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Frozen Food |
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APPLICATION AND STRUCTURE
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| 1. |
Frozen Food |
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1.1) |
Consumption of the frozen food |
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In Japan, it is expected that the consumption of frozen food will be increase more and more in future with the diffusion of microwave oven and changing of life style. More than 10 millions MT per year of the frozen food has been consumed in USA that is the advanced nations of the frozen food. Also, consumption is increasing all over the world especially in western countries and Indonesia.
Not only the progress of freezing technology but also the changing of live environment and the increase of import food exert a influence of the growth of the frozen food in Japan in recent years. For example, fish, shrimp, squid, broiler, barbecue, pea, mixed vegetables, these are import food from south east Asia countries. |
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| 2. |
Production Process of Frozen Food |
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2-1) |
Production process of frozen food |
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- Materials : Sea food, Agricultural products, Meats, etc.
- Pre treatment : selection, cleaning, measurement.
- Cooking : Mixing, Boil, Steam, Fry, Seasoning, Flavoring, etc.
- Freezing : Lower than -15 oC
- Packing : Filling, Pack Up, etc.
- Products : Freezed preservation, distribution
*Depend on the product no 4) and 5) would be change |
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2-2) |
Packaging style for frozen food |
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According as the contents, there are various kind of packaging style and packaging method for frozen food.
In case of (A), frozen products are packed in corrugated fibre board directly. (B) and (C), it is popular type of packaging that the frozen products are packed in outer package individually with or without tray, and then packed in cardboard box. (D) and (E), the frozen products are packed bubble using flexible packaging pouch and carton box, in this case tray located with frozen products sometimes.
(1) Tray
Croquette, fried foods, dumpling, shaomai, etc. are packed in trays with formfitting individual food separations to prevent collapse.
The materials for plastics tray are PS, PP, PE.
It is tendency for tray to recycle or no using from the environmental issue and resources saving in Japan.
(2) Inner, outer package
As for inner package and outer package, they have two type of package (flexible package, rigid container)
PE bag was major product for flexible package in the early years of packaging history, but recently many kind of materials and construction are used for it. Also durable laminated film and beautiful photographic printed package are becoming popular.
Furthermore, aluminium metallized film which has O2 barrier, light resistance and high grade impression are used, boil in bag and/or cook in pouch or flexible package which has excellent heat resistance are used also. It is main packaging form that the three sided seal, pillow type which has tray.
(3) Carton box
Cardboard box which has heat insulation, durability strength and water resistance is popular for frozen food package. |
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| 3. |
Required capability of the materials for frozen food |
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(1) Gas barrier properties
(2) Light shield performance
(3) Low temperature resistance
(4) Aroma preservation performance
(5) Heat sealing performance
(6) Heat resistance |
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3-1) |
Barrier performance for packaging materials |
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Generally, it required for frozen food that the safety preserving term should be more than one year under the condition of around -25 oC. Sublimation of water vapor from the food surface is one of the major reason for the quality deterioration of frozen food. O2 gas barrier is important for the quality keeping also. PE and PP have excellent water vapor barrier, ON and PET have excellent O2 gas barrier, if it required furthermore performance for O2 gas barrier, PVDC coated film or aluminium metallized film are used.
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3-2) |
Light shield performance |
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Ultraviolet shield performance is required in order to prevent food-quality deterioration by oxygen contact or driving by water evaporation. Generally printing is popular method for light shield, but if it required excellent light shield performance, aluminium metallized film are used. |
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3-3) |
Low temperature resistance |
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For keeping the quality of frozen food, puncture strength especially pin-hole resistance is important than gas barrier performance and light shield performance. In case of vacuum packaging, if the pin-hole will happen, quality deterioration by oxygen contact or water vapor evaporation will occur. Therefore, it is very important for keeping the quality to prevent the damage of the packaging. Also low temperature resistance is required strongly, because the preservation system for frozen food from production process to distribution is under the freezed condition. Furthermore, pin-hole resistance, abrasion resistance and impact strength against the rough surface of contents at the low temperature condition are required.
Test Method : Punches with curvatures of 0.032 mm and 0.49 mm are pressed onto a film at rate of 100 mm/min, and the value of stress at the moment of rupture is converted into its pinhole resistance permilimeter thick.
(1) Agricultural products (vegetable)
Pin-hole resistance (prick strength, abrasion resistance, flex crack resistance), mechanical strength and low temperature resistance are required, because of the rough surface, sharp shape and comparatively heavy weight of the contents.
So, ON is quite often used as a base film, EVA and LLDPE which have low temperature resistance are often used as sealant film, and extrusion lamination method is popular for the pouch that packed frozen vegetable.
PET film and metallized film pouch which can be block light entry are used for the green vegetable (green pease, soy bean, mixed vegetable) that easily deteriorate under light.
(2) Sea foods
The edge of frozen sea food is especially sharp and that’s weight is comparatively heavy.
So, ON is quite often used as a base film, EVA and LLDPE which have low temperature resistance are often used as sealant film, and extrusion lamination method is popular.
(3) Meat
Chicken has sharp edge and that’s weight is comparatively heavy same as frozen sea foods.
So, ON is quite often used as a base film, EVA and LLDPE which have low temperature resistance are often used as sealant film, and extrusion lamination method is popular.
(4)Processed foods
In case of pouch for Japanese style pizza, fried noodle, shrimp fried rice which do not use tray, ON is quite often used for them because they require pin-hole resistance especially.
Croquette, shrimp fry, Shaomai, etc. are packed in trays with formfitting individual food separation to prevent collapse, the construction of ON/PE, PET/PE, OPP/PE (CPP) and laminated film which using metallized film are popular.
In case of pouch for meat ball, shrimp with chilli sauce, sauted mixed vegetable, high temperature resistance is required because boiling process is necessary when we eat such kind of frozen processed food . Popular construction is ON/LLDPE (dry lamination)
(5)Business uses
Generally the unit weight of business uses is 1-2kg. Inner large pouch is PE and ON/PE, outer package is cardboard box.
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