3D Printed Foods Texture Measurement

There’s a new frontier in 3D printing that’s only beginning to come into focus: food. Recent innovations have made possible machines that print, cook, and serve foods on a mass scale. People’s growing awareness of the food that they consume and the drive for new customised sensory experiences is pushing for the development of new technologies that can satisfy these new consumers’ standards. 3D printing has made a large impact in many sectors, but its entry into the food industry has not been a simple journey. However, the potential benefits of incorporating 3D printing into food manufacture are significant and far outweigh any teething problems. 3D food printers could:

Improve the nutritional value of meals – a food product or a whole meal can have its ingredients tailored to meet the needs or dietary requirements of a patient in hospital or a care home, leading to a more fortified diet or better recovery. 3D printing also has the potential to make life easier for those people who use health trackers. There is a possibility that in the future, the user’s fitness tracker can send data to the 3D printer, which will output a meal perfectly tailored to that person’s requirements. This ‘personalisation’ has been pointed as the driving force to disrupt traditional ways to produce and deliver food and enchant a variety of customers.

Produce intricate, imaginative sculptures out of everyday foodstuff giving freedom to chefs and manufacturers. This would enable the creation of food products with specific design characteristics, flavours and colours, geometric structures and textural experiences for the consumer. This includes tailoring food to special events, or to incorporate customers’ names or images and thereby enabling customisable appearance.

Reduce food waste – using up food that is otherwise destined to be thrown away. This food might not be attractive enough for sale, such as the ugly leftovers from the production process. However, it can be formed into a more appetising shape with the help of 3D printing. Food products can be printed on demand, so perishable products can be manufactured as and when their need arises. The technology is exciting and opens doors to a sustainable future.

Reduce labour costs and save time as there is no need for manual operation once the print has been launched.

Solve hunger in regions of the world that lack access to fresh, affordable ingredients.

How food is 3D printed

Extrusion, selective laser sintering and binder jetting, and inkjet printing are the three main processes used in 3D printing for food although there are several strategies for achieving the required result within those three techniques. Extrusion is a simple concept, with a nozzle pushing out a layer of food in a similar way that a 3D printer can extrude plastic to make a machine part. Hot-melt extrusion employs food material that has been heated just over its melting point, then extruded and solidified. Chocolate is frequently printed using this method due to its capacity to solidify quickly after being heated.

Selective laser sintering is the technical term for powdered foods being heated up and then being forced to bond to form some solid structure. As it necessitates the use of powdered substances, it's typically employed to make sweets or candies. Inkjet printing relies on gravity to print, with edible 'food ink' being deposited onto a surface, usually that of another food.

Pioneers in 3D printed foods

Some corporations are already using this technology in the fabrication of their products, such as Hershey’s (chocolates), Barilla (pasta noodle), Ruffles (potato chips), Oreo (cookies), and Mazola (fruits and vegetables). In the production of meat-based products, Aleph Farms and Meatech use 3D Printing in the production of laboratory-grown meat.

For consumers who avoid meat for animal welfare or environmental concern reasons, there are companies like Redefine Meat and Novameat who are researching meat that has had its whole structure 3D printed from plant based materials. A common drawback of plant based meat substitutes is that their texture is not close enough to the real thing. However, 3D printing allows structure to be perfectly tailored, fine tuning it to match the mouthfeel and textural parameters of a real piece of meat. You can print layers with 3D printing technology, and each layer can provide something different – such as 'alternative fat' or 'alternative muscle' – so that when you bite into a vegan steak, you get texture in one area, the taste and sensation of fat in another, and the tender meat flavour in yet another. This ‘alt-meat’ is a radical step forward and for this type of food research, a Texture Analyser is essential.

Texture problems associated with 3D Printed Foods

There’s no doubt about it — 3D food printing has come a long way. The first challenge to overcome being the range of food products that have until now been printable. Additionally, the properties of finished 3D printed products require a large amount of research (texture and rheology as well as colours and general appearance) and development along with the printing conditions to achieve them (such as temperature, speeds and raw materials).

Beyond taste and appearance, one of the major factors in consumer acceptability is the texture and mouthfeel of the food. While taste and appearance are the factors that attract more attention during food production and consumer purchase, texture is crucial in food preferences and can make a difference at the time of purchase.

Texture Analysis is the first step in the Research and Development of 3D printed food products, when texture can be unpredictable and must be measured after each iteration of ingredient or process modifications.

How texture analysis can help in 3D printed food development

A Texture Analyser is a very useful tool for the research and development associated with 3D printing. Using food applications as an example, alternative ingredients are often incorporated into food products by use of 3D printing to improve the nutritional profile of that food. A study would be performed to assess the amount of the alternative ingredient that can be added before the texture of the original food is changed significantly. Texture Analysis is then performed on samples with varying percentages of additives and acceptability levels used to determine the optimum payoff between high nutritional content and good textural properties.

Stable Micro Systems manufactures instruments that measure the tensile and compressional properties of raw ingredients, individual materials and finished products. It is important to measure the textural properties of food to ensure they match the expectations of a consumer. As with any manufacturing innovation the end-product must go through a quality control process to assess its mechanical (and sensorial) properties. A Texture Analyser is a crucial part of this procedure, giving a reliable way to test products by applying a choice of compression, tension, extrusion, adhesion, bending or cutting tests to measure their physical or textural properties e.g. firmness, stickiness, crispiness and extensibility, to name but a few.

A range of Texture Analysers are available varying in maximum force capacity and height options suited to the requirements of the application.

A vast range of probes and fixtures can be attached to the instruments depending upon the product/material to be tested.

Want to discuss texture analysis for 3D Printed Foods?

How texture of 3D printing food materials can be measured

Compression and Extrusion

Food materials for printing should have adequate rheological properties that can be easily extruded and maintain their shape. However, there are very few foods that meet this condition and it is still a challenge to process many food materials to be applicable to this method. Any materials that are proposed for 3D printing will require ‘printability’ testing to ensure they possess the correct rheological properties or consistency. Formulations will need to be assessed for their extrudability and the resulting printed products measured by way of a compression test to ensure the texture matches customer expectation.

Typical compression and extrusion tests on a Texture Analyser

Here are specific research examples of where texture analysis has been applied in this way:

3D printing of gels based on xanthan/konjac gums

Printability and Physicochemical Properties of Microalgae-Enriched 3D-Printed Snacks

Customized Shapes for Chicken Meat–Based Products: Feasibility Study on 3D-Printed Nuggets

Feasibility study of hydrocolloid incorporated 3D printed pork as dysphagia food

Fracture and Bending

The Texture Analysis involved in a food 3D printing study is no different from ordinary food Texture Analysis. Printed products such as chocolate may need to be tested in a similar way that they are assessed by a consumer. The method used is simply suited to the food in question, perhaps with emphasis on a property that could vary the most with the 3D printing process. For example, 3D printed biscuits are frequently used as a novelty food as it is so simple to change their colour or design. However, to show off the capability of the 3D printing process, ornate, lacy, open designs are often used. These are not particularly strong and may break apart in storage or transit. To assess their strength, a standard biscuit bend test is used, putting to use a TA.XTplus Texture Analyser and a Three-point Bend Rig. The fracture strength of various designs can be assessed in this way.

A typical three-point bend test on a Texture Analyser

Cutting

How a printed food is bitten into is another parameter of interest. Varying print materials and the internal infill structure can affect the ‘hardness’ of the end product. Many foods are inserted between the upper and lower incisors and bitten into. The force required to do this gives the consumer an indication of its toughness or ‘bite force’. This type of test can be easily imitated using a Texture Analyser with a knife blade attached.

A typical cutting test on a Texture Analyser

How a Texture Analyser can assess 3D printer base powder flowability

Texture Analysis can also be put to use at other stages in the 3D printing process, not just for the measurement of final product properties. For example, the properties of the base powder used in Selective Laser Sintering affect the sintering process as well as the properties of the final product. Powder flow is one of these properties. As each new layer of powder is swept onto the sintering bed, the layer should be uniform and of the correct thickness and distribution. A Powder Flow Analyser (PFA) is a very useful add-on to a Plus Connect Texture Analyser to help measure these flow properties.

The PFA proves an accurate and reliable method of measuring the flow characteristics of dry and wet powders, with capability to measure cohesion, caking and speed flow dependence as well as bulk density and other properties.

The Powder Flow Analyser on the TA.XTplusC Texture Analyser

Texture analysis and its role at NASA

Now that 3D-printing technology has become more vital and relevant than ever, Silicon Valley BeeHex has harnessed this technology (funded by a grant from NASA), to 3D print pizza. The purpose of this invention was to create a way for astronauts to select and product delicious food for themselves on missions. As manned mission to Mars become an ever-increasing possibility, astronauts might be spending much more time in space. To save space-goers from the drudgery of choking down freeze-dried, pre-packaged “space food” day after day, month after month, NASA decided it was time to develop a way to cook in space. As usual, they will need to make sure that all the key aspects of consumer satisfaction of the resulting printed food are in place and this is where a Texture Analyser comes in!

More examples of how Texture Analysis is being applied in 3D printed Food Research

3D printing also has the ability to use alternative protein sources such as insects. There is a reluctance to eat insects in the West, which is unfortunate as they contain an excellent source of protein and are more environmentally friendly than meat, producing less methane and consuming less water. 3D printing allows insect protein to be reformed into a more appealing shape.

Another branch of 3D food printing research involves investigation into printing conditions. The texture of the finished food product depends strongly on various parameters e.g. printing speed and nozzle diameter, involved in the 3D printing process. In this type of study, a range of conditions are used and the texture of the printed product assessed, with the aim of finding the set of variables for a final product with optimum texture.

Here are specific examples of where texture analysis has been applied in this way:

Programmable texture properties of cereal-based snack mediated by 3D printing technology

Development of fiber-enriched 3D printed snacks from alternative foods: A study on button mushroom

3D Extrusion Printability of Rice Starch and Optimization of Process Variables

The need to measure dimensional profiles

If you’ve designed a product in a CAD package and then you print it, one concern will be whether what has been printed is what you designed. In many cases you’ll need your printed object to be dimensionally accurate and iterations of printing your design are almost inevitable to adjust the printing settings to obtain a product that is dimensionally accurate. Accurate digital assessment of physical dimensions thereby becomes a necessity. The Volscan Profiler provides such a solution – a benchtop laser-based scanner that measures the volume, density and dimensional profiles of solid products.

Volscan Profiler models for measurement of volume, density and dimensional profiles

Typical ways of mounting samples in order to scan and measure their dimensional profiles:

Chocolate bar sample ready for scanning and an archived scan of sample

The food industry is experiencing a paradigm shift in its efforts to provide new and exciting consumer eating experiences. To read more about how to apply texture analysis to your 3D printed food developments, you might like to request this article