DOI: 10.6084/m9.figshare.22637281.v1
title: New approach of pressure cooking: low pressure cooking is as efficient as 15 psi cooking for some cases; saving upto 30% of fuel and time over the conventional pressure cooking _ an way to sustainability.

description: <strong>Introduction:</strong> A pressure cooker works on a simple principle: A sealed pot, with a lot of steam inside, builds up high pressure, which helps food cook faster (Bowen et al., 2019). It was invented in the 1600s by a Frenchman by Denis Papin, who wanted to report this new discoveries in physics about pressure and steam into cooking (Ravikumar & Sivamurugan, 2010). He named this pot as “Digester,” but it took quite time to make this digester to safe and standard pressure cookers with developed technologies. In past, these pressure cookers were never considered safe for cooking, because of so many explosion stories related to it (Jana & Bhattacharya, 2017). But most of these concerns have been properly taken care of and thanks to new generation pressure cookers with advanced and sophisticated functions and extra safety features (Atreya et al., 2016; Hassid, 2012). Some people do not prefer pressure cooking. On the other hand, a group of people prefer pressure cookers to prepare food with ease and taste with the help of modern-day cookers. It has been noticed: <br> The food prepared in pressure cookers always takes upto 70% time, yet the quality is better than open pot cooking. The food prepared in the pressure cooker is always great in taste, unlike the one prepared with the traditional method. Rice is the staple food in many places of the world (Fairhurst & Dobermann, 2002). Pulses are too considered as side dishes in most of the places of the world (Dilis & Trichopoulou, 2009). People used to in open pot cooking, don’t prefer pressure cooked rice, pulses and many more recipes (Ballard-Tremeer & Jawurek, 1996; Nienhuys, 2009). As per their concern, the cooked food in pressure cooker (rice, pulses mainly) is different in taste and texture (slimy) which they don’t prefer (Das et al., 2006; Frazier, 2022; Leelayuthsoontorn & Thipayarat, 2006). Though open pot cooking is both time and fuel consuming but their priority of taste is more over the savings (Khatoon & Prakash, 2006). Hence, taking this scenario, an easy going modified process of low pressure cooking (approx. 8 psi) has been adopted to overcome this problem. Cooking with this new method resulted in not only same textured and tasty food as cooked in open pot (rice, pulses mainly) but also saves a lots of fuel and time as compared to normal pressure cooking with 15 psi. This new method even does not need to invest much more but a very little modification can help to make the normal 15 psi pressure cooker to 8 psi mode (will be discussed later). This new method is also a great time and energy saver and this saving is more than the normal pressure cooking with 15 psi in some cases. Though 5 psi, 10 psi, 12 psi cooking are known from past literature (Kyaw et al., 2001) but this 8 psi cooking method is very unique and not documented till now. This method is very much user friendly and leads to a great sustainability (Khatri et al., 2021; Rao, 2016). <strong>Materials and Methods:</strong> To overcome the biasness, some Indian good company made (Prestige, Hawkins, Pigeon, Butterfly, Premier, Kitchen essentials, Renberg) and some local company made (Century, Shyam, Sunkwik) pressure cookers of different capacity (1.5 lires to 10 litres) have been selected to perform the experiments. The pressure cookers which have been selected are aluminium, hard anodized, stainless steel, tri-ply made. All of the selected pressure cookers works on nominal working pressure of 15 psi. These cookers also carry ISI: 2347 marking to confirm International safety standards [https://bis.gov.in/wp-content/uploads/2020/10/PM-IS-2347-Second-Revision.pdf]. Indian LPG (Liquefied Petroleum Gas for domestic purpose) has been used as fuel. As water quality is important for cooking, so standard water (TDS ranging from 200-500) has been used for cooking experiment. The food materials (which are to be cooked) used, were procured from standard Indian grocery shops and markets. A pressure gauge has been fitted on a pressure cooker to check the pressure. An weighing machine is used to monitor the fuel consumption. Standard timer has been used to monitor the time requirement during cooking. Different amount of food materials have been cooked in pressure cookers. As normal pressure cooking time is already known (given in cook book of pressure cookers; https://www.hawkinscookers.com/cookbook.aspx), the modified cooking time has been documented and compared with traditional time. LPG uses have been documented for both normal pressure cooking (15 psi) and 8 psi cooking. Table 1 shows an idea of water amount needed for some of the recipes. For more amount of cooking, the water amount will be increased by unitary method. For rest of the other recipes, any amount of water can be used (Rice were cooked and excess water has been drained to get rid of excess starch for health purpose). To make a standard 15 psi pressure cooker to 8 psi cooker, the regular vent weight is replaced with a less weighted vent weight. Here, for standard pressure cookers used, the single modified vent weight served the purpose to make 8 psi pressure in all pressure cookers. Table 2 shows the details of it. Standard pressure gauge has been fitted to check and confirm the 8 psi pressure level. This is to mention that in some cases, after modification, nominal working pressure maintained to near about 7.5 psi (in Hawkins, Kitchen essentials company) to 8.5 psi (in Butterfly); on an average nearly 8 psi was maintained rest of the cookers. The detail cooking process has been summarized. Table 3 shows the detail of cooking process for various items in 8 psi cooking. Table 4 shows comparison of the total time required for cooking (from switch on the oven to opening of the pressure cooker after completion). Cooking was done in 1.5 liters pressure cooker. Table 5 shows the fuel savings during cooking with 8 psi. Cooking was done in 1.5 liters pressure cooker.[From switched on to switched off]. Table 6 shows comparison of the total time required for cooking (from switch on the oven to opening of the pressure cooker after completion). Cooking was done in 1.5 liters to 10 liters pressure cookers with 8 psi settings and 15 psi settings. [For 1.5 litres; see Table 4]. Table 7 shows comparison of the LPG required for cooking (from switch on the oven to switch off the oven after completion). Cooking was done in 1.5 liters to 10 liters pressure cookers with 8 psi settings and 15 psi settings. [For 1.5 litres; see Table 5]. Table 8 shows the average time savings and average LPG savings for some other recipes with 8 psi cooking. Cooking has been done in 3 litres pressure cooker. This is to mention here that for mutton and Rajma cooking, the modification will be as follow: <br> Bring the cooker to 1st whistle with 8 psi whistle on high flame. Switch off the gas and then wait for 5 minutes, then again switch on the gas and fix the flame on medium mode. Count 1 whistle and then switched off the gas. Wait for 5 minutes. Again switch on the gas to medium flame. Count 2 whistles and switch off the gas and wait for natural cooling of the pressure cooker. 5. Wait for 5 minutes. Again switch on the gas to medium flame. Count 1 whistles and switch off the gas and wait for natural cooling of the pressure cooker. [follow this step for Rajma only]. <strong>Result:</strong> As shown in the previous table i.e. 5-8; it is clear that the time saving with this modified 8 psi cooking is on average upto 25 % whereas the LPG savings is on average upto 40%. The savings are calculated against on 15 psi standard cooking mode. The foremost user friendly issue of this cooking mode (8 psi cooking) is the food texture and taste is just same as compared to open pot cooking. This comparison has been done with those people who are used to with open pot cooking mode. They were not informed about the cooking mode when they were checking the recipe taste and texture (emphasis on rice, dal, vegetables). They did not find such difference. Then they were told that the cooking process was done in pressure cooker with 8 psi pressure cooking mode. They accepted it. So, in person acceptance is the great success of this result. Hence, the author propose a method to convert the domestic pressure cooker (which is being used in kitchen) to 8 psi low pressure cooker. Hence, the formula is as follow: If the standard pressure cooker whistle weighs 75 gm. This whistle maintains 15 psi nominal working pressure as per ISI: 2347 standard. Then to convert the cooker with 8 psi mode just use unitary method; i.e. (75/15)x8=40 gm; so 40 gm whistle is required to make the cooker 8 psi. This has been confirmed with standard pressure gauge fitted with cookers and checked. The result also shows that such savings in LPG and time leads to greener and eco-friendly cooking with less carbon emission i.e. leading to a great sustainability in near future.