AsianScientist (Oct. 21, 2026) –Overcooking your proteins might do more than just make it tough and bitter. A new study has found that high heat modifies proteins in ways that make them harder to digest, and that mice fed with overcooked meat showed lower social novelty behavior, meaning that they became less inclined to spend time with strangers than their familiar peers.
While the study did not establish a causal link between overcooked proteins and behavioral changes, it showed that high temperatures chemically modify the proteins differently than normal cooking, and that this difference could explain the observed behavior of mice in their experiments.
Led by Tomoko Asai of Kyoto University, the researchers first analysed overcooked soy protein isolates (heated at 120 °C for 20 minutes) in a petri dish. They found that about 10 percent of amino acids—the building blocks of protein—were either transformed into new compounds or enmeshed with other amino acids, making them harder to digest.
“Clearly, the same amount of protein does not always mean the same nutritional availability,” said Asai.
They then tested the proteins on 24 mice, half of which were fed normally cooked soy and the other half overcooked soy over a span of six weeks.
“I wanted to know whether food processing changes these proteins’ absorption as well as their biological effects,” said Asai.
After six weeks, the researchers ran four behavioral tests to assess the mice’s anxiety, memory, and social behavior. The two groups performed similarly in three of the tests, suggesting that their anxiety and ability to recognise objects were unaffected.
The fourth test is where the two groups differed. In the test, a mouse is placed in the middle chamber of a three-chamber apparatus. Another mouse—which had grown familiar with the middle mouse from previous experiments—was placed in the left chamber, and a third, unfamiliar mouse was placed in the right.
The middle mouse was allowed to explore either chamber for 10 minutes. The researchers found that the overcooked-protein group spent less time in the right chamber compared with the normal group, indicating a reduced preference for social novelty.
This change could be connected to serotonin, a neurotransmitter involved in emotional regulation and social behavior. Although the overcooked-protein group showed normal levels of serotonin in their brains, their serotonin levels in their bodies were lower.
High heat may have created compounds that interfered with the regulation of serotonin in mice, the researchers said in the study. This could explain why they had lower social novelty behavior while their anxiety levels remained unaffected.
Since the study was performed only on mice, further research is needed to verify whether overcooked proteins do affect social behavior. The team now plans to determine exactly how the proteins are modified by high temperatures and to investigate how these proteins are metabolized by an organism.
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Source: Kyoto University ; Image: topntp26/Magnific
The study can be found at: High-temperature-treated soy protein isolate reduces amino acid availability and alters social novelty in mice
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