Canning and Fish Packaging Technology

Unit 5 - Changes in canned foods and spoilage

5.1.1.2.Undesirable changes

• Loss of amino acid
• Loss of vitamins
• Fat oxidation rancidity

By adopting good manufacturing practice, these can be minimized.

Other changes are,

• Non-enzymatic browning reactions
• Drying and browning solids at the top end
• Retort burn in foods adhered to can surface
• Sulphide blackening in tuna, shrimp and crab meat due to presence of cystine, sysn and methionine (sulphur containing amino acids reacting with tin & iron to form sulphides).
• Internal corrosion by electrochemical reaction catalysed by oxygen and acid, as a result tin and iron gets into foods giving metallic taste to the product. Also, hydrogen is produced and reduces vacuum. If metal content exeeds certain limits the product becomes unacceptable.
• Loss or absorption of moisture by the solids in the pack. These changes lead to alteration in net weight of solids and generally observed in shrimp cans.