Packaging of frozen foods

Packaging of frozen foods

FREEZINGFreezing (-18C)slows growth and activity of microorganisms retards chemical reactions and prevent the action of enzymes.immobilizes most of the moisture present increases the concentration of solutes reduces available water. Whilst the numbers of viable organisms are slightly reduced by freezing, it does not completely sterilize the food.

STAGES IN FREEZINGThe freezing process has three major stages: Cooling Formation of ice crystals (-1to-2C) cooling down to the storage temperature.

COMMERCIAL FREEZING METHODSBlast freezingPlate freezingImmersion or liquid contact freezing

FROZEN FOOD PACKAGE

PROPERTIES OF A GOOD FROZEN FOOD PACKAGE Withstand low and high temperaturesNon-toxicNot impart odours or flavours to the food Barrier to the transmission of water vapourWater resistant Ease of handling in filling and closing equipment Easy printingTamper-resistantMust not fall apart when it becomes damp on thawing

PROTECTION OFFERED BY THE PACKAGEThe packaging must provide protection against the following: DehydrationOxidationLight Flavour and odour lossPhysical damage

TYPES OF PACKAGE

CARTONSCartons made from paperboard, coated with wax or polyethylene, coated paper overwraps are common.The coating gives the board water-resistant characteristics which are useful for wet products.The carton itself gives physical protection Protection against moisture and oxygen transfer is provided by a barrier overwrap or a sealed inner pouch or liner.

DIRECT FILM WRAPS AND BAGSFilm materials vary from unsupported polyethylene and polypropylene films to laminates of polyethylene, polypropylene or polyester.Coating the films with polyvinylidene chloride copolymers may further increase the barrier properties.

BOIL-IN-BAG PACKSThe products are packaged in bags in which they are intended to be cooked before opening and in addition they usually have an outer carton.Foods which produce a strong odour during cooking (e.g. kippers) can be cooked very conveniently in boil-in-bag packages.Examples of various materials which can be used for boil-in-bag products are high density polyethylene and polypropylene.

OVERWRAPPED TRAYSMoulded pulp trays are still in use for the packaging of small cuts of meat, poultry, etc., but expanded polystyrene trays which look whiter and cleaner are a more attractive alternative. Aluminium foil, pressed into a tray form, is also used, particularly for pre-cooked fruit and meat pies.Trays may be internally coated for protection.

PACKAGING MATERIALS FOR DIFFERENT PRODUCTS1. FROZEN POULTRY:Materials used include vacuum grades of PVdC copolymer film, a range of laminates, deep freezing grades of polyethylene and other deep freeze films. 2. FROZEN FISH:For packaging raw, filleted, fish portions, polyethylene films are often used either in the form of pre-made bags or for wrapping on form-fill-seal machines. A PVdC copolymer system is also used in vacuum-packaging some fish such as whole frozen salmon.

3. FROZEN FISH PRODUCTS: 12 m polyester film for items such as fish cakes, in pillow pack style on horizontal form-fill-seal machines. The film is laminated with 50 m polyethylene, which gives an excellent printed effect. 4. FROZEN FRUITS AND VEGETABLES:Plastic films, such as deep freeze grades of polyethylene, made into pillow packs on vertical form-fill-seal machines. Some soft fruits, such as raspberries, are packaged in lidded plastic containers

5.FROZEN EGG AND EGG PRODUCTS:Frozen egg and egg products - in large containers of 10-15 kg capacity, Cans, cartons and plastic bags. Drums with plastic bags are used for bulk shipments.

6.FROZEN DESSERTS:Cartons Thermoformed high-impact polystyrene (HIPS) containers often with printed board inserts.

7.ICE CREAMS:Plastics containers are the main packs. There is also a growing demand for paperboard cartons The printed carton blanks are polyethylene-coated inside, freeze-varnished on the outside and have hood cover closures to give the reclosable feature essential in this type of pack.

8.Cook-freeze products Packaging materials must withstand low and high temperatures Protect the combinations of foods contained in the pack. Aluminium trays as well as ovenable cartons and plastics are commonly used

IFST Guidelines for frozen food packsInclude a moisture vapour barrier to prevent dehydration and weight loss Carry storage instructions Include production date, process details, etc. for easy identification at a later date when repacking occurs Include 'use before' dates on consumer packs

REFERENCE...A Handbook of Food Packaging - Frank A. Paine , Heather Y. Paine Food Packaging ,Principles and Practice - Gordon L.Robertson

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