Dosage by freeze-drying

Freeze-drying, also known as sublimation drying, is a gentle dehydration method performed under vacuum and at low temperature. It allows for the removal of water from 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 is primarily used to determine the free water fraction and evaluate the dry matter content of a product. These parameters are essential for ensuring 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 the rapid freezing of the sample to freeze its molecular structure and prevent the degradation of volatile compounds. Next, the sample is placed under vacuum in a freeze dryer: the reduced pressure allows the water to transition directly from a solid to a 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 to obtain a perfectly dry product.
   The results of the analysis allow for precise quantification of the total water content and calculation of the dry matter . This data is crucial for quality control and the formulation of food, nutraceutical, or phytotherapeutic products.

To complement this analysis, it is often recommended to perform a moisture measurement by thermogravimetry (TGA) , allowing the freeze-drying results to be validated by a complementary method.

Technical specifications

Freeze-drying offers several advantages:

• Preservation of active compounds : low temperatures prevent the denaturation of proteins, enzymes, vitamins or probiotics.
• Non-destructive method : the samples retain their structure and properties after analysis.
• High analytical accuracy : measuring mass before and after drying allows for a rigorous assessment of moisture 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 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) to study the stability and phase transition of materials.

Industrial applications of freeze-drying dosing

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

• Human food : it allows the evaluation of the dry matter content of powders, purees, extracts, dairy products or freeze-dried meals.
• Nutraceuticals and food supplements : used to control the stability of plant extracts, vitamins, probiotics and encapsulated formulations.
• Animal nutrition : dry matter content 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 moisture content is a critical parameter for the 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.
Freeze-drying allows manufacturers to accurately assess dry matter content, enabling them to validate batch conformity, optimize storage conditions, and ensure consistent formulations.

As part of a comprehensive quality control approach, freeze-drying can be integrated with a range of complementary tests such as water activity (Aw) measurement or powder particle size determination . These analyses provide a complete picture 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 based on the matrix , the analytical technique , and specific requirements .
Our scientific team provides personalized support at every stage, from defining the need to delivering the results. In the case of specific requirements (drying temperature, matrix type, target moisture content), we adapt the method accordingly.
Since 2020, YesWeLab has offered manufacturers, distributors, and engineering firms a digital platform for managing their analyses: requesting quotes, tracking samples, and receiving 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.