Principle of Size Reduction in Food Processing
1. Introduction to Size Reduction in Food Industry
Size reduction is a fundamental operation in food processing that involves breaking down large solid food particles into smaller units. It enhances downstream processes like extraction, blending, heat transfer, and improves product quality and processing efficiency.
Also known as comminution, this operation includes various mechanical processes such as crushing, grinding, milling, mincing, and dicing. It plays a crucial role in food manufacturing operations handled by food processing consultants and engineering design experts across various industries.
2. The necessity of size reduction
Food and beverage manufacturers often consult with food manufacturing consultants to optimize size reduction processes for several benefits:
Key Objectives of Size Reduction:
- Increase surface area for improved heat and mass transfer
- Facilitate leaching and solvent extraction
- Enhance product solubility, dispersion, and dissolution
- Enable uniform mixing in solid-solid operations
- Achieve commercial particle size specifications
- Improve packaging, storage, and stability
3. Size reduction procedures
a. Compression:
Working Principle: Two horizontally mounted cylindrical rollers rotate; material is drawn in through the nip and crushed.
Applications: Crushing seeds before oil extraction, bruising soft tissues to aid solvent penetration.
Industry Use: Food oil processing, animal feed manufacturing
b. Impact: Working Principle: Rotating shaft with hammers strikes the material; product escapes through a screen after sufficient size reduction.
Applications: Milling cereals, flour production
Industry Use: Grain processing, pulse flour production, feed manufacturing
c. Cutting: Working Principle: Rotor with knives cuts material against stationary knives; size reduced based on screen size.
Applications: Reducing size of roots, peels, soft plant materials before extraction
Industry Use: Fruit and vegetable processing, waste minimization
d. Attrition: Working Principle: High-speed rotor-stator mechanism creates intense shear forces, resulting in fine emulsification and homogenization.
Applications: Ultra-fine grinding of semi-liquid foods like sauces, purees
Industry Use: Pharmaceutical food, dairy, confectionery, nut paste manufacturing
4. Properties of Comminuted Products
Reduction Ratio = Average feed size / Average product size
- Coarse crushers: Up to 8:1
- Fine grinders: Up to 100:1
- Sphericity is used to evaluate particle shape (value ranges between 0.6–0.7 for irregular particles)
- Particle size distribution and consistency are critical parameters in food quality control, often evaluated by food industry consultants.
5. Conclusion
Size reduction is vital for enhancing the efficiency, functionality, and commercial viability of food products. From food engineering consulting to equipment layout planning, this process underpins many food manufacturing operations. It supports innovation and efficiency by:
- Enabling uniformity in food texture and appearance
- Facilitating efficient processing and cost savings
- Boosting product shelf life and consumer acceptance
With advancements in food processing technology, consultancy for food industry projects often involve tailoring size reduction operations to meet hygiene standards, throughput goals, and specific product characteristics.
6. Reference
Schematic of Colloid Mill – Wikimedia
Why do we need size reduction at all if our product spec doesn't demand a fine powder?
Which size reduction method should I use for oilseeds before extraction?
How is particle size controlled in a hammer mill for flour production?
What equipment principle suits sauces, purees and nut pastes?
What reduction ratio can I realistically expect from a crusher versus a fine grinder?
How do we judge whether the comminuted product is acceptable?
PMG Engineering. (2023). Principle of Size Reduction in Food Processing. PMG Engineering. https://pmg.engineering/Article/191/principle-of-size-reduction-in-food-processing/