SOP: Determination of Net Weight of Frozen Foods

GIFSQ — Global Institute for Food Safety & Quality

Principle

The net weight of the contents of a frozen package is obtained gravimetrically: the frozen package is weighed with its frost and ice, then the contents (including product particles and frost crystals) are removed, the empty package is air-dried, and the difference gives the net weight.

Apparatus required

• Scale of adequate capacity with a sensitivity of 0.01 oz (for packages up to 5 lb)
• Scale of adequate capacity with a sensitivity of 0.025 oz (for packages above 5 lb)

Procedure

Set the scale on a firm support and level it

↓

Adjust the zero-load indicator or rest point and check the sensitivity

↓

Remove frost and ice from the outside of the package, which has been stored in the low temperature storage room, and weigh immediately (A)

↓

Open the package and remove the contents, including any product particles and frost crystals

↓

Air-dry the empty package at room temperature and weigh it (B)

Calculation

Net weight of contents = A − B

• Where,
• A = weight of the frozen package with contents, in the same units
• B = weight of the empty air-dried package, in the same units

Precautions

• Weigh the frosted package immediately after removing it from the low temperature storage room, before the frost melts.
• Remove all product particles and frost crystals from the package before air-drying it.

References

Ranganna, S., Handbook of Analysis and Quality Control for Fruit and Vegetable Products, 2nd edition.