The pH of condensed milk typically ranges from 6.2 to 6.85, making it slightly acidic. This acidity is influenced by the natural pH of milk, the effects of processing, and the addition of sweeteners. Understanding the factors that contribute to the pH of condensed milk is crucial for maintaining its quality and stability.
Natural pH of Milk
Milk has a natural pH of around 6.5 to 6.7, which is slightly acidic. This acidity is due to the presence of various compounds, such as casein, phosphates, and citrates, in the milk.
Effects of Processing
The process of evaporating milk to create condensed milk can lead to a decrease in pH. This is because the concentration of milk increases the activity of hydrolase enzymes, which can break down lactose and other milk components, releasing hydrogen ions and lowering the pH.
Sweetening
The addition of sweeteners, such as sucrose, can also affect the pH of condensed milk. Refined sucrose does not alter the milk pH, but unrefined sugars with high ash content, like brown sugar, can cause a decrease in pH due to the mineral content of the sugar.
Stabilization
To prevent protein precipitation and maintain the stability of condensed milk, alkaline salts like disodium phosphate or calcium acid lactate can be added to adjust the pH of the uncondensed sweetened milk to within the range of 6.75-6.85 before boiling.
Composition
The approximate composition of sweetened condensed milk includes:
| Component | Percentage |
|---|---|
| Fat | 8-9% |
| Non-fat milk solids | 20-22% |
| Lactose | 10-11% |
| Sucrose | 43-45% |
| Moisture | 25-27% |
The high sugar content of condensed milk contributes to its acidic nature.
Quality Control
Maintaining the pH of condensed milk within the range of 6.2 to 6.85 is crucial for its quality and stability. Other important quality parameters include titrable acidity, fat, protein, ash, and carbohydrate content, which can vary depending on the production process and ingredients used.
Conclusion
The pH of condensed milk is influenced by a combination of factors, including the natural pH of milk, the effects of processing, the addition of sweeteners, and the use of stabilizing agents. By understanding these factors and maintaining the appropriate pH range, manufacturers can ensure the quality and stability of their condensed milk products.
References:
1. Jouki, M., Jafari, S., Jouki, A., & Khazaei, N. (2021). Characterization of functional sweetened condensed milk formulated with flavoring and sugar substitute. Food Science & Nutrition, 9, 5119–5130. 10.1002/fsn3.2477
2. US4362756A. (1981). Brown sugar sweetened condensed milk and process for preparing same.
3. A Study on the Quality of Sweetened Condensed Milk Available in the Local Market of Bangladesh. (n.d.). ResearchGate.
4. Condensed Milk – an overview | ScienceDirect Topics. (n.d.). ScienceDirect.
5. Why is evaporated milk slightly more acidic than normal milk? – Quora. (2017, October 25). Quora.