WO2014102675A2

WO2014102675A2 - Method and device for preparing congee

Info

Publication number: WO2014102675A2
Application number: PCT/IB2013/061120
Authority: WO
Inventors: Qiao HUA; Guangwei Wang; Xiaoting QU
Original assignee: Koninklijke Philips N.V.
Priority date: 2012-12-27
Filing date: 2013-12-19
Publication date: 2014-07-03
Also published as: WO2014102675A3

Abstract

The invention relates to a method for preparing congee comprising the steps of: providing a predetermined amount of rice into a congee container;providing weak alkaline water and putting it into the congee container, thereby forming a first mixture of the rice and the weak alkaline water; heating the first mixture in the congee container for a first time duration, thereby forming a partly-cooked congee; and then providing hardness-adjusted water and putting it into the congee container, thereby forming a second mixture of the partly-cooked congee and the hardness-adjusted water; and then heating the second mixture in the congee container for a second time duration. One of the main advantages of this invention is that the overall cooking time period is shortened and even better congee taste can be obtained. The invention also relates to a device for preparing congee.

Description

METHOD AND DEVICE FOR PREPARING CONGEE

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to the field of food processing, and more particularly to a method and device for preparing congee.

2. Description of the Prior Art

Congee, especially rice congee, has been served for humans for a long-period of time. In Asian countries, congee is widely used to feed the infants, the elders and the sick due to its easy digestibility and therapeutical benefits. Nowadays, to prevent an illness of affluence or to lose weight, increasing amount of people prefer a healthy and light diet as a breakfast or supper, like rice congee.

Rice congee, as one of the most prevalent dishes, spreads all over China. It is often eaten with pickled vegetables, salted duck eggs, fried dough sticks or other seasonings. In addition, rice congee with various additives, like meat, vegetables or fruits, is quite popular in south part of China (e.g. Guangdong and Hong Kong).

Normally, congee is known as a simple and convenient diet without complex processing procedure. Compared with making rice, the only difference for consumers to do is to add excess water into the rice cooker, achieving the suggested water/rice ratio. Recent kitchen appliances, like electric rice cooker is always used to make congee. Those products are always improved from the aspect of heating efficiency or pressure control. Besides, consumers gradually realize the critical role of water during daily cooking. However, rarely attention is paid on the influence of water properties (e.g. pH or hardness), and they have no choice but to use tap water or bottled water with various pH or hardness degrees. Moreover, well-cooked congee is sometimes out of expectation, some tastes tough and looks watery, some tastes quite soft with high viscosity.

Traditional method of making congee is boring and time-consuming. The whole process usually takes hours for grains to achieve full fusion of grains and water. Recently, increasing amount of electric kitchen appliances are used to make congee, such as electric rice cookers which mainly focus on the heating power, time or other physical factors. Although these controls improve the taste of products, it still needs around 45 minutes to obtain the desired diet. In the meantime, some electric pressure cookers are developed to make congee from a fast manner. However, the potential safety risks (e.g. explosion resulted from block) exist in case of incorrect operations, and overflowing may happen during congee cooking. Thus, new solutions are necessary required to overcome those problems.

SUMMARY OF THE INVENTION

One object of the present invention is to provide a method for preparing congee in a shorter period of time and with even better taste.

To this end, it is provided a method for preparing congee comprising the steps of:

- providing a predetermined amount of rice into a congee container;

- providing weak alkaline water and putting it into the congee container, thereby forming a first mixture of the rice and the weak alkaline water;

- heating the first mixture in the congee container for a first time duration, thereby forming a partly-cooked congee; and then

- providing hardness-adjusted water and putting it into the congee container, thereby forming a second mixture of the partly-cooked congee and the hardness-adjusted water; and then

- heating the second mixture in the congee container for a second time duration.

According to an example of the invention, the step of providing weak alkaline water comprises the steps of: providing a certain amount of water and sensing its initial pH value; and adjusting the initial pH value of the water into a weak alkaline pH value.

According to an example of the invention, adjusting the initial pH value of the water into a weak alkaline pH value is performed by at least one of: adding a pH additive into the water; adding H⁺/OH^" ion exchange resin into the water; and electrolyzing the water. The pH additive may be baking soda.

According to an example of the invention, providing weak alkaline water and putting it into the congee container comprises the steps of preparing the weak alkaline water in a tank separated from the congee container and pumping it into the congee container.

According to an example of the invention, the step of providing hardness-adjusted water comprises the steps of: providing a certain amount of water and sensing its initial hardness; and adjusting the initial hardness of the water into a desired hardness.

According to an example of the invention, wherein adjusting the initial hardness of the water into a desired hardness is performed by at least one of: adding Ca²⁺ and/or Mg²⁺ containing soluble salt into the water and/or precipitating and separating Ca²⁺ and/or Mg²⁺ from the water; adding Ca²⁺ and/or Mg²⁺ containing soluble salt into the water and/or adding ion exchange resin into the water and exchanging Ca²⁺ and/or Mg²⁺; and adding Ca²⁺ and/or Mg²⁺ containing soluble salt into the water and/or separating Ca²⁺ and/or Mg²⁺ by electro deionization technology.

According to an example of the invention, separating Ca²⁺ and/or Mg²⁺ by electro deionization technology is performed by absorbing Ca²⁺ and/or Mg²⁺ by a gel under a direct volt.

According to an example of the invention, providing hardness-adjusted water and putting it into the congee container comprises the steps of preparing the hardness-adjusted water in a tank separated from the congee container and pumping it into the congee container.

According to an example of the invention, the pH value of the weak alkaline water is 7.5-8.5, preferably 7.8-8.2, more preferably 8.0.

According to an example of the invention, the weight ratio among the rice, the weak alkaline water and the hardness-adjusted water is about 2:3 : 13.

According to another example of the invention, the hardness of the hardness-adjusted water is 2.5-3.5°dH, preferably 2.8-3.2°dH, more preferably 3.0°dH.

According to still another example of the invention, the first time duration is about 10 minutes and the second time duration is about 20 minutes.

The present invention also provides a device for preparing congee comprising: a congee container; a heating component for heating the congee container; a tank separated from the congee container for holding water, the tank comprising a pH adjuster module for adjusting the initial pH value of the water into a weak alkaline pH value and a hardness adjuster module for adjusting the hardness of the water into a desired hardness; a pumping module arranged between the congee container and the tank for pumping water from the tank into the congee container; and a control unit, which is arranged to sequentially:

- control the pH adjuster module to adjust the initial pH value of the water into the weak alkaline pH value;

- control the pumping module to pump the water with the weak alkaline pH value into the congee container after/before rice is put into the congee container; - control the heating component to heat the congee container for a first time duration;

- control the hardness adjuster module to adjust the hardness of the water into a desired hardness;

- control the pumping module to pump the water with the desired hardness into the congee container; and

- control the heating component to heat the congee container for a second time duration.

The present invention also provides a use of weak alkaline water and hardness-adjusted water for shortening cooking time during congee preparation and improving congee taste, wherein the weak alkaline water is at first mixed with rice and heated in a congee container for a first time duration; and then the hardness-adjusted water is added into the congee container and heated for a second time duration.

The advantages for this congee preparing method are listed as below:

- due to the fast cooking program the congee preparing time period is shortened. It is possible to accelerate the leach-out, pasting or swelling degree by adjusting the pH and hardness of cooking water respectively.

- delicious congee is obtained. After cooking with special types of water in a short period, good taste of congee is derived simultaneously.

Other objects, advantages, and novel features of the present invention will be apparent from the following detailed description of a preferred embodiment thereof with reference to the attached drawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a schematic block diagram showing a method for preparing congee according to an embodiment of the present invention;

Fig. 2 is a schematic structural view of a device for preparing congee according to an embodiment of the present invention;

Fig. 3 schematically shows the procedure of cooking congee in an exploded manner according to an embodiment of the present invention;

Fig. 4 is a graph showing water pH effect on the pasting degree of rice congee;

Fig. 5 is a graph showing water hardness effect on the swelling degree of rice congee;

Fig. 6 is a graph showing water hardness effect on swelling degree and hardness of rice congee after 20-minute cooking;

Fig. 7 is a graph showing water hardness effect on other attributes of rice congee after 20-minute cooking;

Fig. 8 shows that amylose is linked by bonds a-1, 4 glucosidic linkages;

Fig. 9 shows that a-1, 6 glucosidic linkages are destroyed in alkaline environment; and

Figs. 10A and 10B show that Ca²⁺ brings about cross-linkages between two phosphoric acid ester groups in the starch, wherein the cross-linkage shown in Fig. 10A occurs in the same glucose chain and the cross-linkage shown in Fig. 10B occurs between two adjacent chains.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

The basic idea is to design a novel congee making method that shortens the cooking time via the adjustment of water properties, and congee with good taste is also available after cooking. This general method is described in Figs. 1 and 3. In the beginning, according to the different types of rice, certain proportion of rice and water is weighed and prepared. Usually, the average weight ratio of rice and water for congee is 1 :8, and for the cooked rice is 1 : 1.5. These ratios may change in dependence on types or qualities of rice used. Meanwhile, the fresh water is sensed by pH sensor 2301B and hardness sensor 2302B (the hardness sensing could also be conducted after pH sensing). Next, at least a part of water is adjusted up to weak alkaline degree, for instance pH 7.5-8.5, preferably 7.8-8.2, more preferably 8.0. Afterwards, water with adjusted pH is cooked with rice (first cooking stage) to gain extensive pasting, around 90% pasting of starch. In the meantime, the hardness of the rest water is adjusted to a certain degree, for instance hardness of 2.5-3.5°dH, preferably 2.8-3.2°dH, more preferably 3.0°dH. After the first cooking stage, water with adjusted hardness is added into previous semi-cooked congee (second cooking stage) to obtain a congee that has full fusion of grains and water. In the end, final congee with good quality is produced. One of the practical examples to explain an embodiment of the invention is that: 75g weak alkaline water is mixed with 50g rice granules at first-step. After cooking for 10 minutes, 325g water with adjusted hardness is put into the cooker. Finally, congee with good taste is available in a more fast way

Now refer to Figs. 1-3, a method 100 and a device 200 for preparing congee are schematically shown. Concretely, the method 100 for preparing congee is started in Fig. 1 at 110 and ended at 170 and includes the following steps: providing a predetermined amount of rice into a congee container 210 (step 120); providing weak alkaline water 310 and putting it into the congee container 210 (step 130), thereby forming a first mixture of the rice and the weak alkaline water 310; heating the first mixture in the congee container 210 for a first time duration (step 140), thereby forming a partly-cooked congee; and then providing hardness-adjusted water 320 and putting it into the congee container 210 (step 150), thereby forming a second mixture of the partly-cooked congee and the hardness-adjusted water 320; and then heating the second mixture in the congee container 210 for a second time duration (step 160).

Concretely, adjusting the initial pH value of the water into a weak alkaline pH value is performed by: adding a pH additive into the water; and/or adding H⁺/OH^" ion exchange resin into the water; and/or electrolyzing the water. The pH additive may be baking soda.

The step of providing hardness-adjusted water comprises the steps of: providing a certain amount of water and sensing its initial hardness; and adjusting the initial hardness of the water into a desired hardness. Adjusting the initial hardness of the water into a desired hardness is performed by at least one of: adding Ca²⁺ and/or Mg²⁺ containing soluble salt into the water and/or precipitating and separating Ca²⁺ and/or Mg²⁺ from the water; adding Ca²⁺ and/or Mg²⁺ containing soluble salt into the water and/or adding ion exchange resin into the water and exchanging Ca and/or Mg ; and adding Ca and/or Mg containing soluble salt into the water and/or separating Ca²⁺ and/or Mg²⁺ by electro deionization technology. Separating Ca^{2 +} and/or Mg^{2 +} by electro deionization technology is performed by absorbing Ca²⁺ and/or Mg²⁺ by a gel under a direct volt.

Further explanations on how this method works are described as below.

Since the major component of milled rice is starch, so water influence on starch is fundamental to understand the basic mechanisms. The main constituents of starch granules are amylopectin (-75% by weight) and amylose. Generally, starch is composed of glucose residues linked by the bonds a-1, 4 and a-1, 6 glucosidic linkages (see details in Figs. 8 and 9).

Congee making involves a process of starch gelatinization which starts after heating to a higher temperature. On one hand, weak alkaline environment promotes the starch gelatinization from several aspects, such as the leach-out of insoluble amylose and the following pasting. Since OH^" accelerates the hydrolysis of rice starch (see details in the foregoing Fig. 9) by damaging the intermolecular bonds of starch molecules, so in the presence of water and heat, more amylose leaches out and therefore leads to a fast increase of pasting to a certain degree. Since restriction of starch swelling occurs when too much amylose pasting surrounding the rice granules, so weak alkaline condition is proper during the pasting stage.

Furthermore, since the starch-phosphate content is correlated to starch-paste peak viscosity and gel-forming capacity, so external compounds, like divalent cation Ca²⁺ influences starch properties through their interaction with phosphate groups (see details in the foregoing Fig. 10). In ionized form of starch, phosphates present in the branched amylopectin introduce repulsive force among the starch molecules. However, divalent cations (e.g. Ca²⁺) generate the cross-linkages between two phosphoric acid ester groups in starch crystal structure, and such linking accounts for the viscosity changes, contraction of starch swelling and lower solubility of the starch. So water with certain amount of minerals severely controls the swelling degree of starch. In addition, our results show that the sensory perception of congee is mostly correlated with the swelling degree of starch (refer to Fig. 6), and large degree of starch swelling and burst leads to the full fusion of rice and water.

Please refer to Fig. 2. A device 200 for preparing congee according to an embodiment of our application comprises: a congee container 210; a heating component 220 for heating the congee container 210; a tank 230 separated from the congee container 210 for holding water, the tank 230 comprising a pH adjuster module 2301 for adjusting the initial pH value of the water into a weak alkaline pH value and a hardness adjuster module 2302 for adjusting the hardness of the water into a desired hardness; a pumping module (not shown) arranged between the congee container 210 and the tank 230 for pumping water from the tank 230 into the congee container 210; and a control unit 240, which is arranged to sequentially:

- control the pH adjuster module 2301 to adjust the initial pH value of the water into the weak alkaline pH value;

- control the pumping module to pump the water with the weak alkaline pH value into the congee container 210 after/before rice is put into the congee container 210;

- control the heating component 220 to heat the congee container 210 for a first time duration;

- control the hardness adjuster module 2302 to adjust the hardness of the water into a desired hardness;

- control the pumping module to pump the water with the desired hardness into the congee container 210; and

- control the heating component 220 to heat the congee container 210 for a second time duration.

The pH adjuster module 2301 provided in the tank 230 includes a pH sensor 2301B for sensing the pH value of the water and a controlled pH adjuster (CPA) 2301 A to adjust the pH value of the water into a desired pH value. The controlled pH adjuster 2301A is a pH additive supplying module, an H⁺/OH^" ion exchange resin or a water electrolyzing module.

The hardness adjuster module 2302 provided in the tank 230 includes a hardness sensor 2302B for sensing the hardness of the water and a controlled hardness adjuster (CHA) 2302A to adjust the hardness of the water into a desired hardness. The controlled hardness adjuster 2302A is a chemical precipitation unit, an ion exchange resin or an electro deionization module.

Fig. 2 is merely a schematic structural view of a device 200 for preparing congee, in which the relative positions of all the settings can be changed and the water tank 230 can be separately divided into two halves, one for adjusting the pH value of the water and the other for adjusting the hardness of the water.

Fig. 3 exhibits an exemplary congee cooking procedure in an exploded manner. In the beginning, the fresh water is determined by a pH sensor 2301B or a hardness sensor 2302B separately (A). After that, through the treatment of CPA 2301 A, certain volume of weak alkaline water (e.g. pH 7-8) is loaded into the rice container 210 and mixed well with certain amount of rice granules. Next, proper heating program is selected and it starts until obtaining extensive pasting (B) (around 10 minutes for rice congee, and time changes for other types of rice). Afterwards, CHA 2302A is manipulated to produce water with certain amount of minerals, and the processed water is injected into the rice container 210 (C). Finally, a full fusion of rice and water is available after proper heating (D) (around 20 minutes for rice congee, but the value changes for other rice types). All in all, this method reduces 1/3 cooking time during the whole congee making process (see Fig. 4 and Fig. 5 for details). In addition, a good taste of congee is obtained at same time, and the sensory perception of congee is largely associated with rice swelling rate (see Fig. 6 for details).

Experimental Results

Typically, 45 minutes are required to achieve 400% swelling degree of the rice for a well cooked congee. In the first period (around 12 minutes), the extensive pasting (>85%) needs to be formed. The mechanism is the pasting and swelling (caused by water-absorption of starch) is correlated tightly during congee cooking. When the pasting of rice congee is below around 85%, congee swells in a lower rate. When the pasting degree achieves around over 97%, the swelling rate of congee reduces due to the obstruction of too much pasts. So the optimal condition for making congee is when the pasting degree lies in around 85% to 97%, and the swelling degree of congee increases in a higher rate.

Fig. 4 shows that at around 9 minute (horizontal coordinate), the highest pasting degree (longitudinal coordinate) was at pH 8 (85%), which was 10%, 14% higher in comparison with pH 6-7 and pH 9-10 respectively. Furthermore, it took at least 12 minutes to achieve 85% pasting by using normal neutral water (pH around 7), so here the condition pH 8 shortens the pasting process for around 3 minutes. Moreover, this condition will accelerate the swelling rate afterwards.

Fig. 5 is a graph showing water hardness effect on the swelling degree of rice congee. From Fig. 5, in the water of 3°dH, the swelling degree (longitudinal coordinate) of congee exhibited a boost after 20 minutes (horizontal coordinate), and achieved 400% after around 30-minute cooking. For the congee cooked under other conditions, only around 350% swelling degree was achieved, and to achieve 400% swelling degree, totally 45 minutes are needed. In addition, the pasting degree of 3°dH at 10 minute was around 80%, which meant the pasting degree was not optimal for accelerating the starch swelling.

Here we add weak alkaline water in the beginning for around 9 minutes to have extensive pasting (85%), then we add water of 3°dH for the following cooking. According to test results, the swelling rate of 3°dH with 85% pasting is higher than that with around 80% pasting. Therefore, the total cooking time to achieve 400% swelling degree is less than 30 minutes, even further reduced by 1/3 of ordinary cooking time.

The horizontal coordinate of Figs. 6-7 represents hardness of water (°dH), the longitudinal coordinate of Fig. 6 represents TPA (Texture Profile Analyser) and swelling results, and the longitudinal coordinate of Fig. 7 represents TPA results. The sign "♦" of Fig. 6 represents the hardness of rice and the sign "■" of Fig. 6 represents the welling results. The sign " A " of Fig. 7 represents cohesiveness results, "x" of Fig. 7 represents gumminess results and "*" of Fig. 7 represents chewiness results. According to Fig. 6 and Fig. 7, the TPA (Texture Profile Analyser) of rice congee shows that the hardness of rice decreased from 0 to 3°dH, and then went up along with increasing hardness of water. Moreover, higher degree of cohesiveness, gumminess and chewiness properties were at 0 and 3°dH. In addition, the swelling degree of starch negatively correlated with rice TPA attributes, such as hardness and chewiness of congee. Considering all the attributes, congee cooked at 0-3 °dH was softer (about 270) than others, and meanwhile, the congee also kept higher, cohesiveness, gumminess and chewiness, which is another benefit for this novel method.

It is to be understood, however, that even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, number, and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.

It should be noted that the abovementioned embodiments illustrate rather than limit the invention and that those skilled in the art would be able to design alternative embodiments without departing from the scope of the appended claims. For instance, although we take rice congee as an example, the method 100 and device 200 for preparing congee are not limited thereto. The method 100 and device 200 according to the invention they can also be applied in preparing other grain congee such as porridge congee and millet congee.

In the 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 apparatus claims enumerating several units, several of these units can be embodied by one and the same item of hardware or software. The usage of the words first, second and third, et cetera, does not indicate any ordering. These words are to be interpreted as names.

Claims

1. A method for preparing congee comprising the steps of:

- providing a predetermined amount of rice into a congee container;

2. The method for preparing congee according to claim 1 , wherein the step of providing weak alkaline water comprises the steps of:

- providing a certain amount of water and sensing its initial pH value; and

- adjusting the initial pH value of the water into a weak alkaline pH value.

3. The method for preparing congee according to claim 2, wherein adjusting the initial pH value of the water into a weak alkaline pH value is performed by at least one of:

- adding a pH additive into the water;

- adding H⁺/OH^" ion exchange resin into the water; and

- electrolyzing the water.

4. The method for preparing congee according to claim 3, wherein the pH additive is baking soda.

5. The method for preparing congee according to claim 1, wherein providing weak alkaline water and putting it into the congee container comprises the steps of preparing the weak alkaline water in a tank separated from the congee container and pumping it into the congee container.

6. The method for preparing congee according to claim 1, wherein the step of providing hardness-adjusted water comprises the steps of:

- providing a certain amount of water and sensing its initial hardness; and

- adjusting the initial hardness of the water into a desired hardness.

7. The method for preparing congee according to claim 6, wherein adjusting the initial hardness of the water into a desired hardness is performed by at least one of:

- adding Ca²⁺ and/or Mg²⁺ containing soluble salt into the water and/or precipitating and separating Ca²⁺ and/or Mg²⁺ from the water;

- adding Ca²⁺ and/or Mg²⁺ containing soluble salt into the water and/or adding ion exchange resin into the water and exchanging Ca²⁺ and/or Mg²⁺; and

- adding Ca²⁺ and/or Mg²⁺ containing soluble salt into the water and/or separating Ca²⁺ and/or Mg²⁺ by electro deionization technology.

8. The method for preparing congee according to claim 7, wherein separating Ca²⁺ and/or Mg²⁺ by electro deionization technology is performed by absorbing Ca²⁺ and/or Mg²⁺ by a gel under a direct volt.

9. The method for preparing congee according to claim 1, wherein providing hardness-adjusted water and putting it into the congee container comprises the steps of preparing the hardness-adjusted water in a tank separated from the congee container and pumping it into the congee container.

10. The method for preparing congee according to claim 1, wherein the pH value of the weak alkaline water is 7.5-8.5, preferably 7.8-8.2, more preferably 8.0.

11. The method for preparing congee according to claim 1, wherein the weight ratio among the rice, the weak alkaline water and the hardness-adjusted water is about 2:3 : 13.

12. The method for preparing congee according to claim 1, wherein the hardness of the hardness-adjusted water is 2.5-3.5°dH, preferably 2.8-3.2°dH, more preferably 3.0°dH.

13. The method for preparing congee according to claim 1, wherein the first time duration is about 10 minutes and the second time duration is about 20 minutes.

14. A device for preparing congee comprising:

a congee container;

a heating component for heating the congee container;

a tank separated from the congee container for holding water, the tank comprising a pH adjuster module for adjusting the initial pH value of the water into a weak alkaline pH value and a hardness adjuster module for adjusting the hardness of the water into a desired hardness;

a pumping module arranged between the congee container and the tank for pumping water from the tank into the congee container; and

a control unit, which is arranged to sequentially:

- control the pumping module to pump the water with the weak alkaline pH value into the congee container after/before rice is put into the congee container;

- control the heating component to heat the congee container for a first time duration;

15. The use of weak alkaline water and hardness-adjusted water for shortening cooking time during congee preparation and improving congee taste, wherein the weak alkaline water is at first mixed with rice and heated in a congee container for a first time duration; and then the hardness-adjusted water is added into the congee container and heated for a second time duration.