Water content, one of the most important properties of food
2001; Elsevier BV; Volume: 12; Issue: 7 Linguagem: Inglês
10.1016/s0956-7135(01)00043-3
ISSN1873-7129
Autores Tópico(s)Isotope Analysis in Ecology
ResumoWater is present in practically every foodstuff. The water content has significant importance for a number of reasons. The determination of water content is therefore the most frequent general analysis performed on foodstuffs. A survey of the most widely used methods is given. They are classified into direct and indirect methods. Direct methods aim at the determination of the water as such. The physical techniques among them are based on a separation of the water. Heating techniques which measure a mass loss under certain conditions are principally problematic as they cannot distinguish between water and other volatile matter. Chemical direct methods are based on a chemical reaction of the water molecules. The most important technique is the Karl Fischer titration. Indirect methods can either measure a property of the sample that depends on the water content, or they observe the response of the water molecules to a physical influence. The latter group comprises the use of low-resolution nuclear magnetic resonance, near infrared spectroscopy and microwave techniques. These extremely rapid methods need a very product specific calibration against a reference method, because water molecules in different bonding situations may behave differently.
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