Preserving Banana Quality: The Role of Modified Atmosphere Packaging (MAP)

Modified Atmosphere Packaging (MAP) plays a crucial role in influencing the flavor and texture of bananas by delaying the ripening process and extending their shelf life.

Flavor: The controlled environment in MAP preserves the natural sweetness of bananas by slowing down the conversion of starches into sugars. As a result, bananas stored in MAP maintain their flavor profile longer, preventing them from becoming overly sweet or developing undesirable off-flavors associated with over-ripening. However, if oxygen levels are too low, anaerobic respiration can occur, leading to off-flavors.

Texture: MAP helps retain the firmness of bananas by slowing the softening process. The reduced oxygen and increased carbon dioxide levels in MAP inhibit enzymatic activities that cause softening, allowing bananas to stay firmer for longer. This is particularly advantageous for transportation and storage. However, an imbalance in gas levels can cause issues like uneven ripening or excessive firmness.

In summary, MAP is an effective method for preserving the quality of bananas, ensuring they remain flavorful and firm over extended periods. This makes it a valuable tool for reducing waste and enhancing the efficiency of banana supply chains.
Preserving Banana Quality: The Role of Modified Atmosphere Packaging (MAP)

History of modified atmosphere packaging (MAP)

Modified atmosphere packaging can be defined as an alteration in the composition of gases in and around fresh produce by respiration and transpiration when such commodities are sealed in plastic films.

Much of original work was done in Australia and New Zealand when beef and lamb carcasses were shipped in the 1930s to the UK was stored in carbon dioxide to help maintain freshness.

During the 1940s and 1950s fresh apples and pears were placed in enclosed warehouse. The natural respiratory activities of the fruit reduced the oxygen and increased the carbon dioxide within storage areas sufficiently to slow respiration markedly.

The stored apples or pears could be consumed as much as six months after the original harvest: and extensions of about double the normal chilled storage shelf-life.

In the 1970s, modified atmosphere packages were used for some retail packs of meat and fish. The new techniques have been developed, including micro-perforation, anti-fogging layers to improve product visibility.

The use of modified atmosphere packaging technology received a significant boost when the retail chain of Marks and Spencer introduced a wide range of fresh MAD meat products in the UK in 1981.

Today, modified atmosphere packaging is used to package anything from fresh salads or individual meat portions, to sandwiches and snacks.

History of modified atmosphere packaging (MAP)

Controlled atmosphere packaging

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

Vacuum packaging

The simplest and most common means of modifying the internal gaseous atmosphere in a pack is by vacuum packaging. The product is placed in a pack made from film of low oxygen permeability, air is evacuated and the package sealed.

It needs a multilayer film composed of high-barrier and heat-sealable layers with low cost. Most multilayer films are generally processed by lamination or coextrusion. The material used as high-barriers layers are polyamide (PA) or nylon, polyethylene terephthalate (PET), polyvinylidene chloride (OVDC) or ethylene vinyl alcohol (EVOH).

Vacuum packaging of respiring foods or foods containing viable microorganisms such as flesh foods is clearly a form of MAP, because after initial modification of the atmosphere by removal of most of the air, biological action continues to alter or modify the atmosphere inside the package.

In vacuum packaging, elevated level of CO2 can be produced by microorganism or by respiring fruits and vegetables.

Under good vacuum conditions the oxygen level is reduced to less than 1%. The barrier properties of the film used restricts entry of oxygen from outside.

In the case of vacuum-packed meat, respiration of the meat quickly consumes the residual oxygen replacing it with carbon dioxide, which eventually increases to 10-20% within the package.

Trend of vacuum packaging technology in frozen food is sought to minimize deterioration changes including microbiological and chemical changes and it is widely used in many kinds of food, particularly in ready meal.
Vacuum packaging

Modified atmosphere packaging

Modified atmosphere packaging (MAP) is an active form of packaging that involved the removal of air from the pack and its replacement with a single gas or mixture of gasses.

The gas mixture used is dependent on the type of product. The proportions of each component is fixed when the mixture is introduced. No further control is exerted over the initial composition and the gas composition is likely to change with time owing to factors such as respiration of the packed product, biochemical changes and the slow permeation of gases through the container.

Gases primarily used include oxygen, carbon dioxide, and nitrogen. Carbon monoxide has limited application in MAP, and sulphur dioxide is commonly used.

Oxygen is necessary for several processes that lead to quality degradation of the product such as fat oxidation browning and pigment oxidation. Therefore, to avoid any of these situations most of atmosphere modifications contain low concentrations or absence of oxygen.

Nitrogen is an inert gas for filling the additional scope to prevent potential collapse.

The gases used should be of a specified purity and should be selected after consideration of the potential microflora in the specific food stuff. Legally the gases are regarded as food additive.

MAP is used for fresh and heat-treated products. If the product is heat-treated, the heat treatment takes place before packaging.
Modified atmosphere packaging

Micro-porous film

Micro-porous films are defined as having a narrow pore-size distribution, usually in the sub-micrometer range although they can range from 0.1 to 10 um. It is common for micr0-porous films to have 1-2 billion pores per square centimeter in a film 10-50 um thick.

Modified atmosphere packaging (MAP) of fresh produce has been an active research area for many years. The problem is that most polymeric films are too impermeable for packaging high-respiring products like broccoli, cauliflower, carrots and cut fruit.

In order of achieving high rates of gas exchange is through the use of micro-porous and perforated films. The gas diffusion constant for a perforation is approximately 4 to 8 million times greater than that of a low-density polyethylene film.

Micro-porous films are prepared by extrusion of filler-containing polymers. The common fillers are CaCO2 or SiO2, although other porous powders may be included.

Gas permeability is controlled by adjusting the filler content, the particle size of the filler and the degree of stretching the film.
Micro-porous film

Equilibrium modified atmosphere packaging

Equilibrium modified atmosphere packaging or EMAP used primarily for fruit and vegetables; either the pack is flushed with required gas mix or the produce is sealed within the pack with no modification to the atmosphere.

Equilibrium modified atmosphere containing 2-5% oxygen and 3-8% carbon dioxide balance by N2, have been shown to delay maturation and softening of vegetables and reduce chlorophyll degradation, microbial spoilage and enzymatic browning.

It is also inhibiting undesirable pinking on prepared leafy green salad vegetables.

Equilibrium modified atmosphere attained are influence by produce respiration rate which itself is affected by temperature, produce type variety, size, maturity and severity of preparation; packaging film permeability; pack volume, surface area and fill weight and degree of illumination.

Inside the package, an equilibrium becomes established when the O2 transmission rate of the packaging film is matched by the O2 consumption of the packaged commodity.

The respiration of the living plant tissue results in the production of CO2 which diffuse through the packaging film, depending in the films CO2 transmission rate.

The type of packaging film selected is based on the film O2 and CO2 transmission rate which is required to obtain a desirable equilibrium modified atmosphere.
Equilibrium modified atmosphere packaging