PACKAGING OF DAIRY PRODUCTS

Lesson 15 B

15.4 Aluminum Containers

1. They provide extreme convenience in preparation and serving of foods.

2. They withstand extremes of temperatures.

3. Foods may be frozen in the package or cooked in it.

4. Aluminum protects the food against moisture, gases and light.

5. General categories are compartmented, folded end, ovals, pie plates, rectangulars, rounds, squares, and specialty items.

6. Newer techniques of forming are now producing smooth flanges and smooth side walls. With smooth flanges flat-web materials can be hermetically sealed on as closures.

7. Coloured containers can be decorated attractively to permit the container to be placed on the table as a server. Soft butter and margarine product are now found in such packages.

15.4.1 Uses of Al – containers

1. Aluminum can was first used in Scandinavia and Switzerland for filling fresh milk, meat and vegetables.

2. It is used as cans and wrappers (foil) for dairy products, chocolates etc.

3. It is also used as component of laminates.

4. It is used as tubes and pre-formed containers for cooking.

5. It is used in Food Processing plants and machines.

6. It has excellent resistance to wide range of corrosive agents like

- Oxalates are more corrosive than hydroxyl acids such as tartaric, malic and citric.

- Chlorides are strong corrosive for pitting

- Sugar reduces corrosion.

7. It does not produce dark sulphur taint.

8. Cans are more readily opened than tinplate cans but will not withstand hydrogen swells to the same degree.

15.5 Glass Containers

With a history dating back to ancient Egyptian civilization, glass is still one of the major packaging materials the world over. Glass containers are one of the stalwarts of food packaging. Narrow-necked glass containers are called bottles and wide necked are called jars.

15.5.1 Bottles

1. Bottles are the most extensively used type of glass container.

2. They may be many different shapes but the neck is always round and much narrower than the body. The neck facilitates pouring and reduces the size of the closures required.

3. Principal uses are for liquids or small sized solids.

4. Until recently, almost all milk was packaged in glass bottles.

5. The increase in supermarket shopping and the decrease in home delivered milk has decreased the usage of glass milk bottles.

6. Glass milk bottles originally were round, tapering to a rather wide mouth with a thick flange. The move to a squared body saved considerable space in the home refrigerator.

7. Glass bottles average about 50 trips and are packed at rates up to 24000 per hour.

8. Brown glass is used sometimes to filter out harmful light (UV light).

9. Bottle closures are formed from aluminum foil, high density polyethylene, polypropylene and paper board.

10. Most closures are applied by automatic machinery at high speeds.

15.5.2 Jars

1. Jars are really very wide mouthed bottles and usually have no appreciable neck.

2. The opening permits the insertion of fingers or a utensil to remove portions of their contents.

3. They may be used for liquids, solids and non pourable semi - liquids such as thick sauces and pastes.

15.5.3 Tumblers

1. These are like jars but they are open-ended.

2. They have no neck and no 'finish'.

3. They are shaped like a drinking glass and are used for products like jams and jellies.

15.5.4 Jugs

1. These are large-sized bottles with carrying handles.

2. Necks are usually short and narrow.

3. They are usually used for liquids in large sizes.

15.5.5 Carboys

1. These are very heavy shipping containers shaped like a short necked bottle and having 10 liters or more capacity.

2. Typically they have been used with a wooden crate holder. Other outer protective frames are now finding use.

15.5.6 Vials and ampoules

1. These are small glass containers.

2. The ampoules are principally used for pharmaceuticals.

3. Vials are sometimes used for small quantities of foods such as spices or food colorants and cultures.

15.6 Trays, Pans and Other Containers

1. This category of packages includes dishes, cups, bowls, pans, or trays such as pie pans and the TV dinner tray.

2. Molded paper and picnic plates both rectangular and round with and without compartmentation have been made for several decades.

3. Pulp board trays are also used to package meats and produce in supermarkets.

4. Aluminum foil containers are available in many shapes.

5. Convolute and spiral wound canisters made from paper are used extensively, with asphalt providing moisture barrier.

6. Aluminum foil liner is used to provide superior moisture barrier.

7. Foil is also incorporated as an inner liner, thereby marking it possible to package liquids.

8. With the introduction of plastic that could be thermoformed, a wide variety of molded plastic boxes, trays, pans and the like became possible.

15.7 Wooden and Cardboard Boxes

• One of the earliest packaging materials, and one that is still very useful, is wood in its various forms.

• Although it is used less frequently as other more sophisticated materials are substituted, it has still an important place in industrial packaging for heavy and or fragile items that require rigidity and strength.

• The different types of packaging made from wood include baskets and hampers, tight and slack barrels, nailed wood boxes and crates, wire bound boxes pallets and skids, and containerization units.

• They are made from lumber, veneer, or plywood.

• Veneer is defined as wood that is less than 3/8" thick, regardless of whether it is sawed, sliced, or rotary-cut.

• The types of fasteners that are used include wire, nails, screws, staples and bands.

15.7.1 Advantages and disadvantages

• With a good strength-to-weight ratio, wood is an economical structural material.

• It does not require very sophisticated equipment to make a box or crate and for very rigid structures in small quantities it is the material of choice.

• For small packages or for large quantities, however, wood does not lend it self to high speed operations or automatic assembly. It therefore has a high labour factor in relation to material costs.

• It is also bulky and often presents a problem of storage space and shipping cubage.

• If rigidity, stacking, strength, protection from the hazards of shipping and light weight are essential, it is difficult to find a better material than wood.

• But if protection from moisture, rapid assembly, low cost, ready availability or attractive appearance is more important, then wooden containers may not be the best choice.

15.7.2 Nailed boxes

There are various methods of constructing a nailed wood box, depending upon the type of service required.

15.7.3 Wire bound boxes

• Very thin lumber is used to make wire bound boxes, and wires around the girth of the container are stapled to the wood at frequent intervals. Wood cleats are placed at the ends and sometimes in between.

• The type and cure of wood used will affect the weight, strength and ease of fabrication of the container.

• Soft woods are earlier to nail but not as strong as hardwood.

• Green lumber is excessively heavy, weaker and will wrap and shrink causing loosening of nails or other fasteners.

• Boxes are usually solidly walled, rectangular shaped, nailed wooden containers and will very in construction and in extra cleats and braces as may be required by the load. The top, bottom, and sides of a box provide the main structural strength.

• Crates are similar to boxes but may be of lighter weight and more open construction - that is spaces may be left between boards or the crack may be fully enclosed or sheathed.

• A crate differs from a box in that the frame members carry the load. The sheath merely encloses, hence sheathing may be corrugated fiber board or thin plywood or light weight lumber.

• Other joining methods may be used for boxes and crates. These include metal fasteners, glues, and wires or wire tapes. When using wires, thinner side, top and bottom sheathing can be utilized as the wires add strength. Cleated ends and stiffeners provide the structured strength required.

• Advantage of wooden boxes and crates depend on the relative cost, strength, and weight ratios involved.

• In most food uses today, wooden containers are being phased out and solid or corrugated fiberboard containers are replacing them. Some wood is still used for reinforcing cleats and bottoms.

15.8 Composite Containers

A composite container is a container made from two or more constituent materials. It usually consists of a paperboard body with metal or plastic ends. The basic principle in a composite type of structure is to use the competition of materials which is best suited for the purpose, in the minimum amounts that are necessary to accomplish the packaging objectives.

• Three basic types are available:

1. Spiral-wound containers: They are made in cylindrical shapes where two or more plies of board are glued together around a mandrel.

2. Convolute-wound composites: They are produced by straight winding and is used for squares, oblongs and ovals in addition to the cylindrical type.

3. Lap-wound: Lap-seam bodies are made from laminated material cut into blanks and joined at the side with adhesive.

• The convolute method Spiral winding does not make as strong a container as convolute winding and for larger packages for which resistance to hazards of shipping and storage is of paramount importance, the convolute construction will outperform spiral winding.

• Body materials used are chipboard and Kraft paper.

• Linings used are vegetable parchment, wax laminates, aluminum foils, glassine and polyethylene coated paper. Other linings can also be used depending on the product to be packaged.

• Composite cans are closed by either a snap-on lid, plug-in lid or a lever lid.

• In the non-detachable type of closure, perforated tops and string-opening devices are used as well as double seamed ends.

• Specific advantages in using composite cans are ease of disposal and economics.

• In recent years, composite cans have widely used for refrigerated dough and other food products.

• Combinations of metal and paperboard or plastic and paperboard, incorporating films, foils, coatings or adhesives where needed are finding applications in many fields. Citrus juice cans, spice boxes, and cocoa canisters are examples among food packages.

• Expensive materials can be kept to a minimum by using them in thin layers, supported by inexpensive paperboard for strength and rigidity.

• In comparison with metal containers, a fabricant will provide far more thermal insulation, which may be good or bad, depending on the type of product it contains.

• If quick freezing is part of the process, the fiberboard will interfere with the rapid cooling.

• On the other hand, it will protect the contents from a temperature change that might be detrimental

15.9 Fibre Drums

1. A large version of the fibre can is the fibre drum that is used for shipping bulk chemicals and other industrial products.

2. Fibre drums are generally used for dry products, although with suitable plastic liners they can be used for pastes and certain types of liquids.

3. A wide range of sizes is available from stock, with end pieces of metal, wood or fiberboard, and body constructions that include a variety of laminations and coatings.

4. Fiber drums are light in weight and they have exceptional strength in proportion to their weight.

5. Although a fibre drum is essentially a single trip container, it is sometimes reconditioned and used for several trips.