Determination of Water Content in Chocolate by Custom-Built Coulometric Karl Fischer Titration (CAT#: STEM-PPA-0131-YJL)

Name: Determination of Water Content in Chocolate by Custom-Built Coulometric Karl Fischer Titration
SKU: STEM-PPA-0131-YJL
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Introduction

The quality of chocolate is very much dependent on its moisture content. Nearly half of a typical chocolate bar is made up of sugar particles in the form of sucrose and lactose, and the presence of excess moisture can lead to microbiological contamination, and degradation of sucrose to glucose and fructose, resulting in poor shelf life and substandard texture. Furthermore, for every additional 0.3 % of water above 1 % total moisture by mass left in chocolate after the conching stage, an extra 1 % fat must be introduced to maintain its smooth quality. Because fat is the most expensive component of chocolate, it is important for manufacturers to track and keep water content below 1 % by weight.

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Principle Applications Procedure Materials

Principle

Karl Fischer titration is used as a reference method for many substances and is a chemical analysis method based on the oxidation of sulfur dioxide by iodine in methanol hydroxide solution. Titration can be performed by volumetric or coulometric methods.
According to the volumetric method, an iodine-containing Karl Fischer solution is added until the first signs of iodine excess appear. Iodine turnover was determined by the volume of the burette containing iodine Karl Fischer solution.
In the coulometric procedure, reacted iodine is generated directly in the titration cell by electrochemical oxidation of iodide ions until traces of unreacted iodine are detected. Faraday's law can be used to calculate the amount of iodine produced by the required charge.

Applications

Food industry; Petroleum industry

Procedure

1. Pre-titrate the instrument.
2. Weigh the sample.
3. Pour the sample into the titration vessel.
4. Stir until the sample dissolves, and titrate to the end point with Karl Fischer titrant.
5. Enter the sample mass and record the moisture determination.