SOP: Determination of Water Capacity of Containers

GIFSQ — Global Institute for Food Safety & Quality

Principle

The water capacity of a container is the volume of distilled water at 20 °C which the sealed metal or glass container will hold when completely filled; it is found by weighing the empty container and the container filled with distilled water at 20 °C.

Apparatus required

• Weighing balance

Reagents

a. Distilled water at 20 °C.

Procedure — Metal containers

Wash, dry, and weigh the empty container after cutting out the lid without removing or altering the height of the double seam (A); select a container which is not damaged in any respect

↓

Fill the container with distilled water at 20 °C to 4.8 mm vertical distance below the top level of the container, and weigh the container thus filled (B)

↓

The difference in weight between B and A is considered the weight of water required to fill the container; note the volume of the water, and express the water holding capacity in ml of water

Procedure — Containers with lid attached otherwise than by double seaming

Remove the lid and proceed in the same way, except that the container is filled with water to the top

Procedure — Glass containers

Wash and dry an empty container undamaged in all respects, and note the weight (A)

↓

Fill the container with distilled water at 20 °C up to the top of the container, and weigh again (B)

↓

Calculate and express the results as in the case of metal containers

Calculation

Water capacity (ml) = weight of container filled with distilled water at 20 °C − weight of empty container

Where,
– A = weight of the empty container
– B = weight of the container filled with distilled water at 20 °C

Precautions

• Use a container that is not damaged in any respect.
• When cutting out the lid of a metal container, do not remove or alter the height of the double seam.
• Fill with distilled water at 20 °C.

References

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

FAO/WHO Codex Alimentarius Commission, CAC/RM 46-1972 — cited in the book.