Determination of Titratable Acidity (Lactic Acid) of a Milk Sample (IS 1479:1960)

Summary

This video tutorial guides viewers through an experiment to determine the titratable acidity of a milk sample. The process involves chemical preparation, density determination, sample preparation, titration, and calculation. Key steps include preparing a 0.1 normal sodium hydroxide solution, determining milk density, and conducting a titration with phenolphthalein as an indicator. The video demonstrates how to calculate the acidity of the milk sample, which is found to be 0.131% as lactic acid. This step-by-step guide is ideal for those interested in learning the process of milk acidity analysis.

Takeaways

• 🧪 The video is an experiment to determine the milk acidity or titratable acidity of a milk sample.
• 📋 The process involves several steps: chemical preparation, milk density determination, sample preparation, titration, and calculation.
• 🔧 Required equipment and chemicals include a balance machine, burette with stand, conical flask, pipette with filler, 0.1 normal sodium hydroxide solution, and phenolphthalein indicator solution.
• 🧴 For the 0.1 normal sodium hydroxide solution, dissolve 4 grams of sodium hydroxide pellets in 900 ml distilled water and make up to 1000 ml, then standardize the solution.
• 🌿 Phenolphthalein indicator is prepared by dissolving 2 grams of fenugreek powder in 100 ml ethanol.
• 🔬 Milk density should be determined separately, with instructions provided in another video linked in the description.
• 🥛 Prepare the sample by taking 10 ml of milk in a conical flask and adding 10 ml of distilled water, then mix well.
• 💧 Add a few drops of phenolphthalein indicator to the milk sample.
• 📏 Conduct titration using 0.1 normal sodium hydroxide solution and note the initial and final burette readings when the solution turns light pink.
• 📊 Calculate the acidity using the formula provided, where the sample's acidity was determined to be 0.131% as lactic acid.

Q & A

What is the purpose of the experiment described in the video?

The purpose of the experiment is to determine the titratable acidity of a milk sample.

What are the key steps involved in the milk acidity test?

The key steps include chemical preparation, milk density determination, sample preparation, titration, and calculation.

What chemicals and equipment are required for this experiment?

The experiment requires a balance machine, burette with stand, conical flask, pipette with filler, 0.1 normal sodium hydroxide solution, and phenolphthalein indicator solution.

How is the 0.1 normal sodium hydroxide solution prepared?

To prepare the 0.1 normal sodium hydroxide solution, dissolve 4 grams of sodium hydroxide pellets in 900 ml of distilled water and make up the final volume to 1000 ml. The solution should be standardized before use.

How is the phenolphthalein indicator prepared?

The phenolphthalein indicator is prepared by dissolving two grams of phenolphthalein powder in 100 ml of ethanol.

What is the first step after preparing the chemicals for the experiment?

The first step after preparing the chemicals is to determine the milk density by following the procedure in a separate video mentioned in the description.

How is the milk sample prepared for titration?

To prepare the milk sample, take 10 ml of the milk sample in a conical flask, add 10 ml of distilled water, and shake it to mix properly.

How is the titration performed in the experiment?

Titration is performed by adding a few drops of phenolphthalein indicator solution to the milk sample, followed by adding 0.1 normal sodium hydroxide solution from a burette with vigorous agitation until the solution turns light pink.

How do you calculate the acidity of the milk sample?

The acidity is calculated by using the sample volume, the volume of sodium hydroxide used (final burette reading minus initial reading), and the density of the milk sample. These values are plugged into the equation provided in the video to determine the acidity as a percentage of lactic acid.

What is the final result obtained in the experiment?

The final result shows that the acidity of the milk sample is 0.131% as lactic acid.