Extraction,Purification And Structural Identification Of Anthocyanins From Purple Potato

Natural pigment anthocyanins have many functions such as anti-oxidation,anti-cancer and so on.It is a potential health colorant.Purple potatos have gradually become the focus of attention because of its rich anthocyanins.At present,the studies on anthocyanins in purple potatoes are not comprehensive enough In order to expand its application in food,cosmetics and other industries,the extraction,purification,structure identification and stability of Purple Potato Anthocyanins were studied in this paper.Anthocyanin from purple potato was extracted by ethanol solvent extraction.Taking the anthocyanins content as the evaluation criterion,the optimum extraction conditions were determined by single factor and response surface optimization experiment:ethanol concentration 69.5%,extraction time 83min,extraction temperature 53?,material-liquid ratio1:24?g/mL?.Under this condition,the anthocyanin content could reach 1.3392 mg/g.It is close to the theoretical value 1.3257 mg/g,which indicates that the result has high reliability.After optimizing the extraction process,the Purple Potato Anthocyanin solution was purified by macroporous resin method.The purification effects of D101,NKA-II,AB-8,HPD-750 and HPD-100,were compared according to their adsorption and desorption rates.Among them,AB-8 resin was the most ideal one.The optimum conditions for purification of anthocyanin were as follows:AB-8 resin 40g was packed into column by wet method,the flow rate of sample solution was 1.5ml/min,the adsorption time was 2h,the desorption solution was 70%ethanol solvent?pH=3?,and the desorption flow rate was 2mL/min.After purification,the color value of anthocyanin was 29.93±0.08,which was 3.7 times higher than that before purification.The purified anthocyanins of purple potato were identified by HPLC-DAD-QTOF,and the structures of thirteen anthocyanins were identified.Petunidin-3-rutinoside-5-glucoside,Petunidin-3-cis-p-coumaroylrutinoside-5-glucoside,Delphinidin-3-glucoside,Pelargonidin-3-gl ucoside,Cyanidin-3-p-coumaroylrutinoside-5-glucoside,Petunidin-3-glucoside,Petunidin-3-p-c oumaroylrutinoside-5-glucoside,Pelargonidin-3-p-coumaroylrutinoside-5-glucoside,Cyanidin-3-glucoside,Peonidin-3-p-coumaroylrutinoside-5-glucoside,Malvidi-3-p-coumaroylrutinoside-5-glucoside,Peonidin-3-feruloylrutinoside-5-glucoside,Pelargonidin-3-rutinoside-5-glucoside.In the stability of purple potato anthocyanins,the effects of pH,light,temperature,oxidizers and reductantsredox,saccharide and metal ions on the stability of anthocyanins were studied comparatively.The results showed that the optimum preservation conditions of purple potato anthocyanins were:4?,pH 3.0 and dark conditions;and H₂O₂ could accelerate the degradation rate of anthocyanins,Na₂SO₃ has instantaneous bleaching effect on anthocyanin solution;5%glucose and sucrose can promote the stability of anthocyanin,lactose can significantly reduce the anthocyanin retention rate,followed by fructose;K⁺and Na⁺has no obvious effect on anthocyanin,while Al³⁺and Ca²⁺has a color enhancement effect on anthocyanin.