Week 7 - Size Reduction, Shape & Size Sorting

Vocabulary flashcards for size reduction, shape and size sorting.

Size Reduction (Comminution)

Reducing the average size of solid pieces using grinding, shearing, compression, adhesion, and impact forces.

Homogenization

Reducing the size of globules in immiscible liquids (e.g., oil and water).

Elastic Stress Limit

The critical stress level beyond which permanent deformation occurs in a food.

Breaking Point

The point at which a food fractures along its lines of weakness when force is applied.

Toxin

Dust created during size reduction that poses health hazards.

Compression (Size Reduction Mechanism)

Pressing food between two solid surfaces, best for soft or friable materials.

Impact (Size Reduction Mechanism)

Striking a particle with a fast-moving solid object, best for hard, crystalline, or amorphous foods.

Attrition (Size Reduction Mechanism)

Rubbing/friction between particles and a hard surface, best for tough or resilient foods.

Shearing (Size Reduction Mechanism)

Cutting food using a sharp blade, best for elastic, pliable, or fibrous materials.

Ball Mills

Rotating steel/ceramic balls in a horizontal cylinder, used for fine powders.

Disc (Plate) Mills

Vertical steel plates grind food from the center to periphery, used for crystalline, oily, and heat-sensitive foods.

Hammer Mills

Chamber with swinging hammers, combining impact and attrition forces, used for spices, cereals, legumes, sugar.

Jet-Pulverising Mills

Uses air jets to circulate food at near-sonic speed, suitable for heat-sensitive foods, used for sugar, salt, cocoa powder.

Roller Mills

A pair of small steel rollers revolve towards each other, crushing food between smooth rollers, used for wheat, oats, other cereals.

Pulping Equipment

Uses compression and shearing forces for juice extraction, oil extraction, purees, pulps.

Homogenization

Reduces particle size to 0.5–30 µm in liquid foods, applying intense shearing forces.

Membrane Emulsifier

Uses nano-porous membranes with uniform pore size and spacing to produce droplets with a narrow size distribution.

Pressure Homogeniser

Uses a high-pressure pump to force liquid through an adjustable gap, producing shearing forces and cavitation.

Rotor-Stator Homogenizers

High-speed mixer using turbines/propellers or forcing food through holes between rotating and stationary elements, produces shearing forces.

Ultrasonic Homogeniser

Uses sound waves to create alternating pressure-compression cycles causing cavitation, resulting in reduced particle size.

Sorting

Separates foods based on a single measurable physical property (e.g., size, shape, weight, colour).

Grading

Evaluates overall quality using multiple attributes

Screen Sorters

Screens with fixed or variable apertures to sort by size.

Disc or Cylinder Sorters

Use shape-specific indentations to pick up correct shapes during rotation.