Model Answer
0 min readIntroduction
Neutralization of cream is a crucial step in dairy processing, particularly in butter manufacturing, where raw cream often develops acidity due to the conversion of lactose into lactic acid by bacterial action. This acidity, if not controlled, can negatively impact the flavor, texture, and shelf-life of the final product, lead to excessive fat losses during churning, and cause curdling during heat treatment like pasteurization. The process involves adding alkaline substances to partially reduce this developed acidity, bringing the cream's pH closer to a neutral range, thereby enhancing its stability and sensory characteristics.
Purpose of Cream Neutralization
The primary objectives of cream neutralization are multifaceted and critical for producing high-quality dairy products, especially butter:
- Reducing Fat Loss: High acidity in cream can lead to increased fat losses in buttermilk during churning, as casein entraps fat globules, causing them to be lost with the buttermilk. Neutralization helps minimize this.
- Improving Flavor and Uniformity: Excessive acidity can result in undesirable off-flavors (e.g., sour or fishy notes) in butter. Neutralization helps to achieve a more consistent and desirable flavor profile.
- Enhancing Keeping Quality: Butter made from high-acid cream deteriorates faster during storage. Neutralization to a suitable pH (typically 6.7 to 7.2 in butter serum) significantly improves its shelf stability.
- Preventing Curdling: During pasteurization, high-acid cream is prone to curdling, which can damage processing equipment and affect product quality. Neutralization stabilizes the cream against heat coagulation.
Types of Neutralizing Agents
Alkaline compounds, commonly referred to as neutralizers, are used to reduce cream acidity. They are broadly classified into two types:
- Lime Type Neutralizers: These include calcium oxides (quick limes), dolomitic or magnesium limes (magnesium and calcium oxides), and hydrated limes (slaked limes). Lime neutralizers are only partially soluble and are used as suspensions. They are generally stronger alkalis but can increase cream viscosity and may cause scorching if not used carefully. The neutralizing action of lime is also partially consumed by reacting with casein and phosphate, reducing its effective neutralizing capacity.
- Soda Type Neutralizers: These are more frequently used and include sodium bicarbonate (baking soda), sodium carbonate (soda ash), caustic soda, and sodium sesquicarbonate. Soda neutralizers are generally preferred due to their better solubility and ease of handling. They react with acids to form salt, water, and carbon dioxide.
Process of Neutralization
The neutralization process involves several key steps to ensure effective acidity reduction without compromising cream quality:
- Acidity Testing: The initial titratable acidity of the cream is determined (typically by titration with standard alkali using phenolphthalein indicator) to calculate the amount of neutralizer needed.
- Calculation of Neutralizer: The quantity of neutralizer is precisely calculated based on the cream's initial acidity, desired final acidity, and the neutralizing factor of the chosen alkali.
- Preparation and Addition: Neutralizers should never be added dry. They are diluted in clean potable water (10-15 times) to form a solution or suspension. This diluted neutralizer is then added slowly and evenly to the cream, ideally when the cream temperature is between 29°C to 32°C (85-90°F), with continuous vigorous stirring for 5-10 minutes to ensure uniform mixing and prevent localized over-neutralization.
- Double Neutralization: For high-acid cream, a "double neutralization" method may be employed. This involves reducing the acidity in two stages, sometimes using a strong neutralizer (like lime or caustic soda) first to bring the acidity down to 0.3-0.4% lactic acid, followed by a milder soda neutralizer after pasteurization and cooling. This helps in managing carbon dioxide release and reducing intense flavor effects.
- Post-Neutralization Pasteurization: After neutralization, the cream is usually pasteurized. Pasteurization further helps in completing the neutralization process by expelling carbon dioxide and destroying microorganisms.
Conclusion
Neutralization of cream is a fundamental practice in dairy technology, particularly for butter production, aimed at controlling acidity to ensure product quality, extend shelf life, and optimize processing efficiency. By carefully selecting and applying appropriate alkaline agents like lime or soda compounds, dairy processors can mitigate issues such as fat loss during churning and off-flavor development. This meticulous pH management ultimately contributes to consumer satisfaction and economic viability in the dairy industry, underscoring its importance in the manufacturing of various cream-based products.
Answer Length
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