DIAAS: Measuring Protein That Matters

How good is protein really?

Walk down any supermarket aisle today and you’ll see it everywhere: “protein enriched,” “extra protein added.” Yogurt, snack bars, pasta, even ice cream and bread, protein are in every corner. From plant-based burgers to insect-based ingredients, alternative proteins are trending, and we’re happily buying them.

But here’s the question we rarely ask: how good is that protein really?

Why protein quality matters

Protein isn’t just a trend- it’s essential for health, supporting muscle, satiety, and longevity. At the same time, the world faces a huge challenge: producing enough high-quality protein sustainably to feed future generations. That’s why understanding and rating protein quality, especially from novel sources, is more important than ever.

Measuring protein: more than a number

Protein quality isn’t just about how much protein a food contains—it’s about how well our bodies can use it. Measuring protein quality helps food innovators optimize products, develop alternative proteins, and close nutrition gaps, ensuring that what we eat truly supports.

The digestibility of a protein depends on the amino acid (AA) composition, how digestible the protein is, and the bioavailability of those amino acids. Since these factors vary widely between protein sources, not all proteins are equally nutritious. The first widely recommended method by WHO/FAO is the Protein Digestibility-Corrected Amino Acid Score (PDCAAS), which expresses protein quality as a percentage based on both AA content and total protein digestibility. In 2013 the FAO/WHO updated their guidance and recommended the more accurate method: Digestible Indispensable Amino Acid Score (DIAAS)

In vitro GI models as useful tool for protein measuring

Testing protein quality in humans (in vivo) is ideal, but ethical constraints, high costs, and low throughput often limit these studies. Even non-invasive methods involving human subjects aren’t suitable for routine use (Moughan, 2025). Animal models offer an alternative, but they show reduced accuracy and conflict with the 3Rs principle of replacing, reducing, and refining animal use.

In vitro gastrointestinal (GI) models, such as TIM Upper GI, provide a powerful alternative. They allow researchers to study digestibility and bioaccessibility with high accuracy, quickly, and without using humans or animals. The FAO Expert Consultation on Protein Quality Evaluation recommends developing and validating these models for rapid, routine, and ethical protein testing, helping researchers and food innovators evaluate protein quality efficiently.

TIM^® and regulatory relevance

The European Food Safety Authority (EFSA) acknowledges DIAAS calculations using true ileal digestibility and indispensable AA profile for novel foods providing a significant amount of protein (main protein source). Multiple publications (Havenaar et al., 2026; Jaeger et al., 2024; Maathuis et al., 2017) show InnoGI’s tiny-TIM system can support research and regulatory processes by accurately and reliably determine true ileal digestibility, aligning with EFSA’s emphasis on reproducible, physiologically relevant approaches for nutritional assessment of novel food.

Recently TIM^® data supported:

• The Protein Brewery (2025)
• Evergrain LCC (2023)
• Fair Insects BV (2021)

Looking ahead

As the demand for alternative and sustainable proteins continues to grow, accurately measuring protein quality will be essential, not just for nutrition, but for innovation and regulation. In vitro models like TIM Upper GI are helping food scientists and innovators meet this challenge efficiently, ethically, and reliably. By combining cutting-edge tools with robust quality assessment methods like DIAAS, we can ensure that the proteins we develop today truly support the health and sustainability of tomorrow.