Overview of Cold Renneting in Casein Manufacturing
Rennet casein is produced through the chemical coagulation of skim milk, primarily using rennet enzymes. This form of casein manufacturing yields a protein with high nutritional content, a bland taste, and exceptional suitability for industrial and food applications. Rennet casein is used in producing cheese substitutes, processed cheese, and even casein-based plastics.
Due to the high cost and limited availability of traditional calf rennet, modern industries now utilize alternatives such as microbial rennets, bovine gastric extracts, and porcine pepsin. These enzymes offer similar coagulation properties, making them valuable in food processing consultancy services and cheese analog development.
Rennet Action: How Coagulation Happens
The enzymatic activity of rennin (chymosin) causes casein coagulation in two steps:
- Hydrolysis of the Phe-Met bond in κ-casein, forming para-κ-casein and glycomacropeptide.
- In the presence of calcium ions, para-κ-casein forms a three-dimensional clot—the basis of casein curd formation.
This mechanism is crucial in dairy processing, especially for companies guided by food processing consultants and engineering design experts.
Traditional Batch Manufacturing of Rennet Casein
Milk Preparation and Coagulation
High-quality, low-acidity skim milk is selected for its calcium content and microbial quality. Pasteurization is carried out at 72°C for 15 seconds, followed by cooling to 31°C. Calf rennet (1:4500) is added to induce setting within 20–30 minutes.
Cutting, Cooking, and Dewheying
- Cutting: Coagulated milk is sliced with cheese blades.
- Cooking: The curd is gently stirred while heating to 50–60°C.
- Dewheying: After curd cooking, whey is drained to isolate the rennet casein.
This stage helps achieve optimum texture and reduce fines loss, crucial in large-scale food manufacturing consultancy operations.
Washing and Dewatering Process
Washing removes lactose, whey proteins, and minerals using a four-stage temperature-controlled process (30°C → 60°C → 75°C → 30°C). Post-wash, mechanical presses are employed for dewatering, reducing moisture content to 60–70%.
Such optimization is common in operations supported by food technology consulting firms seeking high-efficiency in casein recovery.
Continuous Manufacturing of Rennet Casein
Modern Process Flow
In the continuous process, skim milk is combined with rennet (1:7000 to 1:8175) in large silos. Once coagulation occurs, the curd is stirred and pumped into cooking pipes where steam raises the temperature to 50–55°C. The mixture then undergoes:
- Rapid syneresis
- Whey separation
- Standard lactic acid casein processin
Advantages of the Continuous Method
- Reduced enzyme and steam usage
- Lower labor costs
- Higher throughput
- Improved energy efficiency—ideal for food industry consultants managing greenfield food projects
Impact of Process Variables on Casein Plastic Quality
Color Control in Casein Plastics
Key influencing factors:
- Milk heat treatment → Darker casein plastics
- Inadequate washing → Higher lactose → Brown discoloration
- High iron content → Reddish hue in finished plastics
Food engineering consultants recommend unpasteurized milk and controlled washing conditions to ensure better plastic clarity and performance.
Conclusion: Role of Cold Renneting in Food Manufacturing
Cold renneting remains a vital method for high-quality casein production in both batch and continuous systems. From enzyme selection to curd processing, every step must be carefully managed—making this topic crucial for food business consultants, dairy plant designers, and engineering professionals in the food sector.
Back 
PMG stands for Projects Management Group. We provide state-of-the-art Engineering Services to build world-class food processing factories. 
Engineering is the difference between Chaos and Excellence. If you are going to do it, do it right. 
Explore the diverse range of Products in the Food Processing Industry. 
Explore the technologies at the heart of the the Food Processing Industry. 
