Study Of Processing Technology For Purple Potato Granules And Stability Of Its Anthocyanin Based On Isolation And Purification

Purple potato (Solanum tuberosum L.) is a new varieties which is fresh-eating and processable. In this paper, orthogonal experiment was conducted to study the effects of processing procedures on the purple potato granule qualities and to optimize the parameters. The total antioxidant activity, radical scavenging activity and reduction ability of purple potato granules were studied and compared with those of conventional potato granules. The purification parameters of anthocyanin in purple potato granules were optimized and the stability of purified purple potato anthocyanin (PPA) was also evaluated. The conclusions are as follows:1. The results of orthogonal experiment showed that drying condition was the most influential factor on the organoleptic quality of purple potato granules, secondly for the grinding particle size and color-protection time, the cooking time was the relatively the least influential factor. The optimal parameters were color protection for15min, cooking for15min, drying for12hours under60℃and grinding to80-100mesh, under which purple potato granules can be obtained. The amount of PPA was decreased significantly in cooking and drying stages, therefore, the temperature and the high-temperature period in processing procedures should be controlled aiming at protecting the PPA.2. The total antioxidant activity, radical scavenging activity (hydroxyl radical, DPPH and superoxide anion) and the reduction ability of purple potato granules were apparently superior to the conventional potato granules. The flavonoids and polyphenol contents of purple potato granules were higher than those of conventional potato granules. Analyses showed that the difference in PPA content was the main reason for the different antioxidant activity.3. AB-8macroreticular resin was chosen for the purification of PPA. The optimal parameters for static adsorption were absorption for4hours, stripping for2.5hours using70%alcoholic solution. The optimal parameters for dynamic adsorption were2ml/min adsorption velocity,1200ml sample volume,2ml/min stripping velocity and130ml elution volume, under which highly purified PPA can be obtained.4. The stability of PPA was easily undermined in high temperature, illumination or oxidizing conditions. However, low temperature, lucifuge or antioxidative conditons were able to improve the stability. The color of PPA changed at different pH values due to the change of molecular structure.