Optical Rotation

EXTRACTION OF LACTIC ACID AND DETERMINATION OF OPTICAL ROTATION FROM THE FINISHED PRODUCT-LACTOSPORE^®

AIM:

To extract Lactic acid produced by LactoSpore^® and to check its optical property.

PRINCIPLE:
     
Tertiary and quaternary amines such as ALAMINE 336 and ALIQUAT 336 when mixed with suitable diluents like OLEYL ALCOHOL forms a reactive liquid-liquid extraction mixture, for the extraction of organic acids (Lactic acid) from the aqueous medium. These amines forms ion pairs with the undissociated carboxylic acids (Lactic acid), which results in higher extraction efficiency, and forms amine-acid complex based on dipole-dipole interaction.

REQUIREMENTS:

Alamine 336 or Aliquat 336, Oleyl alcohol, Glass wares, Magnetic stirrer, Centrifuge and Filter paper (What man No. 41).

METHOD:

1. Prepare Glucose Yeast Extract Acetate Broth [GYEA Broth-Himedia No. M964] 250 ml and dispense 100ml, 100ml and 50ml into conical flask and autoclave at 121°C for 15 minutes at 15 psi. After autoclaving, incubate the flasks at 37°C for 24hrs to check for sterility.
2. Inoculate 1.0g of LactoSpore^® finished product (15 Billion spores/g) to 2*100ml GYEA broth and incubate for 72 h at 37°C.
3. Take 50ml of the broth in a beaker and add 25ml Aliquat 336 (50% w/v in Oleyl alcohol) and stir it for 45 minutes with the help of a magnetic stirrer at 150 rpm at room temperature.
4. Transfer the mixture into centrifuge tubes and centrifuge for 20 minutes at 2000 rpm to separate the aqueous and organic layers.
5. Carefully transfer the organic layer and filter through What man No. 41. Similarly filter the 50% w/v Aliquat 336, extraction mixture.
6. Check the optical rotation of the sample with the help of the Polarimeter keeping filtered extraction mixture as blank.

Observation:

The blank extraction mixture was loaded and the effect was nullified in the polarimeter. The sample was diluted twice with the extraction mixture and the optical rotation was found to be +0.9°

 Interpretation:

1. LactoSpore^® (15 Billion spores/g) produces Lactic acid in the GYEA broth. 
2. Lactic acid was extracted by reactive liquid-liquid extraction. 
3. The optical rotation was found to be Dextrorotatory i.e. L (+).
4. Bacillus coagulans produces L (+) Lactic acid.

Reference: Turk J Chem. 25 (2001), 223-230.