Published online by Cambridge University Press: 01 June 2009
Photoacoustic signals in the near infrared region (~ 2·75 μm) have been investigated using amplitude and phase information to determine their effectiveness in estimating the water content of milk. The results obtained showed a good correlation between the photoacoustic signal and water concentration (R2 = 0·98) even though photoacoustic saturation was present in the range of wavelengths studied. However, this is not recommended as a fast technique for water determination because of inherent phase fluctuations in the samples analysed.