The present invention relates to a method for preparation of frozen ready-to-eat brown rice. In particular, the method relates to preparation of a fibre rich fried instant fried brown rice whose Glycemic Index is as low as about 36 and shelf life of about 6 months with good sensory profile.
BACKGROUND OF THE INVENTION
Rice is one of the extensively consumed foods and it is a staple food of Indians and many other countries. Palatability of rice is accepted as the most significant element in the development of healthcare food for nursing care centres and home-made meals in the elderly. India is second in rice production, producing more than 155 million metric tonnes of rice per year, behind China, which has the highest production. Rice is the staple food for Indians, and the climate of India, especially the Deccan plateau region, is very suitable for cultivating rice.

Ordinarily, rice is used as white rice so during milling and polishing process of making white rice several nutrients are lost. Glycaemic index of the white rice is higher than that of the brown rice. Brown rice, hulled directly from rough rice, consists of bran layers (6-7%), an embryo (2-3%) and an endosperm (approximately 90%). White rice is brown rice that has removed its bran and germ to make it easier and quicker to prepare, to give it a longer shelf life and, most significantly, to give it a better sensory quality. However, the milling processes used in the removal of the bran and germ often lead to a drastic reduction of many vital nutrients that are necessary for a healthy diet. Brown rice relative to white rice is not only more abundant in essential nutrient components, but also includes many more bioactive components, for example ferulic acid, ? – oryzanol aminobutyric acid (GABA), mostly in germ or bran layers.

With the existing grain-processing technologies a large-scale production of processed grains is possible. Through grinding techniques, the outer bran and germ parts of untouched rice grains (i.e. brown rice) are separated to produce white rice composed mainly of starchy endosperm. Although the findings are not completely consistent, the intake of white rice usually results in a higher postprandial blood glucose reaction as calculated by the Glycemic Index (GI) than the consumption of same amount of brown rice. Higher dietary GI has consistently been associated with an increased risk of type 2 diabetes (T2D) in prospective cohort studies. In addition, brown rice intake may have beneficial effects on T2D risk due to its high content of multiple nutrients, such as fibre, vitamins and minerals, most of which are lost during processing and milling.

Brown rice is not considered suitable staple rice due to its weak texture, poor bran odour, low digestibility and not easy-to-cook characteristics. Therefore, brown rice is preferred only by health-conscious people because of its high nutritious value and it is mostly used as a tool in the fermentation of products such as soybean paste and vinegar or as a pad. However, considering the increased industrialization, prevalence of chronic diseases and shift in dietary pattern it is imperative to provide the vulnerable population with a sustainable solution to combat the current situation of degenerative diseases. Substitution of whole grains, like brown rice, for white rice can reduce the risk of type 2 diabetes. These findings reinforce the suggestion that the bulk of carbohydrate consumption should come from whole grains like brown rice rather than processed grains to help reduce type 2 diabetes.

One of the existing problems is the availability of ready-to-eat brown rice with long shelf life and preserved sensory qualities and traits. Most of the ready-to-eat brown rice preparations either result in loss of sensory qualities (such as texture, taste, appearance, flavour, size, etc.) or have a low shelf-life caused by the contamination. Accordingly, there exists a need for a simple, effective, and economic method for preparing a long lasting, shelf-stable, ready-to-eat brown rice wherein the qualities of the rice such as texture, taste, appearance, flavour, size of freshly prepared rice are preserved while protecting microbial/ bacterial contamination. References are being made here to some of the prior art patents in relation to the subject where certain attempts were made. However, none of these prior art patents solve the current problem at hand.
Patent No. US3086867A (titled ‘Process of preparing a quick-cooking brown rice’) discloses a process comprising partially hydrating raw brown rice grains in water at the temperature above about 1650F, to partially split the bran coat, steaming the partially hydrated rice grains to partially gelatinize the grain surface and firm the grain, steaming the steamed and partially hydrated rice grains to further gelatinize them, and subjecting the rice grains to additional cycles of partial hydration and steaming and then drying the hydrated, gelatinized grains.

In another Patent No. US7935369B2 (titled ‘Germinated brown rice’), it is disclosed that germinating brown rice provides an improved taste and cooking characteristics. Germinated brown rice as disclosed here comprises of at least a direct reducing sugar portion in an elevated quantity compared to the originating brown rice, and further containing alpha-starch, prepared by gelatinizing part of the starch.

Another Patent No. CN101715921A discloses instant brown rice porridge and its method of preparation, the said instant porridge is made with brown rice and water at a weight ratio of 1: 5 to 1: 10, wherein brown rice is organic brown rice, hybrid paddy rice brown rice, late rice brown rice, semilate rice brown rice, early rice brown rice, and water is drinking water.

Yet another Patent No. US5026570A describes a method for preparing freeze-fried rice wherein the process for producing frozen rice consisting primarily of boiling rice in water containing acetic acid and sodium chloride, the acetic acid is approximately 4-8 per cent by weight of the water and the sodium chloride is approximately 0.5-3 per cent by weight of the water and the frozen-drying of boiled rice.

Still another Patent No. US5702745A discloses a process for the preparation of stable, ready-to-eat rice. The process includes the covering of pre-gelatinized rice grains with an emulsifier. Food acid and glucono-delta-lactone are then added to the coated rice to reduce the pH to 4.6 or less. The rice is then heat-treated at a temperature and for a time suitable for sterilization. The resulting products allegedly have similar texture, appearance and taste relative to other commercially developed, healthy, ready-to-each rice products.

The present invention satisfies the drawbacks and other requirements in providing a fibre rich fried ready-to-eat brown rice with long shelf life and preserved sensory traits. The present invention provides a process for making ready to eat brown rice.

OBJECTS OF THE PRESENT INVENTION
The primary object of the present invention is to provide a process for preparing ready-to-eat brown rice.
Another object of the present invention is to provide fibre rich instant ready-to-eat brown rice with highly preserved and good sensory profile and low Glycemic Index (GI).

Yet another object of the present invention is to provide a method for preparation of fibre rich instant ready-to-eat brown rice for the diabetics patients through individual quick frozen technique.
Still another object of the present invention is to provide fibre rich instant ready-to-eat brown rice with high shelf life and low contamination index.
Another object of the present invention is to provide fibre rich instant ready-to-eat brown rice with reduced cooking time and preserved taste and other properties as freshly prepared brown rice.
Yet another object of the present invention is to provide fibre rich instant ready-to-eat brown rice with good sensory profile, low Glycemic Index (GI), and high shelf life.
The other objects, preferred embodiments and advantages of the present invention will become more apparent from the following detailed description of the present invention when read in conjunction with the accompanying claims, examples, figures and tables, which are not intended to limit scope of the present invention in any manner.

SUMMARY OF THE INVENTION
The present invention provides a method for preparation of instant brown rice mix, wherein the method comprises: (a) Soaking brown rice in water at the ratio of about 1:8 - 2.2 (w/v) at a temperature of about 45°C - 55°C for about 55 - 65 minutes; (b) Pressure-cooking the brown rice for about 25 to 35 minutes; (c) Cooling the brown rice; (d) Packing the cooled brown rice; and (e) Individual quick freezing the packed brown rice for about 1 – 5 minutes at a temperature of about -300C to about -500C.
The present invention also provides an instant brown rice mix having the physical parameters as per following: (a) Swelling power (g/g) of about 1.75 g/g to about 2.0 g/g; (b) Water uptake ratio of about 2.25 to about 2.5; (c) Increase in weight after cooking of about 90% to about 120%; (d) Solids loss of about 4.5% to about 5%; (e) Cooking time of about 25 minutes to about 35 minutes; and (f) Gelatinization temperature in the range of about 75°C to about 85°C.
BRIEF DESCRIPTION OF THE DRAWINGS

A general understanding of the invention with its foregoing and other objects will be apparent upon consideration of the following detailed description read in conjunction with the accompanying drawings.

Figure 1 is a graphical representation of comparative glucose response curve between white rice and brown rice.

DETAILED DESCRIPTION OF THE INVENTION
Accordingly, the present invention discloses a method for preparation of fibre rich instant ready-to-eat brown rice which has the texture, taste, flavour and appearance similar to that of a freshly cooked brown rice. The fibre rich instant ready-to-eat brown rice as per the present invention has Glycemic Index as low as about 36, with good sensory profile and a shelf life of about 6 months protecting the bacterial contamination till then.
As per one of the embodiments of the present invention, the method for preparation of fibre rich instant ready-to-eat brown rice comprises of: (a) cleaning and soaking the brown rice at in water; (b) pressure-cooking the brown rice; (c) packing the brown rice after cooling; and (d) individual quick freezing of the packed rice. The method produces the cooked brown rice in freezer bags making it easy to transport. This method also helps the rice to quickly reheat directly from the freezer without thawing, which prevents it from becoming mushy.
In accordance with one of the embodiments of the present invention, a method for preparation of ready-to-eat brown rice includes soaking the brown rice as the first step. Soaking is a hydration process in which water diffuses into rice grains, which is essential for the complete gelatinization of starch. Soaking of rice is a crucial step in the preparation as per the invention, and therefore the ratio of rice to water, soaking temperature, and soaking time is standardised and optimized to obtain the best results.

The ratio of rice and water at the time of soaking was standardized and fond to be most optimum in the range of about 1.75 to about 2.25. Most preferred ratio for rice to water at the time of soaking was found to be 2. Towards standardisation of soaking temperature and soaking time Table 1 illustrates the different attributes of the soaked brown rice such as water uptake ratio, elongation ratio and cooked rice volume under different conditions for soaking temperature and time for brown rice.
S. No. Soaking
Temperature (A) (degree Celsius) Soaking time (B)
(minutes) Water Uptake Ratio (g/g) Elongation Ratio Cooked Rice Volume (ml)
1 40 45 2.91±0.18 1.15±0.02 446.67±2.89
60 2.93±0.06 1.21±0.02 443.33±2.89
75 2.85±0.09 1.18±0.04 441.67±2.89
2 50 45 2.50±0.07 1.17±0.03 451.67±2.89
60 2.90±0.01 1.17±0.03 441.67±2.89
75 2.77±0.15 1.21±0.02 436.67±5.77
3 60 45 2.82±0.16 1.17±0.01 421.67±2.89
60 2.53±0.06 1.24±0.03 418.33±2.89
75 2.33±0.06 1.25±0.03 413.33±5.77
CD values at 5% Factor A- 0.112
Factor B- 0.112
Treatments/(AxB)0.194 Factor A- 0.026
Factor B- 0.026
Treatments/(AxB)- 0.045 Factor A- 3.816
Factor B- 3.816
Treatments/(AxB)- 6.610

Table 1: Standardization of soaking time and temperature
Accordingly, during the standardisation and optimization procedure, it was surprisingly found by the inventor that the most optimum soaking temperature is in the range of 45°C - 55°C, with most preferred temperature being 50°C. Likewise, the most optimum time for soaking is found to be about 55 - 65 minutes, with most preferred time being about 60 minutes. Accordingly, as per one of the preferred embodiments of the present invention, the soaking temperature is in the range of 45°C - 55°C and the time for soaking is about 55 - 65 minutes.
As per another preferred embodiment, the time for pressure cooking the brown rice was standardized and found to be most optimum in the range of about 25 to 35 minutes. Most preferred cooking time was found to be about 30 minutes.
In accordance with yest another embodiment of the present invention, the individually quick frozen (IQF) technique is utilized for freezing the cooled and packed rice in the final step. IQF technology is used to freeze the fried brown rice in food grade aluminium laminate packaging material. The freezing time is standardized at about 1 – 5 minutes at a temperature of about -300C to about -500C. The most preferred standardization for freezing was found to be about 2 minutes at a temperature of about -400C.
Thus, in accordance with one of the most preferred embodiments, the soaking temperature and time for brown rice was standardized at 50° C and 60 minutes, the cooking time was standardized at 30 minutes; and freezing time and temperature was standardized at 2 minutes and -400C, with the main objective of reduction in cooking time by consumer.
Good overall acceptability was observed in terms of organoleptic analysis of the fibre rich instant ready-to-eat brown rice prepared in accordance with the present invention. Results of shelf life studies reveal that the attributes like moisture content, sensory parameters and total viable count were under acceptable limits for the instant brown fried rice for duration of up to 6 months. Therefore, it can be concluded that the instant brown fried rice can be opted as a low Glycemic Index rice meal that can be consumed considering the current life style. Further, fibre rich instant ready-to-eat brown rice prepared in accordance with the present invention was found to have the same or better texture, appearance and taste relative to other commercially developed, healthy, ready-to-each rice products.

In accordance with another preferred embodiment of the present invention, the final cooking parameters and glycaemic index of the ready to eat brown rice prepared by the present invention was arrived by taking into account the following:
a. Analysis of cooking parameters including Swelling power, Water uptake ratio, Increase in weight after cooking(%), Solids Loss (%), Cooking Time (min) and Gelatinization Temperature (°C);
b. Pre- processing of ingredients which includes cleaning, soaking of brown rice, etc.
c. Standardization of the process for the preparation of frozen IQF ready to eat brown rice;
d. Analysis of shelf life study;
e. Analysis of moisture content, sensory evaluation and microbial analysis; and
f. Estimation of glycaemic index of food products.
As per another embodiment of the present invention, the method further includes frying masala including cumin seeds, hot spices, dry mango powder, coriander powders, Asafoetida, salt, turmeric powder and other vegetables in desi ghee and mixing it with cooked brown rice before cooling.
In yet another embodiment of the present invention, the method for preparing fibre rich instant ready-to-eat brown rice from the raw materials include the following Preliminary Processes and Final Processes. Preliminary processing of the raw materials is necessary to improve their functional and nutritional properties, and all the processing steps involved are commercially feasible.
I. Pre-processing of Rice -
i. Cleaning the grains to remove dirt, dust, stones and other foreign material;
ii. Washed in running water; and
iii. Soaking for standardized time.
II. Pre-processing of vegetables -
i. Cleaning the vegetables to remove dirt, dust, stones and other foreign material;
ii. Washed in running water;
iii. Sorting and trimming; and
iv. Frying the vegetables.
III. Final Processing -
i. Cooking soaked rice in pressure cooker for standardized time;
ii. Frying the masalas in desi ghee;
iii. Frying the vegetables;
iv. Adding the masala and fried vegetables in the brown rice;
v. Packing it after cooling; and
vi. Freezing for standardized time and temperature.
According to another preferred embodiment of the present invention, the frozen ready to eat brown rice includes the following key ingredients in the approximate quantity / ratio as provided in Table 2.
Ingredients Quantity
Brown rice 1 kg
Water 2 Litres
Coriander Powder 16 g
Cumin Seeds 100 g
Red chilli 30 g
Hot spices 9 g
Desi Ghee 200 g
Dried mango Powder 5 g
Salt 5 g (per taste)
Asafoetida (Heeng) 1 pinch
Turmeric powder 4g
Table 2
As per one of the embodiments, the physical cooking parameters of the fibre rich instant ready-to-eat brown rice prepared as per the present invention are as following:
1. Swelling power: The swelling power of grain is an important feature that has a direct effect on the acceptability of food products developed from grain. Differences in the proportion of crystalline and amorphous areas in starch granules are the main cause of difference in the water binding potential of grain. In the current study the swelling power of brown rice was obtained as about 1.852 g/g. The optimum range was found to be about 1.75 g/g to about 2.0 g/g.

2. Water uptake ratio: The uptake of water is an important feature of energy consumption. More water absorption requires more cooking energy, and vice versa. The appearance of cooked cereal also influences the amount of water consumed during cooking. In the present study the water uptake ratio of brown rice was obtained as 2.37. The optimum range was found to be about 2.25 to about 2.5.

3. Increase in weight after cooking: The economic worth of grain also reflects the importance of an increase in weight after cooking. In the present analysis, a percent rise in post-cooking weight was found to be 107.55%. The optimum range was found to be about 90% to about 120%.

4. Solid loss: Solids released in cooking water have also been considered essential qualities of cooking quality when the greater release of solids into cooking water usually reduces the final product's nutritional and economic value. The solid loss was found to be 4.80% in the present analysis. The optimum range was found to be about 4.5% to about 5%.

5. Cooking time: Cooking is necessary because it gives food palatability, avoids certain food-borne diseases that may otherwise arise if the food is consumed fresh. This cooking sterilizing effect relies primarily on cooking time and cooking temperature. The cooking time was found to be 30.67 minutes in the current report. The optimum range was found to be about 25 minutes to about 35 minutes.
6. Gelatinization temperature: Cooking time and molecular size of starch fraction are considerations related to grain temperature gelatinization. But the temperature of gelatinization is closely related to the grain content of amylose. The higher the amylose content, the temperature of gelatinization would be higher (Henry and Kettlewell, 1996). In comparison, the higher the gelatinization temperature, the longer the grain takes time to cook, since more amylose-containing grain absorbs more water. The gelatinization temperature was observed at 81°C in the present analysis. The optimum range was found to be about 75°C to about 85°C.
The most preferred and optimum range of these parameters is provided in the Table 3 below.
Sr. No. Cooking parameters Results
1 Swelling power (g/g) 1.852± 0.003
2 Water uptake ratio 2.37± 0.013
3 Increase in weight after cooking (%) 107.55± 0.218
4 Solids Loss (%) 4.80± 0.361
5 Cooking Time (min) 30.67± 0.577
6 Gelatinization Temperature (°C) 81± 2.645

Table 3: Cooking parameters

Shelf life of rice
In accordance with a preferred embodiment of the present invention, the shelf life of frozen fibre rich instant ready-to-eat brown rice is about 6 months. The moisture in the fried brown rice initially was observed as 71.54 per cent which decreased to 63.63 per cent after 6 months of storage in refrigerated conditions. During freezing, ice crystals are formed in the food products and when heated to room temperature these crystals are melted as well as evaporated and consequently moisture content of the frozen rice decreased.
Microbial analysis becomes important because any microbial changes reduce quality of developed food product and hence make them unsafe for consumption and can cause disease. The total bacterial count was initially found to be 3.1×102 on the day of packaging, and after 6 months of storage, it raised to 8.5×102. According to FAO/WHO expert consultation on microbiological requirements (CAC/RCP 15, 1976) a limit of 5x104 mesophilic aerobic 406. The duration of acceptance of cooked rice bacteria is safe for human consumption and the values at or above 106 are unacceptable. Frozen RTE dependent on brown rice can be safely eaten for a period of 6 months under specific refrigerated conditions, according to the findings of microbiological studies.
Parameters Color Aroma Taste Grain separation Grain shape Texture Stickiness Overall acceptability
Scores 8.06±
2.29 6.70±
2.98 6.56±
2.92 6.30± 2.59 5.62±
2.42 6.22±
2.88 6.52± 2.93 9.02± 1.48
*All results are mean±standard error of 50 values
Table 4 : Sensory parameters and their scores
Organoleptic attributes of rice
Organoleptic acceptability usually reflects the consumer’s desire for food. Sensory evaluation of fried brown rice was conducted wherein 50 members were selected to judge the consumer acceptability of fried brown rice. Open pan cooking was preferred to cook the rice and then the cooked rice was fried with ghee and some spices to get the desired product i.e. fried brown rice. The results revealed that the fried brown rice was extremely accepted by the consumers on the basis of over-all acceptability. The color of the product was also liked very much by the panellists and the other parameters viz. aroma, taste, grain separation; texture and stickiness were marginally appreciable by the panel members.
S. No. Food Product Area (mg min/100 ml) (mean+SD) Per cent decrease in AUC
1. Glucose 4898±352.91a
2. White fried rice 2846.5±422.04b 41.88%
3. Brown fried rice 1793.5+314.1c 63.38%
Standard error of mean 98.30
Critical Difference at 5% 343.72

Table 5: Area under blood glucose response curve
All results are mean±standard error of ten values. Different alphabets in superscript in the column show significant difference between values. As is evident, the area under the blood glucose response curve differs significantly for white fried rice and brown fried rice.

Glycaemic index

Glycaemic index of white fried rice and brown fried rice was found to be 62.50 and 36.67 respectively. A significant difference was found between glycaemic index of both rice based recipe. The foods having glycaemic index less than 55 are considered low glycaemic index foods. Formulated brown fried rice come under the category of low glycaemic index foods. Figure 1 shows a comparative glucose response curve between white rice and brown rice. The reason behind the higher glycaemic index of white fried rice might be due to refined milling of the rice grains, due to which most of the nutrients present in outer most layer of the grain has been removed especially fiber, which help in reducing the glycaemic index of food.

S. No. Food Product Glycemic index (mean+SD)
1. White fried rice 62.50 ±1.38 a
2. Brown fried rice 36.67±5.66 b
Standard error of mean 1.95
Critical Difference at 5% 6.74
* All results are mean±standard error of ten values
* Different alphabets in superscript show significant difference between values
Table 5: Glycaemic index
Although the present invention has been described in considerable detail with reference to certain preferred embodiments and examples thereof, other embodiments and equivalents are very much possible. Even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with parameters and other details, the disclosure is illustrative only, and changes may be made in detail, especially in terms of non-essential traits or the procedural steps 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. Thus various modifications are possible of the presently disclosed method without deviating from the intended scope and spirit of the present invention. More particularly, the method as depicted in the present invention is simplified and generalized one and there are several trivial variations possible. Accordingly, in one embodiment, such modifications of the presently disclosed method are included in the scope of the present invention. In addition to the method, there are variants of the presently disclosed fibre rich instant ready-to-eat brown rice all of which are included in the scope of the present invention. Also, unless the context clearly dictates otherwise, it is understood that when a range of value is provided, the tenth of the unit of the lower limit as well as other stated or intervening values in that range shall be deemed to be encompassed within the disclosure. Where the stated range includes one or both of the limits, ranges excluding either or both of those included limits are also included in the disclosure.

WE CLAIMS

1. A method for preparation of instant brown rice mix, the method comprising:
(a) Soaking brown rice in water at the ratio of about 1:8 - 2.2 (w/v) at a temperature of about 45°C - 55°C for about 55 - 65 minutes;
(b) Pressure-cooking the brown rice for about 25 to 35 minutes;
(c) Cooling the brown rice;
(d) Packing the cooled brown rice; and
(e) Individual quick freezing the packed brown rice for about 1 – 5 minutes at a temperature of about -300C to about -500C.
2. The method as claimed in Claim 1 wherein the said ratio of rice to water for soaking during step (a) is 1:2 (w/v).
3. The method as claimed in Claim 1 wherein the said temperature and time for soaking during step (a) is 50°C and 60 minutes.
4. The method as claimed in Claim 1 wherein the said pressure cooking of brown rice during step (c) is carried out for 30 minutes.
5. The method as claimed in Claim 1 wherein the said Individual quick freezing is carried out at the temperature of -400C for about 2 minutes.
6. The method as claimed in Claim 1 wherein the method further comprises frying a mix of cumin seeds, hot spices, dry mango powder, coriander powders, Asafoetida, salt, and turmeric powder in desi ghee, and mixing the fried mix with cooked brown rice before cooling.
7. The method as claimed in Claim 6 wherein the quantity of ingredients of the mix for each 1 kg of the brown rice are as below:
(a) cumin seeds – about 100gm;
(b) hot spices – about 9gm;
(c) dry mango powder – about 5gm;
(d) coriander powder – about 16gm;
(e) Asafoetida – about 1 pinch;
(f) Salt – about 5gm;
(g) Turmeric – about 4gm; and
(h) Ghee – 200gm.
8. Instant brown rice mix having the physical parameters as per following:
(a) Swelling power (g/g) of about 1.75 g/g to about 2.0 g/g;
(b) Water uptake ratio of about 2.25 to about 2.5;
(c) Increase in weight after cooking of about 90% to about 120%;
(d) Solids loss of about 4.5% to about 5%;
(e) Cooking time of about 25 minutes to about 35 minutes; and
(f) Gelatinization temperature in the range of about 75°C to about 85°C.

9. Instant brown rice as claimed in claim 8 wherein the said physical parameters are as per the following :
(g) Swelling power (g/g) of about 1.85 g/g;
(h) Water uptake ratio of about 2.37;
(i) Increase in weight after cooking of about 107%;
(j) Solids loss of about 4.8%;
(k) Cooking time of about 30 minutes; and
(l) Gelatinization temperature of about 81°C;
Wherein the glycaemic index of the rice is in the range of about 35-40 and has the shelf life of about 6 months when stored at sub-zero temperature conditions.
10. Instant brown rice as claimed in claim 8 or 9 wherein the total bacterial count of the instant brown rice is less than 3.5×102.