Step 1: Understanding Butter Overrun:
Butter overrun is the percentage increase in butter weight relative to the milk fat used. This increase results from incorporating moisture, salt, and curd during churning.
Step 2: Overrun Calculation:
The overrun percentage is calculated as follows:
\[ \text{Overrun \%} = \frac{\text{Weight of Butter} - \text{Weight of Fat Used}}{\text{Weight of Fat Used}} \times 100 \]
Step 3: Overrun Example and Legal Standards:
Regulations (e.g., FSSAI in India) mandate butter to contain at least 80% milk fat. The remaining 20% comprises water (up to 16%), salt (up to 3%), and curd.
Consider producing 100 kg of butter with exactly 80% fat.
This butter contains 80 kg of fat and 20 kg of non-fat components.
Applying the formula:
\[ \text{Weight of Butter} = 100 \, \text{kg} \]
\[ \text{Weight of Fat Used} = 80 \, \text{kg} \]
\[ \text{Overrun \%} = \frac{100 - 80}{80} \times 100 = \frac{20}{80} \times 100 = 0.25 \times 100 = 25\% \]
This 25% represents the theoretical maximum overrun at 80% fat. Commercial butter typically has a slightly lower overrun, around 21-23%, due to manufacturers targeting slightly higher fat contents for safety.
Step 4: Commercial Overrun:
Typical commercial butter overrun is 21-23%, balancing yield and regulatory compliance.