I am using catechol as the substrate. I tried to quantify PPO of apple juice but no change in color was noticed. Given, the high content of PPO in apple, I am assuming I am doing something wrong. I used phosphate buffer (pH=6.5), absorbance reading was taken at 405 nm.
Dear Rachana,
Are you using freshly prepared apple juice, or commercially prepared apple juice. I ask as the commercially prepared juice will probably contain an antioxidant, such as vitamin C. This antioxidant would prevent a reaction.
It may be worth checking that the phosphate buffer is not too concentrated, 0.1 M phosphate buffer should be fine. I would be tempted to make it to a pH of 7 or greater, as 6.5 may be too acidic for polyphenol oxidase.
You will probably need to wait for a several minutes, at room temperature for a reaction to start to occur.
Kind regards,
Ade Kujore
Marketing
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Dear Ade,
I am using freshly prepared apple juice. After the addition of enzyme extract to the substrate, approximately how long should we wait? I waited for 30 minutes but didn't work. What is the range of wavelength to quantify PPO?
Thanks,
Rachana
Dear Rachana,
It may be that the initial solution has too high an Absorbance for your spectrophotometer. It is worth checking this possibility. It is also worth performing a wavelength scan within the 350 to 600 nm region.
Kind regards,
Ade Kujore
Marketing
Cecil Instruments Limited
Milton Technical Centre, Cambridge CB24 6AZ
United Kingdom
email:- [email protected]
telephone:- +44 (0) 1223 420821
fax.:- +44 (0) 1223 420475
web site:- www.cecilinstruments.com
Dear Rachana,
I see only now your question, maybe you are not interested anymore... In any case, to determine spectrophotometrically PPO in durum wheat I follow the method described in this article.
Kind regards,
Antonella
Article Molecular and physico-chemical evaluation of enzymatic brown...
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