Post harvest Management of Horticultural Crops (2+1)

Plastic containers and paper trays

Another alternative to the wood for packaging is plastics. Use of plastics in packaging of fresh horticultural produce helps in minimizing the cost of packaging materials and makes the whole process less dependent on scarce materials like wood, thereby, resulting in conservation of environment. The following are the important plastic materials that can be used for packaging of fresh fruits and vegetables.

1. Polypropylene boxes
Polypropylene corrugated board can be used easily for horticultural produce. Added advantage of this material is that it can be reused quite a few times.

2. Stretch/cling wrap
This is actually a polyethylene or polypropylene film which has the property that under tension it stretches and when the tension is released it comes back to its original form. This property helps in packaging the product tightly. The whole operation can be carried out without application of the heat. Eg. cabbage, fresh cut vegetables etc.





3. Moulded plastics (Plastic crate)
Reusable boxes moulded from high-density polythene are widely used for transporting produce in many countries. They can be made to almost any specifications. They are strong, rigid, smooth, easily cleaned and can be made to stack when full of produce and nest when empty in order to conserve space. Despite their cost, however, their capacity for reuse can make them an economical investment.





Fig. Multipurpose plastic crates for horticultural produce



4. Plastic Bags
Plastic bags (polyethylene film) are the predominant material for fruit and vegetable consumer packaging. Besides the very low material costs, automated bagging machines further reduce packing costs. Film bags are clear, allowing for easy inspection of the contents, and readily accept high quality graphics. Plastic films are available in a wide range of thicknesses and grades and may be engineered to control the environmental gases inside the bag. The film material “breathes” at a rate necessary to maintain the correct mix of oxygen, carbon dioxide, and water vapour inside the bag. Since each produce item has its own unique requirement for environmental gases, modified atmosphere packaging material must be specially engineered for each item that respond to temperature and control the mix of environmental gases.

5. Shrink Wrap
One of the newest trends in produce packaging is the shrink wrapping of individual produce items. Shrink wrapping has been used successfully to package potatoes, sweet potatoes, onions, sweet corn, capsicum and cucumbers. Shrink wrapping with an engineered plastic wrap can reduce shrinkage, protect the produce from disease, reduce mechanical damage and provide a good surface for stick-on labels. In this method, vegetables are wrapped in heat-shrinkable plastic film. The main advantages of film wrapping of vegetables are (i) reduced weight loss and extended shelf life, (ii) reduced chilling injury, (iii) minimized vegetable deformation, (iv) reduced decay by preventing secondary infection of packed produce.



Fig. Shrink wrapping of capsicum



6. Rigid Plastic Packages
Packages with a top and bottom that are heat formed from one or two pieces of plastic are known as clamshells. Clamshells are gaining in popularity because they are inexpensive, versatile, provide excellent protection to the produce and present a very pleasing consumer package. Clamshells are used extensively with pre-cut produce and prepared salads.



Fig. Rigid Plastic Package for cut fruits and whole fruit



7. Paper or plastic film
Paper or plastic film is often used to line packing boxes in order to reduce water loss of the contents or to prevent friction damage.

8. Paper pulp trays
Containers made from recycled paper pulp and a starch binder is mainly used for small consumer packages of fresh produce. Pulp containers are available in a large variety of shapes and sizes and are relatively inexpensive in standard sizes. Pulp containers can absorb surface moisture from the product, which is a benefit for small fruit and berries that are easily harmed by water. Pulp containers are also biodegradable, made from recycled materials, and recyclable.





Fig. Packing individual fruit in moulded plastic