Alkaline phosphatase activity (ALP, ALP) assay

Alkaline phosphatase (ALP or PAL) is a key enzyme found in many tissues and biological environments. It catalyzes the dephosphorylation of various molecules and is a major indicator of enzyme integrity, thermal denaturation, and residual biological activity. In industry, measuring alkaline phosphatase, PAL, and ALP activity is particularly strategic for assessing the quality of food products, the efficiency of thermal processes, and the enzyme stability of nutritional formulations.

In the animal nutrition sector, PAL activity is used to control the quality of raw materials or enzymatic additives, verify the proper thermal inactivation of sensitive ingredients, or monitor the stability of functional enzymes. For dairy products, it is also a historical marker used to verify the correct execution of heat treatments such as pasteurization. Excessive residual activity can indicate either poor process control or recontamination.

Analytical methods for measuring PAL/ALP activity

The choice of method depends on the matrix, the desired level of sensitivity, and the industrial objective. The main techniques available are:

• PNPP (p-nitrophenyl phosphate) colorimetric method for measuring enzymatic activity via the release of p-nitrophenol, detected spectrophotometrically
• ELISA for specific enzyme detection, often used in complex extracts or enriched matrices
• Fluorimetry for highly sensitive activity measurements, particularly suited to low residual levels after pasteurization or heat treatment
• UV-visible spectrophotometry to monitor the kinetic evolution of the enzymatic reaction

The analysis conditions (alkaline pH, temperature, substrate) are rigorously controlled in order to obtain a reproducible measurement that is representative of the actual enzymatic activity.

Commonly analyzed matrices

Alkaline phosphatase activity can be measured in a wide variety of matrices, including:

• pasteurized or UHT dairy products
• Animal feed and nutritional premixes
• enzymatic extracts or functional ingredients
• processed plant matrices
• biological extracts not intended for human use
• powders, fermented liquids or products enriched with enzymes

Depending on the matrix, preliminary steps may be necessary: ​​filtration, extraction, dilution, enzymatic stabilization or removal of inhibitors.

Industrial applications of PAL/ALP dosing

Pasteurization and heating control
: PAL is a historical biomarker used to verify the proper execution of heat treatments. Residual activity indicates a process defect or subsequent contamination.

Enzyme formulations and nutritional additives
Measurement of actual enzyme activity, stability control during storage, batch comparison, dose optimization or evaluation of encapsulated enzymes.

Animal nutrition:
Evaluation of the quality of raw materials, control of thermal processes applied to flours, monitoring of enzymatic bioavailability in formulations intended for different animal species.

Research and development
: Monitoring of enzyme kinetics, optimization of inactivation processes, functional characterization of innovative ingredients.

Additional analyses are available in the YesWeLab catalog.

For a complete understanding of enzymatic or protein quality, the following analyses may be relevant:

• total protein assay (Kjeldahl, Dumas)
• analysis of peroxidase activity
• lactoperoxidase activity
• amino acid profile

Why entrust your PAL/ALP analysis to YesWeLab

YesWeLab selects the most suitable laboratory for you based on your matrix, the desired method, and your specific requirements (sensitivity, turnaround time, standards). Our partners are audited for their technical expertise and mastery of enzymatic methods, particularly ELISA, fluorimetry, and spectrophotometry. Most of them hold recognized accreditations (ISO 17025, COFRAC).

Our digital platform allows you to centralize all your analysis requests, track your samples, and easily receive your results. Our scientific team also assists you in selecting the appropriate method, interpreting results, and defining an analytical plan tailored to your industrial objectives.