Titrable Acidity Lab Report

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3.5.2.2 Titrable acidity (per cent)
The method described by Ranganna (1991) was adopted for estimation of titrable acidity. A weighed amount of pulp was transferred to a volumetric flask and the volume was made up with 10 times dilution with distilled water to known amount. After 30 minutes, the suspension was filtered through whatman No. 1 filter paper and the filtrate was used subsequently. An aliquot (10 ml) was taken from the filtrate and titrated against standard sodium hydroxide using phenolphthalein as an indicator. The titrable acidity was expressed as percentage, citric acid and equivalent adopting the following formula.

3.5.2.3 Ascorbic acid (mg/100 ml)
The volumetric method described by Ranganna (1991) was adopted. A known amount of the pulp was transferred to a 100 ml volumetric flask and volume made up with 3 per cent metaphosphoric acid solution. After 30 minutes, the suspension was filtered through whatman No. 1 filter paper. Before actual titration, the 2, 6-dichlorophenolindophenol dye solution was standardized by titrating against standard ascorbic acid solution and the dye factor was calculated. 5 ml of the aliquot was taken from the filtrate and titrated against standardized
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After 10 minutes, the solution was deleaded by adding potassium oxalate crystals in excess and the volume was made up to a known amount with distilled water and filtered through whatman No. 1 filter paper. The filtrate was taken in a burette and titrated against boiling Fehling’s mixture (5 ml of Fehling’s solution A + Fehling’s solution 5 ml of B) till the blue colour faded. Then one ml of methylene blue indicator (1 per cent) was added and the titration was continued till the contents attained a brick red colour and titre value was noted. The percentage of reducing sugar was calculated according to the following

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