Research

New frequency-based approach to 3D printed dysphagia diets

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Scientists from Kyushu University (KU) in Japan and Cardiff University in the UK has developed a new method of 3D printing food gels designed for people with swallowing difficulties.

Led by Associate Professor Shuntaro Tsubaki from KU’s Faculty of Agriculture, the study shows how radiofrequency and microwave heating can be used to control the texture of food intended for dysphagia diets. Dysphagia affects people who find it hard to chew or swallow, often due to age-related conditions, stroke, or neurological disorders.

To prevent choking or aspiration, foods for dysphagia patients must meet strict texture standards. These meals are often pureed or gel-based, but they can lack visual appeal, which affects appetite and overall quality of life. Published in Scientific Reports, the study builds on research into how 3D printing can be used to create meals that are not only safe to swallow but also more visually attractive and nutritionally balanced.

(A) Schematic of emulsion gel ink preparation and (B–D) RF and MW heating devices: (B) 200 MHz, (C) 915 MHz, and (D) 2.45 GHz. Image via KU.
(A) Schematic of emulsion gel ink preparation and (B–D) RF and MW heating devices: (B) 200 MHz, (C) 915 MHz, and (D) 2.45 GHz. Image via KU.

RF/MW approach to dysphagia-safe gels

The researchers prepared an emulsion gel “ink” using egg white protein, xanthan gum, magnesium chloride, canola oil, and an emulsifier. These ingredients were selected because they can form gels with the right firmness and smoothness for dysphagia diets. By exposing the gel ink to radiofrequency (RF) and microwave (MW) heating at different frequencies, the team was able to fine-tune the properties of the resulting gels.

One of the main findings was that frequency played a major role in determining texture. When treated with radiofrequency at 200 MHz, the gels became four times harder than those produced using conventional heating methods. They also retained more water, due to the formation of thicker protein fibers in the gel network. In contrast, microwaves at 2.45 GHz created softer gels with higher adhesiveness and a porous structure. Microwaves at 915 MHz produced intermediate textures.

These differences meant that the printed gels could meet different stages of the official Japanese dysphagia food standards, which define levels of hardness suitable for patients. The firmer gels produced at 200 MHz fit Stage III, while the softer gels made using higher microwave frequencies matched Stage I. This flexibility suggests the method could be tailored to individual swallowing needs.

To demonstrate practical application, the team built a bioprinter using LEGO Mindstorms components combined with radiofrequency and microwave devices. The system extruded the emulsion gel ink through a nozzle and used controlled heating to solidify it into layers. By adjusting flow rates, power levels, and frequencies, the researchers achieved stable printing of gels that matched the textural qualities seen in batch-heated samples.

Microscopic analysis showed that lower radiofrequency caused egg proteins to form dense, water-trapping networks that increased hardness, while higher microwave frequencies produced looser, porous structures that were stickier but less firm. This demonstrates how electromagnetic heating can precisely control food texture.

All of the 3D printed gels met the requirements for dysphagia diets in Japan, showing that the process is both consistent and adaptable. According to the researchers, this approach opens the door to meals that are safe, nutritious, and more visually appealing for patients who often face limited food choices.

While focused on dysphagia diets, the study notes the method could extend to artificial meats and confectionery, with frequency and power control over texture offering a new tool for food design. The team notes that further work will explore how nutrients and flavors can be incorporated into these printed gels, potentially broadening their use both in healthcare and in the wider food industry.

Schematics of 3D bioprinter using (A) MW at 2.45 GHz and (B) RF at 200 MHz. Image via KU.
Schematics of 3D bioprinter using (A) MW at 2.45 GHz and (B) RF at 200 MHz. Image via KU.

3D printing dysphagia meals worldwide

Beyond safety and nutrition, 3D printing dysphagia-friendly food restores dignity and enjoyment to eating, supporting social inclusion by letting patients eat foods that look like “normal meals” at family gatherings or public events.

Earlier this year, Dutch company Gastronology began large-scale production of the Dysphalicious product line, which are essentially 3D printed meals for people with dysphagia. After initially supplying hospitals in April 2023, the meals are now available to home users through QSTA, delivered frozen in portioned boxes. 

Made from fresh vegetables and potatoes, the dishes meet the IDDSI Level 4 standard, offering safe, visually recognizable alternatives to traditional purees. Working with contract manufacturer Budelfood B.V., the current range includes eight plant-based items, with meat options planned, and production capacity is set to expand from 700 kg to 2,500 kg per day.

A few years back, researchers from the University of Technology Sydney (UTS) and Deakin University used 3D printing to create safer, more appealing meals for people with dysphagia. Pureed food was cooked, liquified, and loaded into cartridges before being 3D printed into pre-programmed shapes, making dishes look like cakes or biscuits while retaining a puree texture. 

Conducted at UTS’ Protospace Lab, the study highlighted both nutritional and social benefits, suggesting the technology could help people participate more fully in shared meals. The team concluded that further observational studies and consumer-focused printer designs were needed for broader adoption.

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Featured image shows (A) Schematic of emulsion gel ink preparation and (B–D) RF and MW heating devices: (B) 200 MHz, (C) 915 MHz, and (D) 2.45 GHz. Image via KU.

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