Discuss in detail about the processing of butter along with flow diagram. Enumerate the defects encountered in stored butter.

Butter Processing: A Detailed Overview

Butter production is a carefully controlled process that transforms milk or cream into a stable, palatable product. The core principle revolves around the aggregation of milk fat globules, which are initially dispersed in the milk serum.

1. Raw Material & Preparation

• Milk/Cream Source: Typically, cow’s milk or cream with a fat content of at least 35% is used. The quality of the raw material significantly impacts the final butter quality.
• Pasteurization: Cream is often pasteurized to eliminate pathogenic microorganisms and enzymes that could cause spoilage. Pasteurization typically involves heating the cream to 72°C for 15 seconds, followed by rapid cooling.
• Ripening (Optional): Some butter production processes involve ripening the cream, which introduces lactic acid bacteria to develop characteristic flavor compounds. This is more common in traditional butter production.

2. Churning

Churning is the critical step where milk fat globules coalesce to form butter granules. This process disrupts the membranes surrounding the fat globules, allowing them to join together.

• Mechanism: Mechanical agitation, typically through paddles or rotating blades, is used to disrupt the fat globule membranes.
• Temperature: Churning is usually performed at temperatures between 10-18°C. Lower temperatures promote better granule formation.
• Time: The churning time varies depending on the cream’s fat content and the churning equipment used, but it usually takes between 5-15 minutes.

3. Working (Post-Churning Treatment)

After churning, the butter exists as a mixture of butter granules, buttermilk (the aqueous phase), and residual milk fat. Working is the process of removing the buttermilk and consolidating the butter granules.

• Draining Buttermilk: The buttermilk is drained from the churn. Efficient drainage is crucial for minimizing free fatty acids in the butter, which can contribute to rancidity.
• Washing (Optional): Some butter makers wash the butter granules with cold water to remove remaining buttermilk.
• Malaxation: The butter is then subjected to malaxation – kneading and pressing – to expel any remaining buttermilk and to develop the butter's texture and plasticity. This process also helps to partially crystallize the milk fat.

4. Grain Up/Salting & Coloring (Optional)

• Grain Up: Cooling the butter after working causes the milk fat to crystallize, resulting in a granular texture.
• Salting: Salt is added to butter for flavor, preservation, and to improve its texture. The salt content typically ranges from 1.5% to 2%.
• Coloring: Annatto or other natural colorants are sometimes added to impart a desirable yellow color.

5. Packaging & Storage

The finished butter is then packaged in suitable containers and stored at refrigerated temperatures (typically below 4°C) to maintain its quality and prevent spoilage.

Flow Diagram of Butter Processing

Step	Process	Temperature (°C)
1	Raw Cream Reception & Pasteurization	72°C (Pasteurization)
2	Ripening (Optional)	10-18°C
3	Churning	10-18°C
4	Buttermilk Drainage	10-18°C
5	Malaxation	10-18°C
6	Grain Up & Salting/Coloring (Optional)	Cooling
7	Packaging & Storage	<4°C

Defects Encountered in Stored Butter

Butter is susceptible to various defects during storage. These can be broadly categorized into physical, chemical, and microbial defects.

1. Physical Defects

• Bloom: A whitish coating on the surface of the butter caused by the recrystallization of milk fat. It’s often a result of temperature fluctuations.
• Graininess: An undesirable gritty texture due to large milk fat crystals. Can be caused by slow cooling.
• Crystallization: Large, visible crystals of milk fat.

2. Chemical Defects

• Rancidity: A bitter, off-flavor caused by the oxidation of unsaturated fatty acids. Exposure to light, heat, and oxygen accelerates rancidity.
• Color Changes: Discoloration due to oxidation or the breakdown of pigments.

3. Microbial Defects

• Blowiness: Gas production within the butter due to microbial activity, leading to swelling and distortion.
• Slime Formation: A slimy texture on the surface of the butter, indicating microbial growth.

Prevention of these defects involves proper temperature control during processing and storage, minimizing exposure to light and oxygen, and maintaining high levels of hygiene throughout the production process.