Claims:
1. A pressure cooker, consisting of:
a lid fitted on a vessel containing a food item;
a vent fixed on top of the lid;
a vent weight removably fitted on the vent;
characterized in that, the vent weight in a weight range between 49 gm and 53.5 gm maintains a pressure range between 10.5 psi and 11.5 psi in the vessel.

2. The pressure cooker as claimed in claim 1, wherein the pressure range is obtained by having a cooking temperature range between 115°C and 117°C inside the vessel.

3. The pressure cooker as claimed in claim 1 or claim 2, wherein the pressure range is obtained by the vent with a diameter range between 2.85 mm and 2.95 mm.

4. The pressure cooker as claimed in any one of the preceding claims 1 to 3, wherein the pressure range preserves nutrients of the food item cooked inside the vessel.

5. The pressure cooker as claimed in any one of the preceding claims 1 to 3, wherein the pressure range preserves nutrients of the food item cooked inside the vessel without increasing the cooking time or the temperature.

6. The pressure cooker as claimed in any one of the preceding claims 1 to 3, wherein the pressure range preserves 40-50% nutrients of the food item cooked inside the vessel.

7. The pressure cooker as claimed in any one of the preceding claims 1 to 3, wherein the pressure range preserves vitamins including Vit A, Vit B1, Vit B2, Vit B3, Vit B6, Vit B12, Folic acid, or a combination thereof.

8. The pressure cooker as claimed in any one of the preceding claims 1 to 3, wherein the pressure range preserves minerals including Iron, Potassium, Sodium, Zinc, Manganese, Phosphorus, or a combination thereof.
, Description:FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENT RULES, 2003
COMPLETE SPECIFICATION
[See Section 10, Rule 13]

1.: TITLE OF THE INVENTION
A PRESSURE COOKER.

2. APPLICANT
a) Name : Bajaj Electricals Ltd.
b) Nationality : Indian
c) Address : 45/47, Veer Nariman Road, Fort Mumbai - 400001, Maharashtra, India

3. PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the invention and the manner in which it is to be performed:

FIELD OF THE INVENTION:
The present invention relates to a pressure cooker. Particularly, the present invention relates to preserving nutrition within the food cooked in a pressure cooker.

BACKGROUND:
Conventional pressure cookers are used to cook within reduced time periods, this is achieved by using high pressures achieved at high temperatures. Typically, the pressure at which a pressure cooker operates is maintained by the mass of the vent weight used. Temperature and time are parameters required to increase the temperature within the cooker to generate steam, as the steam builds-up within the cooker, the pressure increases. Generally, a pressure of 14.5 PSI is maintained inside the cooker beyond which the pressure built up lifts the weight of the vent weight to release some steam and thereby reduce the pressure, typically in the form of a “whistle”.

This method of cooking with increased temperature & pressure promotes faster cooking of ingredients and thereby saves time and energy. One may consider such a method of cooking to be ideal for cooking foods with complex proteins such as tough meat items and lentils. However, cooking at high pressure and temperature can also result in a great loss of nutrients such as vitamins and minerals. This concern has stirred many methods and devices to overcome the loss of nutrients as seen in Patents KR100236347B1 which disclose methods of varying the vent weight depending on the food item to be cooked, these inventions are rather complex in the sense that they involve adjusting the vent weight using mechanisms such as removable “rings” to add or subtract the weight and thereby the corresponding pressure. From a user perspective this system can be very dissuading, as pressure cookers are preferred by those wanting a “quick & easy” method of cooking. Therefore, the purpose of using a pressure cooker is itself overcome by these tedious attempts to preserve nutrients. There needs to be a simpler device and method of cooking which can ensure nutrients in the food are preserved at the same time the task of cooking is simplified and quickened. Therefore, there is a need to overcome at least one of the shortcomings listed above.

OBJECTS OF THE INVENTION:
The main object of the present invention is to provide a pressure cooker which ensures cooking at low pressure while ensuring faster cooking time;

Another object of the present invention is to provide a pressure cooker that maintains a low cooking pressure desirable for preserving nutrients;

Another object of the present invention is to provide a pressure cooker that is simple to use while achieving other objects of the present invention;

Another object of the present invention is to provide a pressure cooker wherein the temperature required to achieve the desired pressure is lower than conventionally required, preferably in the range of 115°C and 117°C;

Another object of the present invention is to provide a pressure cooker wherein the desired pressure is lower than conventionally required, preferably in the range of 49gm and 53.5gm;

Yet another object of the present invention is to provide a pressure cooker wherein the diameter of vent weight is maintained at a fixed range between 2.85 mm and 2.95 mm;

SUMMARY OF THE INVENTION
An aspect of the present invention is to provide a pressure cooker, consisting of:
a. a lid with a lid handle;
b. a cooking vessel for containing a food;
c. a vent fixed on the top of the lid;
d. a vent weight removably fitted on the vent.
Wherein, the weight ratio of the vent weight is between 49gm and 53.5gm which maintains an inside cooking pressure range between 10.5 PSI and 11.5 PSI in the vessel.

Another aspect of the present invention is to provide a pressure cooker, wherein the pressure range is obtained by having a cooking temperature range is between 115°C and 117°C inside the vessel.

Yet another aspect of the present invention is to provide a pressure cooker, wherein the range of the pressure is obtained by the vent with a diameter range between 2.85mm and 2.95mm.

Yet another aspect of the present invention is to provide a pressure cooker, wherein the pressure range preserves nutrients of the food item cooked inside the vessel.

Yet another aspect of the present invention is to provide a pressure cooker, wherein, the pressure range preserves nutrients of the food item cooked inside the vessel without increasing the cooking time or the temperature.

BRIEF DESCRIPTION OF DRAWINGS
Fig.1 shows a graph demonstrating the required cooking time using the present invention and prior art technologies.

DETAILED DESCRIPTION OF THE INVENTION
Various embodiments of the present invention relate to a pressure cooker which ensures preserving nutrients within the food being cooked in said cooker.
In an embodiment of the present invention, a pressure cooker having a particular vent weight and diameter, to maintain a low cooking pressure is disclosed
A pressure cooker, consisting of:
a lid fitted on a vessel containing a food item;
a vent fixed on top of the lid;
a vent weight removably fitted on the vent;
wherein, the vent weight in a weight range between 49 gm and 53.5 gm maintains a pressure range between 10.5 psi and 11.5 psi in the vessel.

Reducing the vent weight pressure from the conventional practice to the desired range of 49 gm and 53.5 gm, maintains a low pressure which in turn requires a lower temperature point to reach such lower pressure of 10.5 psi and 11.5 psi. Wherein, the pressure range preserves nutrients of the food item cooked inside the vessel, without increasing the cooking time or the temperature (Fig.1).

In an embodiment of the present invention, a pressure cooker having a particular vent weight, wherein the pressure range is obtained by having a cooking temperature range between 115°C and 117°C inside the vessel is disclosed. The desired low pressure is achieved by having a specific orifice diameter of the vent tube, a mechanical arrangement with valves and preset springs, or a combination thereof. Preferably, the pressure range is obtained by the vent with a diameter range between 2.85 mm and 2.95 mm.
The present invention discloses a pressure cooker for nutritional cooking which despite enabling low pressure and low cooking temperature can result in fully cooked food items without requiring additional time. This surprising result is achieved by the ideal range of vent weight specifications which ensures the desired pressure range of this invention. The present invention therefore achieves desired cooking time while preserving nutrients in the food cooked. Wherein the pressure range preserves up to 40% nutrients of the food item cooked inside the vessel. Particularly, minerals including Iron, Potassium, Sodium, Zinc, Manganese, Phosphorus, or a combination thereof and vitamins including Vit A, Vit B1, Vit B2, Vit B3, Vit B6, Vit B12, Folic acid, or a combination thereof.

While conventional pressure cookers work on high temperatures they also impose high pressure on the food items to be cooked. This leads to loss of nutrients, especially vitamins which is a most undesirable quality. However, achieving short cooking time is an important requirement while using pressure cookers and this is surprisingly achieved by the present invention despite the reduced time and pressure. In the present invention as the temperature builds up steam, due to the reduced weight of the vent weight, the steam is released at a low pressure point (“whistle point”) to ensure the nutrients are maintained, at the same time the steam lost is minimal due to the lower pressure. This allows the “whistle point” to be re-attained sooner in the next cycle.
As opposed to the prior art, where steam is released at a much higher pressure point and therefore with larger force, expelling more steam than in the present invention. The time and temperature required to reach the “whistle point” in the next cycle is therefore larger in the prior art.

EXAMPLES:
Example 1.
A 5 Litre pressure cooker was considered, a vent having diameter of 2.85 mm was fixed on top of the lid and the vent weight of 49 gm was removably fitted on the vent;
The lid was fitted on the cooker vessel containing spinach as the food item to be cooked;
The cooker was heated to a cooking temperature of 115°C and a pressure of 10.5 psi was maintained within the vessel. 50% of nutrients of the spinach cooked inside the vessel was calculated. This was achieved without increasing the cooking time or the temperature as observed in the graph captured as Fig.(1).
Thus the pressure range preserved nutrients of the food item cooked inside the vessel, without increasing the cooking time or the temperature.

Example 2.
A 5 Litre pressure cooker was considered, a vent having diameter of 2.95 mm was fixed on top of the lid and the vent weight of 53.5 gm was removably fitted on the vent;
The lid was fitted on the cooker vessel containing rajma as the food item;
The cooker was heated to a cooking temperature of 117°C and a pressure of 11.5 psi was maintained within the vessel.
45% of nutrients of the rajma cooked inside the vessel was calculated. This was achieved without increasing the cooking time or the temperature as observed in the graph captured as Fig.(1).
Thus the pressure range preserved nutrients of the food item cooked inside the vessel, without increasing the cooking time or the temperature.

EXPERIMENTAL DATA:
Multiple tests were performed to achieve the ideal pressure range which would require a low temperature but at the same time would result in cooking the food item without an increase in time.

At first experiments were made to test the results merely of cooking at various levels of pressure to study and identify the ideal pressure range. Simultaneously, temperature variations were also studied. On achieving the ideal range by means of careful study and calculations, desired results were achieved when the temperature as well as pressure were both kept low. The table below shows that as compared to state of the art cookers and cooking methods, the present invention is surprisingly capable of maintaining much higher levels of nutrition levels while requiring low pressure, temperature and requiring no additional time to achieve the cooking point.
The below tables disclose the advantageous results of using the technology of the present invention. Particularly, the pressure cookers incorporating the technology of the present invention were seen to retain at least 40% vitamins and minerals compared to conventional methods.

The experiments tested nutrient levels including:
Vitamins - Vit A, Vit B1, Vit B2, Vit B3, Vit B6, Vit B12, Folic acid; and
Minerals - Iron, Potassium, Sodium, Zinc, Manganese, Phosphorus.

Table 1: Percent nutrient retention in each method compared to raw nutrients
Ingredients 2L 3L 5L %NR STM %NR BL
%NR NV ( 52 grams , 10.9 Psi ) %NR PC %NR NV ( 52 grams , 10.9 Psi ) %NR PC %NR NV ( 52 grams , 10.9 Psi ) %NR PC
Rice 63.6 61.4 65.1 62.3 65.0 62.2 55.3 41.5
Spinach 83.3 77.6 85.4 73.1 83.0 78.3 68.9 41.5
Carrot 80.5 75.0 77.2 72.0 79.3 73.8 64.1 54.6
Rajma 82.4 81.0 83.9 81.2 84.2 81.0 74.0 65.6
Boneless chicken 78.4 78.3 79.7 78.7 78.0 76.9 61.8 52.7
Potato 83.1 82.5 81.6 83.2 81.8 78.7 73.3 62.3
NV= Present invention, PC= Existing Pressure cooker, STM= Steaming, BL= Boiling, %NR= % nutrient retention

Table 2: Nutrient retention in present invention compared to other methods
Ingredients NV ( 52 grams , 10.9 Psi ) NV vs PC NV vs STM NV vs BL
2L
Rice 63.6 1.6 8.3 22.1
Spinach 83.3 6.9 14.4 41.8
Carrot 80.5 6.9 16.4 25.9
Rajma 82.4 1.4 8.3 16.7
Boneless chicken 78.4 0.4 16.6 25.7
Potato 83.1 1.7 9.9 20.9
3L
Rice 65.1 3.1 9.8 23.6
Spinach 85.4 9.1 16.5 43.9
Carrot 77.2 3.6 13.1 22.6
Rajma 83.9 2.9 9.9 18.3
Boneless chicken 79.7 1.8 18.0 27.0
Potato 81.6 0.2 8.3 19.3
5L
Rice 65.0 3.0 9.7 23.5
Spinach 83.0 6.7 14.1 41.5
Carrot 79.3 5.7 15.2 24.7
Rajma 84.2 3.2 10.2 18.6
Boneless chicken 78.0 0.0 16.2 25.3
Potato 81.8 0.4 8.5 19.5
NV= Nutri vent, PC= Existing Pressure cooker, STM= Steaming, BL= Boiling

As shown in Tables 1 and 2, which disclose the test results of nutrient levels preserved using the present invention, particularly employing the vent weight falling within the range of 49 gm and 53.5 gm, maintaining a pressure range of 10.5-11.5 psi, at least 40% nutrient levels were successfully preserved without any additional time requirement. Please see Figure (1) which shows a graph mapping a comparative analysis of the present invention and various prior art techniques, to clearly show that despite low pressures and temperatures employed by the present invention, the time required to successfully cook the food matched the prior art and in some cases required even lower cooking times as compared to the prior art.