2006, Vol. 27, No. 08

Transcription

1 36 26, Vol. 27, No. 8 PPO ( 2195) (4 ) (1r/min 3min) (PPO) ph PPO 6 8 PPO PPO.33mmol/L(.6%) PPO L-Cys EDTA-2Na 3.mmol/L PPO 29.55% AA CA 4-HR L-Cys EDTA-2Na PPO( ) (BE22339) 3 (196-) 2.3 ( ) MIC M BC [1]. (36 )[M]. :, [2]. ( )[M]. :, [3]. ( )[M]. :, [4],,. [J]., 1996, 26(6): [5],. [J]., 1998, (min) 13(2): 1. [6],. [J]. 2, 1999, 14(1): Fig.2 Effect of ultraviolet radiation on antimicrobials activity of ESTL [7],.,. ( )[J]., 21, (7)( ): 45. [8],,. [J]. 3, 24, 25(11): [9]. [J]., 21, 22(9): [1],,. [J]., 1999, 21(9): [11]. [J]., 22, 23(4): 137- [7] 139. MIC(%)

2 26, Vol. 27, No Characteristics of PPO from Freshcut Artemisia YU Zhi-fang LU Zhao-xin SONG Wen-wen LI Yan (College of Food Science and Technology, Nanjing Agricultural University, Nanjing 2195, China) Abstract The fresh-cut Artemisia after being removed inedible part, cleaned in ice water and cut, smarshed and centrifuged at 4. The obtained crude PPO in the supernatant was used to measure the optimal ph, T and response to phenols. The result showed that the PPO from freshcut Artemisia shows its greatest activity at 4 and ph 6.5, and loss its activity easily when temperature was up 8, while the enzyme after being treated at 95 for 1min will be inactivated completely. The combining capabilitry of PPO from freshcut Artemisia to different phenol substrate was in the order: chlorogenic acid and guaiacol pyrogallic acid tyrosine catechol resorcinol phenol. The PPO shows the highest activity when combined with catechol. The results also showed that all detected chemical inhibitors can slow down the PPO activity. Among all the inhibitors, pyrosulfite has the strongest effect. It can completely inhibit the PPO activity when its concentration is.33mmol/l (i.e..6%) in the system, while EDTA-2Na shows the least inhibiting effect, with the other inhibitors in between. 28kHz ultrasonic wave treated for 1min can somewhat inhibit the PPO activity. On the contrary the improper ultrasonic treatment can enhance the enzyme activity. Key words freshcut Artemisia polyphenol oxidase(ppo) characteristics TS25.9 A (26) cm (4 28.2mm) ph [1 3] (polyphenol oxidase PPO E.C ,6-1) DNS [4] GL-2G- UV-754 UV/VIS 282PC DJ3 HH-6 PPO P P O PPO 5g 6.ml (ph6.4) (4. ) (1r/min 3min) P P O 1.1 [5] PPO YU ml 2.ml (ph5.4) 1.ml 41nm 3.min (U) 2.5 (2 ) 1

3 38 26, Vol. 27, No. 8 A 41/min g FW PPO.5ml PPO 2.ml.2mol/L (ph5.4) 1.ml 4.mol/L ( ) min PPO PPO P P O ph ph PPO min PPO PPO Fig.1 Effect of ph on PPO activity of freshcut Artemisia P P O ph PPO ph ph ph4.4 (ph2. 8.) 2 ph5. [8] [9] 6.8 PPO PPO PPO mol/L 2.2 PPO PPO PPO 4 PPO mol/L [7] 3 [8] PPO 45 [9] PPO [3] PPO PPO PPO ph VC L- EDTA-2Na 8.min PPO PPO ( ) 2 PPO 2 Fig.2 Effect of temperature on the activity of PPO from Artemisia 2.1 p H PPO PPO ph 6.5( 1) PPO 12 [6] ph PPO ph ph2. ( 1) PPO ph ph 2 PPO ( ) ph ph Fig.3 PPO ph ph PPO PPO (min) PPO Effects of temperatures on the PPO stability of Artemisia

4 26, Vol. 27, No PPO PPO 1 PPO ( 3) PPO min PPO 6 4 PPO 5 Fig PPO PPO Combining capacity of PPO from freshcut Artemisia to catechol and chlorgenic acid 4 8 3min PPO 15min 1 PPO K m PPO 8 Table 1 Michaelis constants of PPO with different substrate PPO Michaelis- [5] PPO 95 1.min PPO 2.3 PPO K m PPO PPO [1] Menten Lineweaver- Burk PPO K m 1 ( 4) PPO PPO (1mmol/L) PPO PPO K m PPO ( PPO 4mmol/L) ( 5) Km 1.mmol/L 16.8mmol/L 4 5 PPO PPO PPO K m [1] PPO mmol/L PPO [11] PPO Fig PPO Combining capacity of PPO from freshcut Artemisia to phenols [2] PPO K m PPO PPO PPO PPO PPO PPO PPO [12] 2.4 PPO

5 4 26, Vol. 27, No. 8 PPO 12 PPO 1 L- 8 4-HR(4- ) [3][11] PPO PPO.33mmol/L.38mmol/L L-.51mmol/L 9.66mmol/L 1.14mmol/L Fig mmol/L 2.38mmol/L 4-HR 2.94mmol/L PPO 8 PPO Effect of Zn(AC)2 on PPO from freshcut Artemisia Fig.6 Fig VC 6 VC PPO Effect of VC on PPO from freshcut Artemisia PPO Effect of CA on PPO from freshcut Artemisia Fig.1 Fig.11 1 PPO Effect of pyrosulfite on PPO from freshcut Artemisia PPO Effect of L-Cys on PPO from freshcut Artemisia Fig.8 4-HR 8 4-HR PPO Effect of 4-HR on PPO from freshcut Artemisia Fig PPO Effect of hydrosulfite on PPO from freshcut Artemisia

6 26, Vol. 27, No HR PPO [4] 3 Fig PPO Effect of Phytic acid on PPO from freshcut Artemisia ( 3.mmol/L) EDTA-2Na PPO 29.55%( PPO 3.mmol/L shelf-life of fresh-cut fruits: a review[j]. Trends in Food Science & Technology, 23, (14): ) [7],,. [J]., 25, 26(5): PPO ( 6 PPO ph PPO 6 8 PPO L-Cys.5mmol/L (%) PPO.33mmol/L(.6%) PPO PPO L-Cys EDTA-2Na.6% L-.6% 3.mmol/L PPO 29.55%.12%.14%.25%.5% 4-HR.57% 4-HR L- EDTA-2Na L- (.6%) PPO (.15%) [1]. ( )[M]. :, [2]. [M]. :, 199. [3],,. [J]., L- 24, 14(6): PPO [4] Lamikanra O. Enzymatic effects on flavor and texture of freshcut fruits and vegetables[a]. In Lamikanra, O. Freshcut fruits and vegetables: Science, PPO Technology and Market[C]. CRC Press, LLC, 22, [7] [9] [5] Yu Zhifang, Kang Ruoyi, Lu Zhaoxin. Effects of blanching on the activities of PPO, POD and PAL from Artemisia Selengensis[C]. The 5th PPO International Conference of Food Science and Technology Proceedings, EDTA-2Na PPO 23, (1): [6] Soliva-Fortuny R C, O Martin-Belloso. New advances in extending the [8],,,. [J]., 22, 18(1): ) [9],,,. [J]. L-, 23, (5): HR [1]. [M]. :, 2. [11],,. [J]. ( ), 22, 3: [12],. [M]. : 4-HR PPO, [13] Lozano-de-Gonzales P G, D M Barrett, T E Wrolstad, et al. Enzymatic browning inhibited in fresh and dried apple rings by pineapple juice[j]. ( PPO ) J Food Sci, 1993, 58: [14],,,. [4][13] [J]., 23, (11): HR [15],. [J]., 1997, 16(1): PPO