Chromatography Forum

Hi, I used to work in the food industry & we used a Hunter Colorimeter for measuring the colour values of many types of powdered snack seasonings, spices, also did some colour evaluation of spice oleoresins plated on salts. It is one of the best instruments for measuring surface colour, from what I remember. It measures surface colour based on how the human eye sees colour but without the subjectivity, (the human eye can see 10 million shades of colour, depending of the health & age of the eye) The Hunter uses "L", "a" & "b" values, where an "L" value closer to zero is more white & as it approaches 100=Black, "a" value is +red to -green, "b" value is +yellow to -blue. If I remember correctly, the lamp source light refracts the colours at characteristic angles off the surface of a sample placed in a standard sized petri dish & smoothed carefully to a flat surface. A digital readout is made, for the 3 values, comparing them to a stored "Gold Standard" the target colour that the product is being compared to. Acceptable specifications are programmed in. The instument was standardized daily, but fairly easily with very clean coloured tiles, white, black, and various colours. If you go to the Hunterlab site, I believe they sell various surface colour measurement instruments that may not be as expensive as the Hunter Colorimeter. Some may be portable. The Hunterlab site is a wealth of colour information with some videos. Good luck !

GrenI