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Radio Frequency Food Processing
1
Tom Kuipers Stalam S.p.a.Nove (Vi) - Italy
FACTS & FIGURES
Year of establishment: 1978
Number of employees: 115 (worldwide)
Yearly turnover: EUR. 20+ million (year 2018)
Production capacity: over 120 industrial size machines per year
Sectors: textile and technical-textile (60%), food (35%), others (5%)
Sales organisation: worldwide network of agents (more than 70) and servicing centres (20)
Export share: more than 95%
Export markets: Europe (30%), Asia (50%), Americas & Africa (20%)
Market share: more than 50% worldwide (textile and food, RF technology)
Market position: no. 1 worldwide (textile and food, RF technology)
INDUSTRIAL APPLICATIONS
TextilesDryers for fibres, yarns, fabrics
Technical textilesDryers for glass fibres, latex foam,
polyurethane foam, felt, non-wovens, etc.
FoodPost baking drying, tempering & defrostingPasteurisation & sterilisation, disinfestation
Other applicationsLWIR technology for surface treatments(drying & curing), drying ceramics, etc.
ELECTROMAGNETIC SPECTRUM
RF are non-ionising electromagnetic waves !
THE ELECTROMAGNECTIC SPECTRUM RF heating mechanisms
DIPOLAR VIBRATION-ROTATION
_ _ _ _ _ _ _ _
H+
Electrode
Electrode
+ + + + + + +
o --
H+ H+
o --
H+
H+
o--
H+
Electrode
Electrode
27.12MHz
_ _ _ _ _ _ _ _
+ + + + + + +
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Endogenous (volumetric) heating
Controlled, uniform, fast heating
Selective heating
High energy efficiency
Outstanding quality results
High operational flexibility
RF MAIN CHARACTERISTICS
RF heating vs. Conventional heating
• heat transferred from the outside
by convection, conduction, irradiation
• part of the energy is wasted
• efficiency affected by surface conditions and thermal conduction
• non-uniform temperature distribution
• long heating / drying time
• user cannot control the powerabsorbed by the target
• selective heating is not possible
• heat generated inside the target
(volumetric heating)
• all the energy is dissipatedinside (no energy losses)
• uniform temperature distribution
• very short processing time
• user can set the power to beabsorbed by the target
• user can heat selectively part ofthe target
380÷415 V50Hz
57000 V811000 V
50 Hz
68000 V
DC 27.12 MHz
26000 V
27.12 MHz
ELECTRODE
ELECTRODE
HT TRANSFORMER RECTIFIER
OSCILLATING
CIRCUIT
COUPLING
CIRCUIT
RF EQUIPMENT
WORKING PRINCIPLE
MAIN SUPPLY
LEGEND
0 = Air dielectric constant Vm = Actual voltage on the productr = Product’s relative dielectric constant d0 = Distance between electrodes0r = ’- j” dm = Height of the product
V0 = Electrode voltage
d0 dm Vm
00 r
V0
UPPER ELECTRODE
LOWER ELECTRODE
THE PROCESS CONTROL
P ≈ f ∙ V2 ∙ Kε
d2
f = frequency (27.12 MHz)V = electrodes voltage Kε = product’s RF energy absorption rated = electrodes distance
Operational
parameters
controlled
by the user
Only few and simple adjustments
Outstanding process control and flexibility
• Suitable for products higher than 3-4 cm
RF power applicators: type 1
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• Designed to improve heating of products with varied height
• Uses fixed voltage and the energy applied is adjusted by
raising or lowering the upper electrode
RF power applicators: type 2
• Outstanding energy transfer efficiency to thin products
• Energy applied is adjusted through a variable capacitor
• Lower and controlled electrode voltage (no arching)
RF power applicators: type 3
-
-
+
+
Stalam RF machines in total:
>2400
Stalam RF machine in Food:
>180
In variety of applications: TEMPERING / DEFROSTING
FISH, MEAT, FRUITS,
VEGETABLES,BUTTER
IN BLOCKS OR IQF,
WITH OR WITHOUT PACKAGING
FAST, UNIFORM AND CONTROLLED HEATING PROCESS
IMPROVED PROCES STABILITY FURTHER PROCESSING.
DRASTIC REDUCTION OF DRIP LOSS
NO PRODUCT DETERIORATION
NO BACTERIAL GROWTH
CONTINUOUS (IN-LINE) OPERATION
JUST IN TIME / ON DEMAND
WHITE CRUST BREAD
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– As bread rises in the baking oven, the energy asorbed by the product is constantly changing, the electrode configuration needs to change with it.
– The electrode configuration can be different along the process direction enabling a variable heating approach depending on physical shape.
RF bread baking ADVANTAGES
• reduced baking time, from three to five times less, depending on the chemical-
physical characteristics and the level of baking desired;
• a much shorter baking oven, for a certain production capacity, or a much higher
production capacity in the same space normally occupied;
• an energy efficient process, thanks to the endogenous (direct) heating system . But
electrical energy!
• a higher flexibility, to produce normal crusted bread or white-crust (crust less) bread,
without any product loss (due to crust removal from the normal crusted bread baked
traditionally).
- RAPID INACTIVATION OF ENZYMES AND MICROORGANISMSRESPONSIBLE FOR FOOD DETERIORATION
- END OF LINE CONTINUOUS TREATMENT AVOIDING ANY POST-CONTAMINATION
- EASILY INTEGRATED IN THE AUTOMATED PRODUCTION LINES
- VOLUMETRIC ENDOGENOUS HEATING TO REACH QUICKLY AND UNIFORMLY THE PASTEURIZATION TEMPERATURE
PASTEURISATION of PACKAGED FOOD PRODUCTS
PASTEURISATION OF FRESH PASTA PRODUCTS PASTEURISATION OF FRESH PASTA PRODUCTS
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SINGLE OR MULTI MODULE RF UNIT FOLLOWED BY HOT AIR CONVECTION SYSTEM (TUNNEL OR SPIRAL)
THE RF IS USED TO RAPIDLY INCREASE THE TEMPERATURE OF THE PACKAGED SLICED BREAD UP TO 70-80°C
A HOT AIR HOLDING SECTION KEEPS THIS TEMPERATURE FOR THE REQUIRED TIME
PASTEURIZATION TIME REDUCED 50%, DOUBLE PRODUCTION CAPACITY
PASTEURISATION OF PACKAGED BREAD
CYCLE DESCRIPTION:
10’ RF up to 70 - 80°C
20’ HOLD TIME AT 80°C
PASTEURISATION OF PACKAGED BREAD
PARAMETER U.M. BEFORE RF AFTER RF
COLONY COUNTS AT 30°C
CFU/G > 103 <10
MOLDS CFU/G 3.5 x 102 <10
YEASTS CFU/G >102 <10
INCREASED SHELF LIFE WITHOUT CHEMICAL PRESERVATIVES (ETHANOL, SORBATE, PRIOPIONATE…)
NO RISK OF POST-CONTAMINATION
EASY AUTOMATION (POSSIBILITY TO PASTEURIZE IN TRAYS OR BOXES)
REDUCED FLOOR SPACE AND PROCESS TIME COMPARED TO CONVENTIONAL HOT AIR CONVECTION SYSTEMS
INCREASED PRODUCTION CAPACITY
ENERGY SAVING
BENEFITS OF RF END OF LINE PASTEURISATION
- RAPID & UNIFORM TEMPERATURE RISEWITHIN THE PRODUCT, ALSO IN THE SUSPENDED SOLID PARTICLES OF ANY SIZE, WITH NO RISK OF OVER-PROCESSING THE LIQUID
- MICRO-BIOLOGICAL INACTIVATION (SAFETY) AT LOWER TEMPERATURES AND IN A SHORTER TIME
- BETTER QUALITY OF THE PRODUCT (SENSORIAL, CHEMICAL AND PHYSICAL CHARACTERISTICS, INCLUDING THE STRUCTURAL INTEGRITY OF SOLID PARTICLES)
PASTEURISATION & STERILISATION OF
LIQUID AND PUMPABLE PRODUCTS
- LESS ADDITIVES (COLOURS, FLAVOURS, THICKENERS, ETC.) REQUIRED
- SUITABLE FOR LOW- OR HIGH-VISCOSITY LIQUIDS, WITH OR WITHOUTSUSPENDED SOLID PARTICLES, SLURRY MIXTURES, JUICES WITH PULPS, ETC.
THE “RF/L” TECHNOLOGY DEVELOPED BY STALAM MAKES IT POSSIBLETO CARRY OUT PASTEURISATION AND STERILISATION PROCESSES ATHEATING RATES FROM 1°C/SEC UP TO 100°C/SEC.
PRODUCTION LINES WITH TYPICALTHROUGHPUT OF 2,000 L/H,INCORPORATING THE “RF/L”EQUIPMENT, HAVE BEEN WORKINGFOR SOME YEARS AT LEADINGEUROPEAN DAIRY AND FRUITPREPARATION PRODUCERS.
PASTEURISATION & STERILISATION OF
LIQUID AND PUMPABLE PRODUCTS
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PASTEURISATION OF A STRAWBERRY FRUIT PREPARATION
MESOPHYLIC AEROBIC LOAD:
BEFORE >5000 C.F.U./G
AFTER RF TREATMENT <5 C.F.U./G
SPOROGENIC MESOPHYLIC BACTERIA:
BEFORE >200 C.F.U./G
AFTER RF TREATMENT <5 C.F.U./G
HYPHOMYCETES:
BEFORE >1000 C.F.U./G
AFTER RF TREATMENT <5 C.F.U./G
YEASTS:
BEFORE >1000 C.F.U./G
AFTER RF TREATMENT <5 C.F.U./G
STERILISATION OF APPLE DICE WITH SYRUP
STERILISATION CYCLE (1200 l/h)Pre-heating to 50°C with heat exchanger in 63”RF heating to 105°C in 36”Holding time at 105°C in 18”
PRODUCT DESCRIPTION50% liquid syrup pH 3.4, 1.5 mS/cm, 18° Brix50% solid dice 1.2 x 1.2 x 1.2 cm, pH 3.8
15.3 Log reduction for target microorganism L. plantarum
PASTEURISATION & STERILISATION OF
LIQUID AND PUMPABLE PRODUCTS
The fluid substrate to be treated is continuouslypumped through one or more Teflon tubeshaving a suitable diameter (from DN16 to DN80)depending on product’s characteristics
The tubes are placed between especially designed electrodes (according to the tubediameter and the product’s characteristics)
The temperature achieved is a function of the RF power and of the product flow rate: generally 80-110°C for pasteurisation and
over 120°C for complete sterilisation
“RF/L” technology
no use of steam
energy efficiency >70%
compact lay-out
lower product losses
higher added value
REDUCED PROCESS TIME
REDUCED USE OF THICKENERS, ADDED COLOURS AND FLAVOURS
EASY CLEANING (NO CRUSTING EFFECT) AND LOW MAINTENANCE
COSTS
DOUBLE STERILISATION EFFECT (THERMAL + ELECTROCHEMICAL)
REDUCED FACTORY FLOOR SPACE REQUIREMENTS
HIGH ENERGY EFFICIENCY
BETTER WORKING ENVIRONMENT
CIP SYSTEM CAN BE USED FOR WASHING
PIG SYSTEM CAN BE USED FOR IN-LINE CHANGE AND RECOVERY OF
THE PRODUCT
THE PLANT STERILITY IS MAINTAINED ALSO IN STAND-BY
CONDITIONS
PASTEURISATION & STERILISATION OF
LIQUID AND PUMPABLE PRODUCTS
Advantages over conventional thermal processing
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RADIO FREQUENCY DISINFESTATION OF
DRY AGRICULTURAL COMMODITIES
- Fast and continuous process
- Environmentally safe
- Max product preservation
- Selective and homogeneous
- Suitable for “organic” and “bio” production chain commodities
- High energy & cost efficiency
Pasteurising Dried Mushrooms
Pasteurising Almonds / WalnutsRADIO FREQUENCY CONTINUOUS DRYING OF
AGRICULTURAL COMMODITIES
- Conveyor-type drying tunnel
- In-line continuous processing
- Easy automatization for constant product flow
- Modular construction to achieve high production capacity
- Low temperature drying for thermo-sensitive products
- Accurate control and uniformity of the moisture content
- Suitable for nuts, grains, seeds, beans, cereals and pulses
RF Drying vs. conventional drying
Technical advantages
• high drying speed / High evaporation efficiency(irrespective of product shape, size, density, moisture content)
• No influence of atmospheric conditions on drying(outside air temperature, humidity, dustiness)
• Full operational flexibility (one dryer for all products)
• Instantaneous start / stop (no need for pre-heating / cooling)
• Continuous and “just in time” operation
• Reduced floor space requirement and modular construction
• Improved working conditions(little noise, no heat dispersions, no fumes released)
• Parameters easily controlled
• Full automation easily fitted
Product Quality advantages
• Accurate and consistent residual moisture control
• Outstanding drying uniformity
• Extended shelf-life
• No colour change
• Reduced product loss due to overprocessing
• No surface deterioration (skin loss, cracks, burns)
• Preservation of nutritional and sensorial properties
RF Drying vs. conventional drying
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RF Food commodity Drying: example
RF drying tunnel of post-harvest corn/rice/sorghum processing:
Installation: MULINO MARELLO – Alessandria (Italy) gluten-free dry mill for the food industry
Equipment size: single module 85 kW RF output powerInitial moisture: 20 ÷ 25% w/wFinal moisture: 12 ÷ 14% w/wProcessing time: 40 minutesProduction capacity: 700 ÷ 800 kg/h
POST-BAKING DRYING
- AFTER THE BAKING OVEN
- RAPID AND EFFICIENT DRYING
- UNIFORM AND ACCURATERESIDUAL MOISTURE CONTROL
- NO OVER-BAKING (EXCESSIVE
BROWNING) OF THE SURFACE
- THE PRODUCTION LINE SPEEDCAN BE INCREASED UP TO 25%
- SUITABLE FOR BISCUITS, COOKIES, MERINGUES, SPONGE CAKES,PUFF PASTRY, CRACKERS, BREAD STICKS, APPETISER SNACKS, ...
POST BAKING DRYING
ADVANTAGES OF RF DRYING AFTER THE BAKING OVEN
• INCREASED THROUGHPUT BY EXISTING OVEN WITH HIGHER M.C.
• MOISTURE PROFILE OUT OF THE RF DRYER IS MORE UNIFORM
• REDUCED “CHECKING” OF DELICATE PRODUCTS
• REDUCTION OF ACRYLAMIDE FORMATION
• EXTENDED SHELF-LIFE
• IMPROVED SENSORIAL PROPERTIES
18% 12%Conventional last
oven section.16% 6%
18% 12%
RF Dryer
12% 18% 10%
10%
Non-uniform moisture distribution
Maximum uniformity and consistency
>> moisture levelling effect
REDUCED CHECKING Due to:
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THE PATENTED DOUBLE POLARITY ELECTRODE DESIGN PRODUCES AN EFFICIENT HORIZONTAL FIELD FOR THIN PRODUCTS
MAXIMUM UNIFORMITY AT LOWER VOLTAGES
NO ELECTRICAL ARCING
POST BAKING DRYING RF POST BAKING DRYING
IMPROVING THE PRODUCTION LINE CAPACITY
+10% Floor space = +20% Production capacity
No additional browning during RF Drying > No additional AA.
Increased production capacity from the baking oven enabling a
higher output moisture content - RF performs the final drying
No changes in the recipe
POST BAKING DRYING
TRADITIONAL APPROACH TO REDUCE AA LEVELS:
USE SODIUM OR POTASSIUM CARBONATE
INSTEAD OF AMMONIUM CARBONATE AS
RAISING AGENT
REDUCTION OF BAKING TEMPERATURES
ADDITION OF AMINO ACIDS OR PROTEIN
BASED INGREDIENTS
THESE MODIFICATIONS AFFECT THE TASTE
OF THE PRODUCT
POST BAKING DRYING
35% LOWER AA
FORMATION BASED ON:
CONVENTIONAL BAKING
TO 10% R.M.C. AND USE
OF RF TO GO DOWN TO
4% R.M.C.
REDUCING ACRYLAMIDE - EXAMPLE
POST BAKING DRYING
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Questions....!