Speaking at the 3D Food Printing Conference, in Venlo, the Netherlands, Valerie Vancauwenberghe, PhD student, KU Leuven, MeBioS division, said she looked at 3D printing for candy as part of a project on new methods to print 3D cellular plant tissues for innovative food manufacturing.
Cell walls of plants
Pectin is a naturally-occurring thickening agent most often added to jams, jellies and sweets to help them gel and thicken. It is a carbohydrate (a polysaccharide) found in and around the cell walls of plants.
“Pectin is an edible gel that can be used in a wide range of products, with a variable sweetness, and it is stable enough to print, due to the duration of the material,” said Vancauwenberghe.
“We used a particular type of pectin, called low-methoxylated pectin, in trials creating shapes similar to Gummie Bear sweets, looking at the characteristic of those printed objects and using compression tests to get information about its mechanical properties and rupture stress.”
She added, depending on the composition, the visual aspect of the material can be quite different, it can be transparent or else it can disperse during the printing process, which means it is not well optimized for that kind of printing technique.
“At KU Leuven we developed a prototype printer to print material at room temperature such as pectin gel,” said Vancauwenberghe.
“If we wanted to make candy it would be interesting to see how much sugar we could add without changing the printability of the product. We would need to make the material extrudable at room temperature.”
Not all material is suitable for 3D printing
All fruit has pectin in it, but the amount varies widely, according to Vancauwenberghe. She said it is not always suitable for 3D printing because it is either lacking in iron or calcium for viscosity.
For a product to keep its shape, the PhD student tried different concentrations of ingredients to find a material with preferably edible food properties, with the same texture as fruit or vegetable.
“The porosity can be controlled with the forming agent, so during printing we won’t lose that foamy structure and the printing doesn’t change due to the availability of air bubbles,” she added.
Apples and oranges contain the most pectin, and the pectin from both fruits is used commercially to thicken many different types of products.
Pectin generally needs a high sugar content and some acid, such as citric acid, to activate, and some commercially available pectins include citric acid as an ingredient.