Water in Food Workshop Lausanne 2004 DRY COATING : Techniques & Potentials E. TEUNOU - E. IVANOVA - D. PONCELET Nantes Département du Génie des Procédés Alimentaire
Content Who are we? Importance and Functionality of powders Definitions of coating and principles Potentials of dry coating Case study Perspectives
Who are we? Micro encapsulation and Granular Material Team (Poncelet) Department of food Process Engineering Nantes Micro encapsulation - Encapsulation - Development - Implementation - Application to food area - Granular Materials - Characterisation - Flowability - Spray drying - Coating -
Bioencapsulation Research Group 1990-900 groups - 60 countries - 25 % of industrials. promoting the development of bioencapsulation encouraging multidisciplinary research developing and transferring the technology supporting and organizing training and workshop http://www.bioencapsulation.net Virtual Institute on Bio&MicroEncapsulation Sciences and Technologies 2003-15 partners - 9 countries. VI-BEST promote and support collaboration between RTD develop professional communication tools provide integrated problem solutions and technology transfer offer a contact platform for the industry http://www.ncapsolution.net
Importance & functionality of powders Powder Tons of powders today Stable form Easy to handle (flowability) Reconstitution (Dissolution -Dispersion) Used in various industries (Multiple functional properties) cost = f (functionality)
Trends in powders functionalization Enrichment & Use of additives For Protection Composition Stability Reconstitution Dissolution Dispersion) Dust free Free flowing Nutritive Etc By Mixing Spray drying Agglomeration Granulation Coating
What is coating? Gas: O2, CO2, N2 UV, T Confining for Shell Water vapor Immobilization Protection Releasing functionalization Core Fats Solutions Gastric juices Microorganisms Mechanical constraints
Types of capsules? Physical states Morphology Matrix system Solid - dry or liquid core Wet or dry shell material Soft, elastic or rigid capsules Reservoir system Beads Multi-core Multi-layers Multi-cores
Fluid bed coating (aqueous) Outlet Air Pump Filter Nozzle Sprayed liquid Inlet Air Coating material dissolved in water Fluidized particles Fan Heating
Fluid bed coating (aqueous)
Mechanism of aqueous coating Spraying Spreading Solidification Layering Droplets Many cycles Core Particle Wetting Evaporation Onion Structure Notes The core particle is wetted Similar mechanism is expected when: - The coating material is dispersed in any solution - The coating material is in liquid form
Variation of humidity in the fluid bed Coating time (minutes) 80 60 40 20 0 15 10 5 0 HR (%) X (%) Spray End Spray Water uptake is quite impressive
For Water sensitive products (Powders & active materials) Pharmaceuticals Nutraceuticals Probiotics Vitamins Oils and fats etc Dry coating is imperative Why? Bacterial growth Toxin production Activation Browning Oxidation Unwanted flavors etc
Definitions of Dry Coating Dry coating = Coating without wetting particles with: 1 2 Water Solvent 3 4 Oil or wax Nothing at all
Principles of dry coating: Particle Fines Fines solvent or hot-melt Plasticizer Mechanical forces Film layer a/ Solvent and hot-melt a/ Plasticizer Porous layer c/ Dry powder coating
Principle of dry powder coating:
Dry coating process Use of solvents Cooling Polymer in solvent filter Fan Vacuum pump Solvent recovered Heating pump Fluid bed
Dry coating process Use of plasticizers Plasticizer Air outlet Fine powder plasticizer a) Pan coater Air inlet b) Fluid bed Balance
Dry coating process Dry particles coating Cycle tube Powder inlet Powder outlet Hybridizer Particle trajectory Stator Jacket Blade Rotor
Dry coating process Dry particles coating Rotating vessel Scraper Air inlet Cage Rotating air distributor Stationary hammer Air outlet Fluidised particles Mechano - fusion Rotating fluid bed
Dry coating process Dry particles coating Collar coil N-S S-N AC power supply High speed elliptical Rotor mixer Chamber Guest partcle Magnetic partcle Host particle Rotating vessel Minimum clearence region Magnetic Impact Rotor Particles
Advantages Coated particles are not wetted Time saved High productivity Energy saved Can be processed in existing devices Low pollution (dust free)
Productivity Types of process Aqueous (2 to 8% DM) Solvent (2 to 30% DM) Hot melt (100 % DM) Plasticizer (100 % DM) Dry particles (100% DM) Yield (%) 70-80 70-80 85-99 ~ 90 90-98
Productivity QDM (g/min) 30 25 20 15 10 5 0 Dry Particle Plasticizer Solvent Aqueous 0 10 20 30 Qm (g/min)
Time saved Process time for: - 20% of coating material - 10 kg load Types of process Aqueous or solvent Hot melt Plasticizer Dry particle coating Time (min) 200 60 80 5-10 Without time for: - solution preparation - finishing heating
Energy saved Types of process Aqueous Solvent Hot melt Plasticizer Dry coating particles Energy Air heating Vaporization heat Air heating Vaporization heat Heating of the melting solution Cooling the chamber Ambient temperature Mechanical energy
Multiple potentials Integration of functionalization Ex: Free flowing additives Quick dispersion Ex: Reconstitution of liquids Coating of water sensitive materials Ex: Coating of probiotics
Case study: Dry Coating of Probiotics Core material White polymer beads 835 µm, 828 kg/m3 Dried for 48 hours, 100 C Coating material AQOAT (10 mm) (Synthafarm) Beads photo Plasticizer Triethyl citrate & acetylated monoglyceride
The coating system Air outlet Fine powder plasticizer Air inlet Balance A Wurster (Uniglatt) for dry coating
Example: Coating of probiotics Steps Beads Capsules Aqueous Capsules Plasticizer Initial 0% Process 4% 4% 2% Storage (48h-50% HR) 6% 6% 6% Storage (196h-50% HR) 8% 6% 6% X% of capsules at different steps
Variation of humidity in the fluid bed Coating time (minutes) 80 60 40 20 0 15 10 5 0 HR (%) X (%) Spray End Spray Water uptake is quite impressive
Coating system with Air de-hidration Target: HR = 5% in the fluid bed chamber Air outlet Fine powder De- hydration Unit plasticizer Air Inlet Dry Air Inlet Balance
De-humidification of the inlet air Advantage No wetting Inconveniences Size Cost Others advantages High drying rate Coating at room temperature In clean conditions
27.8 C 23.8g 20.1 C 70% 50C, 20% 14.8g 26 C Drying rate = 23.8-14.8= 9.0g/kg
Case 1: 9 g/kg dry air Case 2: 10.5 g/kg dry air Case 1 Case 2
Dry coating : Advantages Potentials Conclusion Real needs Perspectives Test the new air drying system Methodic study Comparison of different methods Evaluation of potentials Applications
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