What is the purpose of a Moisture Analyser?
A Moisture Analyser is used to measure the moisture content of materials for research, shelf life or production.
Water is present in varying amounts in most products and it is often useful to control the amount of moisture present, as the amount of moisture can give a product different properties, eg thick paint vs paint thinned with water and used to give a paintwash effect, or an apricot that has been dried out to preserve it.
A high moisture content in a product is desirable in some cases, eg in fruit and vegetables, a higher moisture content correlates with increased flavour. However, it is undesirable in others, eg. in wheat it will encourage the growth of undesirable micro-organisms. For this reason, a lower moisture content is also preferred in some food production environments – in order to enhance the shelf life.
Moisture has a large role to play in Food Quality Control. Obtaining consistent moisture levels in production results in a consistent product with less wastage due to spoilage. Often the moisture % in a product is prescribed in the recipe, due to the nature of the product, eg a starch thickened sauce requires a certain moisture level in order to provide a stable result.
Other industries in which moisture content plays a large role in the quality of the product include pharmaceutical, sugar, powdered beverages, plastics, some chemicals and laboratory research.
An A&D Moisture Analyser in use.
How to use a Moisture Analyser:
A Moisture Analyser is an instrument that is made using a balance (what is a Balance?) and a heater that can reach temperatures as high as 800°C. These high temperature are performed whilst the weight of the sample is being recorded by the instrument’s internal computer.
- You place a sample inside a sample pan with tweezers or a small spoon. The sample is then enclosed with a cover.
- The instrument then records the weight of the sample.
- Now the sample is heated with a specially designed heater, usually halogen or infrared. During the heating process, the balance continues to weigh the sample at set intervals.
- When the measurement temperature stabilises and becomes constant, the user is alerted to the result: the moisture content of the sample.
- Some models have software that also record the moisture rate over the time it is being measured.
- Specialised Moisture Analysers can accurately measure amounts as small as less than 1%!
The Difference between using a Moisture Analyser and the Karl Fischer method:
- A Moisture Analyser compares weight before and after heating and drying, whilst a Karl Fischer type analyser titrates KF reagant that contains Iodine to a sample electro-chemically
- The Karl Fischer method provides a measurement of … ppm to 100% water, but is a more complex procedure and the instrument is more expensive
- The data obtained is similar in both methods
- Where the required resolution is under 0.01%, the MS/ MX Moisture Analyser is more suitable in terms of handling, accuracy and running cost
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