Analysis of water in food by near infrared spectroscopy

The analysis of water by near infrared spectroscopy (NIRS) was the first successful application of this rapid technology which has been developed over the past 30 years into a routine method for many agricultural commodities and food constituents. Nowadays, NIRS technology offers many advantages because its rapidity allows more frequent measurements at all stages from purchase of raw materials and ingredients to the control of the finished products. NIRS-methods are well suited to in-line use. Nevertheless the two dominant and broad peaks, near to 1440 and 1930 nm in nearly every NIR spectrum due to water, are responsible for some typical complications in this analysis. Effects of hydrogen bonding and sample temperature are found to affect the reliability of NIRS results.