Dear Pravin, you may wat to try iodmetric titration as well (please see the attached).

I remember that it was possible to use DCP for black currant juice as well but it required additional extraction with toluene to remove dark colour of the juice. Unfortunately, I am away from home and I don't have the book which describes this procedurę with me.

I will beable to check it in a week if it's not to late for you.

Hi,

Instead of using the titration method, i would suggest that you use the spectrometric method for better & consistent result.

Here's another method..

Thanks Aishah and Lukasz

Dear Mr Ojha, conventionally the method for determination of vitamin C in fruit juice is the redox process using 2,6-Dichloro-Indophenol as a indicator. The method was suggested by Mr Aldallal above. Iodimetric method using iodine must not be a good option, because fruit juices is a sample very complex and others substances can be interferents. Another option is to use potassium iodate as a titrant. This substance is a primary standard and it has already been applied for determination of vitamin C in fruit juices. See the file in attachment. The method is more simple than indophenol. The file is in Portuguese but I think that you can easily translate to English  using an electronic tool (google translate, for example). However, if you have electrochemical device, polarography for example, there are many methods for ascorbic acid determination in fruit juices that are more accurate and precise. (Fresenius' Zeitschrift für analytische Chemie

Determination of l-ascorbic acid in fresh and processed fruit and vegetables by differential pulse polarography , 1988, Volume 329, Issue 7, pp 760-763). I hope that this help you.