Lyophilization assay

Freeze-drying, also known as sublimation drying, is a gentle dehydration method performed under vacuum and at low temperatures. It removes the water contained in a sample without altering its heat-sensitive components. This technique relies on pre-freezing the product, followed by direct sublimation of the ice into water vapor, thus bypassing the liquefaction step.
In the laboratory, freeze-drying assays are mainly used to determine the free water fraction and assess the dry matter content of a product. These parameters are essential to ensure the stability, preservation, and quality of formulations, particularly when dealing with matrices sensitive to heat or humidity.

How the method works

The analytical process begins with rapid freezing of the sample , in order to freeze the molecular structure and prevent the degradation of volatile compounds. Then, the sample is placed under vacuum in a freeze dryer: the reduced pressure allows the water to pass directly from the solid state to the gaseous state.
Drying takes place in two stages:

1. Primary drying : removal of ice by sublimation.
2. Secondary drying : removal of residual water bound to the matrix, in order to obtain a perfectly dry product.
   The results of the dosage make it possible to precisely quantify the total water content and to calculate the dry matter . These data are decisive for quality control and the formulation of food, nutraceutical or phytotherapeutic products.

To complete this analysis, it is often recommended to carry out a humidity determination by thermogravimetry (ATG) , allowing the freeze-drying results to be validated by a complementary method.

Technical characteristics

Freeze-drying has several advantages:

• Preservation of active compounds : low temperatures prevent the denaturation of proteins, enzymes, vitamins or probiotics.
• Non-destructive method : samples retain their structure and properties after analysis.
• High analytical accuracy : measurement of mass before and after drying allows for rigorous assessment of humidity and dry matter.
• Adaptability : The method is suitable for a wide range of products, including complex or fragile matrices.

The equipment used for this type of analysis includes freeze dryers with automatic pressure and temperature control, ensuring the reproducibility and traceability of results.

For a complete thermal characterization, freeze-drying can be combined with tests such as differential scanning calorimetry (DSC) or dynamic mechanical analysis (DMA) , in order to study the stability and phase transition of materials.

Industrial applications of freeze-drying dosage

Freeze-drying is a benchmark method in many industrial sectors.

• Human food : it allows the dry matter content of powders, purees, extracts, dairy products or freeze-dried dishes to be assessed.
• Nutraceuticals and dietary supplements : used to control the stability of plant extracts, vitamins, probiotics and encapsulated formulations.
• Animal nutrition : dry matter dosage is essential for adjusting feed formulation, measuring digestibility and ensuring batch consistency.
• Plants and botanical products : freeze-drying preserves the active ingredients (polyphenols, flavonoids, alkaloids, etc.) and allows the extracts to be standardized before incorporation into finished products.

For plant matrices, it can be coupled with complementary analyses such as the determination of total polyphenols or the determination of flavonoids in order to ensure the quality and conformity of the extracts.

Analytical advantages for quality control

Controlling water content is a critical parameter for microbiological stability , shelf life and sensory quality of products. Excess moisture can promote microbial growth, alter organoleptic properties or cause the degradation of active compounds.
Thanks to freeze-drying assays, manufacturers obtain an accurate assessment of dry matter, allowing them to validate batch conformity, optimize storage conditions and ensure consistency of formulations.

As part of a comprehensive quality control approach, freeze-drying can be integrated into a set of complementary tests such as measuring water activity (Aw) or determining the particle size of powders . These analyses provide a complete overview of the product's physical properties and its stability over time.

YesWeLab services and scientific support

YesWeLab collaborates with a vast network of partner laboratories, selected according to strict criteria of quality, competence and certification (ISO 17025, COFRAC, etc.). Each request is analyzed according to the matrix , the analytical technique and the specific requirements of the client.
Our scientific team provides personalized support at each stage, from the definition of the need to the delivery of the results. In the event of particular specificities (drying temperature, type of matrix, target water content), we adapt the method accordingly.
Since 2020, YesWeLab has provided manufacturers, distributors and design offices with a digital platform for managing their analyses: request for quotes, sample tracking and receipt of reports online.

For any specific request or to obtain a quote, contact our team now to benefit from expert support for your freeze-drying and dry matter analyses.