In my previous article, “Semisolid Enteral Nutrition,” I explained formulations that are already semisolid before administration.
This time, I’ll take a closer look at formulations that are delivered in liquid form but may turn into a gel once they reach the stomach.
On August 10, 2025, the Silver Industry Newspaper reported that Morinaga Milk Industry launched a new intragastric gelling product called “Wanoka.”
Although this type of product has existed before, the release of a new one suggests that there still seems to be steady demand for enteral nutrition products.
In this article, I’ll explain the possible mechanism of intragastric gelation, referencing related patent documents.
Disclaimer: This article may contain affiliate links (PR).
It is based on the author’s personal research and perspective, and does not guarantee medical accuracy.
Product purchase or use should always be at your own discretion and responsibility.
Challenges of Enteral Nutrition
Enteral nutrition is often chosen when aging or illness makes oral intake difficult.
Nutrients are delivered through feeding tubes such as nasogastric tubes or gastrostomy, allowing supplementation in a way that is considered closer to physiological intake.
However, several challenges have been pointed out:
- Aspiration pneumonia: Gastric contents may reflux and enter the airway, which can increase the risk of aspiration pneumonia.
- Diarrhea: High-energy formulas often have high osmotic pressure. If they flow too quickly into the small intestine, water is drawn into the lumen, sometimes leading to diarrhea.
- Pressure ulcers: Administration can take time, and when patients remain in the same position for long periods, the risk of pressure ulcers may increase.
Semisolid Nutrition
One approach to these issues is the use of semisolid nutrition.
Because these formulations are more viscous than liquids, they are thought to be less likely to cause gastroesophageal reflux.
They may also enter the intestines more slowly, allowing gentler absorption and reducing the likelihood of diarrhea.
However, premade semisolid formulas can be difficult to administer through narrow nasogastric tubes due to their viscosity.
This is where liquid formulas that gel inside the stomach may provide an option.
The newly launched “Wanoka” by Morinaga Milk Industry is one such example.
This type of product is designed so that the advantages of semisolid nutrition can also be applied when using thinner feeding tubes.
Patent on Nutritional Compositions that Gel in the Stomach
Publication No.: JP 2023-105115 A
Publication Date: July 28, 2023
Title: Nutritional Composition
Applicant: Morinaga Milk Industry Co., Ltd.
Conventional Problems
The typical way to increase viscosity of liquid formulas in the stomach has been by combining low-methoxyl pectin or alginic acid (polysaccharides) with insoluble calcium salts.
Mechanism:
- Insoluble calcium salts ionize under acidic gastric conditions, releasing Ca²⁺.
- Ca²⁺ binds to the –COO⁻ groups of pectin or alginic acid.
- This creates an egg-box structure, leading to gelation.
However, this method has known challenges:
- Unstable emulsions: If emulsification is unstable, gels may aggregate, and nutrients can become unevenly distributed.
- Reduced gastric acid secretion: In elderly individuals with lower gastric acid levels, gelation may not occur sufficiently, leaving reflux and other liquid-related issues unresolved.
In other words, what is needed is:
- More stable emulsions where gels remain evenly dispersed
- Thickening that can occur even with lower levels of gastric acid
Solutions
The patent proposes a combination of casein + oil + polysaccharides + insoluble calcium salts.
Casein
＜α–casein＞
Casein approaches its isoelectric point (the state where positive and negative charges on the molecule balance) under acidic conditions.
Because H⁺ ions are abundant in the stomach, this change is facilitated.
For example, the carboxyl groups (–COOH) in casein exist as negatively charged –COO⁻ near neutral pH.
In acidic conditions, they can accept H⁺ and revert to –COOH, reducing their negative charge.
As a result, repulsive forces between molecules decrease, allowing casein molecules to come closer and aggregate.
This aggregation suppresses liquid flow, which increases viscosity (thickness).
Casein + Oil
Formulas often contain lipids such as medium-chain triglycerides.
Casein has both hydrophilic and hydrophobic domains, allowing it to surround oil droplets like a surfactant and keep them dispersed.
Thus, while acid-induced aggregation of casein contributes to viscosity, casein also supports emulsification, helping to prevent clumping.
Polysaccharides + Insoluble Calcium Salts
In addition, the conventional combination of low-methoxyl pectin or alginic acid + insoluble calcium salts plays a role.
Insoluble calcium salts release Ca²⁺ in the stomach, which binds to the –COO⁻ groups of polysaccharides to form egg-box structures, further enhancing viscosity.
By combining this mechanism with casein, the composition may achieve more stable thickening even when gastric acid is reduced.
While conventional methods sometimes led to uneven thickening, this patent describes a way to stabilize emulsification and maintain more uniform gel dispersion.
According to Morinaga Milk Industry’s product description:
“Casein coagulates like tofu, and pectin forms a gel, producing a double thickening effect.”
This suggests that the product design may be based on a similar mechanism to the patent.
Closing thoughts
In my nursing practice, many patients who receive enteral nutrition are bedridden and unable to speak or move actively.
For such individuals, my focus is always on helping them remain as comfortable as possible.
Semisolid nutrition is considered one option that may help reduce the risks of aspiration and diarrhea, thereby easing patient discomfort.
Enteral nutrition also substitutes for eating—a source of enjoyment.
I often wonder whether even a small part of that “pleasure” could be preserved.
For example, I sometimes imagine a future where enteral formulas could spread taste in the mouth—like something from Doraemon’s world.
That may be far off, but even now, the design of Wanoka’s package, with calming colors inspired by plants and wisteria, offers a sense of aesthetic comfort.
While I expect overall use of enteral nutrition to decrease in the future, the release of new products suggests that there is still ongoing demand.
By understanding the features of both premade semisolid types and intragastric gelling types, caregivers and healthcare professionals may find better ways to support patient comfort and care.
I write technical articles on medical and care materials, and support market entry projects by combining nursing experience with patent knowledge.
Please feel free to contact me via the blog’s form.
Disclaimer: This article is for reference only and does not guarantee accuracy. Please make purchase and use decisions at your own responsibility.
References
- Shokuhin Kaihatsu Labo: https://shokulab.unitecfoods.co.jp/
- Polysaccharide.com: https://www.tatourui.com/
- Morinaga Milk Industry Clinico: https://www.clinico.co.jp/products/variable-viscosity/wanoka8.html
- Morinaga Milk Industry Co., Ltd., Nutritional Composition, JP 2023-105115 A (Published July 28, 2023)
- Takeo Sakai, Anatomy and Physiology, Igaku-Shoin, 2010
- John McMurry, Organic Chemistry, 8th Edition, Tokyo Kagaku Dojin, 2012
- Yoshinobu Urabe, Shin Kenkyu in Chemistry, Sanseido, 2019
