Key Technologies Of Nfc Carrot Juice And The Assessment Of Antioxidant Capacity In Vitro

In this study, carrot was raw material. The key technologies(blanching treatment, enzymatic technology, homogenization and sterilization) and the antioxidant capacity of carrot juice were investigated. With the comparison between dry(microwave, radio-frequency) blanching and wet(water) categories blanching treatment, the effects of carrot POD activity were observed. Combined with the retention of nutrients, the best enzyme inactivation condition of carrot POD activity was observed. Using RSM(response surface methodology) to analysis composite enzymatic technological parameters for carrot juice yield, the condition was optimized. The homogenization condition to improve the stability was also optimized. The sterilization(RF and Pasteurization) was optimized. The antioxidant capacity in vitro of NFC carrot juice was evaluated. The results are as follows:(1) The effects of activity of POD in carrot by microwave, RF and water heat treatment were observed. Using Minitab system, the best conditions: 560 W, 130 s, 110 g were optimized. Under these conditions, POD activity was already loss. Under plate spacing 120 mm, the temperature increase and uniformity by RF blanching were best, treat 50 g carrot for 12.5min, the rate of POD capacity inactivation was 99.98%. In the range of 65~75℃, water blanching of POD activity kinetics was done. The R2 were all above 0.960. Dealed with 100 g carrot under 75℃ for 11 min, POD activity completely inactivated. Compared among three kinds of blanching treatment, microwave treatment was best, which is best on Vc retention and β-carotene retention rate.(2) The response surface methodology(RSM) was used to improve carrot juice yield by composite enzymatic hydrolysis.The optimum conditions were 0.3g/100 g of carrot pulp enzyme dosage, composite enzyme ratio 2.2:10, hydrolysis time 116 min, hydrolysis temperature 41.7℃. Under these conditions, the juice yield was 79.36%. The result is well matched with the predicted value, and well suggests production prediction. After these treatments, pH was increased, the VC content, β-carotene content and SSC were significantly decreased.(3) Homogenization effected carrot juice stability significantly. RF treatment can used to sterilize the carrot juice. Under 35 MPa, 40℃(inlet temperature), homogenized twice, the stability(A660nm) of carrot juice was raised from 0.119 to 0.288. Under 85℃,30 min treatment, 5ml carrot juice was sterilized completely. Optimized by RSM, the optimal conditions were: 5ml carrot juice, plate spacing 150 mm, treating time 15 min. Under these conditions, lgS could descend 4 order of magnitude. Homogenization, sterilization treatment effected little on Vc and β- carotene content.(4) After stored under 4℃ for 14 day, the antioxidant activity in vitro of NFC carrot juice was effects significantly. DPPH antioxidant capacity and FRAP antioxidant capacity were decreased significantly. ABTS antioxidant capacity was decreased not significantly. The effects of antioxidant activity by Pasteurization were less than RF treatment.