Prouducts prossing Technology

Master Degree - Food & Cosmetic Products Engineering - Products Processing Technologies

• Course Instructor: Pr. Abdelilah El Abbasi
• Course Level: Master IPAC (S1)
• Course Objective: To understand food and cosmetic product processing technologies, analyze production stages, and understand the impact of technological choices on product quality. Improve efficiency, sustainability, and competitiveness of associated industries.

What is a Process?

• A process is a set of actions in a specific sequence, leading to a specific end (products and by-products).
• The number of possible processes in any manufacturing industry is enormous.
• Processes can be grouped into unit operations with similar purposes.
• Unit operations were categorized early in the 20th century.

Process Flow Diagrams

• Flow diagrams, also known as flow charts or flow sheets, are the standard graphical representations of processes.
• They show the sequence of operations, raw materials, products, and by-products.
• Additional information like flow rates, temperatures, pressures can be added.
• These are also called block diagrams due to their use of rectangular blocks (operations).

Example: Potato Chips Process Flow Diagram

• The example illustrates a potato chip production process with steps from storage to cooking.
• Key stages include washing, peeling, sorting, slicing, washing, cooking, and conveying to the final product.

Standard Symbols in Process Flow Diagrams

• Standardized symbols are used for frequently occurring equipment elements (pumps, vessels, conveyors, centrifuges, filters, etc).
• Specific symbols represent different types of equipment, facilitating process visualization (e.g., reactor, distillation column, heat exchangers, plate heat exchangers, filters/membranes, centrifugal pumps, pumps, centrifuges).

Engineering Flow Diagram

• The next stage in process development is the creation of an engineering flow diagram.
• This diagram includes secondary equipment (measurement and control systems, utility lines, piping, etc), and details of measurement and control systems.
• Used as a starting point for listing, calculating, and selecting all physical elements of a production line.
• Provides a basis for plant layout development

Plant Layout

• Plant layout (factory layout) is the most effective physical arrangement of industrial facilities, including machines and processing and service departments.
• Crucial for achieving the greatest coordination and efficiency of materials, machines, methods, and manpower in the plant.

Table of Contents of Processing Technologies

• The table lists various food and cosmetic production technologies (e.g., physical properties of materials, size reduction, filtration, centrifugation, extraction, frying, baking, roasting, crystallization, dissolution, mixing, extrusion, dehydration).
• It also covers concentration, preservation, emulsification, and structure processes, emphasizing different aspects of food/cosmetic product processing techniques.

Physical Properties of Materials

• The physical properties of foods and cosmetics are essential for product quality and stability.
• Key qualities are texture, structure, appearance, and stability (e.g., water activity).
• Quantitative knowledge of properties (thermal conductivity, density, viscosity, specific heat, enthalpy, etc) is essential for rational process design.

Mechanical Properties

• Mechanical properties determine the behavior of food materials when subjected to forces.
• Includes elastic, plastic, and viscous deformations.
• Elastic deformation is momentary, plastic is permanent, while viscous is permanent flow.
• Relevant for processing operations like conveying and size reduction alongside consumption aspects like texture.

Types of Stress

• Normal stresses (compressive or tensile) act perpendicular to the material's surface.
• Shear stresses act parallel to the material's surface.
• Classification based on force direction and material relationships for processing understanding.

Thermal Properties

• The thermal properties (thermal conductivity, specific heat, latent heat, diffusivity, phase transition and emissivity) are crucial for process engineering in the food and cosmetic industries.
• Thermal properties influence how heat transfer occurs (conduction, convection, radiation) during heating, cooling, and phase transitions.

Thermal Conductivity and Thermal Resistance

• Thermal conductivity (λ) determines the rate of heat transfer through a food material. It's influenced by moisture levels, temperature, and material structure.
• Thermal resistance (R) is the ratio of temperature difference to heat flow rate. A lower resistance indicates better heat conduction and vice versa.
• Essential for predicting heat transfer speed and product qualities while optimizing procedures.

Specific Heat Capacity

• Specific heat (cp) is the amount of heat that must be transferred to change the temperature of a material by one degree at constant pressure.
• Foods with higher specific heat require more energy to change temperatures. This is essential for process design.

Electrical Properties

• Electrical properties of foods/cosmetics are relevant to microwave and ohmic heating methods.
• These properties influence electrostatic force effects (especially in powders).
• The primary electrical properties are electrical conductivity and dielectric properties.

Structure of Foods

• Most foods are heterogeneous mixtures of different physical phases.
• Structures are visualized through microscopy (microstructure/nanostructure).
• Various structures include cellular, fibrous, gel, emulsion, foam, or powder types.

Food Structures (types):

• Cellular structures (veggies, fruits, muscle).
• Fibrous structures (meat).
• Gels (jelly-like).
• Emulsions (minute liquid droplets dispersed in another).
• Foams (small bubbles in liquid).
• Powders (fine solid particles).

Viscosity

• Viscosity is the internal friction or resistance to flow in a fluid, affected by different layers of the fluid flowing over one another.
• Higher viscosity fluids deform less easily compared to lower-viscosity fluids.
• Viscosity differences (water versus honey) are important for food characteristics and manufacturing. Various materials have distinct degrees of viscosity.

Size Reduction

• Size reduction involves reducing large solid units into smaller units/particles (coarse/fine).
• This is widely used in pharmaceuticals, cosmetics, and food processing industries (e.g., comminution, grinding, milling, micronization).
• Solid-state size reduction is called milling, while emulsification/atomization deals with liquids.

Objectives of Size Reduction

• Increased surface area to enhance the therapeutic effectiveness of drugs.
• Narrow size-range particles for easier and uniform mixing of powders.
• Enhanced texture, flavor, and stability (e.g., improved shelf life) due to reduced sedimentation rates.

Mechanism of Size Reduction

• Impacts (e.g., hammer mills).
• Compression (e.g., roller mills).
• Cutting (e.g., cutter mills).
• Attrition (e.g., fluid-energy mills, jet mills).
• Various mechanisms (impact, compression, cutting, attrition) cause the reduction or grinding of the material.

Laws of Size Reduction

• Griffith theory: Force application depends on crack length.
• Kick's law: Energy required for size reduction is constant for the same reduction ratio, regardless of the original size.
• Rittinger's law: Energy for size reduction is directly proportional to new surface created.
• Bond’s law: Energy for size reduction is proportional to the square root of the diameter of the particle produced.
• Size reduction laws establish relationships between force and energy used depending on the material's structure, size, and properties for effective process engineering.

Factors Affecting Size Reduction

• Selection of mills (considerations of feed, safety, economics, products).
• Hardness of materials.
• Fibrous nature of the material (difficulty in processing).
• Elastic/sticky nature of the material (e.g., waxes, synthetic gums, resins).
• Slipperiness (inverse of stickiness).

Melting Point and Hygroscopic Nature of Materials

• Waxy substances, fats, and oils soften during size reduction (heat generation) requiring cooling.
• Hygroscopic materials absorb moisture, hindering the milling operation and requiring closed systems.
• Abrasive materials produce significant resultant powder with metal wear, often requiring closed-system or inert grinding mills.

Hammer Mill

• Principle: Rapidly moving hammers on a rotor against a stationary material.
• Parts: Casing, rotor with hammers, screen, hopper, screw feeder, and receiver.
• Advantages: Rapid action, continuous operation, easy installation, and control of particle size.
• Disadvantages: High heat buildup, unsuitable for processing sticky or hard materials, loud and continuous noises, potential screen clogging.

Roller Mill (Edge Runner Mill)

• Principle: Crushing effect due to heavy rollers.
• Construction: Two heavy rollers resting on a stone bed.
• Advantages: Suitable for applications where continuous operation is required, minimal attention during operation.
• Disadvantages: More operation space required compared to some other mills.

Fluid-energy Mill

• Principle: Impact and attrition by a high-pressure flow of air or inert gas in a looped pipe, with nozzles; creating high turbulence causing grinding.
• Parts: Loop pipe, nozzles for gas, classifier, and inlet for feed.
• Working: High pressure flow grinds particles to a fine level.
• Advantages: Useful for grinding temperature-sensitive materials (vitamins) and powders for food products (antibiotics), and high energy efficiency, preventing contamination.
• Disadvantages: Tendency for agglomeration, high energy consumption.

Cutter Mill

• Principle: Using sharp blades for chopping material.
• Advantage: Suitable for brittle or fibrous materials; commonly for dry granulation.
• Disadvantage: High-speed operation and likely heat generation.

Micronization

• Micronization is a process reducing the particle size of materials to the micron range for improved characteristics (e.g., bioavailability, solubility, and functionality).
• Relevant in improving the quality and functionality of products in food and cosmetics industries.
• Improved texture, skin penetration, anti-aging, and sun protection are notable benefits.

Size Reduction from Liquids: Atomization

• A process breaking down liquids into smaller particles (droplets) often using high pressure or high-temperature methods.
• Important for food processing, pharmaceuticals, chemical manufacturing for increased surface area.

Spray Drying

• A process converting liquid substances into fine powders efficiently via atomization of feedstock and contacting it with hot air.
• Used for various product creation (instant coffee, milk powder, flavorings, and medicines).
• Conditions are optimized for proper drying and product characteristic retention.

Freeze-drying (Lyophilization)

• Preserves products by freezing, reducing pressure for sublimation, and then using heat to dry them.
• Maintains the product's shape, preventing damage to texture, flavor and nutritional content.
• Used for various foods such as fruits, coffee, and also for pharmaceutical products.
• Follows several steps including freezing, vacuuming, then heating.

Emulsification

• An emulsion is a liquid dispersed in another liquid, different from the other liquids present.
• Emulsions can contain various phases with different densities.
• Stabilized by solid particles or emulsifiers for better consistency.

Emulsification Techniques

• Techniques include: ultrasound, high-pressure homogenization, high-shear mixing, and membrane emulsification.
• Choice of technique is contingent on material properties, required emulsion stability, and potential for heat and shear sensitivity.

Particles as Stabilizers - Pickering Emulsions

• Pickering emulsions are stabilized by solid particles (e.g., inorganic/organic) rather than surfactants.
• The particles adsorb onto the oil-water interface, reducing interfacial tension and maintaining stability.
• This prevents coalescence (joining) of droplets. Applicable in various sectors (food, cosmetics, pharmaceuticals).

Microfibrillated Cellulose as Emulsion Stabilizer

• A natural material derived from cellulose fibrils.
• Offers advantages such as biocompatibility, biodegradability, excellent properties, and various applications ranging from food products (texture modifier, stabilizer, emulsifier) to cosmetics (thickening, stability, and moisture barrier).