in anthocyanins whichhas significant antioxidant and nutritional functions．The anthocyanins of purple sweetpotato is a kind of safe，stable，high quality natural pigment．Because of its uniqueadvantages，in recent years it has become a hot spot what scholars from various countriesare racing to develop and research for．In this paper，the fresh purpul sweet potato produced in Hubei province was selectedto extract anthocyanins，and the compound enzyme and ultrasonic assisted extractionmethod to btain anthocyanins was researched，and its physicochemical properties werestudied．The results were as folloes：α-amylase and cellulase-assisted extraction was used to extract anthocyanins frompurple sweet potato，the optimum extraction conditions of compound enzyme-assistedextraction of purple sweet potato pigment were：hydrolysis temperature was60℃，hydrolysis time was1.5h，the dosage of the alpha-amylase was80u/mL，the cellulasedosage was50u/mL．Under these conditions，the extract content of anthocyanins was4.374mg/g．And the method of ultrasound-enzymatic assisted extraction was tried，whenthe Ultrasonic conditions were time of30min，temperature of60℃，power of40W，thecrude extraction of ultrasonic-enzyme assisted method was4.892mg/g．AB-8macroporous resin was used to purify the anthocyanins extracted from purplesweet potato，and the purification conditions which contained about adsorption anddesorption were optimized．The experimental results showed that：when the pigmentsolution pH was3.0，sample concentration was35.0μg/mL，the sample flow rate was2.0ml/min，were best for adsorption；when the ethanol solution pH was2.0，the ethanolsolution concentration was70%，the desorption speed of2.0ml/min，were best fordesorption．Under laboratory conditions，the preparation of the pigment was optimized．UV-visible light scans and infrared spectra were used to analysis the prepared pigment，theresults showed that：the product had anthocyanins,typical absorption peaks，the mainingredient in the pigment products was anthocyanins，and there was the acylation of theanthocyanin component in it．The pure color of the pigment E1%1cm(525nm) was10.47，yield was0.61%．The physical and chemical properties experiments of the pigment showed that，it was showing a color of bright red in water and acidic solution，and more stable in acidicsolution． Light and temperature would affect the stability of the purple potatoanthocyanins，it was better to avoid prolonged high-temperature heating in practicalapplications，and keep away from light and high temperature for storing．In theexperiments of metal ions， Fe3+and Cu2+can enriched the purple sweet potatoanthocyanins，but Zn2+，etc.，were done bad things to its stability．In addition，the pigmentwas sensitive of ascorbic acid，sodium nitrite and sodium sulfite，so should avoid usingboth of them together．...