WO2012127412A1

WO2012127412A1 - Preparation of food controlled by a taste sensor

Info

Publication number: WO2012127412A1
Application number: PCT/IB2012/051318
Authority: WO
Inventors: Eng Cheng Khaw; Jingwei Tan; Declan Patrick Kelly; Qi Zhou
Original assignee: Koninklijke Philips Electronics N.V.
Priority date: 2011-03-24
Filing date: 2012-03-20
Publication date: 2012-09-27

Abstract

An embodiment of the invention proposes a more accurate method and device for preparing food. The method comprises the steps of: determining (S24) a first set of reference values related to a taste parameter, each value of said set being associated with a respective stage of the preparation process; detecting (S28) a first set of sensor values by a sensor at a set of given stages of the preparation (S26) process, and controlling (S30) the preparation (S26) process according to the first set of sensor values, and the corresponding reference values being associated with the set of given stages. The preparation may be controlled dynamically according to the first set of sensor values related to taste and the corresponding reference values. Thus, the preparation process more accurately provides the desired food.

Description

PREPARATION OF FOOD CONTROLLED BY A TASTE SENSOR

Technical field

[001] The present invention relates to kitchenware, and particularly to preparing food. Background of the invention

[002] The current automatic devices for preparing food, such as rice cookers and coffee machines, usually prepare the food according to a pre-determined preparation scheme. For example, as to rice cookers, the preparation scheme includes how to heat the rice with water from room temperature to the boiling temperature, how to maintain the boiling temperature for a certain time duration for the purpose of cooking rice and boiling away the excess water, and how to keep the cooked rice warm. These preparation schemes were designed by the manufacturer or vendor of the device according to experiments aimed at preparing the food for a desired taste, and these schemes are stored in the devices in order to be loaded and used by the devices.

Summary of the invention

[003] It can be seen that the preparation scheme in the current devices is fixed, and the device prepares the food strictly in conformity with the scheme. However, since the preparation conditions, such as the food ingredients and the water quality in the user's kitchen, may be different from those used by the manufacturer in the experiment for pre-determining the preparation scheme, the taste of the food produced in the user's kitchen according to the scheme may differ from the desired taste obtained in the experiment. Thus, the devices according to the prior art have the drawback of taste deviation from the desired taste in the case that the preparation conditions vary. Generally, the user has to practice choosing the dose, mode and parameters many times before he obtains the desired taste. And, if he changes the ingredients or the ingredients change due to natural variation, the taste will differ again.

[004] Therefore, it would be advantageous to achieve a more accurate preparation method that could provide the desired food, even if the preparation conditions vary.

[005] To address this concern, in a first aspect of the invention, there is provided a method of preparing food, comprising the steps of:

- determining a first set of reference values related to a taste parameter, each value of said set being associated with a respective stage of the preparation process;

- detecting a first set of sensor values by a taste sensor at a set of given stages of the preparation process, and

- controlling the preparation according to the first set of sensor values and the corresponding reference values being associated with the set of given stages.

[006] In this aspect, in the preparation process, the preparation is monitored via the first set of sensor values related to a taste parameter, and the preparation may be adjusted dynamically according to the first set of sensor values and the corresponding reference values. Thus, the preparation can more accurately provide the desired food.

[007] In a preferred embodiment, the step of detecting the first set of sensor values uses at least one of the following methods:

- voltammetry method;

- near - infrared spectroscopy method;

- ultrasound method;

- pH method;

- optical/infrared imaging method;

- density measuring method.

[008] This embodiment provides various ways of detecting the first set of sensor values for both solid and liquid food.

[009] In a further preferred embodiment, said voltammetry method comprises:

- detecting voltammetric data of the solution of the food by using at least two different metal electrodes and/or at least two different electric frequencies;

- conducting a principal component analysis on the voltammetric data so as to obtain the first set of sensor values. [0010] In this preferred embodiment, multiple metal electrodes and/or multiple electric frequencies could increase the amount of information contained in the first set of sensor values, thus providing more accurate control. And the principal component analysis could decrease the data size of the first set of sensor values, thus decreasing the overhead of the control according to the first set of sensor values.

[0011] In a preferred embodiment, a stage is defined by at least one of:

- a temperature point or a temperature range during the preparation of the food;

- a time point or a time duration during the preparation of the food;

- a pressure point or a pressure range during the preparation of the food;

- a manner of preparing the food.

In this embodiment, the stages can be defined by various factors depending on the preparation, and more flexible control is provided.

[0012] In another preferred embodiment, when said stage is defined by said ranges or the manner of preparing the food, for a certain stage in said set of given stages, said controlling step controls the preparation so as to make it enter the stage following said certain stage, when the first set of sensor values at the certain stage conforms to the reference values associated with the certain stage, or when the preparation in the certain stage reaches a maximum time length defined for the certain stage.

[0013] In this embodiment, the reference value serves as a threshold between the stages. The preparation proceeds to the next stage, when the first set of sensor values matches the reference values, namely when the necessary taste of the food in this stage has been achieved. Therefore, the embodiment enables a more accurate preparation.

[0014] In a preferred embodiment, the method further comprises a step of:

- obtaining a target taste of the food;

said determining step determines the first set of reference values according to the target taste.

[0015] In this embodiment, a target taste of the food is taken into consideration for determining the first set of reference values. That is to say, the method henceforth controls the preparation according to the target taste so as to provide the desired food with this target taste.

[0016] In a preferred embodiment, the method further comprises a step of: - obtaining features of the food ingredients that are used for preparing food; said features correspond to at least one of:

- the type of the food ingredients;

- the dose of the food ingredients;

- the quality of the food ingredients;

- the freshness of the food ingredients;

and said determining step determines the first set of reference values according to said features of the food ingredients.

[0017] In this embodiment, features of the food ingredients are taken into consideration for determining the first set of reference values. That is to say, the method henceforth controls the preparation according to the features of the food ingredients so as to provide desired food that matches the features of the food ingredients.

[0018] In a further preferred embodiment, the step of obtaining features of the food ingredients comprises at least one of:

- receiving said features from a user interface;

- detecting said features.

[0019] The embodiment provides specific ways of obtaining the features of the food ingredients.

[0020] In a still further preferred embodiment, said step of detecting said features comprises the steps of:

- detecting, by a sensor, a second set of sensor values related to features of the food ingredients;

- determining the features, by matching the second set of sensor values with at least one second set of reference values in a predefined plurality of second sets of reference values, wherein each second set of reference values is associated with one respective feature of the food ingredients.

[0021] This embodiment provides a specific way of detecting the features of the food ingredients by sensors.

[0022] In a still further preferred embodiment, when the food ingredients comprise at least two types, each type is associated with one second set of references, and the step of determining the features determines the type and percentage of each type by:

- finding a weighted average matching the second set of sensor values, said weighted average being calculated by weighting and summing at least two second sets of reference values associated with at least two types based on their respective percentages;

- taking the types and their respective percentages corresponding to the weighted average as the types and percentages of the food ingredients.

[0023] This embodiment provides a specific way of detecting both type and percentage of each one of the blended ingredients, thereby achieving a more accurate control.

[0024] In a still further preferred embodiment, when the food ingredients comprise at least two types, each type is associated with one set of reference values related to the taste parameter, and the step of determining the first set of reference values calculates a weighted average as the first set of reference values, said weighted average is calculated by weighting and summing the sets of reference values associated with the types, based on their respective percentages.

[0025] This embodiment considers the type and percentage of each ingredient in blended ingredients for controlling the preparation so as to obtain a proper first set of reference values. Therefore, a more accurate control is achieved to obtain the desired food.

[0026] For many kinds of food, water is either an important ingredient for cooking the food or a major component of the food. In a preferred embodiment, the method of preparing the food uses water, and the method further comprises a step of:

- detecting third values related to characteristics of water by a sensor;

said controlling step controls the preparation according to the third values.

[0027] In this embodiment, the water used for preparing food is also used for controlling the preparation thereof, as a result of which a more accurate preparation is achieved to obtain the desired food.

[0028] In a preferred embodiment, the preparation comprises at least one of:

- cooking;

- brewing;

- fermenting;

- decocting. [0029] This embodiment can be used for cooking nourishment, brewing beverages, fermenting alcoholic drinks as well as decocting herbal drinks.

[0030] In a second aspect of the invention, there is provided a device for preparing food, comprising:

- a first unit for determining a first set of reference values related to a taste parameter, each value of said set being associated with a respective stage of the preparation process;

- a second unit for preparing the food;

- a first sensor for detecting a first set of sensor values at a set of given stages of the preparation process carried out by the second unit, and

- a controller for controlling the second unit to produce the food according to the first set of sensor values, and the corresponding reference values being associated with the set of given stages.

[0031] These and other features of the present invention will be described in detail in the embodiment part.

Brief description of the drawings

[0032] Features, aspects and advantages of the present invention will become obvious by reading the following description of non- limiting embodiments with the aid of the appended drawings.

[0033] Fig. 1 shows a block diagram of a device 1 for preparing food;

[0034] Fig. 2 shows a flowchart of the method of cooking rice, according to an embodiment of the invention;

[0035] Fig. 3 shows a sensor used in an embodiment of the invention;

[0036] Fig. 4 shows a generated pulse and the response received from the sensor;

[0037] Fig. 5 shows eigenvalues for different types of rice;

[0038] Fig. 6 shows eigenvalues of rice being cooked at different temperatures;

[0039] Fig. 7 shows eigenvalues of rice being washed for different time durations;

[0040] Fig. 8 shows eigenvalues of rice being soaked for different time durations; [0041] Fig. 9 shows eigenvalues for different types of coffee beans;

[0042] Fig. 10 shows eigenvalues of coffee at different temperatures;

[0043] Fig. 11 shows eigenvalues of coffee for different steeping time durations;

[0044] Fig. 12 shows eigenvalues of coffee at different pressure values.

Detailed description of embodiments

[0045] As shown in Fig. 1, the device 1 for preparing food comprises:

- a first unit 10 for determining a first set of reference values related to a taste parameter, each value of said set being associated with a stage of the preparation process;

- a second unit 12 for preparing the food;

- a first sensor 14 for detecting a first set of sensor values at a set of given stages of the preparation process by the second unit, and

- a controller 16 for controlling the second unit to produce the food according to the first set of sensor values, and the corresponding reference values being associated with the set of given stages.

[0046] Preferably, the device 1 further comprises a third unit 18(not shown in the

Figs) for obtaining features of the rice. In the embodiment shown in Fig. 1, the third unit 18 comprises a second sensor 180 and a fourth unit 181, the operations of which will be described below.

[0047] Preferably, the device 1 further comprises a fifth unit 20 for obtaining a target taste of the food.

[0048] A method of preparing food, comprising the steps of:

- detecting a first set of sensor values by a sensor at a set of given stages of the preparation process, and

- controlling the preparation process according to the first set of sensor values, and the corresponding reference values being associated with the set of given stages.

[0049] The term "food" in this specification is to be interpreted in a broad sense, and should be understood to comprise eatable solid food such as staple food, for example rice, and drinkable liquids such as non-alcoholic beverages, for example tea, coffee, alcoholic beverages, for example beer, wine and spirits, and herbal medicinal drinks. Thus, preparing food according to this specification comprises cooking the eatable solid food such as rice, brewing drinks such as tea and coffee, decocting herbal medicines and fermenting drinks such as beer, wine and spirits.

[0050] The device and method for preparing food according to an embodiment of the invention will be elucidated with reference to figures 1 to 12. The following embodiment uses the cooking of rice as an example. Brewing coffee according to the invention will also be described.

[0051] As shown in Fig. 2, preferably, in step S20, the third unit 18 obtains features of the rice. The features correspond to at least one of:

- the type of rice;

- the dose of the rice;

- the quality of the rice;

- the freshness of the rice.

[0052] In one embodiment, the third unit 18 comprises a user interface for receiving the features input by the user.

[0053] In another embodiment, the third unit 18 comprises a detector for detecting the features.

[0054] Specifically, the detector comprises a second sensor 180 for detecting a second set of sensor values related to features of the rice, and a fourth unit 181 for

determining the features, by matching the second set of sensor values with at least one second set of reference values of a predefined plurality of second sets of reference values, wherein each second set of reference values is associated with one respective food ingredient feature.

[0055] In one example, as to the dose of rice, a pressure sensor 180 can be used for detecting a second set of sensor values related to the dose (weight) of rice. A predefined plurality of second sets of reference values related to dose levels are prestored in the device 1, wherein each second set of reference values is associated with one respective weight of rice. The fourth unit 181 can determine the dose of rice by matching the second set of sensor values with one second set of reference values and taking the dose associated with the matched second set of reference value as the dose of rice. For example, the pressure sensor 180 comprises a pressure sensitive resistor. Under a constant voltage applied across the resistor, the value of the current flowing through the resistor is different when a different weight is placed on the resistor. Each current value is stored, with reference to the respective weights, as a second set of reference values. In an implementation of the embodiment, after the rice is placed on the resistor, the current value flowing through the resistor is detected as the second set of sensor values. And the fourth unit 181 retrieves the corresponding weight by reference to the detected current value.

[0056] In another example, as to the type of rice, since different types of rice generally have a different taste, an e-tongue type sensor 180 can be used for detecting the different tastes. In an embodiment using a voltammetry method, as shown in Fig. 3, the sensor 180 is an array of 6 metal electrodes forming a resistive sensor based on multifrequency pulse generation. In Fig. 3, A is a counter electrode, B is a reference electrode made of AgCl, C are noble-metal electrodes of Gold, Silver, Titanium, Tungsten, Palladium and Platinum respectively, and D is ground. E is an insulating housing of the sensor, and F is an electrode holder. When the electrodes are placed in the solution and the voltage is applied, each of the electrodes performs an electrolysis with the counter electrode. Each one of the electrodes will show the difference in their ohmic response. The counter electrode will collect the

back-current data for the subsequent computation. As shown in fig. 4, 4-1 is a low frequency pulse and 4-2 is the corresponding current response from the liquid; and 4-3 is a high frequency pulse and 4-4 is the corresponding current response from the liquid. Different currents under the same pulse conditions can reflect the different tastes of the liquid, thus this sensor can measure tastants in liquids. In this case, the rice is soaked in water for a certain period of time and the sensor is used to detect the taste of the water. By applying multiple pulses (excitations), via multiple metal electrodes and multiple frequencies, instead of only one excitation via only one electrode and one frequency, the accuracy and sensitivity of the detection can be increased. It can be readily understood that the number of electrodes and frequencies is not limited, and even one electrode and one frequency are also feasible for implementing the invention.

[0057] Upon the sampling and collection of the detection data series, the PCA (principal component analysis) method is adopted to reduce the data size while maintaining the useful information in the data. With the final eigenvalues of the sampled data series mapped on the axes of two principal components PC1/PC2, the instantaneous taste characteristic is captured. Fig. 5 shows the different eigenvalues in [PCI, PC2] for different types of rice, wherein I stands for the organic rice short grain, II stands for Thai long grain, and III stands for glutinous grain. The temperature condition is 20 degrees Celsius, and a 10Hz frequency is used in the Pt electrode, 100Hz is used in the Pd electrode and 10Hz is used in the Wu electrode. The eigenvalues I, II and III serve as the second sets of reference eigenvalues. The sensor 180 detects the second set of sensor eigenvalues of the rice, and the fourth unit 181 determines the type of rice, by matching the second set of sensor eigenvalues of the rice and one of the three second sets of reference eigenvalues. Tastant mapping between the second set of sensor eigenvalues and the second set of reference eigenvalues can be performed by various numerical methods. For example, in the MMSE (minimum mean square error) method, one of the three second sets of reference eigenvalues, with a minimum mean square error with respect to the second set of sensor eigenvalues of the rice, is selected as a matching set, and the type associated with this matching set is the type of the rice.

[0058] In a more complicated case, the rice is blended by using at least two types of rice. The fourth unit 181 determines the type and percentage of each type by finding a weighted average matching the second set of sensor values. The fourth unit 181 calculates the weighted average by weighting and summing at least two second sets of reference values associated with at least two types, based on their respective percentages. And the fourth unit 181 takes the types and their respective percentages corresponding to the weighted average as the types and respective percentages of the rice.

[0059] In one embodiment, as shown in Fig.5, the detected second set of sensor eigenvalues is IV. First, the fourth unit 181 could acquire the types of blended rice by analyzing the second sets of sensor eigenvalues IV and the scope of possible combinations of the second sets of reference eigenvalues I, II and III. It is assumed that the rice is a blend of two types of rice. It can be seen that the second set of sensor eigenvalues IV is outside the possible range of combinations of either reference eigenvalues I and II or II and III, but is within the possible range of combinations of I and III. Therefore, the fourth unit 180 could acquire the types organic short grain and glutinous grain. Then, the fourth unit 180 could calculate the percentage of each type by means of the following formula:

[0060] In said formula, Vrv is the second set of sensor eigenvalues, Vi and Vm are the second sets of reference eigenvalues of respectively the organic short grain and glutinous grain, and x is the percentage of the organic short grain.

[0061] The physical meaning of this equation is that the second set of sensor values matches the weighted average of the second sets of reference values of the types, based on their percentages.

[0062] In the case that more principal components (PCs), besides PCI and PC2, are obtained in the PCA, it will become easier to determine the type and percentage of each type of blended food.

[0063] In practice, obtaining features of the rice can be done either before heating the rice in water, or at the beginning of the heating process.

[0064] Preferably, in step S22, a fifth unit 20 obtains a target taste of the cooked rice. In one embodiment, the target taste corresponds to at least one of:

Hardness (intensity);

adhesiveness;

resilience;

cohesiveness;

springiness;

gumminess; and

chewiness.

[0065] Practically, the fifth unit 20 could comprise a user interface for receiving taste selection data input by the user, and this taste selection may be the degree of one or more of the above features. Alternatively, the taste selection input by the user may be a menu selection of the cooked rice, such as porridge, rice for frying and so on, and the fifth unit 20 correlates the menu selection with the degree of the above target tastes. It should be noted that the target taste of rice is not limited by the above, and any taste - related feature, e.g. gustatory, tactual, or olfactory, falls within the scope of the target taste. Still, alternatively, the fifth unit 20 can choose the target taste, based on the obtained features of the rice. For example, it will aim to achieve an ideal taste for this rice type.

[0066] After the features of the rice as well as the target taste are obtained, in step

S24, the first unit 10 determines a first set of reference values related to a taste parameter according to the features of the rice as well as the target taste. Each value of said set is associated with a respective stage of the cooking process. In a preferred embodiment, the reference values correspond to the same sensor 180 as that used for obtaining the features of the rice, thus enabling re-using the same sensor. The reference values are measured by the manufacturer through cooking experiments under one specific cooking scheme, and stored in the device 1. It should be noted that the reference values can also correspond to a sensor different from the above e-tongue sensor 180 for obtaining the features of the rice.

[0067] In one case, the rice is organic short grain, and the stages are defined by the temperature of cooking rice. Fig. 6 shows the first set of reference eigenvalues with a frequency of 100Hz for Au, 10Hz for Pd, IHz for Wu and 100 Hz for Ti. The five first sets of reference eigenvalues indicate the intensity of the rice and are detected by the above sensor at 20°C, 40°C, 60°C, 80°C and 99°C during the cooking process. The rice is cooked to obtain a desired taste, and the eigenvalues of the rice follow this path. That is to say, the first set of reference eigenvalues reflect the taste formation path of the cooked rice, and if the

eigenvalues of the rice being cooked are detected by the sensor following this path, the cooked rice should have the desired taste.

[0068] In another case, the rice is a blend of organic short grain and glutinous grain, like the above example. In this case, both type and percentage of the rice have been determined, and the first unit 10 calculates, as the first set of reference eigenvalues, a weighted average of the sets of reference eigenvalues associated with the organic short grain and glutinous grain, based on their corresponding percentages. The following formula describes the calculation:

P_IV = X*P_I + (100%-X)*P_III

[0069] In this formula, Pi is the set of reference eigenvalues for organic short grain,

Pin is the set of reference eigenvalues for glutinous grain, x is the percentage of organic short grain. Ppv is the first set of reference eigenvalues for the blended rice. It should be noted that the weighted average is calculated by using the reference eigenvalues for each of the respective temperatures. The formula is based on the assumption that each type of rice in the blend will still behave in the same way as in the pure form, so that the blended rice will behave proportionally to the percentages of the different types.

[0070] After the first set of reference eigenvalues is determined, in step S26, the second unit 12 starts to heat the rice with water, using the specific cooking scheme corresponding to the one used for obtaining the first set of eigenvalues.

[0071] During the heating process, at one or more temperatures, in step S28, the first sensor 14 detects the first set of sensor eigenvalues of the preparation process by the second unit 12. The first sensor 14 may be the same sensor as the above sensor 180. For example, at a temperature of 40°C, the first sensor 14 detects the first set of sensor eigenvalues of the rice with water.

[0072] Then, in step S30, the controller 16 controls the second unit 12 according to the first set of sensor eigenvalues at the temperature of 40°C and the reference eigenvalues being associated with the temperature of 40°C.

[0073] Specifically, if there is no deviation between the first set of sensor eigenvalues and the reference eigenvalues at the temperature of 40°C, or the deviation is below a certain threshold, the controller 16 controls the second unit to heat the rice with water still according to the predefined cooking scheme. If the deviation is above a certain threshold, the controller 16 will control the second unit 12 to cook the rice according to a modified cooking scheme, for example according to new heating parameters, such as a lower heating power at a certain level so as to prolong the heating time (the controller may decrease the power of the heater), increased pressure (the controller may close the vapor valve), or an increased specific amount of water (the controller may open the water inlet to add additional water). How said controlling is performed may be dependent on the deviation between the first set of sensor eigenvalues and the reference eigenvalues, and is stored in device 1. In another example that relates to the cooking of soup, when there is a deviation between the first set of sensor eigenvalues and the reference eigenvalues, the controller 16 may add a certain amount of suitable flavorings to the soup. The specific ways of controlling are not limited to the above examples, and those skilled in the art could design suitable ways according to the practical requirements.

[0074] Preferably, the above steps S28 and S30 are executed at different temperatures. Thus, the cooking process is tuned more frequently, enabling the desired taste to be obtained more accurately.

[0075] In the above embodiment, the stages are defined by the temperature of cooking rice. However, the stages are not limited to this embodiment, and other factors such as the time point of preparing the food, or the pressure level at which the food is prepared can also be used to define the stages.

[0076] It should be noted that the stages can also be defined by other factors. For example, the stages can be defined by temperature ranges, time durations or pressure ranges involved in the preparation of food. Further, the stages can also be defined by the manner of preparing the food, such as the heating power. In another example of cooking soup, the cooking process comprises a plurality of stages, and each stage is associated with a respective temperature and level of heating power. For example, stage 1 relates to the temperature from room temperature to the boiling temperature and a high heating power, stage 2 relates to the boiling temperature in combination with high heating power, and stage 3 relates to the boiling temperature in combination with a low heating power. The reference value associated with one stage serves as a threshold from this stage to the next stage. Specifically, the first sensor 14 detects the first set of sensor values at stage 2. And the controller 16 controls the cooking process, making it enter stage 3 when the first set of sensor values at stage 2 conforms to the reference value associated with stage 2, thereby controlling the cooking so as to proceed to stage 3 from stage 2 when the taste in stage 2 has met the requirement. Otherwise, the cooking process is maintained in stage 2 which relates to the taste, and the first sensor and the controller repeat the above function again. Preferably, there is a maximum time length defined for stage 2, and the controller 16 controls the cooking process to move on to stage 3 when the preparation in stage 2 has reached the maximum time length. As a result of this maximum time length, it must be accepted that the cooking process in stage 2 cannot meet the taste requirement.

[0077] In the above embodiment, the first set of reference values comprises a plurality of reference values at different stages to reflect the taste - formation path. It should be noted that the first set of reference values may also contain only one reference value.

[0078] The above embodiment uses heating rice with water as an example to describe the application of the invention to the cooking of rice. The invention is not limited to heating, and is also applicable for other processing steps in the cooking of rice.

[0079] In one example, the rice needs to be washed to remove excessive starch and the amount of the removed starch relates to the taste of the cooked rice. In this example, eigenvalues associated with the starch washed away at different washing durations can be detected in order to control the washing process. As shown in Fig. 7, A is "no washing", B is 2 minutes of washing and C is 4 minutes of washing. The eigenvalues can reflect the amount of starch washed off the rice. In an implementation, after 2 minutes of washing, the first sensor 14 can detect the first set of sensor values of the water and compare them with B. If the amount of starch removed is not enough, the controller can increase the intensity of washing.

[0080] In another example, the rice needs to be soaked in the amylase leaching -out cooking phase so as to leach out excessive amylase, and the amount of amylase leached out relates to the taste of the cooked rice. Eigenvalues associated with the amount of the leached out amylase for different soaking durations can be detected to control the soaking process. Fig. 8 shows the eigenvalues for different soaking durations at a temperature of 55°C. A is 5 minutes, B is 10 minutes and C is 20 minutes. In an implementation, after 5 minutes of soaking, the device 1 can detect the first set of sensor values of the solute and compare it with A. If the amount of leached out starch is not enough, the controller can prolong the time duration for starch leach-out.

[0081] It should be noted that the term "preparing" in the invention covers all processing steps related to the preparation of food, such as the above heating, washing, soaking and other unmentioned processing steps.

[0082] The above embodiments describe the application of the invention to the cooking of rice. Another embodiment of the invention relating to brewing coffee will be described below.

[0083] First, the third unit 18 obtains the features of the coffee bean. Taking the type of coffee bean as an example, the third unit 18 detects the type of coffee bean by the e-tongue sensor 180. The e-tongue sensor 180 can be configured to detect the second set of sensor values, such as the taste -.contributing factors of coffee such as intensity, acidity or bitterness. Fig. 9 shows the eigenvalues in [PCI, PC2] of a solution of five different types of coffee beans at room temperature. 1 is Espresso, 2 is Sumatra, 3 is Guatemala bella vista, 4 is Colombia, and 5 is Kenya coffee beans. And the fourth unit 181 compares the detected second set of sensor eigenvalues of the solute of the coffee beans with the 5 sets of reference eigenvalues of these five types, and determines the type of coffee bean.

[0084] And the fifth unit 20 could obtain the target taste by either of receiving the target taste via a user interface, or according to the type of the coffee beans.

[0085] Then, the first unit 10 determines the first set of reference eigenvalues according to the features of the coffee beans and the target taste of coffee. In one case, the stage is defined by the temperature and Fig. 10 shows the first set of reference eigenvalues of Colombia coffee beans at different brewing temperatures of 85°C and 95°C. These two reference eigenvalues, which indicate the intensity of the coffee, are obtained by the manufacturer of the device through coffee brewing experiments using a certain brewing scheme, and stored in device 1.

[0086] Since water is an important component in the process of brewing the ground coffee beans and constitutes the majority component of coffee, the water used influences the taste of the coffee to a certain degree. Preferably, the device 1 also detects third values related to characteristics of the water by means of a sensor. The third value can relate to the content of some substances such as mineral substances. And the controller controls the second unit to brew coffee according to the third value. For example, in one case, the reference eigenvalues do not change and the brewing scheme can be adjusted by the controller, based on the third value, so as to prevent a deviation between the first set of sensor values of the coffee and the reference values. In another case, the first unit further determines the first set of reference values according to the third value, and the controller controls the second unit according to the first set of sensor values and the reference values. This solution is advantageous for preparing food using water, such as brewing beverages such as tea, decocting liquid herbal medicine, or fermenting alcoholic drinks such as beer.

[0087] Then, the second unit 12 brews the ground coffee beans according to the same brewing scheme. [0088] During the brewing process, the first sensor 14 detects the first set of sensor eigenvalues at a temperature of 85°C. And the controller 16 controls the second unit 12 to brew according to the first set of sensor eigenvalues and the reference eigenvalue at a temperature of 85°C. For example, if there is a deviation between them, the controller 16 controls the second unit 12 to conduct the brewing process by using fine-tuned brewing parameters such as heating power. Those skilled in the art could design suitable ways of controlling the brewing process, and the specification will not give further details.

[0089] Using said tuned brewing parameters, the second unit 12 continues to brew coffee. And when the temperature reaches 95°C, the first sensor 14 detects the first set of sensor eigenvalues at a temperature of 95°C again, and the controller 16 controls the second unit 12 to brew according to the first set of sensor eigenvalues and the reference eigenvalues at a temperature of 95 °C again.

[0090] The invention is also applicable for other processing steps in the process of brewing coffee.

[0091] In one example, the coffee is left to steep in water. Fig. 11 shows the reference eigenvalues for the first time of steeping to the fourth time of steeping; each time of steeping uses 50ml water, and these values indicate the intensity of the coffee. In Fig. 11, 1st is the first time of steeping, 2nd is the second time of steeping, 3rd is the third time of steeping and 4th is the fourth time of steeping. The first sensor 14 can detect the first set of sensor eigenvalues of the coffee at a given time of steeping, and the controller 16 may control the next steeping step according to the detected first set of sensor eigenvalues and the reference eigenvalues, for example by increasing or decreasing the amount of water used for steeping.

[0092] In another example, the pressure also influences the taste of the coffee. Fig. 12 shows the reference eigenvalues of A brewing, B mild pressure of French press, and C 15 Bar of espresso machine. In the case that a French press is used by device 1 to make coffee, the first sensor 14 detects the first set of sensor eigenvalues and the controller 16 controls the second unit 12 according to the detected first set of sensor eigenvalues and the reference eigenvalues for French press, for example resulting in increasing or decreasing the pressure when there is a deviation between the values. In the case that an espresso machine is used, the operation of the first sensor and the controller is similar.

[0093] The above embodiment uses voltammetric e-tongue sensors to detect the first set of sensor values. E-tongue sensors are preferable for beverages. For foods cooked in water such as rice, e-tongue like sensors can also be used to indirectly sense the tastant formation by measuring properties of the water used for cooking. For solid foods, near - infrared spectroscopy and ultrasound can be used for measuring the cooking process. Other methods such as a pH method, an optical/infrared imaging method and a density measuring method are also applicable. Those skilled in the art can understand that any method capable of capturing the taste information of the food can be used, and hence the taste information obtained using all kinds of methods falls within the scope of the first set of reference values, the second set of reference values, the first set of sensor values and the second set of sensor values. Application of these methods for detecting the taste is known to those skilled in the art, and the specification will not give a further description.

[0094] The above units can be implemented by way of software, hardware or a combination thereof. For example, the program codes achieving the functions of the first unit, the fourth unit and the controller are stored in a memory. These codes are loaded and executed by a micro controller unit (MCU) which controls the device 1. And the first sensor, the second sensor and the second unit can be implemented by hardware entities. Those skilled in the art could implement embodiments of the invention in various ways according to the concept and principle taught by the description.

[0095] Those of ordinary skill in the art can 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

CLAIMS: What is claimed is:

1. A method of preparing food, comprising the steps of:

2. A method as claimed in claim 1 , wherein said step of detecting the first set of sensor values uses at least one of the following methods:

- voltammetry method;

- near - infrared spectroscopy method;

- ultrasound method;

- pH method;

- optical/infrared imaging method;

- density measuring method.

3. A method as claimed in claim 2, wherein said voltammetry method comprises:

- conducting a principal component analysis on the voltammetric data so as to obtain the first set of sensor values.

4. A method as claimed in claim 1 , wherein said stage is defined by at least one of:

- a time point or a time duration during the preparation of the food;

- a pressure point or a pressure range during the preparation of the food;

- a manner of preparing the food.

5. A method as claimed in claim 3, wherein when said stage is defined by the ranges or manner of preparing the food, for one specific stage in said set of given stages, said controlling step controls the preparation process to enter the stage following said specific stage, when the first set of sensor values at the specific stage conforms to the reference values associated with the specific stage, or when the time duration in the specific stage reaches a maximum time length defined for the specific stage.

6. A method as claimed according to claim 1, further comprising a step of:

- obtaining a target taste of the food;

7. A method as claimed according claim 1, further comprising a step of:

- obtaining features of the food ingredients that are used for preparing food; said features correspond to at least one of:

- the type of the food ingredients;

- the dose of the food ingredients;

- the quality of the food ingredients;

- the freshness of the food ingredients;

8. A method according to claim 7, wherein said step of obtaining features of the food ingredients comprises at least one of:

- receiving said features from a user interface;

- detecting said features.

9. A method as claimed in claim 8, wherein said step of detecting said features comprises the steps of:

- determining the features, by matching the second set of sensor values with at least one second set of reference values of a predefined plurality of second sets of reference values, wherein each second set of reference values is associated with one respective feature of the food ingredients.

10. A method as claimed in claim 1 , wherein the method is used for the preparation of food by using water, and the method further comprises a step of:

- detecting third values related to characteristics of water by a sensor;

said controlling step controls the preparation according to the third values.

11. A method as claimed in claim 1 , wherein the preparation comprises at least one of:

- cooking;

- brewing;

- fermenting;

- decocting.

12. A device for preparing food, comprising:

- a first unit (10) for determining a first set of reference values related to a taste parameter, each value of said set being associated with a respective stage of the preparation process; - a second unit (12) for preparing the food;

- a first sensor(14) for detecting a first set of sensor values at a set of given stages of the preparation process carried out by the second unit, and

- a controller (16) for controlling the second unit (12) to prepare the food according to the first set of sensor values and the corresponding reference values being associated with the set of given stages.

A device as claimed in claim 12, wherein said stage is defined by at least one of:

- a temperature point or a temperature range during the preparation the food;

- a time point or a time duration during the preparation of the food;

- a pressure point or a pressure range during the preparation of the food;

- a manner of preparing the food.

A device as claimed in claim 12, further comprising:

- a third unit (180, 181) for obtaining a target taste of the food; said first unit (10) determines the first set of reference values according to the

15. A device as claimed in claim 12, further comprising:

- a fifth unit (20) for obtaining features of the food ingredients that are used for preparing food;

said features correspond to at least one of:

- the type of the food ingredients;

- the dose of the food ingredients;

- the quality of the food ingredients;

- the freshness of the food ingredients;

and first unit (10) determines the first set of reference values according to said features of the food ingredients.