Gas-tight cold stores (CA/ULO/DCA)

Frequently asked questions

• What is a CA bearing?

  A controlled atmosphere warehouse (CA warehouse) is a highly specialized facility for storing fruit and vegetables. In this gas-tight refrigerated warehouse, not only are the temperature and humidity strictly controlled, but the air composition, in particular the oxygen and carbon dioxide content, is also stabilized to precise values. By specifically reducing the oxygen content and increasing the carbon dioxide content, the ripening process of the fresh products is significantly slowed down. These optimum air conditions can either be set manually or achieved through the natural ripening process of the fruit in the gas-tight room, as oxygen is consumed and carbon dioxide is produced during the ripening process.

• What is a ULO bearing?

  A further development of the CA storage concept is Ultra Low Oxygen storage (ULO storage), in which the oxygen content is kept extremely close to the minimum level required to maintain biological ripening activity. This allows the ripening of the fruit to be reduced to a minimum, significantly extending its shelf life and enabling longer storage without the fruit over-ripening.

• What is a DCA bearing?

  DCA warehouses use dynamic control technology to optimize the oxygen and carbon dioxide content during storage. Each process has its own specific technology for measuring and regulating the atmosphere in the storage rooms.

• How long can I store my fruit in CA storage facilities?

  The storability of fruit types in CA storage facilities depends on the type and variety of fruit.
  Long-term storage is particularly practiced for pome fruit. The shelf life of apples, for example, is 1 to 10 months without any major loss of quantity or quality. It is also possible to extend the shelf life by using ULO storage or DCA storage.

• What are the conditions in CA warehouses?

  The following conditions are typical inside CA warehouses during fruit storage:

  • low temperature (-1 to 6 °C, depending on fruit and variety)
  • high humidity (90-95 %)
  • low oxygen content (usually 2 to 3 %)
  • increased carbon dioxide content (2 to 5 %, depending on the fruit and variety)

• Am I allowed to enter a CA warehouse?

  A CA warehouse in operation must not be entered under any circumstances! This also applies to DCA warehouses and ULO warehouses!
  Even after operation of such a warehouse, it must be ensured that sufficient ventilation has taken place before entering.

• What is important for optimal CA storage?

  The following points are important for optimum CA storage:

  • The optimum harvest date is crucial for the quality of storage.
  • Only apples with a good supply and a controlled atmosphere should be selected for long-term storage.
  • The store should be filled as quickly as possible, ideally within a week.
  • When stacking the fruit, care should be taken to ensure good ventilation.
  • The oxygen content should not be lowered until the fruit has reached its final temperature.
  • Specific storage conditions for each apple variety must be observed.
  • The relative humidity should be kept between 92% and 95%.
  • When storing different varieties together, the requirements of the most sensitive variety should be taken into account.
  • Only reliable and regularly calibrated measuring devices should be used.
    
    The above points are no substitute for case-by-case and individual consideration.

• How do I operate my CA warehouse economically and energy-efficiently?

  The following points are particularly important for the economical operation of a CA warehouse:

  • Invest in energy-efficient refrigeration units and insulation to minimize energy consumption. This is important right from the start of planning.
  • Optimize the space utilization of CA warehouses by using the space efficiently and utilizing it as much as possible.
  • Fruit should be stored as cool as possible. Hot goods require high energy consumption to cool them down first.
  • Avoid opening the door unnecessarily and keep it open for as short a time as possible to minimize energy loss. This point is usually underestimated. In practical tests, a large part of the energy is used during storage. Leaving the doors open is a very important part of energy loss.
  • Monitor and regulate the temperature continuously to ensure optimum cooling with minimum energy input.
  • Ensure that air circulation in the CA warehouse is not obstructed to ensure even cooling and minimize energy consumption, taking into account the placement of products in storage to ensure efficient air circulation and cooling.
  • Clean and maintain CA storage and cooling units regularly to maintain efficiency and optimize energy consumption. Leaks and breakdowns often lead to avoidable losses.
  • Use energy-saving lighting options in the CA warehouse. LED lamps are recommended.
  • Site-specific energy generation such as a PV system can be a useful addition for self-consumption.

  We will be happy to assist you with the analysis and support you with the implementation.

• Why a CA warehouse from Plattenhardt+Wirth?

  With over 60 years of experience in this sector, we know our customers' requirements for the optimum CA warehouse. Our many years of expertise with different types of fruit and operating processes enable us to create customized planning. To ensure quality, we rely on innovations and tried-and-tested solutions:

  • Our in-house CA doors ensure storage throughout the entire period. With doors that have been in use for over 40 years and still work, we guarantee the longevity and efficiency of the rooms. We use as few maintenance-prone components as possible.
  • Our own planning department is complemented by our own fitters. They ensure the quality you need in your business throughout the entire construction process.
  • Even after completion, our service technicians will help out as quickly as possible. Should something happen or a repair be necessary, we will be there for you as quickly as possible.
  • Efficiency and cost-effectiveness are important to us. Only a well-planned warehouse can provide you with the efficiency that is necessary for successful operation. This includes energy efficiency, optimal warehouse layout and consideration of the longevity of your premises.

• Advantages of a CA warehouse

  CA (controlled atmosphere) storage offers a number of advantages for the long-term storage of agricultural products. By using a controlled atmosphere, low temperatures and high humidity, the freshness and quality of the stored products are preserved.

  The controlled atmosphere in a CA storage facility makes it possible to control the oxygen and carbon dioxide content. Targeted measurement and control techniques can be used to set the optimum level of these gases to prevent the degradation of valuable ingredients and the over-ripening of products.

  Low temperatures are another decisive factor for long-term storage. By cooling the storage rooms, the natural ripening processes are slowed down, which leads to a longer shelf life for the products. Refrigerated storage rooms offer the possibility to customize a specific temperature and thus ensure appropriate storage for different agricultural products.

  High humidity is also important to maintain the freshness of fruit and other products. The high humidity prevents the products from drying out and preserves their juicy texture and taste. Controlled humidity levels help to maintain quality and prevent the growth of mold or bacterial spoilage.

• Functionality

  The operation of a CA store is based on a controlled atmosphere to slow down the ripening process of fruit and other products and extend their shelf life. This contrasts with two other storage methods: ULO (Ultra Low Oxygen) and DCA (Dynamic Controlled Atmosphere).

  CA warehouses use gas-tight rooms to control the oxygen and carbon dioxide content. This is done using specific measurement and control techniques to set the optimum gas content. Low temperatures play an important role in slowing down the ripening process. Refrigerated storage rooms make it possible to individually adjust the temperature for different products.

  ULO warehouses use an extremely low oxygen content combined with a moderate concentration of carbon dioxide. This enables longer storage without the fruit overripening. DCA storage, on the other hand, uses dynamic control technology to optimize oxygen and carbon dioxide levels during storage. This enables a longer storage period with consistent quality.

  The outstanding features of CA bearings include the ability to individually adjust the gas content to prevent the degradation of ingredients and excessive ripening. ULO bearings offer a long storage time, while DCA bearings allow dynamic adjustment of the atmosphere. Each method has its own specific technique for measuring and regulating the atmosphere in the storage rooms.