Extraction,Purification And Stabilization Of Purple Corn Anthocyanidin

Anthocyanidin is a water-soluble natural pigment, being used in foods, cosmetics and medicine for its nutritional and pharmacological functions. The purple corn and its byproduct have high anthocyanidin contents and at low cost. Consequently, they have the potential capacity to provide high quality and quantity anthocyanidin for food industry as a natural pigment or a nutritional ingredient.In this paper, optimization of the conditions for extracting and purifying anthocyanidin from purple corn was carried out and the effects of light, heating, pH and some food additives on the stability of anthocyanidin was investigated. The conclusions of the study are summarized as follows.(1) The highest extraction yield was 88.02% by the ethanol heating extraction method. The optimization conditions were extraction time 75 min, extraction temperature 40℃, material and liquid ratio 1:20,95% ethanol:0.1 mol/L HC1=1:1. The optimization conditions of ultrasound-assisted extraction of purple corn anthocyanidin were 95% ethanol:0.1 mol/L citric acid:distilled water= 4:1:3, material and liquid ratio 1:8, extraction time 36 min, extraction temperature 40℃, ultrasonic times 97, ultrasonic power 400W. The highest extraction yield was 94.82%. The extraction yield of the scale-up experiment was 90.49%.(2) The purification of the purple corn anthocyanidin was studied by AB-8 macroporous resin. The maximal adsorption and desorption of static test were 97.5% and 93.9%, respectively. The results showed that the suitable adsorption temperature was 30℃, pH=3, adsorption time 2.5 h; 70% ethanol was the optimum solution; and the optimum time for desorption purple corn anthocyanidin was 1.5 h. The maximal desorption of dynamic test was 89.6%. The optimization conditions were the adsorption speed 1 mL/min, the sample concentration 20 mg/mL, the sample value 30 mL, desorption speed 2 mg/mL. The anthocyanidin color was increased 35 times。(3) Investigation of some factors such as pH, temperature, lighting and food additives on the stability of purple com anthocyanidin was also studied. The results showed that the purple com anthocyanidin was stable in the lighting and unstable in the high temperature. With the pH increasing, the degradation index increased. Vc could decreased the stability of anthocyanidin, but glucose and sucrose had no influence on the stability of anthocyanidin.