Introduction to Dairy Plant Technology
An overview of the key concepts, processes, and equipment used in modern dairy processing facilities.
1. What Is a Dairy Plant?
| Aspect |
Description |
| Definition |
A facility where raw milk is transformed into a range of safe, stable, and market‑ready dairy products (milk, cream, cheese, yogurt, butter, powders, etc.). |
| Core Objectives |
• Preserve nutritional value
• Extend shelf‑life
• Ensure microbiological safety
• Achieve consistent product quality |
| Typical Scale |
Small‑holder plants (≤ 10 t / day) → Large integrated complexes (> 10 000 t / day). |
2. Main Stages of Dairy Processing
-
Milk Reception & Preliminary Checks
- Sampling & Testing: temperature, pH, fat, protein, bacterial count, antibiotic residues.
- Cooling: rapid reduction to ≤ 4 °C (often 2 °C) to inhibit microbial growth.
-
Standardization & Adjustment
- Fat & Solids‑Not‑Fat (SNF) Adjustment: blending skimmed and cream milk to meet product specifications.
- Addition of Ingredients: vitamins, minerals, stabilizers, cultures, enzymes.
-
Heat Treatment
- Pasteurisation: 72 °C for 15 s (HTST) or 63 °C for 30 min (LTLT).
- UHT (Ultra‑High‑Temperature): 135–150 °C for 2–5 s → extended shelf‑life (up to 6 months).
- Sterilisation/Retort: > 120 °C for longer periods for canned dairy.
-
Separation & Clarification
- Centrifugal Separators: split cream from skim milk.
- Clarifiers / Filters: remove sediments, spores, and stray fat globules.
-
Homogenisation
- Purpose: break fat globules to 1–5 µm, preventing cream separation and improving mouthfeel.
- Typical Pressure: 15–25 MPa (2,000–3,600 psi).
-
Fermentation / Coagulation (Product‑Specific)
- Yogurt & Cheese: inoculation with starter cultures, addition of rennet, controlled temperature & pH.
- Butter: churning of cream to aggregate fat globules.
-
Aging / Ripening (Cheese)
- Controlled temperature (4–15 °C) and humidity (80–95 %).
- Development of flavor, texture, and rind.
-
Packaging
- Primary: aseptic cartons, PET bottles, glass, plastic tubs, foil‑wrapped cheese blocks.
- Secondary/Outer: cartons, shrink‑wrap, pallets.
-
Cold Chain & Storage
- Refrigerated Warehouses: 0–4 °C for fluid products, –18 °C for frozen or powdered forms.
- Logistics: insulated trucks, temperature‑monitored distribution.
3. Core Equipment & Their Functions
| Equipment |
Primary Function |
Typical Process Parameters |
| Milk Cooling Tank |
Rapidly lower milk temperature after reception |
2–4 °C, flow rate 0.5–2 |