Freezing Technology

7.3.1 Vaccum packaging

• It is a viable technology in seafood processing.
• It is wide spread in the meat industry for fresh, processed and cured products but has faced difficulties in its application to seafood.

Condition in the vaccum package

It is brings several changes

1. A drastic reduction in O₂ content
2. An increase in CO₂
3. Increase in acidity

Advantages:

•  It increase the shelf life of fish (ie., It is very good barrier to O₂)
• Variety of spoilage organisms is substantially decreased
• Microbial growth is prevented entirely (Partially)

Packaging Materials

Light, water, heat, O₂, bacteria and are consider to be an affecting factors in this packaging.

Light

The length of the exposure, the wave length and intensity of light and permeability of the package to the light affect nutrients.

Temperature

This type of packaging material greatly affect the rate at which heat i.e. transferred to and from the food.

This is important for both refrigerated and frozen seafood.

Insulating containers like Styrofoam food trays greatly reduce the transfer of heat of the fish.

Oxygen

Excessive amount of O₂ promote seafood deterioration through the oxidation of fats, the degradation of some amino acids and the destruction of certain vitamins.

The effects of O₂ are related to the atmosphere pressure,humidity and temperature.

Exposure of the package contents to O₂ may occur through loose closure, puncture and or diffusion through the packaging materials itself. Permeability of O2 also affected by the moisture and temperature.

Disadvantages of vaccum packing

Ø   Doesn’t ensure free from microbial activity.

Ø   The O₂ impermeable materials required are relatively expensive and  appropriate equipment is needed.