.jpg)
Image Credits: Mark Yuill/shutterstock.com
Thermal analysis is an essential process for characterizing raw materials and finished goods in the food production industry.
Most foods are exposed to shifts in their temperature during production, storage, transport, cooking, and consumption. Temperature variations cause changes in the physical and chemical qualities of food components, which has an impact on the overall qualities of the final product.
Seeing how temperature impacts various food materials allows food manufacturers to optimize production methods, product quality, and transportation methods. Therefore, it is critical for food scientists to have analytical methods to monitor the transformations that take place in foods when their temperature changes.
Moreover, food products are directly tied to public health issues. For that reason, various international or national guidelines exist which dictate the various processes for quality control of food products.
Essential Temperature-Dependent Qualities of Food Materials
While there are a number of food qualities related to temperature, the most essential, temperature-dependent qualities are density, phase transition and gelation.
Materials that do not undergo phase transitions typically become less dense as temperature rises. This is due to the atoms in the material moving more vigorously when they acquire thermal energy, causing the space between molecules to increase. The temperature-dependent density of a food material is often utilized by engineers to create processes or devices, like containers for transporting materials. In materials that go through phase transitions have a temperature-dependent variation in density that is more dramatic.
Referring to when a material goes from one physical state to another, phase transitions in the food industry includes melting, crystallization and evaporation. The overall qualities of foods may be dramatically transformed when major components go through phase transitions. Analytical tools can track phase transitions by assessing the qualities of a material, like density and rheology, through a phase transition.
Many foods have components that form a gel when the food is heated or cooled under particular conditions. The physical qualities of gels, like appearance and stability, depend on the type, construction, and interactions of gelatine molecules, or water particles they entrap. Formed by heating or cooling, gels may be either thermo-reversible or thermo-irreversible. Gelatine is a type of cold-setting, thermo-reversible gel, while egg-white is a heat-setting thermo-irreversible gel.
For products that form a gel, it is crucial to understand the temperature at which gelation occurs, the gelation rate, and the character of the gel that is established. Thus, thermal analytical tactics are needed by food scientists to assess these properties.
Analytical Techniques
There are five primary techniques used to perform thermal analysis in the food industry, thermogravimetry, dilatometry, rheological thermal analysis, differential thermal analysis (DTA) and differential scanning calorimetry (DSC).
Thermogravimetric techniques continually assess the mass of a sample as it is heated or cooled at a regulated rate or is held at a selected temperature for a set length of time. Thermogravimetry is useful for tracking processes that involve a shift in the mass of a food material, and applications typically involve evaporation, desorption and vaporization behavior, as well as thermal stability, decomposition, and compositional investigation.
A dilatometer measures the change in density of a material based on time or temperature. Dilatometry measurements are commonly used for tracking the crystallization and melting of fats in foods.
Rheological techniques for thermal analyses assess the shift in the rheological qualities of a sample based on temperature. These solutions tend to be used to track the temperature-dependent rheological qualities of liquids, gels, and solids, and are utilized by food researchers to design foods with desired qualities or to optimize processes.
DTA is a process for establishing the gap in temperature between a test substance and a reference material versus time or temperature as the two specimens are exposed to an environment that is heated or cooled at a manipulated rate. The dynamics of these reactions over the course of the investigation provides data about the kind of transition(s) taking place.
DSC is a method for documenting the energy needed to keep a zero-temperature difference between a test sample and a reference cell which are either heated or cooled at a set rate. The most useful things that can be examined by DSC are melting point, melting range and melting behaviou. DSC is used to figure out qualities such as heat of fusion, purity and oxidation stability.
Disclaimer: The views expressed here are those of the author expressed in their private capacity and do not necessarily represent the views of AZoM.com Limited T/A AZoNetwork the owner and operator of this website. This disclaimer forms part of the Terms and conditions of use of this website.