Step 1: Understanding the Concept:
Cold-tolerant (psychrotolerant) molds can slowly grow on the surface of frozen meat during long-distance transportation or storage at sub-freezing temperatures (\(-5^\circ\text{C}\) to \(-9^\circ\text{C}\)).
This microbial growth causes distinct surface defects and spoilage.
Step 2: Detailed Explanation:
When meat is stored or transported at sub-freezing temperatures, bacterial growth is completely inhibited.
However, certain psychrotolerant molds can tolerate low water activity and sub-zero temperatures, allowing them to grow slowly on the meat surface.
The most common mold responsible for producing circular, black colonies known as "black spot" spoilage on frozen beef, mutton, or lamb is *Cladosporium herbarum*.
The black coloration is caused by the dark melanin pigments present in the mold's mycelium and spores.
While these black spots do not produce harmful toxins, they ruin the appearance of the meat, make it unappealing to consumers, and require deep trimming before sale.
Other psychrotolerant molds can cause different defects, such as "white spot" (caused by *Sporotrichum carnis*) and "whisker" growth (caused by *Thamnidium chaetocladioides*).
Therefore, *Cladosporium herbarum* is the primary cause of black spot spoilage.
Step 3: Final Answer:
The psychrotolerant mold responsible for black spot spoilage in frozen meat is *Cladosporium herbarum*, which corresponds to Option (C).