Project to quantify stability of natural food colours
In the first phase of a testing project due to be completed next month, the group is assessing colours from chlorophyll, anthocyanins and lycopene in both confectionery and beverage applications.
According to Wayne Morley, head of food innovation at Leatherhead Food Research, the findings will help manufacturers determine their product formulations by providing a quantitative analysis of the stability of certain natural colours.
“It’s generally accepted that natural colours tend to have reduced stability compared to artificial colours. But what we’re looking for is to be able to make a rapid assessment of what a product’s shelf-life will be when using a particular colour,” he said.
“We want to give a more quantitative view of what the stability will be like, rather than just saying it is ‘less’ stable than with artificial colours.”
Accelerated deterioration protocols
The stability of food or beverage applications is determined by a number of factors, all of which are linked to their ultimate shelf-life. These include microbiological factors (such as the growth of yeast or mould), organoleptic properties (the taste, texture or smell) and physical stability (for example separation or sediment formation).
Leatherhead’s testing service for natural colours aims to accelerate the deterioration that products undergo in order to obtain an early indication of their stability.
“We develop accelerated protocols, which usually involve storing the product at high temperatures, in intense light or in more humid conditions. Then we try to relate the product’s accelerated behaviour to standard room temperature behaviour so we can get an idea of what the stability and shelf-life would be,” explained Morley.
In order to conduct this testing, the group’s facility is equipped with climate chambers that can be adjusted to temperatures from -10°C to 90°C, a humidity range of 10 per cent to 90 per cent, and with UV, white light or other light conditions on request.
Assessment
Colour measurements are assessed using a number of techniques, including the HunterLab colorimeter (which provides colour measurement in solid, granular, flake, powder, paste and liquid form), the Spectrophotometer (which measures absorbance at specific wavelengths relating to the colour shade of the sample) and trained sensory and consumer panels.
Once the first phase of the project is completed, Leatherhead will make its findings available to members in a report, and will also prepare a paper for scientific publication, said Morley.
He added that a follow-on project is currently being discussed, which could look at the behaviour of different colour ingredients or different food and drink applications.
