| Since 2002, acrylamide (AA) obtained numerous attentions owing to its presence in fried and bake food, as well as its neurotoxicity, reproductive toxicity and carcinogenicity to human. Therefore, inhibiting AA formation in food processing became essential. It has been shown that the flavonoids could inhibit A A formation. Ampelopsis grossedentata, rich in flavonoids, is a new food raw material which could potentially inhibit the information of AA. Thus, this study reported a method that could effectively extract and purify flavonoids from Ampelopsis grossedentata. This study also examined the inhibition effect on AA by flavonoid monomers and total flavonoids with different purification levels from Ampelopsis grossedentata. The main research methods and results were as follows:(1) Extraction of total flavonoid from Ampelopsis grossedentata. Response surface methodology was employed to optimize the extraction conditions by using ultrasonic-assisted ethanol method to extract total flavonoids from Ampelopsis grossedentata. Based on single-factor tests, a four-factor and three-level center composite experimental design of Box-Behnken was adopted to investigate the influence of four main factors including ethanol volume fraction, ultrasonic treatment temperature, ultrasonic treatment time and liquid-solid ratio. The results indicated that the impact of various factors on yield of total flavonoids from Ampelopsis grossedentata were in descending order of ultrasonic treatment time, ethanol volume fraction, ultrasonic treatment temperature and liquid-solid ratio. The optimum conditions of ultrasonic-assisted ethanol extraction technology of total flavonoids from Ampelopsis grossedentata were as follows:ethanol volume fraction was 67%, ultrasonic treatment temperature was 58 ?, ultrasonic treatment time was 28 min and liquid-solid ratio was 22.5:1 (mL/g). The maximum predicted yield for total flavonoids from Ampelopsis grossedentata was 38.45%, and the actual yield was 38.74%, which was near to the predicted yield, showing that there was a high fitting degree between predicted and real numerical values. The experimental results are valuable for application in production, because the response surface methodology is scientific and effective.(2) Purification of total flavonoids from Ampelopsis grossedentata with Macroporous Adsorption Resin and Polyamide. Column packed with HPD-100 macroporous adsorption resin was used to initial purification for extraction of total flavonoids, and polyamide was used to the second step purification. The results showed that the optimum adsorption parameters by HPD-100 macroporous adsorption resin were as follows:the sample total flavonoid mass concentration was 6 mg/mL, the sample flow rate was 1 mL/min, the sample volume was 130 mL, on this condition, the adsorption rate was 97.14%; The optimum desorption parameters were as follow:the eluent concentration was ethano-water (70:30, v/v), with 40 mL as an eluent at an eluting flow rate of 1 mL/min, on this condition, the desorption rate was 94.10%. After the treatment with HPD-100 macroporous adsorption resin, the purity of total flavonoids increased from 55.00% to 72.25%. The optimum adsorption parameters by polyamide were as follows:the sample total flavonoid mass concentration was 6 mg/mL, the sample flow rate was 2 mL/min, on this condition, the adsorption rate was 99.57%; The optimum desorption parameters were as follows: ethanol-water (70:30, v/v), with 55mL as an eluent at an eluting flow rate of 1 mL/min, on this condition, the desorption rate was 76.50%. After the treatment with polyamide, the purity of total flavonoids increased from 72.25% to 80.75%.(3) The inhibition effect on AA by flavonoid from Ampelopsis grossedentata. Three flavonoid monomers i.e. dihydromyricetin, myricetin, myricitrin with different concentrations from Ampelopsis grossedentata and total flavonoid with different purification levels were added into the potato flour, respectively. Then the mixture was fried in 180 ? for 200 s, and the acrylamide in sample was quantitatively and qualitatively analyzed by high performance liquid chromatography. The results showed that all of the six flavonoids from Ampelopsis grossedent had inhibition effect on AA in varying degrees; the inhibition effects of dihydromyricetin and myrietin from flavonoid monomers were obviously, when the concentration of dihydromyricetin was 10-7 mol/L, the maximum inhibition rate reached 19.64%, and when the concentration of myricetin was 10-8?10-6 mol/L, the maximum inhibition rate reached 18.86%-20.62%; the inhibition effect of the twice purification total flavonoid from total flavonoids was best, when the concentration of twice purification total flavonoid was 10-1 mg/mL, the maximum inhibition rate reached 57.16%. |
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