3D-printed vegetable purees preserve nutrients and “offer dignity” to patients with dysphagia

05 Feb 2021 --- Researchers have developed a novel way to create “food inks” from fresh and frozen vegetables that preserves their nutrition and flavor better than existing methods.

These purees can then be 3D-printed into appealing shapes to help ensure that people with dysphagia, a condition making swallowing difficult, consume all the nutrients they need.

NutritionInsight speaks to members of the team behind this technology, which was developed at Nanyang Technological University, Singapore (NTU Singapore), Singapore University of Technology and Design (SUTD) and Khoo Teck Puat Hospital (KTPH).

“Food printing could be used as a way to realize personalized nutrition and food texture modification,” says Gladys Wong, co-principal investigator and senior principal dietitian from KTPH.

Currently, healthcare professionals use silicone molds to serve pureed foods in a more visually appetizing way. In addition to being labor- and time-intensive, this method also requires storage.

“This [new technology] could improve productivity by automated printing of meals, which otherwise is labor-intensive if prepared via the conventional institutional kitchen methods.” Visually appealing meals could positively impact patients’ physical health and mental state of mind.

A playground for “recipe designers”
Wong explains that 3D food printing could eventually be used as a playground for “recipe designers” like dietitians, food technologists and chefs, where they can create texture-modified recipes using any edible ingredients, including insect protein or food waste.

“This can then be masked into familiar dishes of high nutritive value. Additionally, food printing technology can help standardize meal production. Regardless of who prepares the meal, it allows the production of nearly identical food with the same texture.”

Avoiding hydrocolloids
Normally, food inks are made from pureed foods in liquid or semi-solid form, then 3D-printed by extrusion from a nozzle, and assembled layer by layer.

However, the dehydrated food and freeze-dried powders used as food inks usually contain a high percentage of food additives such as hydrocolloids (HCs) to stabilize the ink and enable a smoother printing process. 

High concentration of HCs usually changes the taste, texture and aroma of the printed food, making it unappetizing. When the technology is used to prepare food for patients with dysphagia, this may lead to reduced food consumption and malnutrition.

Exploring vegetables
To avoid high concentrations of HCs, the research team explored various combinations of fresh and frozen vegetables to make the food inks stable.

Vegetables can be broadly classified into three categories, with each requiring a different hydrocolloid treatment to become printable. 

For instance, garden pea, carrot and bok choy were chosen as representatives in each category, requiring no HCs, one type of HC and two types of HCs, respectively. 

All the vegetables are steamed and pureed before hydrocolloids are added if necessary. The final texture of the shaped products still feels like a puree. Images with blue boxes show optimized ink formulations. Print scores in top right corner show shape fidelity and shape stability.

Providing dignity
The researchers say their technique better preserves the nutrition of printed food, while also making it more palatable. This new method of making food inks should lead to increased meal consumption by patients, contributing positively to their physical health and mental state of mind.

“Our technology helps to provide dysphagic patients with adequate nutrient-rich and safe diets. Their feeding is more dignified, enabling them to socialize and consume meals that look, feel and taste like regular food,” says Yi Zhang, the principal investigator from the NTU team.

Zhang continues that the method can be used easily in hospitals, nursing homes and daycare centers for the aging population with dysphagia and other swallowing disorders.

As the population in many parts of the world skews increasingly elderly, industry has been addressing many health issues associated with aging. 

Last year, Hormel Foods’ Health Labs division unveiled Thick & Easy IDDSI Level 5 Ready Meats to provide safe, enjoyable nutrition for those on dysphagia diets.

Meanwhile, SternLife developed six supplementary and seven nutritionally complete medical foods to tackle malnourishment and dysphagia.

More than a novelty
The team behind the 3D-printed purees is now developing a multi-nozzle printer. Chua Chee Kai, corresponding author and the head of pillar, engineering product development at SUTD, says that this will enable easy nutrition customization. In turn, this will greatly extend the applicable scenarios of 3D food printing.

“3D food printing is more than a novelty. I believe it will be a viable approach in the near future in providing sustenance and nourishment to our increasingly aging population,” emphasizes Wong.

Members of the team were also behind a project last year that developed a way to 3D print milk-based products at room temperature without additives. 

By Katherine Durrell