Tailoring texture in a mycelium yogurt alternative using oat bran fractions

Imagine a world where your morning yogurt isn't made from cow's milk, but from a microscopic, fuzzy forest growing in a tank. This is the exciting frontier of "mycelium" food science. Mycelium is the root-like network of fungi (think of the white threads you see under a mushroom cap), and it's packed with protein and fiber, making it a super-healthy, eco-friendly alternative to animal products. But there's a catch: while mycelium is great for making fake meat that looks like steak, turning it into a smooth, creamy yogurt is surprisingly difficult. Real yogurt gets its gooey, spoonable texture because milk proteins clump together into a perfect gel when they get sour. Fungal proteins, however, are wrapped in a tough, fibrous armor that doesn't clump the same way, often leaving you with a watery, grainy mess instead of a creamy treat.

To fix this, scientists have been trying to add "helpers" to the mix, like oat bran (the outer husk of an oat grain), which is famous for making things thick and smooth. But oat bran is a bit of a mixed bag: it has a slippery, water-loving part (soluble fiber) and a gritty, chunky part (insoluble fiber). The big question is: which part of the oat is the real hero for making mycelium yogurt feel like the real deal? Does the slippery part make it smooth, or does the chunky part hold it together? This study dives into that mystery, testing different ways to split oat bran apart to see which version creates the best texture for a fungal yogurt.

The Great Oat Split

In this study, researchers from the University of Helsinki and a company called Mush& decided to play with the ingredients of a mycelium-based yogurt. They started with a base made of fungal mycelium (grown from a specific type of mushroom called Phellinus linteus) and then added oat bran in three different forms:

1. Whole Oat Bran Concentrate (OBC): The full, uncut package.
2. Soluble Fraction (SF): The "slippery" part, rich in a special fiber called β-glucan, which dissolves in water.
3. Insoluble Fraction (IF): The "gritty" part, which stays solid and is rich in starch and protein.

They mixed these oat ingredients with the fungal base and added two different types of yogurt starters (bacteria) to see what happened. One starter was Lactiplantibacillus plantarum (let's call him "L. Plantarum"), and the other was Lactobacillus helveticus ("L. Helveticus"). They also added a probiotic friend, Bifidobacterium, to see if the yogurt would be healthy for your tummy.

The Bacteria Battle

First, they watched the bacteria party. The results were clear: L. Plantarum was the star of the show. It grew like crazy, reaching about 9 log CFU g⁻¹ (a fancy way of saying a huge number of bacteria), and it helped the probiotic Bifidobacterium grow to the same impressive level. It also ate up the sugar (glucose) very efficiently.

L. Helveticus, on the other hand, was a bit of a wallflower. It didn't grow as much, didn't help the probiotic friend grow, and left a lot of sugar uneaten. Interestingly, even though L. Plantarum was the better party animal, both bacteria managed to make the yogurt sour enough (reaching a pH of 4.3–4.7) in about 5 hours. So, while one was better at growing, both could make the yogurt sour.

The Texture Twist: Gritty vs. Smooth

Here is where the story gets surprising. You might think that the "slippery" soluble oat fraction (SF), which is full of the famous thickening fiber β-glucan, would make the best, thickest yogurt. But the data told a different story.

• The Soluble Fraction (SF) Yogurt: This version had the tiniest particles, making it look very uniform and smooth. However, it was the weakest of the bunch. It had the lowest thickness (viscosity), the least "bounce" (elasticity), and it leaked the most water (syneresis). It was like a smoothie that turned into soup; it just couldn't hold its shape.
• The Insoluble Fraction (IF) Yogurt: This version, which had the least amount of the famous β-glucan, turned out to be the strongest. It had the highest thickness, the best elasticity (it bounced back like a gel), and it held onto water the best, leaking very little. It was thick, cohesive, and spoonable.
• The Whole Oat (OBC): This was a happy medium, performing well but generally leaning toward the strong, thick characteristics of the insoluble fraction.

The researchers found that the "gritty" insoluble particles acted like tiny, invisible bricks inside the yogurt. Even though they didn't dissolve, they physically packed together to create a sturdy structure that held water and kept the yogurt thick. The "slippery" soluble fibers, while great for making things smooth, actually made the structure too weak to hold up on its own.

The Heat Test and The Spoon Test

To be sure, the scientists didn't just trust their eyes; they used machines to measure the yogurt.

• Heat: When they heated the yogurt, the versions with the insoluble oat (IF) and whole oat (OBC) could withstand higher temperatures before breaking down, suggesting they were more stable.
• Spoonability: A team of trained tasters confirmed the machine's findings. They described the IF and OBC yogurts as "thick," "cohesive" (sticking together), and "spoonable." The SF yogurt was described as "homogeneous" (very uniform) but lacked that satisfying thickness.

The Verdict

The study concludes that if you want to make a mycelium yogurt that feels like a real, creamy treat, you shouldn't just rely on the soluble, slippery fibers. Instead, the insoluble, chunky parts of the oat bran are the secret weapons. They provide the structural "scaffolding" that makes the yogurt thick and stable.

While the choice of bacteria matters for making a healthy probiotic product (with L. plantarum being the clear winner for growth), the texture of the yogurt is mostly controlled by how you treat the oat bran. By separating the oat into its soluble and insoluble parts, food scientists can now "tailor" their products: use the insoluble part if you want a thick, spoonable yogurt, or mix in the soluble part if you want a smoother, more uniform texture. It's a new way to build better plant-based foods, proving that sometimes, a little bit of grit is exactly what you need to make something smooth.