Capabilities of near-infrared spectroscopy to analyse changes in water bonding during honey crystallisation process

To characterise the changes occurring in honey under the influence of crystallisation process near-infrared spectroscopy has been used. The technique involved analysing the same type of honey by subtracting its crystallised spectrum from the liquid spectrum. The comparison of the difference spectra made it possible to determine specific water bonding processes affected by crystallisation. The surface area under the peak obtained during absorption by water was in the range of wavenumber nu < 5330; 4965 > cm(-1) with the maximum at nu = 5155 cm(-1). It was found out that the area under the peak was directly related to water activity changes that occurred in honey during the crystallisation process. A regression equation between the area under the peak and water activity assumed a linear form characterised by a high value of the determination coefficient R-2.