Packing fruit and vegetables
Packing fruit and vegetables
Dr. Eng. MARZENA UCHEREK
Department of Goods Packaging,
Faculty of Commodity Science, Kraków University of Economics
FERMENTATION AND FRUIT AND VEGETABLE INDUSTRY • 3/2004
Current trends in the development of fruit and vegetable packaging systems
The work outlines modern solutions in the field of packaging systems for fruit and vegetables. The principle was presented along with an indication of the practical possibility of using a packaging system such as: gas mixture packaging (MAP and CAP).
Regardless of the use of many types of traditional packaging, recently there has been a trend towards new solutions in the field of fruit and vegetable packaging. Technical progress in the field of packaging systems for plant products most often concerns:
• the use of new or modified materials and the implementation of technologies that enable reducing the material consumption of packaging or reducing energy consumption,
• increasing the efficiency of packaging machines,
• improving the quality of packaging, its functional properties or suitability for reprocessing
Modified and controlled atmosphere packaging (MAP and CAP)
The biggest problem with the overproduction of fruit and vegetables is their seasonal supply, which can be extended by using technologies that accelerate or delay their ripening. Numerous theoretical works and experiments have practically confirmed the possibility of reducing the intensity of breathing, inhibiting the growth of bacteria and fungi and the development of physiological diseases, as well as reducing the mass loss of plant raw materials by the simultaneous use of cooling and a gas environment with a changed composition in relation to atmospheric air. This type of solution turned out to be packaging systems in a mixture of gases, known as modified atmosphere packaging (MAP).
In the MAP system, the air in the packaging is replaced with a gas mixture in which the proportions of individual ingredients are strictly defined during packaging and constant at the time of introduction, and no exchange of atmosphere takes place during storage. However, over time, due to respiration of the packaged product and as a result of the exchange of components of a given gas mixture with the ambient atmosphere, its composition may slowly change, and an equilibrium modified atmosphere (EMA) is established inside the package.
However, the use of the CAP system involves constant control of the established atmosphere composition and the need to correct and compensate for changes caused by the respiration of products and the microorganisms they contain and the permeability of packaging.
When selecting modified atmosphere packaging systems, the following factors are taken into account:
• type and degree of processing of horticultural products,
• storage conditions (optimal temperature and factors limiting storage time),
• properties of gases used in packaging,
• type of packaging material
Fresh fruits and vegetables are "breathing" products, i.e. they consume and produce carbon dioxide and water vapor. Therefore, when designing the MAP system, in order to achieve the optimal gas composition and relative humidity for various fruits and vegetables, it is necessary to select a film with an appropriate permeability and packaging design, while maintaining the appropriate ratio of the product mass to the foil surface. Nitrogen, carbon dioxide and oxygen are usually used to modify the atmosphere, although it is also possible to use nitrogen oxide, carbon oxide, sulfur dioxide or other gases. The role of each gas is different .
When packaging in a modified atmosphere, a reduced oxygen content and an increased nitrogen and carbon dioxide content are usually used. By reducing the O2 content or increasing the CO2 content, one can observe, among others: reducing the rate of ripening and respiration of fruits and vegetables, their production of ethylene, their softening, chlorophyll degradation and enzymatic browning.
The optimal CA (Control Atmosphere) composition for storing fruit and vegetables is determined individually, taking into account factors such as: type and variety of stored fruit or vegetables, their sensitivity to carbon dioxide concentration or oxygen deficiency, degree of ripeness, storage period and transport and storage temperature.
TABELA zalecane warunki przechowywania niektórych odmian owoców i warzyw
TABLE recommended storage conditions for some varieties of fruit and vegetables
Table 1 presents sample recommendations for storing fruit and vegetables in the most effective atmosphere composition for a given type [1, 2, 4, 6, 10, 13].
The basic criterion for selecting packaging material when packing fresh fruit and vegetables is its ability to maintain the appropriate ratio.
Type of fruit
or vegetable |
Temperature [°C] |
CO2
[%] |
O2
[%] |
Humidity
[%] |
| Apples |
0-2 |
1-5 |
2-3 |
95 |
| Asparagus |
0 |
9 |
5 |
95 |
| Bananas |
4-16 |
2-5 |
2-5 |
95 |
| Kiwi |
0 |
5 |
2 |
90 |
| Mango |
10 |
10 |
5 |
90 |
| Cherries |
0-5 |
10-15 |
3-10 |
95 |
| Peaches |
0 |
0,5 |
1,5 |
93 |
| Avocado |
5 |
9 |
2 |
85 |
| Lettuce |
0 |
1,5 |
3 |
98 |
| Strawberries |
1 |
20 |
17 |
90 |
Properties of packaging films used to obtain MA (Modified Atmosphere)
• High degree of permeability to oxygen, carbon dioxide and ethylene, adapting to the respiration of the product in various temperature ranges. For vegetables with high respiratory intensity, traditional plastic films such as low-density polyethylene (LDPE), polyvinyl chloride (PVC), ethylene vinyl acetate (EVA) and oriented polypropylene (CPP) are not sufficiently permeable to gases.
Recently, modern highly permeable ultra-low density polyethylene films - ULDPE, microporous (MPOR) or microperforated (MP) with holes up to several mm in diameter or with windows made of fabric or nonwoven fabric (especially large packages made of thick foils) have been produced.
• Good transparency and gloss so that the consumer can check the freshness of the product, e.g. films with a higher 18% vinyl acetate content (haze less than 2%), as well as films produced from ultra-low density polyethylene (haze up to 6%).
In order to protect the packaging film against loss of transparency caused by condensation of water vapor during storage at lower temperatures, it is often covered with an anti-fog layer using non-ionic ethoxylates or hydrophilic fatty acid esters, which lower the surface tension of water drops. The moisture then spreads evenly on the foil and thus does not deteriorate its transparency and permeability.
• Possibility of accurate, tight closure, enabling the maintenance of the proper composition of MA, e.g. polyolefins, which include ultra-low density polyethylene and polypropylene, and ethylene vinyl acetate copolymer (E/YAC) with 18% vinyl acetate content.
• Possibility of accurate, tight closure, enabling the maintenance of the proper composition of MA, e.g. polyolefins, which include ultra-low density polyethylene and polypropylene, and ethylene vinyl acetate copolymer (E/YAC) with 18% vinyl acetate content.
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