Page 179 - Agriculture_Form_3
P. 179
Agriculture for Secondary Schools
4. Conduct the Clot-on-Boiling (CoB) test by heating a small amount of milk
over a flame. Observe if the milk curdles or remains smooth. Record your
observation.
5. Carry out the alcohol test by mixing a small portion of milk with an equal
FOR ONLINE READING ONLY
amount of alcohol in a test tube or glass. Shake gently and observe whether
the milk remains smooth or forms lumps. Record the result.
6. (If facilities allow or are available) Observe a demonstration of the Methylene
blue or Resazurin test, or watch a video showing how these tests are conducted
to detect bacterial load in milk. Discuss how colour changes relate to milk
freshness.
7. Record all your observations in a result table and identify which milk samples
are suitable or not suitable for processing.
Milk processing
Although most of the milk sold from farms is raw, such milk is unsafe, and it
spoils quickly due to microbes. To make it safer and increase its value and shelf
life, milk is processed into other products. Processing methods range from simple
heat treatment at home to advanced techniques in large factories. Even small-
scale farmers and youth groups can process milk into basic products like mala,
yoghurt, ghee, and butter using simple tools. This helps reduce spoilage, improve
nutrition, and bring extra income.
In commercial milk processing plants, milk goes through several steps to ensure
safety and quality. These include receiving and storing, clarification (removing
dirt), and pasteurisation, that is, heating milk to 63 – 72 ℃ briefly to kill harmful
microbes without changing the taste of milk. Ultra-high temperature (UHT)
treatment is also used in some factories. This heats milk to 135 - 150 ℃ for a
few seconds, allowing it to last longer without refrigeration. Figure 9.12 shows a
flow chart of these main steps in commercial milk processing and how the final
products are distributed.
170 Student’s Book Form Three
17/09/2025 14:12
AGRICULTURE F3.indd 170 17/09/2025 14:12
AGRICULTURE F3.indd 170
