WO2020248040A1 - Vacuum microwave drying of high sugar content liquids - Google Patents

Vacuum microwave drying of high sugar content liquids Download PDF

Info

Publication number
WO2020248040A1
WO2020248040A1 PCT/CA2019/050850 CA2019050850W WO2020248040A1 WO 2020248040 A1 WO2020248040 A1 WO 2020248040A1 CA 2019050850 W CA2019050850 W CA 2019050850W WO 2020248040 A1 WO2020248040 A1 WO 2020248040A1
Authority
WO
WIPO (PCT)
Prior art keywords
food product
range
product
vacuum
vacuum chamber
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/CA2019/050850
Other languages
French (fr)
Inventor
Guopeng Zhang
Braden KNIGHTS
Shafique AHMED
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Enwave Corp
Original Assignee
Enwave Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority to JP2021564803A priority Critical patent/JP2022535501A/en
Priority to AU2019450892A priority patent/AU2019450892A1/en
Priority to US17/595,521 priority patent/US20220183329A1/en
Priority to PE2021001779A priority patent/PE20220116A1/en
Priority to SG11202111449XA priority patent/SG11202111449XA/en
Priority to CA3136640A priority patent/CA3136640C/en
Priority to PH1/2021/552665A priority patent/PH12021552665A1/en
Priority to PCT/CA2019/050850 priority patent/WO2020248040A1/en
Priority to MX2021012956A priority patent/MX2021012956A/en
Priority to EP19933042.4A priority patent/EP3982755A4/en
Priority to CN201980097187.2A priority patent/CN113993391A/en
Application filed by Enwave Corp filed Critical Enwave Corp
Priority to KR1020217035808A priority patent/KR20220021460A/en
Priority to BR112021020970A priority patent/BR112021020970A2/en
Publication of WO2020248040A1 publication Critical patent/WO2020248040A1/en
Priority to CONC2021/0013897A priority patent/CO2021013897A2/en
Priority to CL2021002766A priority patent/CL2021002766A1/en
Priority to ZA2021/08678A priority patent/ZA202108678B/en
Priority to ECSENADI202180849A priority patent/ECSP21080849A/en
Priority to IL288413A priority patent/IL288413A/en
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Classifications

    • A—HUMAN NECESSITIES
    • A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
    • A23B—PRESERVATION OF FOODS, FOODSTUFFS OR NON-ALCOHOLIC BEVERAGES; CHEMICAL RIPENING OF FRUIT OR VEGETABLES
    • A23B2/00—Preservation of foods or foodstuffs, in general
    • A23B2/90—Preservation of foods or foodstuffs, in general by drying or kilning; Subsequent reconstitution
    • A23B2/97—Preservation of foods or foodstuffs, in general by drying or kilning; Subsequent reconstitution using irradiation or electric treatment, e.g. ultrasonic waves
    • A—HUMAN NECESSITIES
    • A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
    • A23B—PRESERVATION OF FOODS, FOODSTUFFS OR NON-ALCOHOLIC BEVERAGES; CHEMICAL RIPENING OF FRUIT OR VEGETABLES
    • A23B2/00—Preservation of foods or foodstuffs, in general
    • A23B2/10—Preservation of foods or foodstuffs, in general by treatment with pressure variation, shock, acceleration or shear stress
    • A23B2/103—Preservation of foods or foodstuffs, in general by treatment with pressure variation, shock, acceleration or shear stress using sub- or super-atmospheric pressures, or pressure variations transmitted by a liquid or gas
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26—DRYING
    • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B3/00—Drying solid materials or objects by processes involving the application of heat
    • F26B3/32—Drying solid materials or objects by processes involving the application of heat by development of heat within the materials or objects to be dried, e.g. by fermentation or other microbiological action
    • F26B3/34—Drying solid materials or objects by processes involving the application of heat by development of heat within the materials or objects to be dried, e.g. by fermentation or other microbiological action by using electrical effects
    • F26B3/347—Electromagnetic heating, e.g. induction heating or heating using microwave energy
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26—DRYING
    • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B5/00—Drying solid materials or objects by processes not involving the application of heat
    • F26B5/04—Drying solid materials or objects by processes not involving the application of heat by evaporation or sublimation of moisture under reduced pressure, e.g. in a vacuum
    • F26B5/042—Drying solid materials or objects by processes not involving the application of heat by evaporation or sublimation of moisture under reduced pressure, e.g. in a vacuum for drying articles or discrete batches of material in a continuous or semi-continuous operation, e.g. with locks or other air tight arrangements for charging/discharging
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26—DRYING
    • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B5/00—Drying solid materials or objects by processes not involving the application of heat
    • F26B5/04—Drying solid materials or objects by processes not involving the application of heat by evaporation or sublimation of moisture under reduced pressure, e.g. in a vacuum
    • F26B5/048—Drying solid materials or objects by processes not involving the application of heat by evaporation or sublimation of moisture under reduced pressure, e.g. in a vacuum in combination with heat developed by electro-magnetic means, e.g. microwave energy

Definitions

  • the invention pertains to methods of drying food products having a high sugar content, such as honey and molasses. Background
  • Dehydration of organic materials is commonly done in the food processing industry to preserve the products for storage or to create products that are used in the dehydrated form, for example dried herbs and various kinds of chips. It is known to dehydrate food products by vacuum microwave dehydration. Examples of this in the patent literature include WO 2009/049409 dated April 23, 2009, WO 2009/033285 dated March 19, 2009, WO 201 1/085467 dated July 21 , 2011 , WO 2013/010257 dated January 24, 2013, and WO 2014/085897 dated June 12, 2014. Vacuum microwave drying is a rapid method that can yield products with improved quality compared to air-dried and freeze-dried products. Because the drying is done under reduced pressure, the boiling point of water and the oxygen content of the atmosphere are lowered, so nutritional components sensitive to oxidation and thermal degradation can be retained to a high degree.
  • the present inventors have discovered that high sugar content food products can be dried using vacuum microwave drying to produce a commercially-acceptable product by using processing conditions that include a vacuum pressure in the range of 45 to 250 Torr (60 to 333 mbar). This has been found, surprisingly, to minimize or prevent foaming of the product and dry the product at a temperature that prevents burning, while reducing the moisture content to a very low level.
  • a method of dehydrating a food product having a sugar content of at least 20 wt.% comprising the steps of: (a) loading the food product into a vacuum chamber; (b) exposing the food product to a vacuum pressure in the range of 45 to 250 Torr (60 to 333 mbar) in the vacuum chamber; (c) exposing the food product to microwave radiation during step (b), whereby the food product is dehydrated; and (d) unloading the dehydrated food product from the vacuum chamber.
  • Figure 1 is a schematic diagram of a vacuum microwave dehydration apparatus suitable for carrying out the process of the invention.
  • the method of the invention dehydrates high sugar content food products using a vacuum microwave apparatus.
  • this is done by exposing the food product to a selected vacuum pressure and to microwave radiation in a vacuum chamber for a selected residence time, thereby heating the product and reducing moisture to a desired level.
  • the process is done on a continuous-throughput basis, in which the product is fed into a vacuum chamber and conveyed through the vacuum chamber from an input end to an output end, for a selected residence time, during which microwave generators irradiate the product with microwave radiation.
  • the process is done on a batch basis, by loading the vacuum chamber, processing the product and then opening the vacuum chamber to remove the dried product.
  • the dried product may be milled to form a powder.
  • the food products suitable for processing by the invention have a high sugar content, in the range of 20 to 85 wt.%, alternatively in the range of 40 to 80 wt.%.
  • honey and molasses have a sugar content of about 80 wt.%, com syrup about 75 wt.% and sweetened condensed milk about 50 wt.%. This is much higher than the sugar content of most other food products that would be processed using vacuum microwave drying, which are commonly less than 10 wt.% sugar.
  • the high sugar content food products for processing by the present invention are typically in the form of a viscous liquid.
  • the process uses vacuum pressures in the range of about 45 to 250 Torr (60 to 333 mbar), alternatively 50 to 250 Torr (66.7 to 333 mbar), alternatively 50 to 200 Torr (66.7 to 267 mbar), alternatively 50 to 100 Torr (66.7 to 133 mbar), in the vacuum chamber.
  • the present inventors have determined that processing high sugar content products at less than about 45 Torr, or less than 50 Torr, results in uncontrollable foaming during vacuum microwave drying at any microwave power density suitable to dry the product; and that processing at vacuum pressures above 250 Torr does not dry the viscous liquid to a porous structure, which is preferred.
  • Pressures in the range of 45 to 250 Torr have been found suitable to control foaming and splashing of high sugar content products, prevent collapse of the product structure, and permit the product to be dried to a low moisture content and form a uniform finished product.
  • the food product dries in the vacuum chamber at a temperature that is high enough to ensure proper drying while not being high enough to burn the product.
  • suitable temperatures of the product during drying are in the range of 75 to 125°C, alternatively in the range of 90 to 110°C.
  • Suitable microwave power densities are in the range of 100 to 3000 kW per kg of food product. Lower power densities will eventually dry the product but require too long a drying time to be commercially practical. Higher power densities have been determined to cause excessive foaming or splashing of high sugar content liquids during drying.
  • maltodextrin is added to the food product prior to drying. For example, 5 to 30 wt.% may be added. This has been determined to assist in the drying process and produce a more porous, evenly-dried product, having a more even pore distribution. Residence times in the vacuum chamber in the range of 30 to 90 minutes, alternatively 40 to 70 minutes, have been found suitable for drying most high sugar content materials. Following the dehydration step, the dried product is unloaded from the vacuum chamber. The final moisture level of the dried material may be in the range of 0 to 10 wt.%, alternatively in the range of 1 to 4 wt.%.
  • the dehydration process is done using a continuous throughput vacuum microwave drying apparatus in which the pressure is less than atmospheric and microwave generators are arranged to irradiate the product, at a constant or variable energy output.
  • the food product to be dried is loaded into the vacuum chamber at its input end and is moved through the vacuum chamber to its output end.
  • the dehydrated product is then unloaded from the output end of the vacuum chamber.
  • FIG. 1 schematically illustrates an apparatus for carrying out the process on a continuous throughput basis.
  • the vacuum microwave dehydrator 10 comprises a vacuum chamber 12 having an input end 14 for introduction of the material and an output end 16 for removal of the dried product.
  • a first airlock 18 is arranged at the input end and a second airlock 20 at the output end, for loading and unloading the product.
  • a conveyor 22 is provided to transport the material on trays, typically at constant speed, from the input end to the output end of the vacuum chamber.
  • a microwave source 24 is arranged to irradiate microwave energy into the vacuum chamber.
  • a vacuum source 26 is operatively connected to the vacuum chamber for reducing the pressure inside it to a pressure below atmospheric
  • the drying apparatus 10 includes components that are conventionally required for vacuum microwave dehydrators, including a condenser, a refrigeration unit, a vacuum pump, a water load system, and a programmable logic controller (PLC) for controlling the operation of the system, including controlling the conveyor drive motors, the microwave generators, the vacuum pump, the refrigerant pumps and the airlocks.
  • PLC programmable logic controller
  • An example of a vacuum microwave dehydrator suitable for carrying out the process of the invention is a travelling wave-type apparatus, as disclosed in WO 201 1/085467, commercially available from EnWave Corporation of Delta, BC, Canada under the trademark quantaREV.
  • a travelling wave-type apparatus as disclosed in WO 201 1/085467, commercially available from EnWave Corporation of Delta, BC, Canada under the trademark quantaREV.
  • the high sugar content food product is fed into the vacuum chamber on trays and is conveyed across a microwave-transparent window on a conveyor belt while being subjected to vacuum pressure and microwave radiation.
  • Food products suitable for dehydration by the method of the invention include honey, molasses, maple syrup, agave syrup, caramel, corn syrup, date syrup and sweetened condensed milk, and other sugary viscous liquids.
  • a 133 gram sample of date syrup having an initial moisture content of about 25 wt.% was processed in a vacuum microwave apparatus at a vacuum pressure of 25 Torr and a microwave power level of 1200 W.
  • the product started foaming within 30 seconds and overflowed its dish. It could not be dried to a finished product.
  • a sample of honey weighing 69 g and having an initial moisture content of 20 wt.% was processed in a batch-type vacuum microwave drier.
  • the vacuum pressure was 60 + 2 Torr.
  • the microwave output power was a constant 1200 W.
  • the residence time was 52 minutes. No product foaming or burning was observed.
  • the final temperature of the product was 100°C .
  • the final product weight was 56.5 g and the final moisture content was 2.3 wt.%.
  • the product dried to an even, porous structure that could be easily milled into a powder.
  • Example 3 A sample of honey (Manuka) weighing 7,855 g and having an initial moisture content of about 15-20 wt.% was poured onto parchment-lined trays and processed in a continuous-throughput vacuum microwave drier (a quantaREV machine, made by EnWave Corporation). The vacuum pressure was 90 ⁇ 5 Torr. The microwave output power was a constant 4 kW. The residence time was 40 minutes. No product foaming or burning was observed. The final temperature of the product was 104°C. The final product weight was 6,582 g and the final moisture content was 2.5 wt.%. The product dried to an even, porous structure.
  • a quantaREV machine a quantaREV machine
  • a sample of white com syrup weighing 136.5 g and having an initial moisture content of about 22 to 25 wt.% was poured into a parchment-lined tray and processed in a batch-type vacuum microwave drier.
  • the vacuum pressure was 80 ⁇ 2 Torr.
  • the microwave output power was a constant 1200 W.
  • the residence time was 60 minutes. No product foaming or burning was observed.
  • the final temperature of the product was 77°C.
  • the final product weight was 106.9 g and the final moisture content was 2.6 wt.%.
  • the product dried to an even, porous structure.
  • a sample of white corn syrup was mixed with 20 wt.% maltodextrin.
  • the mixed sample weighed 95.2 g and had an initial moisture content of about 20 wt.%. It was poured into a parchment-lined tray and processed in a batch-type vacuum microwave drier.
  • the vacuum pressure was 80 ⁇ 2 Torr.
  • the microwave output power was a constant 1600 W.
  • the residence time was 50 minutes. No product foaming or burning was observed.
  • the final temperature of the product was 77°C.
  • the final product weight was 76.4 g and the final moisture content was 1 .5 wt.%.
  • the product dried to a cake similar in structure to Styrofoam. It was observed that maltodextrin appeared to assist in forming the structure, causing a more even pore distribution.
  • a sample of date syrup weighing 133 g and having an initial moisture content of about 25 wt.% was processed in a batch-type vacuum microwave drier.
  • the vacuum pressure was 50 ⁇ 2 Torr.
  • the microwave output power was 800 W for 20 minutes, followed by 1600 W for 25 minutes, followed by 2400 W for 10 minutes. No product burning was observed.
  • the final temperature of the product was 105°C.
  • the final product weight was 101 .1 g and the final moisture content was 1 .6 wt.%.
  • the product dried to an even, porous structure.
  • a sample of molasses weighing 127.9 g and having an initial moisture content of about 20 wt.% was poured into a parchment-lined tray and processed in a batch- type vacuum microwave drier.
  • the vacuum pressure was 80 ⁇ 2 Torr.
  • the microwave output power was 1200 W for 60 minutes, followed by 2000 W for 700 seconds. No foaming or product burning was observed.
  • the final temperature of the product was 1 10°C.
  • the final product weight was 103.9 g and the final moisture content was 1 .5 wt.%.
  • the product dried to an even, porous structure.
  • a sample of molasses was mixed with 20 wt.% maltodextrin.
  • the mixed sample weighed 92.5 g and had an initial moisture content of about 18 wt.%. It was poured into a parchment-lined tray and processed in a batch-type vacuum microwave drier.
  • the vacuum pressure was 80 + 2 Torr.
  • the microwave output power was a constant 1600 W.
  • the residence time was 50 minutes. No product foaming or burning was observed.
  • the final temperature of the product was 100°C.
  • the final product weight was 76.5 g and the final moisture content was 0.8 wt.%. It was observed that maltodextrin appeared to assist in forming the final product structure.
  • a sample of Eagle BrandTM sweetened condensed milk weighing 56.9 g and having an initial moisture content of about 25 wt.% was processed in a batch-type vacuum microwave drier.
  • the vacuum pressure was 60 ⁇ 2 Torr.
  • the microwave output power was 1200 W for 10 minutes, followed by 2000 W for 30 minutes. No foaming or product burning was observed.
  • the final temperature of the product was 90°C.
  • the final product weight was 43.2 g and the final moisture content was 1 .2 wt.%.
  • the product dried to an even, porous structure.

Landscapes

  • Engineering & Computer Science (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Molecular Biology (AREA)
  • Microbiology (AREA)
  • Wood Science & Technology (AREA)
  • Food Science & Technology (AREA)
  • Chemical & Material Sciences (AREA)
  • Zoology (AREA)
  • Polymers & Plastics (AREA)
  • Physics & Mathematics (AREA)
  • Biomedical Technology (AREA)
  • Biotechnology (AREA)
  • Electromagnetism (AREA)
  • Freezing, Cooling And Drying Of Foods (AREA)
  • Confectionery (AREA)
  • Jellies, Jams, And Syrups (AREA)
  • Drying Of Solid Materials (AREA)
  • Dairy Products (AREA)
  • General Preparation And Processing Of Foods (AREA)
  • Toxicology (AREA)

Abstract

A method of drying high sugar content food products such as honey and molasses in a vacuum microwave chamber. The method comprises loading the food product into the vacuum chamber, and exposing the food product to a vacuum pressure in the range of 45 to 250 Torr (60 to 333 mbar) in the vacuum chamber while irradiating the food product with microwave radiation. This dries the food product and forms a porous structure. The method minimizes or prevents foaming and dries the product at a temperature that prevents burning, while reducing the moisture content to a very low level.

Description

Vacuum Microwave Drying of High Sugar Content Liquids
Field
The invention pertains to methods of drying food products having a high sugar content, such as honey and molasses. Background
Dehydration of organic materials is commonly done in the food processing industry to preserve the products for storage or to create products that are used in the dehydrated form, for example dried herbs and various kinds of chips. It is known to dehydrate food products by vacuum microwave dehydration. Examples of this in the patent literature include WO 2009/049409 dated April 23, 2009, WO 2009/033285 dated March 19, 2009, WO 201 1/085467 dated July 21 , 2011 , WO 2013/010257 dated January 24, 2013, and WO 2014/085897 dated June 12, 2014. Vacuum microwave drying is a rapid method that can yield products with improved quality compared to air-dried and freeze-dried products. Because the drying is done under reduced pressure, the boiling point of water and the oxygen content of the atmosphere are lowered, so nutritional components sensitive to oxidation and thermal degradation can be retained to a high degree.
Although a wide range of food products can be dried by vacuum microwave processing, successful drying of liquid food products having a high sugar content has not been achieved in the prior art. This type of product, having a sugar content greater than 20 weight percent, is typically in the form of a viscous liquid. Such products experience foaming and splashing at the vacuum pressures conventionally used during vacuum microwave drying. Further, the structure of the product collapses in the vacuum chamber, trapping moisture that cannot be removed without burning of the product. There is a need in the food processing art for an effective method of drying high sugar content products.
Summary of the Invention
The present inventors have discovered that high sugar content food products can be dried using vacuum microwave drying to produce a commercially-acceptable product by using processing conditions that include a vacuum pressure in the range of 45 to 250 Torr (60 to 333 mbar). This has been found, surprisingly, to minimize or prevent foaming of the product and dry the product at a temperature that prevents burning, while reducing the moisture content to a very low level.
According to one embodiment of the invention, there is provided a method of dehydrating a food product having a sugar content of at least 20 wt.%, comprising the steps of: (a) loading the food product into a vacuum chamber; (b) exposing the food product to a vacuum pressure in the range of 45 to 250 Torr (60 to 333 mbar) in the vacuum chamber; (c) exposing the food product to microwave radiation during step (b), whereby the food product is dehydrated; and (d) unloading the dehydrated food product from the vacuum chamber.
These and other aspects and features of the invention will be apparent from the following description of the specific embodiments.
Brief Description of the Drawing
Figure 1 is a schematic diagram of a vacuum microwave dehydration apparatus suitable for carrying out the process of the invention.
Detailed Description of Preferred Embodiments
The method of the invention dehydrates high sugar content food products using a vacuum microwave apparatus. In general terms, this is done by exposing the food product to a selected vacuum pressure and to microwave radiation in a vacuum chamber for a selected residence time, thereby heating the product and reducing moisture to a desired level. In one embodiment, the process is done on a continuous-throughput basis, in which the product is fed into a vacuum chamber and conveyed through the vacuum chamber from an input end to an output end, for a selected residence time, during which microwave generators irradiate the product with microwave radiation. In another embodiment, the process is done on a batch basis, by loading the vacuum chamber, processing the product and then opening the vacuum chamber to remove the dried product.
If desired, the dried product may be milled to form a powder.
The food products suitable for processing by the invention have a high sugar content, in the range of 20 to 85 wt.%, alternatively in the range of 40 to 80 wt.%. For example, honey and molasses have a sugar content of about 80 wt.%, com syrup about 75 wt.% and sweetened condensed milk about 50 wt.%. This is much higher than the sugar content of most other food products that would be processed using vacuum microwave drying, which are commonly less than 10 wt.% sugar. The high sugar content food products for processing by the present invention are typically in the form of a viscous liquid. The process uses vacuum pressures in the range of about 45 to 250 Torr (60 to 333 mbar), alternatively 50 to 250 Torr (66.7 to 333 mbar), alternatively 50 to 200 Torr (66.7 to 267 mbar), alternatively 50 to 100 Torr (66.7 to 133 mbar), in the vacuum chamber. The present inventors have determined that processing high sugar content products at less than about 45 Torr, or less than 50 Torr, results in uncontrollable foaming during vacuum microwave drying at any microwave power density suitable to dry the product; and that processing at vacuum pressures above 250 Torr does not dry the viscous liquid to a porous structure, which is preferred. Pressures in the range of 45 to 250 Torr have been found suitable to control foaming and splashing of high sugar content products, prevent collapse of the product structure, and permit the product to be dried to a low moisture content and form a uniform finished product. The food product dries in the vacuum chamber at a temperature that is high enough to ensure proper drying while not being high enough to burn the product. For example, suitable temperatures of the product during drying are in the range of 75 to 125°C, alternatively in the range of 90 to 110°C.
Suitable microwave power densities are in the range of 100 to 3000 kW per kg of food product. Lower power densities will eventually dry the product but require too long a drying time to be commercially practical. Higher power densities have been determined to cause excessive foaming or splashing of high sugar content liquids during drying.
In some embodiments, maltodextrin is added to the food product prior to drying. For example, 5 to 30 wt.% may be added. This has been determined to assist in the drying process and produce a more porous, evenly-dried product, having a more even pore distribution. Residence times in the vacuum chamber in the range of 30 to 90 minutes, alternatively 40 to 70 minutes, have been found suitable for drying most high sugar content materials. Following the dehydration step, the dried product is unloaded from the vacuum chamber. The final moisture level of the dried material may be in the range of 0 to 10 wt.%, alternatively in the range of 1 to 4 wt.%.
In one embodiment, the dehydration process is done using a continuous throughput vacuum microwave drying apparatus in which the pressure is less than atmospheric and microwave generators are arranged to irradiate the product, at a constant or variable energy output. The food product to be dried is loaded into the vacuum chamber at its input end and is moved through the vacuum chamber to its output end. The dehydrated product is then unloaded from the output end of the vacuum chamber.
Figure 1 schematically illustrates an apparatus for carrying out the process on a continuous throughput basis. The vacuum microwave dehydrator 10 comprises a vacuum chamber 12 having an input end 14 for introduction of the material and an output end 16 for removal of the dried product. A first airlock 18 is arranged at the input end and a second airlock 20 at the output end, for loading and unloading the product. A conveyor 22 is provided to transport the material on trays, typically at constant speed, from the input end to the output end of the vacuum chamber. A microwave source 24 is arranged to irradiate microwave energy into the vacuum chamber. A vacuum source 26 is operatively connected to the vacuum chamber for reducing the pressure inside it to a pressure below atmospheric
The drying apparatus 10 includes components that are conventionally required for vacuum microwave dehydrators, including a condenser, a refrigeration unit, a vacuum pump, a water load system, and a programmable logic controller (PLC) for controlling the operation of the system, including controlling the conveyor drive motors, the microwave generators, the vacuum pump, the refrigerant pumps and the airlocks.
An example of a vacuum microwave dehydrator suitable for carrying out the process of the invention is a travelling wave-type apparatus, as disclosed in WO 201 1/085467, commercially available from EnWave Corporation of Delta, BC, Canada under the trademark quantaREV. Using such apparatus, the high sugar content food product is fed into the vacuum chamber on trays and is conveyed across a microwave-transparent window on a conveyor belt while being subjected to vacuum pressure and microwave radiation.
Food products suitable for dehydration by the method of the invention include honey, molasses, maple syrup, agave syrup, caramel, corn syrup, date syrup and sweetened condensed milk, and other sugary viscous liquids.
Examples Example 1
As a control, a 133 gram sample of date syrup, having an initial moisture content of about 25 wt.% was processed in a vacuum microwave apparatus at a vacuum pressure of 25 Torr and a microwave power level of 1200 W. The product started foaming within 30 seconds and overflowed its dish. It could not be dried to a finished product.
Example 2
A sample of honey weighing 69 g and having an initial moisture content of 20 wt.% was processed in a batch-type vacuum microwave drier. The vacuum pressure was 60 + 2 Torr. The microwave output power was a constant 1200 W. The residence time was 52 minutes. No product foaming or burning was observed. The final temperature of the product was 100°C . The final product weight was 56.5 g and the final moisture content was 2.3 wt.%. The product dried to an even, porous structure that could be easily milled into a powder.
Example 3 A sample of honey (Manuka) weighing 7,855 g and having an initial moisture content of about 15-20 wt.% was poured onto parchment-lined trays and processed in a continuous-throughput vacuum microwave drier (a quantaREV machine, made by EnWave Corporation). The vacuum pressure was 90 ± 5 Torr. The microwave output power was a constant 4 kW. The residence time was 40 minutes. No product foaming or burning was observed. The final temperature of the product was 104°C. The final product weight was 6,582 g and the final moisture content was 2.5 wt.%. The product dried to an even, porous structure.
Example 4
A sample of white com syrup weighing 136.5 g and having an initial moisture content of about 22 to 25 wt.% was poured into a parchment-lined tray and processed in a batch-type vacuum microwave drier. The vacuum pressure was 80 ± 2 Torr. The microwave output power was a constant 1200 W. The residence time was 60 minutes. No product foaming or burning was observed. The final temperature of the product was 77°C. The final product weight was 106.9 g and the final moisture content was 2.6 wt.%. The product dried to an even, porous structure.
Example 5
A sample of white corn syrup was mixed with 20 wt.% maltodextrin. The mixed sample weighed 95.2 g and had an initial moisture content of about 20 wt.%. It was poured into a parchment-lined tray and processed in a batch-type vacuum microwave drier. The vacuum pressure was 80 ± 2 Torr. The microwave output power was a constant 1600 W. The residence time was 50 minutes. No product foaming or burning was observed. The final temperature of the product was 77°C. The final product weight was 76.4 g and the final moisture content was 1 .5 wt.%. The product dried to a cake similar in structure to Styrofoam. It was observed that maltodextrin appeared to assist in forming the structure, causing a more even pore distribution.
Example 6
A sample of date syrup weighing 133 g and having an initial moisture content of about 25 wt.% was processed in a batch-type vacuum microwave drier. The vacuum pressure was 50 ± 2 Torr. The microwave output power was 800 W for 20 minutes, followed by 1600 W for 25 minutes, followed by 2400 W for 10 minutes. No product burning was observed. The final temperature of the product was 105°C. The final product weight was 101 .1 g and the final moisture content was 1 .6 wt.%. The product dried to an even, porous structure. Example 7
A sample of molasses weighing 127.9 g and having an initial moisture content of about 20 wt.% was poured into a parchment-lined tray and processed in a batch- type vacuum microwave drier. The vacuum pressure was 80 ± 2 Torr. The microwave output power was 1200 W for 60 minutes, followed by 2000 W for 700 seconds. No foaming or product burning was observed. The final temperature of the product was 1 10°C. The final product weight was 103.9 g and the final moisture content was 1 .5 wt.%. The product dried to an even, porous structure.
Example 8
A sample of molasses was mixed with 20 wt.% maltodextrin. The mixed sample weighed 92.5 g and had an initial moisture content of about 18 wt.%. It was poured into a parchment-lined tray and processed in a batch-type vacuum microwave drier. The vacuum pressure was 80 + 2 Torr. The microwave output power was a constant 1600 W. The residence time was 50 minutes. No product foaming or burning was observed. The final temperature of the product was 100°C. The final product weight was 76.5 g and the final moisture content was 0.8 wt.%. It was observed that maltodextrin appeared to assist in forming the final product structure.
Example 9
A sample of Eagle Brand™ sweetened condensed milk weighing 56.9 g and having an initial moisture content of about 25 wt.% was processed in a batch-type vacuum microwave drier. The vacuum pressure was 60 ± 2 Torr. The microwave output power was 1200 W for 10 minutes, followed by 2000 W for 30 minutes. No foaming or product burning was observed. The final temperature of the product was 90°C. The final product weight was 43.2 g and the final moisture content was 1 .2 wt.%. The product dried to an even, porous structure.
As will be apparent to those skilled in the art in the light of the foregoing disclosure, many alterations and modifications are possible in the practice of this invention without departing from the scope thereof. Accordingly, the scope of the invention is to be construed in accordance with the following claims.

Claims

Claims
1 . A method of dehydrating a food product having a sugar content of at least 20 wt.%, comprising the steps of:
(a) loading the food product into a vacuum chamber;
(b) exposing the food product to a vacuum pressure in the range of 45 to 250 Torr (60 to 333 mbar) in the vacuum chamber;
(c) exposing the food product to microwave radiation during step (b), whereby the food product is dehydrated; and
(d) unloading the dehydrated food product from the vacuum chamber
2. A method according to claim 1 , wherein the food product has a sugar content in the range of 20 to 85 wt.%.
3. A method according to claim 1 , where the food product has a sugar content of at least 40 wt.%.
4. A method according to claim 1 , wherein the food product has a sugar content in the range of 40 to 80 wt.%.
5. A method according to any preceding claim, wherein the pressure in step (b) is in the range of 50 to 250 Torr.
6. A method according to any preceding claim, wherein the pressure in step (b) is in the range of 50 to 200 Torr.
7. A method according to any preceding claim, wherein the pressure in step (b) is in the range of 50 to 100 Torr.
8. A method according to any preceding claim, wherein the dehydrated food product has a moisture content in the range of 0 to 10 wt.%.
9. A method according to any preceding claim, wherein the dehydrated food product has a moisture content in the range of 1 to 4 wt.%.
10. A method according to any preceding claim, wherein the product temperature during step (c) is in the range of 75 to 125°C.
11. A method according to any one of claims 1-9, wherein the product temperature during step (c) is in the range of 90 to 110°C.
12. A method according to any preceding claim, wherein the residence time of the food product in the vacuum chamber is in the range of 30 to 90 minutes.
13. A method according to any one of claims 1-1 1 , wherein the residence time of the food product in the vacuum chamber is in the range of 40 to 70 minutes.
14. A method according to any preceding claim, wherein a power density of the microwave radiation is in the range of 100 to 3000 kW/kg of the food product.
15. A method according to any preceding claim, further comprising the step of adding maltodextrin to the food product before step (a).
16. A method according to claim 15, wherein the maltodextrin is in the range of 5 to 30 wt.% of the food product.
17. A method according to any preceding claim, wherein the method is done on a continuous throughput basis.
18. A method according to any preceding claim, further comprising the step of milling the dehydrated food product to form a powder.
19. A method according to any preceding claim, wherein the food product comprises a viscous liquid.
20. A method according to any preceding claim, wherein the dehydrated food product is porous.
21. A method according to any preceding claim, wherein the food product is selected from the group consisting of honey, molasses, maple syrup, agave syrup, caramel, corn syrup, date syrup and sweetened condensed milk.
q
PCT/CA2019/050850 2019-06-14 2019-06-14 Vacuum microwave drying of high sugar content liquids Ceased WO2020248040A1 (en)

Priority Applications (18)

Application Number Priority Date Filing Date Title
CN201980097187.2A CN113993391A (en) 2019-06-14 2019-06-14 Vacuum microwave drying of high sugar content liquids
US17/595,521 US20220183329A1 (en) 2019-06-14 2019-06-14 Vacuum microwave drying of high sugar content liquids
PE2021001779A PE20220116A1 (en) 2019-06-14 2019-06-14 MICROWAVE VACUUM DRYING OF LIQUIDS WITH HIGH SUGAR CONTENT
SG11202111449XA SG11202111449XA (en) 2019-06-14 2019-06-14 Vacuum microwave drying of high sugar content liquids
CA3136640A CA3136640C (en) 2019-06-14 2019-06-14 Vacuum microwave drying of high sugar content liquids
PH1/2021/552665A PH12021552665A1 (en) 2019-06-14 2019-06-14 Vacuum microwave drying of high sugar content liquids
PCT/CA2019/050850 WO2020248040A1 (en) 2019-06-14 2019-06-14 Vacuum microwave drying of high sugar content liquids
MX2021012956A MX2021012956A (en) 2019-06-14 2019-06-14 Vacuum microwave drying of high sugar content liquids.
KR1020217035808A KR20220021460A (en) 2019-06-14 2019-06-14 Vacuum microwave drying of liquids with high sugar content
JP2021564803A JP2022535501A (en) 2019-06-14 2019-06-14 Vacuum microwave drying of high sugar content liquids
AU2019450892A AU2019450892A1 (en) 2019-06-14 2019-06-14 Vacuum microwave drying of high sugar content liquids
EP19933042.4A EP3982755A4 (en) 2019-06-14 2019-06-14 VACUUM MICROWAVE DRYING OF LIQUIDS WITH HIGH SUGAR CONTENT
BR112021020970A BR112021020970A2 (en) 2019-06-14 2019-06-14 Method of dehydrating a food product
CONC2021/0013897A CO2021013897A2 (en) 2019-06-14 2021-10-15 Vacuum microwave drying of liquids with high sugar content
CL2021002766A CL2021002766A1 (en) 2019-06-14 2021-10-21 Vacuum microwave drying of liquids with high sugar content.
ZA2021/08678A ZA202108678B (en) 2019-06-14 2021-11-05 Vacuum microwave drying of high sugar content liquids
ECSENADI202180849A ECSP21080849A (en) 2019-06-14 2021-11-15 MICROWAVE VACUUM DRYING OF HIGH SUGAR LIQUIDS
IL288413A IL288413A (en) 2019-06-14 2021-11-25 Vacuum microwave drying of high sugar content liquids

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/CA2019/050850 WO2020248040A1 (en) 2019-06-14 2019-06-14 Vacuum microwave drying of high sugar content liquids

Publications (1)

Publication Number Publication Date
WO2020248040A1 true WO2020248040A1 (en) 2020-12-17

Family

ID=73781173

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/CA2019/050850 Ceased WO2020248040A1 (en) 2019-06-14 2019-06-14 Vacuum microwave drying of high sugar content liquids

Country Status (18)

Country Link
US (1) US20220183329A1 (en)
EP (1) EP3982755A4 (en)
JP (1) JP2022535501A (en)
KR (1) KR20220021460A (en)
CN (1) CN113993391A (en)
AU (1) AU2019450892A1 (en)
BR (1) BR112021020970A2 (en)
CA (1) CA3136640C (en)
CL (1) CL2021002766A1 (en)
CO (1) CO2021013897A2 (en)
EC (1) ECSP21080849A (en)
IL (1) IL288413A (en)
MX (1) MX2021012956A (en)
PE (1) PE20220116A1 (en)
PH (1) PH12021552665A1 (en)
SG (1) SG11202111449XA (en)
WO (1) WO2020248040A1 (en)
ZA (1) ZA202108678B (en)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
IT201900009801A1 (en) * 2019-06-21 2020-12-21 Wealth & Res Trading Ltd Apparatus and method for producing dry food pasta

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102058004A (en) * 2010-10-29 2011-05-18 江南大学 Solid honey candy and preparation method thereof
CA2876537A1 (en) * 2012-07-13 2014-01-16 Island Abbey Foods Ltd. Solid agave syrup compositions
CA2818377C (en) * 2012-12-07 2015-01-20 Enwave Corporation Microwave vacuum-drying of organic materials
CA2781644C (en) * 2010-01-18 2015-09-29 Enwave Corporation Microwave vacuum-drying of organic materials
CA2833280C (en) * 2011-07-19 2015-11-24 Enwave Corporation Microwave vacuum-drying of organic materials

Family Cites Families (20)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2089062A (en) * 1935-12-30 1937-08-03 Albert C Hougland Machine and method for concentrating molasses and like products
US4045639A (en) * 1973-01-16 1977-08-30 Food Processing Systems Corporation Continuous microwave and vacuum dryer
CA1217376A (en) * 1982-12-28 1987-02-03 Kazumitsu Taga Dehydrated food product and method of producing same
US4640020A (en) * 1985-11-27 1987-02-03 Mcdonnell Douglas Corporation Zoned microwave drying apparatus and process
DK159488A (en) * 1988-03-23 1989-09-24 Danske Sukkerfab PROCEDURE FOR CONTINUOUS DRYING OR EVAPORATION OF A MATERIAL AND APPARATUS FOR EXERCISING THE PROCEDURE
JPH01273600A (en) * 1988-04-25 1989-11-01 Calpis Food Ind Co Ltd:The Method for producing granular sugars
US5020237A (en) * 1989-01-03 1991-06-04 The J. M. Smucker Company Method and apparatus for dehydrating fruit
CH681042A5 (en) * 1989-07-03 1992-12-31 Bucher Guyer Ag Masch
US5003143A (en) * 1990-04-09 1991-03-26 Progressive Recovery, Inc. Microwave sludge drying apparatus and method
RU2029206C1 (en) * 1992-06-01 1995-02-20 Эдуард Александрович Новосельцев Drying plant for viscous liquid materials
US6128831A (en) * 1999-06-03 2000-10-10 Durance; Timothy Douglas Process for drying medicinal plants
CA2296124A1 (en) * 2000-01-14 2001-07-14 Huny Hunks Ltd. Dried honey
US6312745B1 (en) * 2000-07-07 2001-11-06 The University Of British Columbia Process for dehydration of berries
TWI251472B (en) * 2005-06-02 2006-03-21 Kurotech Co Ltd System for drying and sterilizing foods and method therefor
CA2649936A1 (en) * 2009-01-15 2010-07-15 John Lawrence Rowe Honey product having a low water content
BR112015011291B1 (en) * 2012-11-16 2020-12-15 Nuwave Research Inc. APPLIANCE AND METHOD FOR VAPORIZING A VAPORIZABLE DIELECTRIC SUBSTANCE FROM A MATERIAL, SYSTEM FOR VAPORIZING A VAPORIZABLE SUBSTANCE FROM A MATERIAL, USE OF THE APPLIANCE AND METHOD OF UNIFORMING A MATERIAL MATERIAL MATERIAL MATERIAL
US10578359B2 (en) * 2014-06-11 2020-03-03 Enwave Corporation Microwave vacuum-drying of organic materials
CA3016462C (en) * 2016-03-03 2021-11-23 Ocean Spray Cranberries, Inc. Fruit and vegetable products
WO2019063739A1 (en) * 2017-09-28 2019-04-04 Rhodia Operations Process for drying polysaccharides
TR201720995A2 (en) * 2017-12-21 2018-03-21 Eti Gida Sanayi Ve Ticaret Anonim Sirketi Molasses Powder And Production Method Of This Powder

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA2781644C (en) * 2010-01-18 2015-09-29 Enwave Corporation Microwave vacuum-drying of organic materials
CN102058004A (en) * 2010-10-29 2011-05-18 江南大学 Solid honey candy and preparation method thereof
CA2833280C (en) * 2011-07-19 2015-11-24 Enwave Corporation Microwave vacuum-drying of organic materials
CA2876537A1 (en) * 2012-07-13 2014-01-16 Island Abbey Foods Ltd. Solid agave syrup compositions
CA2818377C (en) * 2012-12-07 2015-01-20 Enwave Corporation Microwave vacuum-drying of organic materials

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See also references of EP3982755A4 *

Also Published As

Publication number Publication date
PE20220116A1 (en) 2022-01-26
PH12021552665A1 (en) 2022-09-19
CL2021002766A1 (en) 2022-07-08
MX2021012956A (en) 2021-11-25
CN113993391A (en) 2022-01-28
ZA202108678B (en) 2022-07-27
EP3982755A1 (en) 2022-04-20
AU2019450892A1 (en) 2021-11-25
EP3982755A4 (en) 2023-01-18
CO2021013897A2 (en) 2022-01-17
KR20220021460A (en) 2022-02-22
CA3136640A1 (en) 2020-12-17
IL288413A (en) 2022-01-01
US20220183329A1 (en) 2022-06-16
SG11202111449XA (en) 2021-11-29
BR112021020970A2 (en) 2021-12-21
CA3136640C (en) 2023-03-14
ECSP21080849A (en) 2021-12-30
JP2022535501A (en) 2022-08-09

Similar Documents

Publication Publication Date Title
US11278635B2 (en) Method and apparatus for pasteurizing and dehydrating cannabis
CN104769377B (en) The micro-wave vacuum of organic material
US9155133B2 (en) MVD method and device for drying and buffering organic moist products
US4622757A (en) Cogeneration microwave food dryer
US5165948A (en) Process for dehydrating a product based on fats
CA3136640C (en) Vacuum microwave drying of high sugar content liquids
CZ20024272A3 (en) Method and apparatus for drying books and similar paper-based material
US20210212347A1 (en) Vacuum microwave drying of foods with pulsed electric field pre-treatment
EP3993642B1 (en) Apparatus and method for producing dry pasta
US20240280318A1 (en) Methods and apparatus for drying cannabis
RU2018245C1 (en) Method for drying food products
RU2333036C1 (en) Method of granular materials treatment
CA3098803A1 (en) A process for drying fruits and vegetables
JPS63223481A (en) Drier for cereals
CA3108130A1 (en) Apparatus and method for vacuum microwave-dehydrating of organic materials
WO2024013658A1 (en) Apparatus and method for reducing the water content in vegetal or animal inorganic and/or organic compounds
PL238222B1 (en) Method for drying of timber
WO2022077103A1 (en) Method of making dried vegetable snack products
WO2016135683A1 (en) Method for the accelerated aging of rice
RU2262051C2 (en) Method and device for drying loose dielectric materials
Snezhkin et al. Estimation of thermal efficiency of driers working with materials with various initial humidity
HK40074751A (en) Apparatus and method for producing dry pasta
HK40074751B (en) Apparatus and method for producing dry pasta
JPS61227734A (en) Method of dehydrating vegetable or the like with heat of oil
UA82421C2 (en) Method for drying cocarboxylase hydrochloride

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 19933042

Country of ref document: EP

Kind code of ref document: A1

ENP Entry into the national phase

Ref document number: 3136640

Country of ref document: CA

WWE Wipo information: entry into national phase

Ref document number: NC2021/0013897

Country of ref document: CO

REG Reference to national code

Ref country code: BR

Ref legal event code: B01A

Ref document number: 112021020970

Country of ref document: BR

ENP Entry into the national phase

Ref document number: 2021564803

Country of ref document: JP

Kind code of ref document: A

ENP Entry into the national phase

Ref document number: 20217035808

Country of ref document: KR

Kind code of ref document: A

ENP Entry into the national phase

Ref document number: 2019450892

Country of ref document: AU

Date of ref document: 20190614

Kind code of ref document: A

NENP Non-entry into the national phase

Ref country code: DE

ENP Entry into the national phase

Ref document number: 112021020970

Country of ref document: BR

Kind code of ref document: A2

Effective date: 20211019

WWE Wipo information: entry into national phase

Ref document number: 2019933042

Country of ref document: EP

WWP Wipo information: published in national office

Ref document number: NC2021/0013897

Country of ref document: CO