EP-4739142-A1 - A THERMAL TREATMENT SYSTEM AND METHOD

EP4739142A1EP 4739142 A1EP4739142 A1EP 4739142A1EP-4739142-A1

Abstract

A system and method for the thermal treatment or blanching of food product. The system comprises a horizontally rotatable auger with perforated flights to convey the product from and a supply side to discharge, enveloped by a cylindrical body partially filled with water, guaranteeing entire submersion the product. A first part of the auger is supplied with hot water at first temperature and discharges water from the cylindrical body near the product inlet side of the auger. A second part of the auger is supplied with hot water at a second temperature and discharges water from the cylindrical body near the product outlet side of the auger. It has been found that in this way a compact and cleanable rotary screw type thermal treatment or blanching system is provided, with two successive zones providing optimal process controllability, the ability of low temperature energy reclaim, minimization of the use of fresh make-up water and minimal product damage.

Inventors

NIJDAM, JELLE LUUTZEN

Assignees

Solutherm B.V.
Tummers Beheer B.V.

Dates

Publication Date: 20260513
Application Date: 20240702

Claims (20)

1. A thermal treatment system, comprising a treatment chamber (9) having a product inlet (4) for receiving product to be treated and a product outlet (5) for discharging the product, wherein the treatment chamber (9) includes a horizontal rotatable auger (2) to convey the product in a product flow direction (X) from the product inlet (4) to the product outlet (5), wherein the treatment chamber (9) has at least one liquid supply port (36, 37) for feeding thermal treatment liquid into the chamber, wherein the treatment chamber (9) has at least one first liquid discharge port (33, 41) for discharging treatment liquid from the chamber (9), the first discharge port being located upstream with respect to the at least one supply port (36, 37), viewed relative to said product flow direction (X), for example near the product inlet (4), wherein the treatment chamber (9) has at least one second liquid discharge port (31, 28) for discharging treatment liquid from the chamber, the second discharge port (31, 28) being located downstream with respect to the at least one supply port (36, 37), viewed relative to said product flow direction (X), for example near the product outlet (5), wherein the auger (2) is preferably uninterrupted, viewed along a longitudinal direction of the chamber (9), wherein the system is preferably configured such that the product can remain entirely submergedin treatment liquid during transport through the chamber (9) from the product inlet (4) to the product outlet (5).
2. A thermal treatment system according to claim 1, wherein each liquid supply port (36, 37) includes at least one injection nozzle for injecting treatment liquid into the chamber (9), the nozzle extending opposite a flight of the auger (2), for example below the auger (2).
3. A thermal treatment system according to claim 1 or 2, wherein the horizontal rotatable auger (2) has a perforated flight.
4 A thermal treatment system according to any of the preceding claims, wherein the treatment chamber (9) is configured to be partially filled with thermal treatment liquid for providing entire submersion of product to be treated, wherein the treatment chamber (9) preferably includes a cylindrical body which partially envelops the auger (2), at least for a lower part.
5. A thermal treatment system according to any of the preceding claims, including a plurality of spaced-apart liquid supply ports (36, 37) extending along the treatment chamber (9), between the product inlet (4) and product outlet (5), wherein the liquid supply ports (36, 37) are located for example in or near a bottom of the chamber (9), for example at various locations along the length of the chamber (9).
6. A thermal treatment system according to claim 5, including a common manifold (26) for supplying liquid to each of the liquid supply ports (36, 37), wherein the manifold (26) is preferably divided in separate manifold sections associated with different liquid supply ports (36, 37), in particular such that no direct liquid transport is possible between the sections of the manifold (26).
7. A thermal treatment system according to claim 6, wherein a first section of the manifold (26) is coupled to the first liquid discharge port (33) for receiving discharged liquid therefrom, wherein a second section of the manifold (26) is coupled to the second liquid discharge port (31) for receiving discharged liquid therefrom.
8. A thermal treatment system according to any of the claims 5-7, including heating means (38, 23), for example at least a first heater (38) and a second heater (23), for heating liquid that is fed to at least a first port (36) of the of liquid supply ports to a first treatment temperature and for heating liquid that is fed to at least a second port (37) of the of liquid supply ports to a second treatment temperature, the second treatment temperature being higher than the first treatment temperature.
9. A thermal treatment system according to any of claims 5-8, including pumping means (34, 22), for pumping liquid to at least a first port (36) of the of liquid supply ports at a first flow rate and for pumping liquid to at least a second port (37) of the of liquid supply ports at a second flow rate, for example a second flow rate that differs from the first flow rate.
10. A thermal treatment system according any of claims 5-9, including flow control means (21, 46, 47) for controlling flow to each of the plurality of liquid supply ports (36, 37), for example such that a longitudinal position of liquid supply into the chamber (9) can be selected or adjusted.
11. A thermal treatment system according any of the preceding claims, wherein the system is configured such that the treatment chamber (9) is divided into a first treatment zone (43) and second treatment zone (44), the horizontal auger (2) extending through both zones, in particular such that the auger (2) can pass product between the first treatment zone (43) and second treatment zone (44) in a submerged manner, each treatment zone being associated with at least one individual liquid supply port (36,37) as well as a respective individual liquid discharge port (33, 41), whereby during operation treatment liquid is preferably transported in counterflow with a main longitudinal product transport direction in the first zone (43) and in parallel direction with the main product transport direction in the second zone (44).
12. The system according to claim 11, wherein a location of a vertical imaginary interface (45) between the first treatment zone (43) and the second treatment zone (44) is located at a point between an inlet side and an outlet side of the auger (2), wherein a flight of the auger (2) penetrates the imaginary interface between the first treatment zone (43) and the second treatment zone (44).
13. A thermal treatment method, for example a blanching method, utilizing the system according to any of the preceding claims, wherein the method includes: -feeding treatment liquid into the treatment chamber (9), containing the rotating horizontal auger (2), via the at least one liquid supply port (36, 37); -feeding product into the treatment chamber (9) via the product inlet (4); -transporting the product, in a product flow direction, from the product inlet (4) to the product outlet (5), at least partly by the rotating auger (2); -discharging treatment liquid upstream of said at least one liquid supply port (36, 37) via the at least one first liquid discharge port (33, 41); and discharging treatment liquid downstream of at least one liquid supply port (36, 37) via the at least one second liquid discharge port (31, 28).
14. The thermal treatment method according to claim 13 in combination with at least claim 5, wherein treatment liquid is fed to a first port (36) of the at least one liquid supply port at a first treatment temperature, wherein treatment liquid is fed to a second port (37) of the at least one liquid supply port at a second treatment temperature, the second treatment temperature being different from, e.g. higher or lower than, the first treatment temperature.
15. The thermal treatment method according to claim 13 or 14 in combination with at least claim 5, including controlling flow to the plurality of liquid supply ports (36, 37), in particular for selecting or changing a longitudinal position of liquid supply into the chamber (9), for example by opening one or more ports at a first longitudinal position and closing one or more ports at one or more other longitudinal positions.
16. The thermal treatment method according to any of claims 13-15 in combination with at least claim 5, wherein treatment liquid is fed to a first port (36) of the at least one liquid supply port at a first flow rate, wherein treatment liquid is fed to a second port of the at least one liquid supply port at a second flow rate, wherein the first flow rate and the second flow rate are independently controlled.
17. The thermal treatment method according to any of claims 13-16, whereby a first treatment process of the product, for example a heating process, takes place in a first zone (43) in counterflow with the treatment liquid, whereby a second treatment process of the product takes place in a second zone (44) wherein the treatment liquid flows in the same direction as the product flow direction, the first zone (43) and second zone (44) being traversed by the rotating auger (2).
18. The thermal treatment method according to claim 17, whereby a liquid flow rate across an imaginary interface (45) between the first zone (43) and second zone (44) is negligible as compared to each of liquid flow rates through the zones (43, 44) and/or compared to each of liquid flow rates through the supply ports (36, 37).
19. The thermal treatment method according to any of claims 13-18, wherein water, for example fresh water, is supplied to the at least one supply port (36, 37) as treatment liquid.
20. The thermal treatment method according to any of claims 13-19, comprising the submersion of the product in and transport through the treatment liquid in the chamber (9) during a certain predefined treatment time, whereby this treatment time consists of a first interval and a second interval, whereby during the first interval the product is exposed to a first liquid circulation (W 1), at a first temperature and a first liquid quality, in counterflow with a main direction of transport of the product through the chamber (9), and whereby during the second interval the product is exposed to a second liquid circulation (W2), at a second temperature and a second liquid quality, parallel to the main direction of transport of the product through the chamber, whereby the relative duration of the first and second interval as portions of an overall treatment time can preferably be selected or adjusted or more or less freely chosen, wherein in particular said first and second liquid quality is associated with concentrations of from the product into the treatment liquid dissolved matters.

Description

Title: A thermal treatment system and method FIELD OF THE INVENTION The present invention relates to a thermal treatment system and corresponding method, for example for blanching of food products, such as e.g. fruits, vegetables or potatoes. BACKGROUND TO THE INVENTION Blanching is a thermal treatment process of food products such as fruits, vegetables or potatoes, whereby the product is subjected to warm water or steam for one or more well defined respective durations to one or more well defined elevated temperatures with the purpose to, for example, inactivate enzymes, modify the product texture, preserve colour, improve flavour or nutritional values or to remove trapped air. The blanching process usually precedes one or more other unit operations, such as cooling and/or cooking and/or freezing and/or frying and/or drying. An example of a blanching process of green vegetables is described in EPO 124627. The herein described stepwise blanching process is characterized by a first step of relatively short duration (1 to 30 sec) during which the products are exposed to a relatively high temperature (90 to 100°C), followed by a second step of longer duration (1 to 60 min) with lower temperature (45 to 90°C). Certain products might preferably be exposed to a third blanching step. The combination of these specific steps appears to improve the firmness, texture and/or colour of the products after a certain period of frozen storage, approaching the quality of the fresh raw materials. The blanching of potatoes usually serves to deactivate enzymes, leach of sugars and/or improve quality aspects of the final product such as for example swelling power, water solubility, stability during frying, colour and/or digestibility. The temperature of potato blanching processes ranges typically from 70 to 90°C, with a residence time ranging from typically 15 to 35 min. The blanching of potatoes commences with the hydration of cells as the product temperature increases, followed by the melting of crystals, arrangement of starch chains from ordered to disordered and the separation of amylose and amylopectin, the so-called gelatinization process. The blanching process of potatoes is usually followed by a cooling process, whereby the starch chains realign, reorder and form interconnecting hydrogen bonds, the so-called retrogradation process. This process takes typically 15 minutes or longer and is completed when the core temperature of the product has decreased ideally to 12°C. The temperature evolutions and durations of the respective blanching and cooling processes, i.e. the gelatinization and retrogradation processes, can have substantial influence on one or more of the aforementioned quality aspects of the final potato product. Industrial blanching processes usually make use of either a belt or a screw to convey the product. In case of a belt conveyor, the product is distributed to a certain layer thickness on top of a water permeable conveying belt. Multiple sprayers are mounted inside the blancher above the product and belt to supply water of a certain temperature to the product layer. After passing through the product layer and belt, the water is collected in a water collection tank underneath the belt, after which a part of the collected water is pressurized again by a pump, reheated in a heat exchanger or by direct steam injection and returned to the sprayers. Another part of the water might be drained from the collection tank, to be replaced by a similar amount of fresh make-up water, in order to maintain the concentrations of into the blanching water dissolved matters, such as for example leached of sugars, below a certain maximum. The installation of multiple successive collection tanks, pumps, heaters and sprayers permits to expose the product on the belt to a predefined temperature evolution throughout the blanching process. As described above, such process controllability is in some cases essential to attain optimal product quality. Furthermore, multiple of such successive compartments permits the reuse of drained water from compartments with relatively low concentrations of dissolved matters as make-up of compartments with relatively high concentrations, in order to limit the consumption of fresh make-up water for the blanching process. Blanching processes typically require a lot of energy for heating up the entire product mass, from a relatively low supply temperature to a relatively high temperature required for the blanching process. An advantage of belt blanchers is that compartments which require lower blanching temperatures might be heated with excess heat from other processes released at slightly higher temperatures. Another advantage of belt blanchers is that products on the belt are not exposed to any mechanical stresses. Such blanchers are therefore especially advantageous for vulnerable products, which are relatively sensitive to mechanical abuse. Belt blanchers hence seem to offer certain advantages