Controlled Atmosphere Storage Technology

Controlled atmosphere storage emerges as a highly successful innovation in the fruit and vegetable sector of the 20th century. This technology focuses on adjusting oxygen (O2) levels and elevating carbon dioxide (CO2) compared to the ambient air. It may also include the removal of ethylene and the introduction of carbon monoxide. The core of controlled atmosphere storage involves continuous monitoring and precise adjustment of these gases within the storage container to meet predetermined levels.

Excessive levels of CO2 or insufficient O2 can lead to irreversible damage to fruits or vegetables, with the manifestations of damage varying across products and depending on the intensity of the impact.

The primary use of controlled atmosphere storage has been in slowing down the ripening process of apples and pears. The widespread adoption of mechanized handling, utilizing bulk bins and pallets, coupled with advancements in technology for maintaining precise conditions of temperature, humidity, oxygen, carbon dioxide, and ethylene, has resulted in a significant global expansion of controlled atmosphere storage since the mid-20th century.

Another application of controlled atmosphere storage is evident in grain storage. Fundamental techniques involve drying the grain to below 12% moisture content before sealing it in a structure or silo. Drying is achieved using aeration fans as the grain enters a controlled atmosphere enclosure. Throughout the storage period, aeration and fans are deployed to control temperature and humidity.
Controlled Atmosphere Storage Technology

Controlled atmosphere packaging technology

Controlled atmosphere storage is the storage in which atmosphere of oxygen, carbon dioxide and nitrogen (and sometimes other gases) are controlled by external control systems.

Another term sometimes used in ‘intelligent’ packaging which may include monitoring the package and possibly making adjustment based on this information.

Controlled atmosphere (CA) storage has been shown to be a technology that can contribute to these consumer requirements in that in certain circumstances, with certain varieties of crop and appropriate treatment, the marketable life can be greatly extended.

Advances in controlled atmosphere storage technology include faster establishment of desired atmosphere, less fluctuation in O2 and CO2 levels, ability to change atmospheric composition as needed during storage, and ability to scrub ethylene from the storage environment.

Commercial use of controlled atmosphere storage is greatest in apples and pears worldwide; less on kiwifruits, avocados, persimmons and pomegranates, nuts and dried fruits and vegetables.
Controlled atmosphere packages allow reaching markets that are geographically far from the point of packaging for sensitive materials. Indeed, the sophistication of such packages will increase costs and the trade-off with alternative technologies such as refrigeration will likely be determined by balancing convenience and economics.
Controlled atmosphere packaging technology

Storage of vitamin A

It has long been established that vitamin A (retinol) is an essential component of human diet and must be acquired from the diet as either preformed A or provitamin carotenoids, which subsequently converted in the body to the biologically active retinoids, retina and all-trans retinoic acid.

Vitamin A is normally transported in the blood linked to a specific protein, retinol binding protein (RBP). Specific proteins on cell surfaces and within cells are also involved with intracellular transport of the vitamin.

RBP circulates as a 1:1 molar complex; filtration and loss from the kidney are prevented by prealbumin, The normal concentrations in plasma are 40 to 50 ug per mL for RBP and 200 to 300 ug per mL for prealbumin.

Human liver

RBP binds retinol and this RBP-retinol complex is then secreted into circulation where it is transported to the target tissue to meet tissue vitamin A needs.

Vitamin A is fat soluble and is primarily stored in the liver, where RBP is synthesized. The liver holds over 90 percent of the body’s vitamin A reserves, with the rest deposited in fat tissue, lungs and kidneys.

The liver plays a pivotal role in the uptake, storage and maintenance of circuiting plasma vitamin A levels by mobilizing its vitamin A store.

In a well nourished person, vitamin A stores are generally sufficient to last many months on a vitamins A-deficient diet before signs of deficiency appear.
Storage of vitamin A