Oat starch can produce a thick paste during heating. Alpha-amylase helps convert that starch into shorter carbohydrates so an oat base can be mixed, pumped and processed more easily. The target is controlled liquefaction with the required mouthfeel, rather than the maximum possible starch breakdown.
What alpha-amylase does
Alpha-amylase cleaves internal alpha-1,4 linkages in starch, producing a mixture of dextrins and shorter sugars. It is principally a viscosity-control enzyme in this process. It does not selectively turn all starch into glucose, and it does not replace the protein-modifying action of protein glutaminase.
Which Scientific & Technical product should I choose?
- Medium-temperature alpha-amylase: the current product listing specifies at least 2,300 FAU/g, a 15–65°C operating range and pH 3.5–8.0. Cook the oat slurry separately if required, then cool before adding this grade. Do not expose it to a high-temperature cooking stage and assume it remains active.
- High-temperature alpha-amylase: the current listing specifies 30,000 U/mL, a 15–99°C range and pH 3.5–10.0. It is the more appropriate grade to investigate when liquefaction must overlap with hotter processing. Confirm activity and stability at the actual hold temperature and duration.
- FAU/g and U/mL describe different assays and concentration bases. These products must not be substituted at equal volume or by comparing their numerical activities directly. The high-temperature product's stated assay uses soluble starch at pH 6.0 and 70°C.
A practical bench-development workflow
- Prepare identical oat slurries from one oat lot. As an illustrative screening formulation, use 100 g oats plus 900 g water for 1 kg slurry; this is 10% oats by mass, not 10% measured dry solids. Record oat moisture and composition.
- Disperse thoroughly and establish a cooking profile that gelatinises the starch without scorching. Oat variety, particle size and previous heat treatment influence this step. Check for residual starch rather than treating one cooking time as universal.
- For the medium-temperature grade, a proposed initial screen is 55–60°C after cooking. For the high-temperature grade, investigate 70–80°C where equipment and starch preparation allow. These are development settings within the listed ranges, not proven oat-milk optima.
- Measure slurry pH. A proposed starting screen around pH 6.0–6.5 avoids unnecessary large pH changes; confirm suitability using the current product technical data sheet and actual oat base.
- Obtain a starting dose for the selected grade from Scientific & Technical, then compare an untreated control with 0.5×, 1× and 2× that dose. Sample at 15, 30 and 60 minutes using identical mixing.
- Stop activity in each analytical sample with a validated method. Measure viscosity after cooling all samples to the same test temperature, and compare the finished beverage after the intended thermal process.
Calculate the dose on a defined basis
Record enzyme addition as g product/kg dry oats or mL product/kg dry oats, together with activity and assay definition. If a tested dose is d mL/kg dry oats and the batch contains M kg dry oats, the addition is d × M mL. For example, a hypothetical selected dose of 1 mL/kg requires 100 mL for 100 kg dry oats; this illustrates arithmetic, not a recommended dose.
Troubleshooting
- Still too thick: check gelatinisation, dispersion, enzyme survival and mixing before increasing dosage. Persistent viscosity may also arise from oat beta-glucan or other components.
- Too thin after processing: shorten the hold or reduce dose, and check whether residual amylase continued to act during heating or storage.
- Little sweetness despite a strong viscosity decrease: this can be a normal liquefaction result. Choose beta-amylase for maltose production or controlled glucoamylase treatment for glucose, according to the required sugar profile.
- Concern about beta-glucan retention: do not infer preservation from the name alpha-amylase. Check side activities and measure beta-glucan properties where they are part of the product specification.
How the four enzymes fit together
Alpha-amylase shortens starch chains to control viscosity. Beta-amylase releases maltose from accessible chain ends. Glucoamylase releases glucose and can further hydrolyse maltose. Protein glutaminase modifies protein-bound glutamine to improve protein functionality. Select the sugar-producing enzymes according to the desired maltose/glucose profile; all four are not mandatory in every recipe.
A development sequence is: disperse oats in water; cook and liquefy starch with a suitable alpha-amylase; cool and adjust pH for beta-amylase when a maltose-rich profile is wanted; use glucoamylase only where additional glucose formation is intended; establish compatible conditions for protein glutaminase; stop enzyme activity using a validated process; separate coarse solids as required; formulate, homogenise and apply the validated final preservation process. Compare protein treatment before and after separation if protein recovery matters.
For a maltose-led formulation, start with alpha-amylase plus beta-amylase and compare it with alpha-amylase alone. For a glucose-led formulation, evaluate alpha-amylase plus glucoamylase. If both saccharifying enzymes are used, measure both sugars: adding glucoamylase can shift the balance away from maltose. Protein glutaminase addresses protein functionality in either route.
Do not assume one temperature and pH suit all four enzymes. The listed beta-amylase pH range ends at 6.0, whereas the protein-glutaminase optimum is 6.0–7.0. Establish sequential stages first and adjust pH where needed. A nominal overlap does not prove efficient simultaneous operation.
Finishing and quality checks
Enzyme treatment is one part of beverage manufacture. Filtration or centrifugation, oil addition, mineral salts, homogenisation and the final heat treatment can all change the result. Test the finished formulation, including any calcium fortification, rather than judging the enzyme-treated slurry alone.
Measure viscosity at a defined temperature and shear condition, solids, glucose or sugar profile, protein recovery, sedimentation and sensory properties. For a barista product, also test steaming, foam drainage and stability in the intended coffee. Record the actual heating and cooling profile, not only the vessel set point.
Confirm residual enzyme activity after the stopping step. Enzyme inactivation and microbiological preservation are separate validation requirements; the trial holding conditions in this guide are not a pasteurisation, UHT or shelf-life specification. Avoid enzyme dust and aerosols and follow each product's safety data sheet.
Evidence and scope
Published oat-milk work has evaluated alpha-amylase alone and with other processing treatments, with different effects on composition and sensory properties. Those findings support application testing; they do not validate the example settings above for these commercial preparations.
Babolanimogadam et al. (2023): effects of alpha-amylase and other treatments on oat milk
View medium-temperature alpha-amylase
View high-temperature alpha-amylase
Beta-Amylase for Oat Milk: Maltose Production and Sweetness Control
Glucoamylase for Oat Milk: Controlled Sweetness and Saccharification
Protein Glutaminase for Oat Milk: Protein Solubility and Functionality
Process development and supply
Contact Scientific & Technical with your oat loading, batch size, enzyme grades, temperature and pH profile, target sweetness and protein specification. These details allow a trial dose and scale-up plan to be matched to your process.
Discuss your oat-milk application
