How is plant protein peptide produced?

Beyond Biopharma | Plant Protein Peptide FAQ

Short answer: Plant protein peptide is produced by controlled enzymatic hydrolysis. A plant protein isolate is dispersed in water, a food-grade protease is dosed under a set pH, temperature and time, and the reaction is stopped once the target degree of hydrolysis is reached. The liquor is then clarified, refined for colour and taste where needed, concentrated and spray dried into a powder that is specified by degree of hydrolysis and molecular weight distribution.

Step 1: preparing the protein feedstock

The process begins with a plant protein isolate, or in some cases a concentrate. Feedstock quality decides a large part of the final result: residual oil, fibre, starch, phytate and pigment all carry through into the peptide and show up later as haze, colour, off-notes or ash. The isolate is dispersed in water at a controlled solids level so that the enzyme has consistent access to the substrate, and the slurry is brought to the pH and temperature the chosen enzyme needs.

Step 2: choosing the enzyme system

Hydrolysis is carried out with food-grade proteases, usually a defined enzyme preparation rather than a single purified enzyme. Endopeptidases cut bonds inside the protein chain and lower molecular weight quickly; exopeptidases work from the chain ends and strip terminal amino acids, which is a common way to reduce bitterness. Blends are used to reach a target molecular weight distribution while keeping the taste acceptable, and the enzyme preparation, its activity and its carrier all have to be declared and controlled like any other processing aid.

Step 3: controlling the reaction

pH, temperature, enzyme-to-substrate ratio and time are the four levers. Temperature and pH are held at the optimum of the chosen preparation, and the enzyme dose and reaction time set how far the hydrolysis goes. Progress is followed in process, often by keeping pH constant with a base and converting the base consumed into a degree of hydrolysis value, and the batch is stopped at the target rather than at a fixed clock time.

Step 4: stopping the reaction and removing solids

The reaction is ended by heating to inactivate the enzyme, and in some processes by shifting the pH. Insoluble material is then removed by centrifugation, filtration or a combination of the two, because any solids left in the liquor will appear as sediment in the finished powder. This step is also where the process decides how clean the peptide solution will be in a clear beverage.

Step 5: refining colour, odour and taste

Many plant peptides are treated further before drying. Adsorbents and activated carbon reduce colour and some bitter and beany notes, membrane filtration such as ultrafiltration separates molecular weight fractions and removes salts, and a controlled heat or vacuum step can strip volatile off-notes. Debittering is a design decision: it raises cost and can shift the molecular weight profile, so it should be specified against a sensory target rather than applied by default.

Step 6: concentrating and drying

The refined liquor is concentrated by evaporation or reverse osmosis to a practical solids level and then spray dried. Inlet and outlet temperatures, feed rate and atomisation set the particle size, bulk density and reconstitution behaviour of the powder. A well run dryer gives a free-flowing powder that dissolves without lumps; a poorly run one gives fine dust, caking or slow wetting.

Enzymatic versus acid hydrolysis

Enzymatic hydrolysis is the standard route for food peptides because it works under mild conditions, keeps the amino acid composition largely intact and allows the degree of hydrolysis to be tuned. Acid hydrolysis is harsher: it needs strong acid and heat, generates a high salt load when neutralised, and can destroy or convert some amino acids, so it is used for specific technical hydrolysates rather than for products where taste and nutrition both matter.

What the process controls, and what it does not

Hydrolysis changes chain length, not the amino acid composition of the source, so the protein quality of the feedstock is largely carried through into the peptide. What the process does control is solubility, clarity, viscosity, thermal behaviour, colour, ash and bitterness. Every batch is normally released against a certificate of analysis covering protein content with the nitrogen conversion factor stated, degree of hydrolysis, molecular weight distribution, solubility, pH, moisture, ash, heavy metals, microbiological limits and the allergen statement. Acceptable ranges and methods should always be confirmed against the supplier certificate and current applicable regulations.

Related reading

See what degree of hydrolysis means, the molecular weight range of plant peptides and how peptide, hydrolysate and isolate differ.