Brewing flavour control

ALDC in Brewing: Preventing Diacetyl Before It Forms

Use ALDC to prevent diacetyl formation in brewing. Plan early addition, fermentation checks and total potential diacetyl measurements.

Prepared by Scientific & Technical Updated 23 September 2026
ALDC in Brewing: Preventing Diacetyl Before It Forms

Choose the right enzyme

FeedstockProcessing targetEnzyme to investigateWhat to measure
Early fermentationIntercept alpha-acetolactateSuitable ALDC gradePotential diacetyl
Diacetyl already presentAssess existing maturation needFermentation-quality investigationFree diacetyl
Two ALDC preparationsCompare formulation strengthGrade-specific dose basisConsistent flavour endpoint

These comparisons identify useful development endpoints; they are not universal dose or operating-condition recommendations.

Plan the process

  1. 1

    Plan early addition

    Establish the untreated fermentation’s diacetyl and precursor behaviour using the intended yeast.

  2. 2

    Compare grades

    Select a supplier-supported early addition point and compare the two ALDC formats on a justified basis.

  3. 3

    Measure diacetyl potential

    Measure free and total potential diacetyl at defined fermentation and maturation stages.

  4. 4

    Confirm finished flavour

    Confirm the release endpoint and repeat the treatment under normal process variation.

ALDC acts on alpha-acetolactate, a diacetyl precursor, and converts it towards acetoin. Its practical role is prevention: the process should give the enzyme access to the precursor before unwanted diacetyl forms.

Distinguish precursor conversion from diacetyl removal

ALDC is not a direct chemical eraser for diacetyl already present in beer. A late addition should not be expected to reverse an established flavour problem immediately. Record when the precursor is generated and how the chosen yeast and fermentation schedule behave. Preserve the normal fermentation-quality checks instead of assuming enzyme addition makes maturation assessment unnecessary.

Match the grade and addition point

The range includes a brewing formulation and a concentrated ALDC preparation. Confirm their activity, dose basis and thermal compatibility separately. Do not apply a generic hot-mash enzyme instruction without checking that it is appropriate for the supplied ALDC grade. Record actual contact time and temperature through the planned addition and fermentation sequence.

Measure both free and potential diacetyl

Use an appropriate validated method for the beverage and distinguish present diacetyl from precursor that can later contribute to it. A sensory check alone may miss a process risk or be confounded by other flavours. Compare untreated and treated fermentations through the intended release point, including yeast performance and other quality attributes. Select the treatment using the complete maturation result.

Troubleshooting

  • Diacetyl remains after late addition: distinguish existing diacetyl from remaining precursor.
  • No apparent benefit: check addition timing, thermal exposure and formulation activity.

Common questions

Does ALDC directly destroy existing diacetyl?

Its principal target is alpha-acetolactate, so prevention and correction of existing diacetyl are different tasks.

Can I skip the final flavour check?

No. Verify the actual finished-beer endpoint.

Evidence and scope

These are proposed development comparisons, not validated production recipes or guaranteed performance results. Use current grade-specific technical data for the starting dose and operating conditions. Record the enzyme lot and assay definition, and confirm performance in the finished process before scale-up.

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Process development and supply

Share your feedstock, batch size, temperature and pH profile, treatment time and target specification with Scientific & Technical. Select a relevant product below to see current pack sizes, price and availability, and buy online. For blends and kits, confirm the component selection and conditions against your intended application.

Follow each preparation’s technical and safety data sheets, including storage and handling instructions. Avoid generating enzyme dust or aerosols.

Recommended products

Choose the products that match your process. Each card explains its role in this application; you do not need every enzyme in one recipe.

Benefits are application targets; confirm dosage and performance in your finished formulation.

References and supporting evidence

Research and manufacturer examples support the application rationale; they do not establish identical performance for every commercial preparation.

  1. IUBMB enzyme nomenclature — EC 4.1.1.5

    Reaction classification supporting the mechanism discussed; a family example where applicable, not confirmation of the supplied preparation’s exact activity profile or process settings.

  2. Scientific & Technical — Brewer's alpha acetolactate decarboxylase (ALDC)

    Current product information; confirm the technical sheet, intended-use documentation and lot specification for the supplied preparation.

  3. Scientific & Technical — alpha acetolactate decarboxylase (ALDC)

    Current product information; confirm the technical sheet, intended-use documentation and lot specification for the supplied preparation.