WO2013098698A1

WO2013098698A1 - Methods and devices for cooking starch-containing food

Info

Publication number: WO2013098698A1
Application number: PCT/IB2012/057363
Authority: WO
Inventors: Eng Cheng KHAW; Declan Patrick Kelly; Fei Xue; Jingwei Tan; Jiani TANG
Original assignee: Koninklijke Philips Electronics N.V.
Priority date: 2011-12-26
Filing date: 2012-12-17
Publication date: 2013-07-04

Abstract

The invention provides methods and devices for cooking starch-containing food. The method of processing starch-containing food comprises the steps of: heating(S20)the starch-containing food and water to generate a mixture comprising starch-containing food and soup; separating (S21) a first portion of the soup from the mixture according to a separating scheme; a first cooking step (S22) for cooking the remaining mixture according to a first cooking scheme; and a second cooking step(S23)for cooking the separated soup according to a second cooking scheme. The first cooking scheme is different from the second cooking scheme. By using the embodiments of this invention, each of the first and the second cooking step will contribute to the final quality of the soup and that of the remaining mixture, independently.

Description

METHODS AND DEVICES FOR COOKING STARCH-CONTAINING FOOD

Technical field

[001] The present invention relates to kitchenware, and particularly to methods and devices for cooking starch-containing food.

Background of the invention

[002] Rice is a common staple food in East Asia. Nowadays there are various automatic rice cookers. US Patent Application with Publication Number US2007/0190221 Al discloses a method and apparatuses for healthy rice cooking and removing starch in rice. The application discloses a rice cooker, including: an inner pot, an outer case with control buttons, a power input terminal, a thermostat component, a control circuit, a rice cooker lid and a heater plate. The inner pot is placed inside the outer case, and the heating plate, the thermostat and the control circuit are placed at the bottom of the inner pot. A starch removing device is placed between the bottom of the inner pot and the outer case, and the starch removing device comprises: a heating plate, a power input terminal, a thermostat component, a control circuit disposed at the bottom, a medium case inside the outer case, a water storage trough at the exterior of the medium case, a water drainage trough between the medium case and the outer case, and an evaporating tube at the bottom of the water storage trough. The ends of the evaporating tube are connected with the water storage trough and the inner pot through a channel, whereas, the water drainage trough is connected with a valve and the bottom of the inner pot through channels. By using this rice cooker, the rice can be soaked and cleansed with flowing water before cooking the rice. The process removes a portion of the starch in rice, thereby lowering the starch content in rice, which is beneficial to human health.

Summary of the invention

[003] Prior art document US2007/0190221A1 discloses methods and apparatuses for removing starch in rice, wherein the rice is cleansed with flowing water before being cooked. However, the prior art treats the discharged water as waste. In fact, the flowing water that is discharged from the rice not only includes starch but also includes other nutrients. Besides, sometimes starch is also needed as a user may prefer a starch-rich taste.

[004] In addition, in the traditional congee cooking process, water and rice are confined in the same compartment, and the rice and water are subject to the same temperature changes, which may restrict the process of soup production and granule production, because of the following factors:

[005] - The consumer may not be able to control the soup (watery, creamy, sticky criteria) and the granules (adhesive/granular, hard/soft, chewy/fluffy criteria) independently of each other.

[006] - The leaching-out of the grain-amylose is impeded by the pasting effect of the solute.

[007] - The water absorption of amylopectin is affected by the pasting of the amylose (if the rice grains are mixed with the pasting soup).

[008] Therefore, the embodiments of the present invention propose methods and devices for cooking starch-containing food and soup separately.

[009] The cooking of starch-containing food, for example rice, is a complex and progressive process. Starch is present in rice granules in two forms: amylose (straight-chain polysaccharide) and amylopectin (branched polysaccharide). Amylose and amylopectin react differently with water during the heating process, due to their structural difference, leading to three phenomena, namely:

a) Amylose leaching-out (from the rice granules): When soaking in water, amylose, with its straight-chain structure, will leach out from the granules, whereas amylopectin will not.

b) Amylose pasting (in the rice-solute): When amylose is heated in water, it will attract water molecules with its hydroxyl radicals and reduce the viscosity of the rice solute. c) Amylopectin water-absorption (in the rice- granules): As the heating process progresses, the branch-chain of the amylopectin will open up and absorb water molecules by weak bonding between its hydroxyl stems. [0010] All these three phenomena take place concurrently, but they each have their peak moments, according to the temperature and water conditions. Within a fixed dose of water and at an ascending temperature, the leaching-out of amylose will reach its peak at around 55degC(°C), and will slow-down as the solute is getting saturated. Pasting will reach its peak at around 70degC, as the amylose chains extract more free water molecules and even start to mutually attract each other and affect the viscosity of the rice-solute. At a higher temperature, the effect of amylopectin water-absorption will prevail, as the branch-chains of the granules will open up and attract more water molecules. The rice grain will eventually absorb all the water and become swollen and softened. The optimum water absorption temperature is about lOOdegC.

[0011] Based on the above observations, in a first aspect of the invention, a method of processing starch-containing food comprises the steps of:

[0012] - heating the starch-containing food and water to generate a mixture comprising starch-containing food and soup;

[0013] - separating a first portion of the soup from the mixture according to a separating scheme, to generate a separated soup and a remaining mixture;

[0014] - a first cooking step for cooking the remaining mixture; and

[0015] - a second cooking step for cooking the separated soup.

[0016] According to the embodiments of the invention, each of the first and the second cooking step will contribute to the final quality of the soup and that of the remaining mixture, independently.

[0017] It is to be noted that the term "process starch-containing food" in the context of this invention means cooking raw food to obtain cooked food which is ready for consumption.

[0018] In the above embodiment, a first portion of soup is separated from the mixture of starch-containing food and soup, and the separated soup and the remaining mixture are cooked separately; therefore, the embodiment provides a more flexible way of cooking food, wherein the expected result (including taste, appearance, etc) of the cooked food and cooked soup can be controlled independently. In another embodiment of the first aspect, the method further comprises the following step before the first and the second cooking step: obtaining data reflecting the expected result relating to processed starch-containing food; determining a first cooking scheme according to the obtained data; and determining a second cooking scheme according to the obtained data; and the first cooking step is carried out according to the first cooking scheme and the second cooking step is carried out according to the second cooking scheme.

[0019] In this embodiment, the obtained data may be provided by the user input, and the method may individually adjust the first cooking scheme and the second cooking scheme according to the obtained data; therefore, the result relating to the processed starch-containing food may be controlled flexibly.

[0020] In another embodiment, the first cooking step comprises a heating step, and the first cooking scheme comprises a temperature controlling scheme.

[0021] The temperature controlling scheme may comprise the following parameters:

[0022] - temperature at which the remaining food is heated;

[0023] - duration that the remaining food is heated;

wherein the second cooking scheme comprises at least one of the following:

[0024] - temperature at which the separated soup is to be heated;

[0025] - duration that the separated soup is to be heated.

[0026] In this embodiment, the specific parameter of the first cooking step, such as temperature and duration of heating the remaining mixture, and the specific parameter of the second cooking step, such as temperature and duration of heating the soup, are controlled separately; therefore a more specific cooking method is provided.

[0027] The duration of heating may depend on the manner of heating. For example, if the soup is heated consistently, then the duration of heating the soup represents the total time that the soup is heated by the heater; if, on the contrary, the soup is heated intermittently, which means the heater for heating the soup is turned on and off alternately, then the duration of heating the soup represents the time of the total duration.

[0028] In another embodiment, the processing method further comprises the following step before the step of separating:

[0029] - obtaining data reflecting the expected result relating to processed starch-containing food;

[0030] - determining the separating scheme according to the obtained data.

[0031] With this embodiment, the separating scheme may be determined dynamically based on the obtained data, and the obtained data includes user input or the data predetermined and stored in the MCU.

[0032] To be more specific, the separating scheme comprises at least one of the following:

[0033] - time point at which the first portion of the soup is to be separated from the mixture;

[0034] - temperature at which the first portion of the soup is to be separated from the mixture;

[0035] - amount of soup to be separated from the mixture.

[0036] The separating scheme influences the result of the processed starch-containing food. The time point and the temperature at which the soup is to be separated from the mixture, as well as the amount of soup to be separated from the mixture, will further influence the result of the cooked food and cooked soup.

[0037] Furthermore, in another embodiment, the temperature, at which the first portion of the soup is to be separated, corresponds to one of the following:

[0038] - the temperature of the starch leaching-out stage of the starch-containing food;

[0039] - the temperature of the starch pasting stage of the starch-containing food; or

[0040] - the temperature of the water absorption stage of the starch-containing food.

[0041] When the soup and the starch-containing food are separated at different temperatures or time points, the result, such as taste, appearance of the produced rice and produced soup will be influenced.

[0042] In another embodiment, the first cooking scheme further comprises a water supplying scheme which specifies when and how to add water during the first cooking step, the water supplying scheme comprising:

[0043] - time point at which the fresh water is to be added into the remaining mixture; [0044] - temperature of the remaining mixture when the fresh water is to be added into the remaining mixture;

[0045] - temperature of the fresh water to be added into the remaining mixture; and

[0046] - the amount of fresh water to be added into the remaining mixture;

[0047] and the first cooking step further comprises:

[0048] - adding fresh water according to the water supplying scheme;

[0049] - cooking the remainingd mixture with the added fresh water according to the first cooking scheme.

[0050] In this embodiment, the fresh water is added into the remaining mixture to help the remaining mixture to be further cooked.

[0051] Further to the above embodiment, the time point at which the fresh water is to be added into the remaining mixture corresponds to the temperature of the starch leaching-out stage of the remaining mixture, and the first cooking step further comprises:

[0052] - repeating the steps of separating the first portion of soup, adding water and cooking the remaining mixture with the added fresh water for a given cycle.

[0053] In this embodiment, since the steps of separating, adding water and cooking the remaining mixture with the added fresh water are repeated for a given cycle, and the remaining mixture is at the temperature corresponding to the starch leaching-out stage of the food, more starch leaches out of the food, which influences the result, such as taste, appearance, etc, of the cooked food and cooked soup.

[0054] In another embodiment, after the step of the first and the second cooking steps, the method further comprises the following step:

- mixing a second portion of the cooked soup and the cooked remaining mixture.

[0055] With this step, a congee is obtained from granules and soup which have been separately controlled.

[0056] In the above description, the first portion and the second portion of soup both represent at a least a portion of the soup, wherein the first portion of soup may include the entire soup and the second portion of soup may also include the entire soup. Those skilled in the art of cooking may also appreciate that the amount of the first portion and the amount of the second portion may be the same or different in order to achieve various cooking effects.

[0057] In a second aspect of the present invention, there is provided a food cooker, comprising:

[0058] - a container comprising a first chamber, the first chamber being configured to contain starch- containing food and water;

[0059] - a first heater coupled with the first chamber for heating the starch- containing food and the water in the first chamber to generate a mixture comprising starch-containing food and soup;

[0060] - a separating unit for separating a first portion of the soup from the first chamber and transferring it (?) into a second chamber;

[0061] - the second chamber is configured to receive soup separated from the first chamber;

[0062] - a second heater coupled with the second chamber for heating the separated soup in the second chamber; and

[0063] - a controller coupled with the separating unit and configured to control the separating unit to separate a first portion of the soup from the first chamber and transfer it (?) into the second chamber according to a separating scheme, and the controller is further coupled with the first and the second heaters and configured to control the first heater to cook the remaining mixture; and to control the second heater to cook the separated soup.

[0064]

Brief description of the drawings

[0065] Features, aspects and advantages of the present invention will become obvious by reading the following description of non-limiting embodiments with the aid of appended drawings. In the drawings, same or similar reference numerals refer to the same or similar steps or means.

[0066] Fig. 1 shows a schematic block diagram of a rice cooker 10, according to an embodiment of the invention;

[0067] Fig. 2 shows the flowchart of the method of cooking rice, according to an embodiment of the invention;

[0068] Figs. 3(A) and 3(B) show a schematic view of a rice cooker 10 , according to an embodiment of the invention.

[0069] Figs. 4(A) and 4(B) show a schematic view of a rice cooker 10 , according to another embodiment of the invention.

[0070] Figs. 5(A) and 5(B) show a schematic view of a rice cooker 10, according to another embodiment of the invention.

[0071] Figs. 6(A) and 6(B) show a schematic view of a rice cooker 10, according to another embodiment of the invention.

[0072] Fig. 7 shows the molecular formula of amylase; and

[0073] Fig. 8 shows the molecular formula of amylopectin.

Detailed description of embodiments

[0074] Prior to the elucidation of embodiments of the present invention, some facts on gelatinization (also called pasting) are given:

[0075] (i) Hydro xyl-bonding: Gelatinization is a progressive hydration process, based on the change of hydroxyl bonding of water and the glucose-unit of the polysaccharide.

[0076] (ii) Glycosidic-bonding: glycosidic bonding, however, is a bond between glucose-units on the polysaccharide that determines the macro-structure of the rice (amylose or amylopectin).

[0077] (iii) Amylose, straight-chain structure, is based on [1, 4] glycosidic chain. The molecular formula of amylose is shown in Fig. 7.

[0078] (iv) Amylopectin, branched-chain structure, branches on [1, 6] glycosidic chain. The molecular formula of amylopectin is shown in Fig. 8.

[0079] (v) Both amylose and amylopectin (on a straight chain) will be attacked by H₂0, and break down into shorter chains from macro structures and contribute to the leaching out at around 50~55degC.

[0080] (vi) Amylopectin (on the branched structure) retains the granule structure, and attracts the hydroxyl radical of the H₂0, and contributes to the water-absorption phenomenon (throughout the granule-boiling process).

[0081] (vii) The short-chains of amylose/amylopectin suspended in the water will attract the water molecules through hydroxyl bonding, and thus reduce the fluidity of the water, and cause the pasting effects in water (where viscosity is increased), due to the reduction of free water molecules.

[0082] As shown in Fig. 1, the food cooker 10 comprises:

[0083] a first chamber 101 and a second chamber 102. The first chamber 101 is configured to contain starch- containing food and water.

[0084] The food cooker 10 further comprises a first heater 103 coupled with the first chamber 101 for heating the starch- containing food and the water in the first chamber 101 to generate a mixture comprising starch-containing food and soup;

[0085] a separating unit 104 configured for separating a first portion of the soup from the first chamber 101 and transferring it (?) into the second chamber 102, to generate, separated from each other, a soup and a remaining mixture. The second chamber 102 is configured to receive soup separated from the first chamber 101.

[0086] The food cooker 10 further comprises a second heater 105 coupled with the second chamber 102 for heating the separated soup in the second chamber; and

[0087] a controller 106 coupled with the separating unit 104 and configured to control the separating unit 104 to separate a first portion of the soup from the first chamber 101 and transfer it (?) into the second chamber 102 according to a separating scheme, and the controller 106 is further coupled with the first and the second heaters 103,105 and configured to control the first and second heaters 103,105 to cook the remaining mixture and to cook the separated soup.

[0088] Preferably, as shown in Fig. 1, the rice cooker 10 further comprises a first unit 107, a water supplying unit 108, a third heater 109, a mixing unit 110. The water supplying unit 108 further comprises a condensing unit 301 (shown in Fig. 3(A)). The function of these units will be described in the following part in combination with the following figures. [0089] The method of processing starch-containing food, comprising the steps of:

[0090] - heating the starch-containing food and water to generate a mixture comprising starch-containing food and soup;

[0091] - separating a first portion of the soup from the mixture according to a separating scheme;

[0092] - a first cooking step for cooking the remaining mixture; and

[0093] - a second cooking step for cooking the separated soup.

[0094] The device and method for processing starch-containing food according to embodiments of the invention will be elucidated with reference to figures 1 to 6.

[0095] In the following, the method and device for processing rice are taken as examples for elucidating the embodiments of the invention. However, those skilled in the art may appreciate that starch-containing food is not limited to rice, it may also include: pumpkin, winter squash, red bean, Coix Seed (or also called Pearl Barley), broad bean, soybean, mung bean, red bean, potato, noodle, banana, and other grains, vegetables or fruits that contain starch, preferably in an amount in excess of 10% depending on different cultivars.

Furthermore, among these staple foods, normally amylose is about 1/3 or 1/4 of amylopectin.

[0096] Besides, in the following embodiments, for simplicity, we use "cooked rice" to describe the state of rice after the cooking process, i.e. cooked rice which is ready for consumption.

[0097] As shown in Fig. 2, in step S20 of the method, first the rice and water are heated to generate a mixture comprising rice granules and soup. This operation is for example carried out by the first heater 103.

[0098] Then, in step S21 of the method, a first portion of the soup is separated from the mixture according to a separating scheme. This operation is for example carried out by the separating unit 104.

[0099] The separating scheme comprises at least one of the following:

[00100] - time point at which the first portion of the soup is to be separated from the mixture; [00101] - temperature at which the first portion of the soup is to be separated from the mixture;

[00102] - the amount of soup to be separated from the mixture.

[00103] The separating scheme may be predetermined and stored in the controller 106 of the rice cooker 100.

[00104] For example, the separating scheme may be a group of predetermined parameters stored in the controller 106 of the food cooker 10, such as predetermined time point, temperature or amount of soup to be separated from the mixture. Then, when the predetermined time point or temperature is reached, the separating unit 104 automatically separates the soup from the mixture.

[00105] The predetermined time point for discharging the soup may be controlled by a timer (not shown in the figures). The temperature for discharging the soup may be controlled by a thermometer or a temperature sensor (not shown in the figures). The amount of soup separated from the mixture may be detected and controlled by a unit such as an ultrasonic detector (not shown in the figures). Ultrasonic sensors work on a principle similar to radar or sonar which evaluates attributes of a target by interpreting the echoes from radio or sound waves respectively. Ultrasonic sensors generate high frequency sound waves and evaluate the echo which is received back by the sensor. Sensors calculate the time interval between sending the signal and receiving the echo to determine the distance to an object. This technology can be used for measuring fullness of a tank. To measure the amount of liquid in a tank, the sensor measures the distance to the surface of the fluid. Therefore, the amount of the soup to be discharged from the first chamber 101 can be controlled.

[00106] Alternatively, the separating scheme may be dynamically determined by the controller 106 according to the data reflecting expected results relating to processed starch-containing food which is obtained by the first unit 107.

[00107] The data reflecting expected results relating to processed rice may comprise either the data reflecting expected results relating to processed rice granules or the data reflecting expected results relating to processed rice soup, or both. Furthermore, the processed food may relate to the result of the individual rice granules and individual soup before mixing, or it may relate to the mixture, such as congee that comprises both the rice granules and soup.

[00108] Said data reflecting expected results relating to processed rice granules comprises at least one of the following:

hardness;

adhesiveness;

resilience;

cohesiveness;

springiness;

gumminess; and

chewiness.

[00109] Besides, the data reflecting expected results relating to processed soup comprises at least one of the following:

[00110] - watery;

[00111] - creamy;

[00112] - sticky.

[00113] The term, "watery" means that there is still plenty of water not participating in gelatinization, so the soup is very "diluted" like water, while "creamy" means that the water is almost absorbed by the starch through gelatinization, so the soup is "thick" like a cream. Both watery and creamy represent the thickness of the processed soup.

[00114] "Sticky" means that the water/starch is partially gelatinized up to the point where itis below the peak viscosity point, thus, it may not be very thick, but it is lip-sticky.

[00115] Practically, the first unit 107 comprises a user interface for receiving data relating to expected results of starch-containing food which are input by the user separately. Alternatively, the expected result input by the user may be a menu selection of the results of a combination of rice granules and soup, such as sticky congee, watery congee, and then the first unit 107 correlates the menu selection with the result of the rice granules and soup separately.

[00116] As to the parameter for the separation of the soup from the mixture, for example, the temperature at which the first portion of the soup is to be separated corresponds to one of the following:

[001 17] - the temperature of the starch leaching-out stage of the starch-containing food;

[001 18] - the temperature of the starch pasting stage of the starch-containing food; or

[001 19] - the temperature of the water absorption stage of the starch-containing food.

[00120] Table 1 shows the following:

[00121] - the relationship between the separation parameter and the quality of the produced granules and produced soup;

[00122] - the relationship between the remaining mixture processing parameter and the quality of the produced granules and produced soup;

[00123] - the relationship between the separated water processing parameter and the quality of the produced soup.

[00124] In said table 1 , T represents temperature while t represents time. Table 1 is only illustrative for the parameters that influence the quality of the cooked rice and the quality factors, and the parameters and quality factors should not be limited to those shown in table 1.

[00125] From table 1 , for example it is clear that when the separation step is performed when the temperature is lower than the starch leaching-out temperature, the rice granule is the hardest, and is more adhesive and less cohesive, and the produced soup is thinner and less sticky.

[00126] When the separation step is performed when the temperature is lower than the peak pasting temperature, the rice granule is softer, and less adhesive and cohesive, and the produced soup is thick and more sticky.

[00127] When the separation step is performed when the temperature is higher than the peak pasting temperature and lower than the water boiling temperature, the rice granule is harder, and most adhesive and less cohesive, and the produced soup is thicker and most sticky.

[00128] Table 1

Thick

ness

Adhesiv cohesive (water Stickin

Process Parameter Condition hardness

eness ness or ess creamy

)

T < T

more least less leaching-o hardest

adhesive cohesive thinner sticky ut

T

Temeparatu leaching-o

less more re T of ut < T < T softer

adhesive cohesive thicker sticky separation peak-pasti

ng

Tpeak-pas

most less most ting< T < harder

adhesive cohesive thicker sticky

Separatio T boiling

n t < t

more least less time point t leaching-o hardest

adhesive cohesive thinner sticky ut

t

leaching-o

less more time point t ut <t < t softer

adhesive cohesive thicker sticky peak-pasti

ng

peak-pasti

most less most time point t ng <t < t harder

adhesive cohesive thicker sticky boiling

t < t

more less

leaching-o harder - - adhesive cohesive

ut

t

time point t leaching-o

less

Remainin of ut <t < t softer - - adhesive cohesive

g mixture water-additi peak-pasti

processin on ng

t > t

g

peak-pasti most less

harder - - ng ; < t adhesive cohesive

boiling

amount A of A < less more harder - - water/remai normal cohesive sticky ning water

dosage

A >

normal more less softer - - water cohesive sticky dosage

longer at

T < T less more

softer - - leaching-o adhesive cohesive

ut

longer at

T

duration of leaching-o more less more harder

the heating ut < T < T adhesive cohesive thicker sticky peak-pasti

ng

longer at

Tpeak-pas more less more softer

ting<T < adhesive cohesive thicker sticky T boiling

t< t

less leaching-o - - - thinner sticky ut

t

time point t leaching-o

more of ut <t< t - - - thicker sticky water-additi peak-pasti

on ng

t

peak-pasti more

Separated - - - ng< t < t thicker sticky soup

boiling

A< normal

less water - - - amount A of thinner sticky dosage

water/remai

A> normal

ning more water - - - thicker sticky dosage

longer at

duration of

T< T - - - - - the heating

leaching-o ut longer at

T

leaching-o more

- - - ut < T< T thicker sticky peak-pasti

ng

longer at

Tpeak-pas more

- - - ting <T < thicker sticky T boiling

[00129] It can be easily understood that given a certain amount of rice and water which are consistently heated, the temperature is correlated with the duration of heating. Therefore, there may be a correlation between the time point of separation and the temperature of the mixture when separation occurs. Therefore, details of the time point for separation will not be given for simplicity.

[00130] Figs. 3(A), 4(A) and 5(A) show the mixture in the first chamber 301,401 and 501, respectively, before the separation step, while Figs. 3(B), 4(B) and 5(B) show the remaining mixture in the first chamber 301,401 and 501, respectively, and the separated soup in the second chamber 302,402 and 502, respectively, after the separation step. As to the separating unit 104, a variety of units may be used for the function of separating unit 104.

[00131] For example, as shown in Figs. 3(A) and 3(B), for the separating unit 104 use may be made of a valve 307 that is coupled to the controller 106 (not shown in Figs. 3(A) or 3(B)). When the controller 106 determines that the soup should be separated from the mixture, the controller 106 sends an instruction to the valve 307 to open, thereby causing the first portion of the soup to be discharged from the first chamber 301 through the valve 307, and subsequently the controller 106 controls the valve 307 to close, for example in reaction to the feedback that the predetermined amount of soup has been discharged, which feedback is sent by the ultrasonic detector. By means of the controller 106 and the valve 307, the amount of separated soup can be controlled accurately. [00132] In another embodiment, as shown in Figs. 4(A) and 4(B), the separating unit 104 may be comprised of a pump 407 and a pipe 408 that interconnect the first and second chambers 401 and 402. The pump 407 is coupled with the controller 106. When the pump 407 receives a signal from the controller 106 to separate the soup from the mixture, the pump 407 pumps the soup from the first chamber 401 into the second chamber 402 via the pipe 408.

[00133] In still another embodiment, as shown in Figs. 5(A) and 5(B), the separating unit 104 may take the form of a carrier 507 located at the bottom of the first chamber 501 for holding the mixture, and the carrier 507 is movable. The carrier 507 can be controlled to move upwards and downwards such that the rice granules can be fully immersed into the soup or can be fully out of the soup. The carrier 507 may take a plurality of forms, such as a basket, a shelf, a tray, or a curtain, etc. Besides, the carrier 507 has apertures or a screen allowing the soup to pass through. For example, the carrier 507 may be in the form of a mesh tray or basket having apertures smaller than the size of rice grains, so as to allow the soup to pass through. And the carrier 507 is controlled to move upwards to lift the rice granules out of the soup, and then the first and second chambers 501 and 502 are formed to contain the remaining mixture and the soup separately.

[00134] After the separation step S21, the method performs a first cooking step S22 for cooking the remaining mixture and a second cooking step S23 for cooking the separated soup. Those skilled in the art may understand that the first cooking step S22 and the second cooking step S23 do not imply any order, and they only represent two different cooking steps.

[00135] After said separation, the first cooking step may be carried out according to a first cooking scheme. The first cooking scheme could be just to continue the rice cooking as a common rice cooker, i.e. the first cooking step comprises cooking the remaining mixture (rice and water) by heating the mixture till the water is fully vaporized so as to obtain cooked rice. Meanwhile, the second cooking step for cooking the separated soup is carried out according to a second cooking scheme, for example, to maintain the temperature of the soup at 70°C. In this example, the rice and rice soup are obtained at the same time and both with the best taste.

[00136] In another example, the first cooking scheme and the second cooking scheme may be predetermined and stored in the controller 106 of the rice cooker 10. The first cooking scheme may comprise a temperature controlling scheme for specifying how to control the temperature of the remaining mixture during the first cooking step. For example, if the user wants sticky rice, the temperature controlling scheme may specify that the temperature of the mixture should be kept at the pasting stage temperature for more time because this results in sticky rice. Then, the first heater 103 heats the remaining mixture according to the temperature controlling scheme comprised in the first cooking scheme. The second cooking scheme may be stored in the controller 106 of the food cooker 10, for example, to specify the temperature at which the separated soup should be maintained. Then, the second heater 105 maintains the separated soup at the temperature specified in the second cooking scheme.

[00137] It is to be noted that the first cooking scheme and the second cooking scheme are different. Therefore, the rice soup and the rice and water mixture are treated independently according to their own characteristics and taste requirements.

[00138] Alternatively, the first cooking scheme and the second cooking scheme may be dynamically determined according to the data reflecting an expected result relating to the cooked food and cooked soup, which is obtained by the first unit 107.

[00139] Since the step S21 of separating the first portion of soup from the mixture, the step S22 of the first cooking step and the step S23 of the second cooking step are interrelated, the following example is used for illustration.

[00140] For example, when the obtained data reflects that the expected result relating to processed starch-containing food is soft rice granules and sticky soup, then the controller 106 determines that the separating scheme is, for example, the time point of separation that corresponds to the end of the starch leaching-out stage, for example, at around 55 degC, when more amylose leaches out from the rice granules, and the produced rice granules at this stage are softer. Since the soup with more amylose is discharged from the mixture, less starch is contained in the remaining mixture, and therefore the pasty effect in the remaining mixture is weakened.

[00141] Then, in the first cooking step S22, the remaining mixture is heated continuously to the temperature of boilingwater , i.e. lOOdegC, so that the rice granules are ready for consumption. Since the remaining mixture contains less starch, the pasty effect in the remaining mixture is weakened, so that the water absorption effect is not impeded by the pasty effect, and the produced rice granules are softer.

[00142] The first cooking step is, for example, carried out by the first heater 103 in Fig. 1 and is denoted as 303, 403 and 503 in Fig. 3(A) - Fig. 5(B), respectively. According to the different structure of the first heater, the position of the first heater may also vary. For example, as shown in Figs. 3(A) and (B), the first heater 303 is located at the bottom of the first chamber 301, while, as shown in Fig. 5(A), the first heater 503 is mounted on both the bottom and the side wall of the first chamber 501 , while in Fig.5 (B), the first heater 303 is mounted on the side wall of the first chamber 501 and the second heater 505 is at the bottom of the first chamber 501. Those skilled in the art may understand that here the words first and second are used for representing units that heat different chambers. The heater used to heat the first chamber is called the first heater and the heater used to heat the second chamber is called the second heater. Each heater may be equipped with a thermometer or temperature sensor, to detect the temperature of the target that is heated by the heater. Since the working principle of the thermometer or temperature sensor is well known in the art, it will not be repeated here for simplicity.

[00143] Besides, in the second cooking step S23, the separated soup is heated to the temperature corresponding to the pasty stage of starch, for example, around 70degC, and maintained at 70degC for a longer period of time; for example, by controlling the second heater 105 to be alternately on and off, the temperature can be maintained at 70degC, and then the separated soup is rapidly heated to lOOdegC and thus is ready for consumption; since the soup is maintained in the pasty stage of starch for a longer period of time, the pasty effect of soup is sufficient, and the produced soup is sticky.

[00144] The above embodiment illustrates that the soup and the mixture are separated at the end of the starch leaching-out stage of the mixture. Of course, the soup and the mixture may be separated during the starch pasting stage of the mixture, after which the temperature of the separated soup may be maintained for some time and then increased to the water boiling temperature, or the separated soup may be rapidly heated to the boiling temperature and then the temperature of the soup is maintained at said level. Alternatively, the soup and the mixture may be separated during the amylopectin water absorption stage.

[00145] Of course, the separated soup may not be heated to the water boiling temperature, for example it may be heated to up to 90degC, so that those volatile derivatives are maintained in the soup, whose vaporizing point is below 100 degC, such as:

[00146] - Vitamins; and

[00147] - Proteins (amino acids).

[00148] Therefore, in the embodiments above the nutrients are maintained in the soup and the loss thereof due to evaporation is precluded.

[00149] The above embodiments illustrate scenarios in which the remaining mixture has enough water for cooking the remaining rice to the point where it is ready for consumption. In another embodiment, since the amount of soup in the remaining mixture may not be enough for cooking the remaining rice to the point where it is ready to serve, or when the remaining mixture needs more water to be cooked to the point where it is more fluffy and softer, the method may further comprise a step of adding water; the first cooking step may further comprise adding fresh water according to a water supplying scheme. The term fresh water here means the water that is added to the mixture after the separation of the soup from the mixture. The water supplying scheme is included in the first cooking scheme.

[00150] This step is, for example, implemented using a water supplying unit 108. To be specific, the fresh water may be provided by condensing the steam evaporated by heating the mixture. Referring to Fig. 3, the water supplying unit 108 may further comprise a condensing unit 306 connected to the first chamber 301, and configured to receive the steam evaporated from the first chamber 301, condense the steam evaporated from the first chamber 301 into water and provide the condensed water back to the first chamber 301. The condensing unit 306 utilizes the steam evaporated from the first chamber 301, which saves the water resource.

[00151] Alternatively, fresh water may be provided by a tank (not shown in figures) connected to the water tap.

[00152] The water supplying scheme comprises at least one of the following:

[00153] - time point at which the fresh water is to be added into the remaining mixture;

[00154] - temperature of the remaining mixture when the fresh water is to be added into the remaining mixture;

[00155] - temperature of the fresh water to be added into the remaining mixture;

[00156] - the amount of fresh water to be added into the remaining mixture.

[00157] The temperature of the remaining mixture can be detected by the thermometer described above, and its operating principle is known to those skilled in the art and will not be described in detail here. Those skilled in the art may appreciate that there is a relationship between the temperature of the remaining mixture and the cooking stage of the remaining mixture generally, which will be illustrated in the following:

[00158] For example, fresh water may be added to the remaining mixture by the water supplying unit 108 when the remaining mixture is in the starch leaching-out stage (which corresponds to a temperature ranging from 50degC to 60degC). When the fresh water is added into the mixture during the starch leaching-out stage of the remaining mixture, the amount of starch leaching out from the rice granules of the remaining mixture will be larger as the amount of water added increases, which will additionally lead to a more thorough water-absorption in the boiling stage, and thus produce softer cooked granules.

[00159] In another example, fresh water may be added to the remaining mixture when the remaining mixture is in the amylopectin water absorption stage (which corresponds to a temperature around lOOdegC). When fresh water is added into the mixture during the amylopectin water absorption stage of the remaining mixture, the water-absorption becomes more thorough as more water is added, and thus results in softer cooked granules.

[00160] The time point that fresh water is to be added into the remaining mixture may also be roughly related to the cooking stage (for example amylose leaching-out, amylose pasting and amylopectin absorbing water) of the remaining mixture, and thus to the temperature of the remaining mixture. For example, in conventional rice cooking, it takes about 10 minutes to soak the rice with water, the rice and the water being at a temperature below about 60degC, for example 55degC, during which period the leaching-out of amylose starch reaches its peak. Then, it takes about 6 minutes to heat the rice and water to a temperature lower than the water boiling temperature, and during this period the pasting of amylose starch occurs. Subsequently, it takes about 20 minutes to bring it to the boil, during which period the water absorption of amylopectin starch occurs.

[00161] Although the correlation between the time duration during which the food is cooked and the temperature of cooking the food may exist in some situations, those skilled in the art should understand that the temperature of cooking the food may also depend on other factors such as the amount of food and water; therefore, the above correlation is rough and may vary with different situations.

[00162] Besides, the temperature of the fresh water to be added into the remaining mixture also influences the target result of the cooked rice. For example, when the soup is separated from the mixture at the end of the starch leaching-out stage of the mixture, it is advantageous if the fresh water also has the temperature corresponding to that of the starch leaching-out stage of the mixture, that is 50-60degC, so that the temperature of the remaining mixture will not change after the addition of the water, and the temperature condition for a thorough leaching-out of amylose will be maintained.

[00163] Alternatively, at the end of the leaching-out stage, fresh water may be added into the mixture with a higher temperature than the pasting temperature (?) (for example 80degC), which allows water absorption to proceed with minimal impedance from amylase pasting.

[00164] The step of heating the fresh water in the water supplying unit 108 is for example carried out by a third heater 109. The third heater 109 is coupled with the controller 106 and heats the water in the water supplying unit 108 according to the instruction of the controller 106.

[00165] In another embodiment, when the temperature of the remaining mixture to which the fresh water is to be added corresponds to the temperature of the starch leaching-out stage of the starch-containing food, the first cooking step further comprises repeating the steps of separating the first portion of soup, adding water and cooking the remaining mixture with the added fresh water for a given number of cycles. The number of cycles may be predetermined or may be dynamically determined by the controller 106. In this way, more amylase leaches out from the starch-containing food e.g. rice.

[00166] In another embodiment, the method further comprises mixing a second portion of the separated soup and the remaining mixture after the first and the second cooking step. Preferably, the step of mixing the second portion of the separated soup and the remaining mixture is carried out after the water in the mixture has been heated to the boiling temperature, so that the taste and appearance of the rice granules will not be changed much. After having been cooked separately, the soup and the rice are mixed again to finally obtain congee; the method of cooking congee in this way allows the user to select different taste combinations in terms of the rice granules and the soup. This congee cooking method is therefore more flexible.

[00167] The mixing function of the mixing unit 110 may be carried out by the pump 407 that pumps the soup back into the first chamber 401 as shown in Figs. 4(A) and 4(B); in order to enable bi-directional operation of the pump, the pump 407 is preferably a bi-directional pump.

[00168] Alternatively, referring to Figs. 5(A) and 5(B), the mixing function of the mixing unit 110 may be carried out by the screen or meshed carrier 507 described above. When the controller 106 determines that the mixture and the soup are to be mixed, the controller 106 instructs the carrier 507 to move downwards, so that the remaining mixture in the first chamber 501 is submerged into the soup and the two are mixed together.

[00169] Fig. 6(A) shows the remaining mixture before the mixing step, while Fig. 6(B) shows the mixture after the mixing step. Referring to Fig. 6(A) and Fig. 6(B), the mixing function of the mixing unit 110 may be carried out by a rotating unit, such as a pair of doors 607 mounted side by side, each of the doors being hinged along one side to allow the doors to pivot in the downward direction towards the open state. The axis of rotation is horizontal. When the controller 106 determines that the mixture and the soup are to be mixed, the controller 106 instructs the pair of doors 607 to rotate to the open state, so that the mixture in the first chamber 601 falls into the second chamber 602 and the remaining mixture and the soup are mixed together. Those skilled in the art may appreciate that the shape andlocation of the rotating unit are only illustrative and are non-limiting. For example, the axis of the rotating unit may be mounted along the diameter of the first chamber 601 so as to enable smooth rotation of the rotating unit when the first chamber 601 has a round cross section.

[00170] The above units can be implemented by way of software, hardware or combinations thereof. For example, the controller can be implemented by software and the program codes achieving the functions are stored in a memory and are loaded and executed by a micro controller unit (MCU). The MCU also controls the hardware components. Those skilled in the art could implement embodiments of the invention in various ways according to the concept and principle taught by the description.

[00171] Those of ordinary skill in the art could understand and realize modifications to the disclosed embodiments, through studying the description, drawings and appended claims. All such modifications which do not depart from the spirit of the invention are intended to be included within the scope of the appended claims. The word "comprising" does not exclude the presence of elements or steps not listed in a claim or in the description. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. In the practice of the present invention, several technical features in the claim can be embodied by one component. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim.

Claims

What is claimed is:

1. A method of processing starch-containing food, comprising the steps of:

- heating (S20) the starch-containing food and water to generate a mixture comprising starch-containing food and soup;

- separating (S21) a first portion of the soup from the mixture according to a separating scheme, to generate a separated soup and a remaining mixture;

- a first cooking step (S22) for cooking the remaining mixture; and

- a second cooking step (S23) for cooking the separated soup.

2. The method according to claim 1 , wherein the first cooking step (S22) is carried out according to a first cooking scheme, and the second cooking step (S23) is carried out according to a second cooking scheme.

3. The method according to claim 2, further comprising the following steps before the first and the second cooking step (S22, S23):

- obtaining data reflecting the expected result relating to processed starch-containing food;

- determining the first cooking scheme and/or the second cooking scheme according to the obtained data.

4. The method according to claim 2, wherein the first cooking scheme comprises a temperature controlling scheme, and the first cooking step (S22) comprises a heating step according to the temperature controlling scheme.

5. The method according to claim 1 , further comprising the following steps before the separating step (S21):

- determining the separating scheme according to the obtained data.

6. The method according to claim 5, wherein the separating scheme comprises at least one of the following: - time point at which the first portion of the soup is to be separated from the mixture;

- temperature at which the first portion of the soup is to be separated from the mixture;

- amount of soup to be separated from the mixture.

7. The method according to claim 6, wherein the temperature at which the first portion of the soup to be separated corresponds to one of the following:

- the temperature of the starch leaching-out stage of the starch-containing food;

- the temperature of the starch pasting stage of the starch-containing food; or

- the temperature of the water absorption stage of the starch-containing food.

8. The method according to claim 2, wherein the first cooking scheme further comprises a water supplying scheme, the water supplying scheme comprising at least one of the folio wings:

- time point at which the fresh water is to be added into the remaining mixture;

- temperature of the remaining mixture when the fresh water is to be added into the remaining mixture;

- temperature of the fresh water to be added into the remaining mixture; and

- the amount of the fresh water to be added into the remaining mixture;

and the first cooking step (S22) further comprises:

- adding fresh water according to the water supplying scheme;

- cooking the remaining mixture with the added fresh water according to the first cooking scheme.

9. The method according to claim 8, wherein the temperature of the remaining mixture when the fresh water is to be added into the remaining mixture corresponds to the temperature of the starch leaching-out stage of the remaining mixture, and the first cooking step (S22) further comprises:

- repeating the steps of separating (S21) the first portion of soup, adding water and cooking the remaining mixture with the added fresh water for a given number of cycles.

10. The method according to claim 1, further comprising the following step after the step of the first and the second cooking step (S22, S23): - mixing a second portion of the cooked soup and the cooked remaining mixture.

11. A food cooker (10) comprising:

a first chamber (101,301,401,501,601) configured to contain starch-containing food and water;

a first heater (103, 303, 403, 503) coupled with the first chamber (101,301,401,501,601) for heating the starch-containing food and the water in the first chamber (101,301,401,501,601) to generate a mixture comprising starch-containing food and soup; a separating unit (104) for separating a first portion of the soup from the first chamber

(101.301.401.501.601) and transferring it (?) into a second chamber (102,302,402,502,602), to generate a separated soup and a remaining mixture;

the second chamber (102,302,402,502,602) configured to receive soup separated from the first chamber (101,301,401,501,601);

a second heater (105,305,405,505) coupled with the second chamber

(102.302.402.502.602) for heating the separated soup in the second chamber (102,302,402,502,602); and

a controller (106) coupled with the separating unit (104) and configured to control the separating unit (104) to separate a first portion of the soup from the first chamber (101,301,401,501,601) and transfer it (?) into the second chamber (102,302,402,502,602) according to a separating scheme, and

the controller (106) is further coupled with the first heater (103, 303, 403, 503) and the second heater (105,305,405,505) and configured to control the first heater (103, 303, 403, 503) to cook the remaining mixture and to control the second heater (105,305,405,505) to cook the separated soup.

12. The food cooker according to claim 11, wherein the controller (106) is configured to control the first heater (103, 303, 403, 503) to cook the remaining mixture according to a first cooking scheme, and

to control the second heater (105,305,405,505) to cook the separated soup according to a second cooking scheme.

13. The food cooker according to claim 12, further comprising a first unit (107) for obtaining data reflecting the expected result relating to processed starch-containing food; the controller (106) is further configured to determine the first cooking scheme and/or the second cooking scheme according to the obtained data; and/or to determine the separating scheme according to the obtained data.

14. The food cooker according to claim 13, wherein the first cooking scheme comprises a temperature controlling scheme, and the first heater (103, 303, 403, 503) is configured to heat the remaining mixture according to the temperature controlling scheme.

15. The food cooker according to claim 11, wherein the separating scheme comprises at least one of the following:

- time point at which the first portion of the soup is to be separated from the mixture;

- the amount of soup that is to be separated from the mixture.

16. The food cooker according to claim 15, wherein the temperature at which the first portion of the food soup is separated corresponds to one of the following:

- the temperature of the starch pasting stage of the starch-containing food; or

- the temperature of the water absorption stage of the starch-containing food.

17. The food cooker according to claim 12, further comprising a water supplying unit (108) coupled with the controller (106), wherein the first cooking scheme comprises a water supplying scheme, the water supplying scheme comprising at least one of the following:

- temperature of the fresh water to be added into the remaining mixture;

- the amount of the fresh water to be added into the remaining mixture;

wherein the controller (106) is further configured to control the water supplying unit (108) to provide water to the first chamber (101,301,401,501,601) according to the water supplying scheme; and to control the first heater (103, 303, 403, 503) to cook the remaining mixture with the newly added water according to a temperature controlling scheme included in the first cooking step.

18. The food cooker according to claim 17, wherein the time point at which the fresh water is to be added into the remaining mixture corresponds to the temperature of the starch leaching-out stage of the starch-containing food, and

the controller (106) is further configured to control the separating unit (104), the water supplying unit (108) and the first heater (103, 303,403, 503 ) to repeat in turn the steps of separating the first portion of soup, adding water, and heating the remaining mixture with the fresh water for a given number of cycles.

19. The food cooker according to claim 17, further comprising a third heater (109) coupled to the water supplying unit (108) for heating the water to the temperature of fresh water to be added into the remaining mixture.

20. The food cooker according to claim 17, wherein the water supplying unit (108) further comprises a condensing unit (306,406,506) connected to the first chamber (101,301,401,501,601), for receiving steam from the first chamber (101,301,401 ,501,601), condensing the steam evaporated from the first chamber (101,301,401,501 ,601) into water and providing the condensed water back to the first chamber (101,301,401,501,601).

21. The food cooker according to claim 11, further comprising a mixing unit (110) for mixing a second portion of cooked soup in the second chamber (102,302,402,502,602) and the cooked remaining mixture in the first chamber (101,301,401,501,601).

22. The food cooker according to claim 11, wherein the separating unit (104) further comprises:

- a valve (307) for discharging the first portion of the soup from the first chamber (101,301 ,401,501,601) through the valve (307) when the valve (307) is open;

- a pump (407) for pumping the first portion of the soup from the first chamber (101,301,401,501,601) to the second chamber (102,302,402,502,602); or

- a perforated or meshed carrier (507) for holding the starch-containing food and said carrier being movable such that the starch-containing food can be controlled between being fully immersed into the soup and being fully out of the soup.