DRY COATING : Techniques & Potentials

Transcription

1 Water in Food Workshop Lausanne 2004 DRY COATING : Techniques & Potentials E. TEUNOU - E. IVANOVA - D. PONCELET Nantes Département du Génie des Procédés Alimentaire

2 Content Who are we? Importance and Functionality of powders Definitions of coating and principles Potentials of dry coating Case study Perspectives

3 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 -

4 Bioencapsulation Research Group 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 Virtual Institute on Bio&MicroEncapsulation Sciences and Technologies 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

5 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)

6 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

7 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

8 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

9 Fluid bed coating (aqueous) Outlet Air Pump Filter Nozzle Sprayed liquid Inlet Air Coating material dissolved in water Fluidized particles Fan Heating

10 Fluid bed coating (aqueous)

11 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

12 Variation of humidity in the fluid bed Coating time (minutes) HR (%) X (%) Spray End Spray Water uptake is quite impressive

13 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

14 Definitions of Dry Coating Dry coating = Coating without wetting particles with: 1 2 Water Solvent 3 4 Oil or wax Nothing at all

15 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

16 Principle of dry powder coating:

17 Dry coating process Use of solvents Cooling Polymer in solvent filter Fan Vacuum pump Solvent recovered Heating pump Fluid bed

18 Dry coating process Use of plasticizers Plasticizer Air outlet Fine powder plasticizer a) Pan coater Air inlet b) Fluid bed Balance

19 Dry coating process Dry particles coating Cycle tube Powder inlet Powder outlet Hybridizer Particle trajectory Stator Jacket Blade Rotor

20 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

21 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

22 Advantages Coated particles are not wetted Time saved High productivity Energy saved Can be processed in existing devices Low pollution (dust free)

23 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 (%) ~

24 Productivity QDM (g/min) Dry Particle Plasticizer Solvent Aqueous Qm (g/min)

25 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) Without time for: - solution preparation - finishing heating

26 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

27 Multiple potentials Integration of functionalization Ex: Free flowing additives Quick dispersion Ex: Reconstitution of liquids Coating of water sensitive materials Ex: Coating of probiotics

28 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

29 The coating system Air outlet Fine powder plasticizer Air inlet Balance A Wurster (Uniglatt) for dry coating

30 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

31 Variation of humidity in the fluid bed Coating time (minutes) HR (%) X (%) Spray End Spray Water uptake is quite impressive

32 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

33 De-humidification of the inlet air Advantage No wetting Inconveniences Size Cost Others advantages High drying rate Coating at room temperature In clean conditions

34 27.8 C 23.8g 20.1 C 70% 50C, 20% 14.8g 26 C Drying rate = = 9.0g/kg

35 Case 1: 9 g/kg dry air Case 2: 10.5 g/kg dry air Case 1 Case 2

36 Dry coating : Advantages Potentials Conclusion Real needs Perspectives Test the new air drying system Methodic study Comparison of different methods Evaluation of potentials Applications

37 Thanks for your... And...