Maintaining The Cold Chain For Preserving Products

Food is an essential of life. The food industry is a crucial sector for the balance of an economy, especially in our modern world. However, the production of food also impacts on our environment. Refrigeration plays an important role in retail stores to maintain the food at the required temperature, but in doing so, it significantly contributes to greenhouse gas emissions both directly and indirectly. It is used in all stages of the chain, from food processing, to distribution, retail and final consumption in the home. The food industry employs both chilling and freezing processes where the food is cooled from ambient to temperatures above 0°C in the former and between 18°C and 35°C in the latter to slow the physical, microbiological and chemical activities that cause deterioration in foods.

You deal with fresh, easily spoilt goods every day. The quality of the products must always be immaculate so that inferior goods are not brought into circulation. But how can you ensure that the environmental conditions at all relevant locations always fulfill the requirements? The use of advanced instrumentation and sensors in the food industry has led to continuing improvement in food quality control, safety, and process optimization. Measuring instruments and monitoring systems from Dpstar support you in these tasks. Dpstar is a leading provider of industrial measurement and instrumentation solutions for the food and beverage industries. We have over 30-years’ experience in providing reliable, high-quality instruments and can help you achieve efficiency and sustainability with accurate, high-precision control and monitoring equipment that complies with the strictest hygiene requirements.

The Purpose Of Refrigeration

Today‘s consumers place high demands on food quality. This begins with the optical appearance of the foods, whether vegetables, meat, and sausages, poultry, or dairy products. Everything needs to look fresh and appetizing, or it will not go into the shopping cart. In order to eliminate risk factors, food retailers must follow the HACCP concept. Among other things, this concept prescribes adherence to the cold chain. The purpose of refrigeration is to keep the temperature of the refrigerated goods at the designated level so as to slow down the rate of deterioration of perishable food or to keep cold beverages chilled. A refrigeration system utilises the evaporation and condensation of refrigerants to achieve the transfer of heat from the refrigerated space (low temperature) to a heat sink (high temperature), which is normally the air outside the building. Most of the energy consumption by refrigeration systems lies on refrigeration packs (racks of compressors) and is mainly influenced by two aspects: the amount of heat gained in cabinets and the rate of heat rejected at condensers. The first one is affected by the designated cabinet temperature requirement, the rate of product replacement, cabinet aisle temperature, and indoor humidity. The second one is dependent on the surface area of the condensers, the rate of airflow, and outdoor air temperature. Foods must be stored continuously at defined temperature limit values, typically at least -18 °C for deep-frozen goods and +4 °C to +8 °C in the refrigerated range. If refrigeration temperatures are not adhered to, leading to the sale of spoilt foods, there is a threat of considerable damage to the reputation. As there are several refrigerated sites in every supermarket, their monitoring and documentation involve a great deal of effort for the dealer.

What is CO2?

Carbon dioxide (CO2) is commonly regarded as the ideal natural refrigerant. It is a non-toxic, non-flammable, odourless, colourless gas, however, high concentrations can cause unconsciousness and even death, so accurate, reliable monitoring is necessary for safety reasons and for the rapid detection of potential leaks. It must be taken into account that CO2 cannot be detected through smell, therefore, as it is denser than air, it can displace oxygen to limits that are harmful to health. As it gives off no odour, it may be the case that, if there is a leak, the technician is not able to detect it. Such characteristics make it vital to pay special attention to leak detection, having an alarm system that can detect and warn in time of the presence of CO2 and having an emergency ventilation system. Furthermore, the high pressure of the gas when it leaks will cause an explosion, with splashes of refrigerant with residues in solid form at very low temperature at the speed of sound. CO2 should never be charged in liquid form when the system is at a lower pressure than the triple point (5.2 bar). If you were to do so, the liquid entering the system would suddenly change state, turning into dry ice and remaining in that state inside the system.

What is CO2?

Carbon dioxide (CO2) is commonly regarded as the ideal natural refrigerant. It is a non-toxic, non-flammable, odourless, colourless gas, however, high concentrations can cause unconsciousness and even death, so accurate, reliable monitoring is necessary for safety reasons and for the rapid detection of potential leaks. It must be taken into account that CO2 cannot be detected through smell, therefore, as it is denser than air, it can displace oxygen to limits that are harmful to health. As it gives off no odour, it may be the case that, if there is a leak, the technician is not able to detect it. Such characteristics make it vital to pay special attention to leak detection, having an alarm system that can detect and warn in time of the presence of CO2 and having an emergency ventilation system. Furthermore, the high pressure of the gas when it leaks will cause an explosion, with splashes of refrigerant with residues in solid form at very low temperature at the speed of sound. CO2 should never be charged in liquid form when the system is at a lower pressure than the triple point (5.2 bar). If you were to do so, the liquid entering the system would suddenly change state, turning into dry ice and remaining in that state inside the system.

Cold Storage Applications

Food ripening / maturing
Storage
Processing
Transportation
Packaging
Dry ice manufacturing

Refrigeration Processes Involved in Food Processing

01 Pre-cooling

Rapid cooling is necessary to retard the metabolism of food products and to increase their life span. The lesser the temperature is, the better the quality and longevity of the cuisines. Based on the type of the food product, different refrigeration techniques have been proposed.

02   Chilling

After precooling, the food product has to be chilled and maintained at the favourable temperature. The chilling and conservation temperatures depend on the sensitivity of the product for high-sensitivity products.

03  Freezing

Freezing is a process of lowering the temperature of a product below its solidification point. Freezing hinders the metabolism of the fruit and vegetable products. Longer the product remaining frozen, longer is its durability for storing.

04 Super-cooling 

These are new processes implemented for the storage of food products. Supercooling is lowering down the temperature of a food product just below its freezing point without any formation of ice.

Cold Storage Applications

Food ripening / maturing
Storage
Processing
Transportation
Packaging
Dry ice manufacturing

Refrigeration Processes Involved in Food Processing

01 Pre-cooling

Rapid cooling is necessary to retard the metabolism of food products and to increase their life span. The lesser the temperature is, the better the quality and longevity of the cuisines. Based on the type of the food product, different refrigeration techniques have been proposed.

02   Chilling

After precooling, the food product has to be chilled and maintained at the favourable temperature. The chilling and conservation temperatures depend on the sensitivity of the product for high-sensitivity products.

03  Freezing

Freezing is a process of lowering the temperature of a product below its solidification point. Freezing hinders the metabolism of the fruit and vegetable products. Longer the product remaining frozen, longer is its durability for storing.

04  Super-cooling 

These are new processes implemented for the storage of food products. Supercooling is lowering down the temperature of a food product just below its freezing point without any formation of ice.

Benefits of Reliable CO2 Measurements

Increasing Worker Safety

Maximizing Production

Optimizing Product Quality

Keep Food Fresh

Locating Leaks As Soon As Possible

Ensure Optimal Refrigerator Performance

Better Control Leads To More Predictable & Better Quality

Refrigerant Filling & Maintenance Cost Money

What Makes Vaisala’s CO2 Sensors Unique?

Vaisala uses a single-beam and dual-wavelength NDIR (Non-dispersive infrared) technology for measuring CO2. The patented CARBOCAP® technology is used in all its CO2 sensors. The CARBOCAP® sensor allows for measurement of both the CO2 absorption signal and a reference signal using a single set of components. Because of this, Vaisala is getting a real reference measurement in every measurement cycle. This eliminates the most common drift factors normally associated with all other NDIR sensors. The results of this breakthrough are excellent long-term stability, a long service life and the ability to function in the most demanding environments, including warm, humid, and dusty environments. This technology incorporates a unique tunable band pass filter that was developed by Vaisala and is manufactured in their own state-of-the-art cleanroom. Vaisala CARBOCAP® sensor technology is well suited to a wide range of applications, from ppm (parts per million) to percentage-level CO2 measurements. Since the final customer value for each industrial application is unique, it depends on the product line how the CARBOCAP® sensor technology is implemented.

The Vaisala CARBOCAP® carbon dioxide sensor uses IR sensing technology to measure the volumetric concentration of CO2. It features a unique electrically tunable Fabry-Perot Interferometer (FPI) filter for dual-wavelength measurement. This means that in addition to measuring CO2 absorption, the CARBOCAP® sensor also performs a reference measurement, which compensates for any changes in the light source intensity as well as for dirt accumulation and contamination. This makes the sensor extremely stable over time.

The Optical Infrared (IR) Measurement Technology

  • Infrared light is absorbed by different gases at a known light wavelength
  • A filter in front of the detector only passes light in the CO2 bandwith
  • The detector measures the intensity of the light and converts this into the CO2 concentration

Tunable Bandpass Filter

Carbon Dioxide and Safety

Carbon dioxide is a non-toxic and non-flammable gas. However, exposure to elevated concentrations can induce a risk to life. Whenever CO2 gas or dry ice is used, produced, shipped, or stored, CO2 concentration can rise to dangerously high levels. Because CO2 is odorless and colorless, leakages are impossible to detect, meaning proper sensors are needed to help ensure the safety of personnel.

Effect of Different Levels of CO2
Concentration Effect
350 – 450 ppm Typical atmospheric concentration
600 – 800 ppm Acceptable indoor air quality
1,000 ppm Tolerable indoor air quality
5,000 ppm Average exposure limit over 8-hour period
6,000 – 30,000 ppm Concern, short exposure only
3 – 8% Increased respiration rate, headache
> 10% Nausea, vomiting, unconsciousness
> 20% Rapid unconsciousness, death

Benefits of CARBOCAP® Sensors

Benefits of CARBOCAP® Sensors

Dpstar’s CO2 measurement is based on a unique CARBOCAP® technology with a built-in true reference measurement that enables long-term stability and ensures reliable measurement. The products require minimal maintenance and calibration.

Stability

The unique design of CARBOCAP® results in recommended calibration intervals of up to 5 years.

24/7 Occupation

Suitable for use in spaces occupied 24/7 as well as dusty and dirty industrial environments.

Long lifetime

Its microglow light source is rated for 15+ years of stable light output providing many years of trouble-free use.

Out of the box performance

Shows correct values immediately after power-up because the CARBOCAP® does not need to “learn” its environment like other technologies do.

Optimal Locations for CO2 Transmitters

  • Avoid locations where people may breathe directly onto the sensor. Also, avoid placing sensors close to intake or exhaust ducts, or near windows and doorways.
  • In demand-controlled ventilation wall-mounted sensors provide more accurate data on ventilation effectiveness than duct-mounted sensors. Duct-mounted sensors are best suited to single-zone systems and should be installed as close to the occupied space as possible to allow for easy maintenance access.
  • When measuring CO2 for the purposes of personnel safety, transmitters should be installed close to potential leakage points to enable early detection. The geometry, ventilation, and airflow of the monitored area need to be taken into account. The number and location of the CO2 transmitters should be based on a risk assessment.

Our Products Solutions

Our Products Solutions

Talk to an Expert

Our CO2 measurement devices are based on our unique, second-generation CARBOCAP® technology, which ensures exceptional stability, and are delivered with a NIST traceable calibration certificate. They are easy to use, require little maintenance, and have a low total cost of ownership. Meet the goals of your gas detection program with personalized guidance from our team of experts.

Get In Touch With Our Experts Today!

Dpstar Group
No 35, Jalan OP ½, Pusat Perdagangan One Puchong,
Off Jalan Puchong, 47160 Puchong,
Selangor Darul Ehsan, Malaysia.
Email: [email protected]

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