Question:
The defect, known as "mould buttons" in sweetened condensed milk is caused by :
The defect, known as "mould buttons" in sweetened condensed milk is caused by :
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To prevent mold buttons, canned condensed milk must be packaged under a vacuum or an inert gas headspace to deprive any mold spores of the oxygen required for germination.
Updated On: Jul 21, 2026
- Aspergillus repens
- Aspergillus niger
- Torulalactis condense
- Mycobacterium tuberculosis
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The Correct Option is A
Solution and Explanation
Step 1: Understanding the Concept:
Sweetened condensed milk is preserved by its high sugar concentration, which creates high osmotic pressure that inhibits most bacterial growth.
However, certain osmophilic or xerophilic microorganisms can still cause spoilage if oxygen is present in the container headspace.
Detailed Explanation:
"Mould buttons" are firm, colored (brown, reddish, or yellow) button-like masses of mold mycelia that form on the surface of sweetened condensed milk during storage.
This defect is primarily caused by Aspergillus repens (and sometimes certain species of Penicillium).
These molds are xerophilic, meaning they can grow in environments with low water activity (\(a_w\)).
If small amounts of air are left in the headspace of the can during packaging, these mold spores germinate on the surface of the milk.
As they grow, they produce enzymes that coagulate the proteins locally, forming the characteristic firm "buttons."
Let us review the other options:
- Aspergillus niger: A common mold, but not typically associated with the formation of buttons in condensed milk.
- Torulalactis condense (or Torulopsis): A yeast species that can cause gaseous fermentation (blowing of cans) but does not form mold buttons.
- Mycobacterium tuberculosis: A pathogenic bacterium that does not grow in condensed milk.
Step 2: Final Answer:
The mold button defect in sweetened condensed milk is caused by Aspergillus repens.
Sweetened condensed milk is preserved by its high sugar concentration, which creates high osmotic pressure that inhibits most bacterial growth.
However, certain osmophilic or xerophilic microorganisms can still cause spoilage if oxygen is present in the container headspace.
Detailed Explanation:
"Mould buttons" are firm, colored (brown, reddish, or yellow) button-like masses of mold mycelia that form on the surface of sweetened condensed milk during storage.
This defect is primarily caused by Aspergillus repens (and sometimes certain species of Penicillium).
These molds are xerophilic, meaning they can grow in environments with low water activity (\(a_w\)).
If small amounts of air are left in the headspace of the can during packaging, these mold spores germinate on the surface of the milk.
As they grow, they produce enzymes that coagulate the proteins locally, forming the characteristic firm "buttons."
Let us review the other options:
- Aspergillus niger: A common mold, but not typically associated with the formation of buttons in condensed milk.
- Torulalactis condense (or Torulopsis): A yeast species that can cause gaseous fermentation (blowing of cans) but does not form mold buttons.
- Mycobacterium tuberculosis: A pathogenic bacterium that does not grow in condensed milk.
Step 2: Final Answer:
The mold button defect in sweetened condensed milk is caused by Aspergillus repens.
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