The Application of Infrared Technology in the Food Industry
   

Infrared technology (within the electromagnetic wave range of 0.72 to 1000μm) has gradually been applied in military and civilian research fields such as aerospace, aviation, remote sensing, industrial inspection, food, chemical engineering, and the oil industry. People rationally select applications for other concerned fields based on the different spectral bands of infrared spectra, as there is no clear division of the infrared spectrum; the division varies in different research fields. We have introduced it into the food industry, and it has become a habit to do so.***Near-infrared (0.72~3μm) is used for rapid detection, such as moisture content and protein content measurement; mid-infrared (3~40μm) is widely applied for counterfeit detection; far-infrared (40~1000μm) is primarily used for heating and drying, like curing tobacco and dehydrating fruits and vegetables; high infrared (0.76~3) is generally used for heating.***The microwave oven is a classic example of high infrared applications.

I. Principle

2.1 Near-Infrared Detection Principle

Near-infrared spectroscopy is a type of frequency-doubled and fundamental frequency absorption spectrum within the molecular vibration spectrum, primarily absorbing hydrogen-containing groups. It encompasses information about the composition and molecular structure of most organic compounds. Due to the varied genetic makeup of different organic compounds and the differing energy levels of various groups, different groups and the same group in different chemical environments exhibit distinct absorption wavelengths for near-infrared light. With low absorption coefficients and minimal heat generation, near-infrared spectroscopy serves as an effective carrier for information acquisition. When exposed to near-infrared light, light of the same frequency as the groups resonates, transferring energy to the molecules through changes in molecular dipole moments. However, since the frequency of near-infrared light differs from the sample's vibrational frequency, this infrared light is not absorbed. Therefore, when a sample is irradiated with near-infrared light of continuously changing frequencies, the transmitted near-infrared light becomes weaker in certain wavelength ranges and stronger in others due to the selective absorption of the sample to different frequencies of near-infrared light. The transmitted infrared light then carries information about the organic components and structure. By analyzing the light density of the transmitted or reflected light with a detector, the content of the component can be determined. This method of detection, which uses transmitted light to carry information, is known as near-infrared transmission detection.

Due to the ability of near-infrared technology to quickly and accurately test samples, near-infrared devices can be installed on production lines to continuously monitor raw materials, finished products, and semi-finished goods in real-time during production. This facilitates the timely detection of quality changes in materials and products, enabling prompt adjustments to maintain product quality stability.

2.2 Principle of Far-Infrared Drying and Sterilization

Due to its spectrum being situated between visible light and infrared, infrared radiation possesses both light and wave properties, propagating straight through space at the speed of light. It can reflect, transmit, and absorb on the surface of objects, with no medium heat loss. It undergoes qualitative changes with variations in wavelength.***Its penetration and thermal effects are demonstrated. The inherent motion frequency (vibration or rotation) of water and its molecular or group, converted to wavelengths, is approximately in the 2.5~200μm band, matching the frequency of far infrared rays. Far infrared rays can penetrate into the tiny gaps between particles within food, triggering changes in the internal energy levels of molecules, causing an intensification of molecular movement and internal heating, leading to a sharp increase in temperature. At the same time, the liquid water within the food follows the direction of the temperature gradient from inside to outside and is consistent with the humidity gradient direction, with the thermal diffusion of water within the food and the evaporation of surface moisture all occurring in a positive direction.***Status, thus***The drying process was accelerated, reducing the drying time. Additionally, the moisture content in the wet food was...***Upon exposure to infrared radiation, changes become solidified, metabolic disorders occur, and activity disappears.***The synergistic effect of the aforementioned functions has been achieved.***Energy-efficient, sterilization, and drying process.

2.3 High Infrared Heating Principle

Lately,***Infrared radiation heating technology has extended to shorter wavelengths, and the term "high infrared" can also be found in magazines, referring to "high density infrared radiation heating" (high density infrared), commonly known as high infrared.

We can describe high infrared technology as follows:

Utilized high-frequency (short-wave) infrared radiation heating lamps.

2. Utilized a high-density heating layout;

3. Utilizing high-intensity radiant heating methods.

The shorter the infrared wavelength, the more easily it is absorbed by closely packed molecules to produce heat. During the drying and curing process of organic coatings, metals tend to absorb short-wave infrared radiation, while organic coatings are transparent to short-wave infrared radiation. Therefore, the high infrared tube's 0.76~3μm wavelength energy transmits through air and coatings, directly heating the metal workpieces. The inner surface of the coating first gels and solidifies, while the moisture and air from the inner layer are pushed out to the outer surface of the coating. Although the metal temperature***At 400°C, the surface of the organic coating does not form a skin first.***Enhanced Heating Efficiency

Section II: Practical Applications of Infrared Technology in the Food Industry

3.1 Application of Near-Infrared Technology in the Food Industry

3.1.1 Characteristics of near-infrared technology

No pre-treatment, no pollution, convenient and quick.

Near-infrared light possesses strong penetrating power. It can directly detect samples without any pre-treatment, piercing through glass and plastic packaging, and does not require any chemical reagents. Compared to conventional analytical methods, it does not pollute the environment and can save a substantial amount of reagent costs. Near-infrared instruments have short measurement times, completing the detection in minutes or seconds and printing out the results.

2. Non-destructive

Non-destructive testing is a significant advantage of near-infrared technology. Leveraging this advantage, near-infrared technology can be used for non-destructive inspection of fruit and vegetable raw materials and finished products. Installing near-infrared devices in fruit and vegetable storage facilities enables automatic detection of produce, saving a substantial amount of labor and resources.

3. Online Inspection

Due to the rapid detection capabilities of near-infrared technology, it is feasible to install near-infrared devices on the production line for continuous online monitoring of raw materials, finished products, and semi-finished goods. This facilitates timely detection of quality changes in raw materials and products, allowing for prompt adjustments to maintain product quality stability. The development and application of fiber optic cables and optical probes make long-distance detection a reality. Moreover, long-distance detection technology...***Applicable for Pollution***The application in environments detrimental to both humans and instruments, such as high pressure and high temperature, has laid a foundation for the development of near-infrared networking technology.

4. Multi-component simultaneous detection

Multi-component simultaneous detection is a major reason for the widespread adoption of near-infrared technology. Under the same mode, multiple components can be measured simultaneously, such as in the wheat measurement mode, where protein content, moisture content, hardness, sedimentation value, and rapid mixing ratio can all be determined at once.***Simplified the measurement operation. Different components have an impact on the measurement results, as other components also absorb near-infrared light during the measurement process.

3.1.2 Application of Near-Infrared Technology in the Food Industry

Research on near-infrared technology began in 1930. In the 1950s, Curcio and Petty utilized near-infrared projection spectroscopy on "opaque" bodies to determine their transmission rates, initiating research on moisture detection. However, non-destructive and non-damaging moisture testing in most food and agricultural products was challenging for near-infrared. In the early 1960s, Norris and Buller applied near-infrared reflectance spectroscopy to analyze the moisture content of grain crops, marking a new chapter in the application research of this technology in the fields of agricultural products and their processing, and the food industry. Since then, examples and methods of near-infrared technology applications in food and agricultural product processing have been continually proposed, primarily used in engineering for food component analysis, quality testing, and on-line quality testing and control. Quality testing and on-line detection and control are often based on component analysis. Conventional chemical analysis boasts high accuracy and...***Sex, and it also forms the basis for many modern instrumental analysis techniques. However, whether it's chemical analysis or instrumental analysis, the time-consuming nature of sample pretreatment, the experiments themselves, and the destructive nature to materials are often not permissible in many situations. For example: wheat and rapeseed are stored and transported based on quality, and it takes 2 hours to determine the protein content in wheat using standard chemical analysis, 18 hours for the oil content in rapeseed, and approximately two days for the lysine content. Meanwhile, the unloading time for trucks is only 5 minutes. After arrival, the quality is identified through chemical analysis, and then stored based on quality, which requires a long waiting period, inevitably affecting the entire operational process.

Near-infrared technology can provide timely feedback with its speed, accuracy, and real-time nature, thus filling this gap and is increasingly favored by industry researchers.***。