Effect Of Fermentation On Purple Potato Pigment And Development Of Purple Potato Wine And Its Antioxidant Activity Evaluation

Fermentation technology during extracting pigment process by fermenting was studied in this paper, and then under this technology combined with brewing technology of fruit wine development of purple sweet potato fermentation wine was also studied, and its total antioxidant activity, total flavonoids, ability of scavenge hydrogen peroxide, eliminating hydroxyl radical ability, total polyphenol were evaluating. At the same time, analytical procedure of purple sweet potato color with color-value measurement and measuring method of above index of red wine were optimized. The results were as follows:Fermentation technology was studied during the process of extracting pigment from purple sweet potato. Purple sweet potato plasm : water = 1:1, the temperature of liquefying is 85～90℃, addingα-amylase at the amount of 0.4 g/kg, and react in pH 5.8～pH 6.5. The optimum condition of saccharification was identified by response surface methodology and using Design-expert software. Saccharification reacts in the condition of pH5.30, the temperature is 55.18℃, adding glucoamylase at the amount of 2.99 g/kg, and response time is 5.76h. The fermentation temperature was identified on 25℃.The optimum processing technology of fermented purple sweet potato wine was identified. The fermentation temperatures is 30℃, using Actiflore F33 yeast strain, adding sugar at the amount of 18 %. The final product has its own features and advantages, the typical burgundy, clear and brilliant, velvety and harmonious, particularly mellow, full-bodied with aroma of purple sweet potato.The influence factors of determining purple sweet potato color with color-value measurement were studied and the optimum condition was identified. The optimum detection wavelengthλmax=529 nm, pH=3, adding bleach dosage at the amount of 0.5g/mL, bleaching time was 5 min.The optimum condition to detect the total flavonoids of purple sweet potato fermentation wine was identified after studied the influence factors during the detection. Take certain samples, adding 2.0 mL NaNO3, standing for 6 min after shaking. Then added 1.0 mL Al(NO3)3, standing for 6 min after shaking. Adding 2.0 mL 1.0 mol/L NaOH, and volume to graduation with 60 % alcohol, then standing for 15 min before to detect. Control sample was according to the above operation except for adding rutin. Absorbency was determined at 510 nm, and drew the standard curve of rutin. Calculated total flavonoids content of purple sweet potato with rutin standard curve and value A.The influence factors of ability to scavenge hydrogen peroxide of purple sweet potato fermentation wine were studied and the optimum condition was identified. Adding 1 mL H₂O₂, a drop of ammonium molybdate, 2 mL Phosphoric acid solution, 2 mL potassium iodide, 100 mL distilled water, then standing for 15 min in the shade after shaking. Adding 1 mL starch solution to the above solution after using Na₂S₂O₃ titrate it. The total volume V₁ of Na2S2O3 was recorded, which it titrated solution to colorless. The other sample was according to the above operation except for adding certain wine. Then the titration volume V₂ of Na2S2O3 was recorded. Then calculated the results follow the formula.The optimum condition to detect the ability to eliminating hydroxyl radical of purple sweet potato fermentation wine was identified after studied the influence factors during the detection. Add 1.0 mL 7.5m mol/L ammonium ferrous sulfate solution, 0.1 mL 0.4g/mL hydrochloric acid solution and 2.0 mL 7.5 mmol/L salicylic acid solution in 10 mL colorimetric cylinder. Then add 1.0 mL 7.5 mmol/L H₂O₂ and volume to the graduation with distilled water. Detected absorbance A0 at 523 nm after the solution was standing for 1 h at 35℃. Another sample was operated according to the above operation except for adding certain wine and absorbance Ax was determined at 523 nm. Some wine was volume to graduation with distilled water and its absorbance Ax0 was determined at 523 nm. The results were calculated follow the formula.The influence factors of determining total polyphenol of purple sweet potato fermentation wine were studied and the optimum condition was identified. Adding 2.00 mL distilled water, 1.00 mLFc, 3.00 mL 7.5 %Na₂CO₃ and a specified volume of gallic acid solution. The absorbance was determined at 760 nm after reacting in the condition of 60℃for 67 min. The standard curve of gallic acid was drawn according to value A and gallic acid content. The other sample was operated according to the above operation except for certain wine to instead gallic acid and determined its absorbance. The content of total polyphenols was calculated according to gallic acid standard curve and value A.It prove the products have very good antioxidant activity by the result of determination on its total flavonoids content, total antioxidant capacity, total polyphenol content, the ability of scavenge hydrogen peroxides and hydroxyl radicals.