Preparation of Lactate from the fermentation of cabbage (Sauerkraut).

Authors Avatar

Aim: Preparation of Lactate from the fermentation of cabbage (Sauerkraut)

Equipment and Materials:

  • 300g of finely shredded cabbage
  • 300 cm³ 3% w/v sodium chloride solution
  • Small metal weights
  • Burette containing 0.1 M sodium hydroxide solution
  • Phenolphthalein indicator solution and pipette.
  • Elastic bands
  • Hoffman clip
  • Large paper bag
  • A pair of scissors
  • Temperature probe
  • pH probe
  • 15 cm³ bent glass pipette with 3 cm rubber tubing
  • Beaker
  • Adhesive tape.

Method:

300 g of finely shredded cabbage and sodium chloride was placed in 1 dm³ beaker. Three slices of plastic bags with three small holes were cut for the pH probe, the temperature probe and a pipette. The plastic cover was placed over the surface of the cabbage. The probes were inserted through the holes cut and were made as airtight as possible with adhesive tape. A rubber band was placed around the beaker and pressed down with two weights to prevent as much air as possible. The initial pH and temperature were recorded daily for 6 days. Samples of the acid produced (Lactate) were taken for the calculation of the acid content.

Diagram:

Results and Calculations:

Sampling of acid content - 5cm³ of the acid was removed using a pipette and was added to distilled water in a beaker. This mixture was titrated against 0.1 M of sodium hydroxide using 2 drops phenolphthalein as the indicator since we are titrating a strong base against a weak acid. Results obtained from the titration are shown below:

Result table

Average titre volume = 5.65 + 5.70 + 5.50

                                          3

                            = 5.62 cm³

% Lactic acid = titre volume, cm³ x molarity of NaOH x mol. mass of Lactate

                                                    cm³ sample x 10

Titre volume = 5.62 cm³

Molarity of NaOH = 0.1 M

cm³ sample = 5cm³

Molar mass of lactate =

                   molecular formula – CH3CHOHCOOH (2-Hydroxypropanoic acid)

                                             = (12 x 3) + (1 x 6) + (16 x 3)

                                             = 36 + 6 + 48

                                             = 90g/mol

Join now!

% Lactic acid = 5.62cm³ x 0.1M x 90 g/mol

                                     50

                    = 1.0116

                   

                    = 1.01 %.

Evaluation:

The aim of this experiment was to produce lactic acid and find the acid content produced. This involved fermenting finely shredded pieces of cabbage in salt solution under anaerobic conditions then titrating the product ...

This is a preview of the whole essay