Extraction, Purification And Stability Of Anthocyanins From Grape Skins

Anthocyanins are flavonoids. It is reported that anthocyanins have various nutritional functions, such as antioxidation, antimutagenicity and improvement of sight. Anthocyanins are natural technicolored pigments, which can dissolve in water. As an important by-product in the grape wine and grape juice industry, the grape skins have a large quantity of anthocyanins. Extracting and purifying the anthocyanins of grape skins, and making them into high-quality and safe pigments are useful.This thesis used grape skin as material. The optimal parameters of extracting anthocyanins from grape skin by ultrasonic wave, the purification parameters of anthocyanins by macroporous resin and the stability of anthocyanins were studied. These above studies can provide references for exploration and application of the use of grape skin resources.The results were as follows:(1) The results from single-factor and orthogonal experiments showed the optimal temperature for extraction was 70℃, the concentration of ethanol was 60% and the pH was 0.5.(2) AB-8 macroporous resin had good performance for absorption and de-absorption for the anthocyanins of grape skins. The absorption time was 2.0h. The optimal parameters of purification of anthocyanins were as follows: the best pH value 2.0, feeding rate 2.0BV/h, concentration of anthocyanins 0.4mg/mL. The best elution condition was 95% ethanol, 2.0 pH.(3) The stability test of anthocyanins from grape skins showed anthocyanins from grape skins with different pH had different visible spectrum and different colors. Antiseptic, glucose, sucrose , Zn²⁺, Na⁺ and K⁺ had little influence on the stability of anthocyanins from grape skins;Na2SO3, Vc influenced the stability of anthocyanins from grape skins to some extent. Temperature and light affected the stability of anthocyanins from grape skins. H2O2, Cu²⁺, Fe²⁺, Fe³⁺ had great influence on the stability of anthocyanins from grape skins.