Scientists Identify Yeast RNA That Can Induce and Control Beer Haze

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Beer turbidity, a characteristic highly valued in certain styles such as NEIPA or wheat beers, has traditionally been attributed to colloidal particles such as grain proteins, hop polymers, and small suspended particles.

But a new Danish study led by Esben Due Yding, titled Yeast RNA–protein interactions generate beer haze, introduces an unexpected factor: the use of yeast RNA extracts to induce significant turbidity in crystal-clear lager beers.

Key Findings of the Study

The researchers took two European crystal-clear lager brands and added RNA-rich extracts derived from yeast cells, successfully triggering extreme turbidity in both beers.

The resulting haze was caused by the interaction of RNA with a specific protein called protein Z present in beer; the turbid particles measured approximately 1 micrometer in diameter.

When the turbidity was treated with ribonuclease (an enzyme that breaks down RNA), the haze disappeared, demonstrating that intact RNA strands are essential in this case for haze formation.

Variations in pH and ionic strength of the medium also affected the haze: increasing ionic strength (for example, by adding salt) reduced turbidity; additionally, as the pH approached the isoelectric point of protein Z, turbidity also decreased.

This suggests that the haze is mediated by electrostatic interactions between RNA and protein Z.

Relevance for Beer Production

Taken together, these results broaden the understanding of haze mechanisms in beer, suggesting that not only grain and hop components are involved, but that residual genetic material from yeast may also play a role.

1. Greater Control Over Appearance

For breweries producing “hazy” styles, this pathway allows modulating turbidity by controllably adding RNA extracts or adjusting their residual presence.

2. A New Variable to Consider

In processes where clarity is desired (for example, in crystal-clear lagers) and where filtration or clarification is performed, this factor can cause unexpected turbidity if RNA residues remain in the yeast system.

3. In Tune with Market Trends

Although many traditional lagers favor transparency, the rise of hazy styles has opened the door to new controlled “hazy lager” varieties enabled by new tools such as RNA.

Practical Implications and Considerations

When preparing yeast or using recirculation processes, it is advisable to monitor RNA release into the medium (for example, during partial autolysis). Avoiding excessive cell rupture that releases RNA could reduce unwanted turbidity.

In systems where enzyme addition is permitted, food-grade ribonucleases could be explored to degrade residual RNA and minimize unwanted haze.

pH adjustments during cold crash or clarification stages, as well as control of ionic content (salts, calcium, magnesium), can modulate the strength of interaction between RNA and protein Z, altering haze formation.

The study showed that the same dose of RNA generated different levels of turbidity in two lager brands. This indicates that the protein background or wort compounds influence the magnitude of the effect, so each brewery will need to calibrate its additions.

It is important to analyze not only the immediate haze, but also its stability over time: is the generated turbidity stable for months? Does it settle over time or does it remain colloidal?

Latent Risks and Challenges

• If RNA is used deliberately, it must be ensured that it does not affect microbiological stability (RNA is not direct nutrition, but residues could alter microflora under extreme conditions).
• Partial degradation of RNA can produce small particles that do not form appreciable turbidity, but could influence flavor or other technical parameters.
• From a regulatory or sensory standpoint, any addition (even of yeast extracts) must be evaluated to ensure it does not introduce unwanted flavors or side effects.

Main Conclusions

The Danish study revealing that yeast RNA extracts can induce extreme turbidity in lager-type beers represents a significant advance in understanding haze formation in beer.

It not only expands the range of possible mechanisms beyond grain proteins and plant polymers, but also opens new tools for brewers to control the appearance of their products.

For the brewing industry, this implies a new variable to monitor (the presence of residual RNA), the possibility of using enzymes to degrade it or modulate its effect through pH and ion control, and the opportunity to experiment with hybrid styles (for example, “hazy lager”).

Of course, further study across different styles, mashing conditions, yeast strains, and conditioning times will be needed to measure the practical efficacy and stability of RNA-induced haze.

References

Yding, E. D., Caille, O., Gosselin, Y., & Andersen, M. L. (2025). Yeast RNA–protein interactions generate beer haze. Journal of Agricultural and Food Chemistry, 73(30), 18953–18959. https://doi.org/10.1021/acs.jafc.5c03980

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