Pressure Cooking

Introduction

Pressure cooking of meat is becoming increasingly more widespread and popular in the Ready Meal & Food Processing Industry. There are several clear & accepted benefits of using this technology, when compared to traditional atmospheric simmering & cooking methods. The Theory

Pressure cooking of food products works because pressure, volume & temperature are all related. When pressure higher than atmospheric conditions is created in an enclosed chamber, and the contents are heated, they’re able to reach a higher core temperature, so cooking at temperatures above the atmospheric water boiling point of 100°C is possible. For example; when water is heated to a temperature is 121°C in an enclosed steam jacketed pressure kettle, we know that due to the laws of physics, the equivalent internal pressure will always be at 1 bar. Benefits

Pressure cooking is beneficial to the food industry because tougher cuts of meat such as beef or lamb, where cooking under atmospheric conditions can normally take up to 2 hours to soften and tenderise under atmospheric conditions, can be cooked within 20 to 30 minutes under pressure to achieve the same or better result. This process offers food producers massive time savings, as well as providing the benefit of being able to produce high quality succulent & tender meat, where tough, sinewy, inter-connective tissues such as collagen etc.. are completely broken down and dissolved. This is a clear a benefit in the manufacture of products such as pies, casseroles etc..

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The shorter cooking period is also beneficial in terms of lowering the overall energy usage and production costs, as well as improving overall operational efficiency. There are also spin-off benefits of using fully enclosed pressure cookers, such as; improved odour control by controlled removal of cooking vapours & condensation, consistency & repeatability of production processes, retention of moisture & flavour in the product, etc… Many of our UK & Overseas clients are using this feature extensively, and our list of clients include Wrights Pies Food Group, 2SFG, Morrison’s, Hollands Pies, Poole’s Pies, Kerry Foods, WC Rowe, Ginsters, Rhodes Foods, Piemans – amongst others.

The pressure cooking process is not strictly limited to meat; pulses, beans & chick peas are amongst many other types of ‘long-cook’ vegetable products that have been successfully pressure cooked using this method. How We Pressure Cook - The BCH Process Meat is placed in the pressure cooking vessel – normally a scraped surface cooking kettle – very similar in design to a typical sauce cooker but with a sealable lid, and initially brought up to atmospheric boiling temperature. The kettle lid is sealed using lid swing bolt clamps which are manually engaged. Several safety interlocks are used to protect operators during the lid opening & closing procedure, as well as during the cooking process itself. Prior to this stage vegetables, onions, meat etc… can be browned atmospherically using the steam jacket at a sufficient heating temperature/pressure range. When the kettle contents reach initial atmospheric boiling point, the main pressure cooker vent valve is automatically closed. This enables the internal pressure to build inside the kettle. A digital pressure transducer paired with a head-temperature probe constantly monitor the internal cooking pressure and temperature inside the pressure kettle.

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The cooking process is controlled using a PLC, which operates in conjunction with the probes – the PLC uses the information to control the flow of steam allowed into the jacket, and the simmer temperature which regulate the internal pressure.

When the product reaches the desired pressure cooking temperature, the a process countdown timer is initiated, and upon time completion, the internal pressure is gradually removed using an automatic ‘blow-down’ process, which enables the kettle to return to atmospheric conditions. At the end of the pressure cycle, it’s possible to add pressure sensitive ingredients such as softer vegetables, pre-cooked items, and pressure sensitive starches, flavours etc... in order to complete the final cooking procedure.

BCH 1000kg Pressure Cooker

BCH Pilot Plant Trial – Pressure Cooked Meat (Drained)

The pressure cooking equipment is provided with full safety features in accordance with UK & EU safety legislation.

Typical Process Time

A typical pressure cooking cycle using a 1000kg batch pressure cooker can take up to around 30 minutes - which includes the initial boiling stage to 100°C, pressure cooking and holding at a temperature usually between 106°C and 108°C (106°C is equivalent to a pressure of 0.25 bar) for around 15 to 20 minutes, and then de-pressurisation, which returns the cooker to atmospheric conditions.

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As mentioned previously, a comparable atmospheric cooking process can easily take 2 hours or more. It’s also worth noting that certain meat types or different meat cuts will benefit from differing pressure cooking temperatures.

BCH Pilot Plant Trial – Pressure Cooked Black Beans & Rice Dish for a North American Cajun Dish

Onward Cooling Process

To optimise to cooking cycle even further it’s possible to transfer the cooked product from the pressure cooker by vacuum, and then rapidly cool under vacuum conditions, in order to achieve a product temperature below 5°C. This cooling process can usually be achieved in normally 30 to 50 minutes depending upon the product being cooled.

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Next Steps

If you’re interested in viewing the pressure cooking process, BCH have a 50kg demonstration pressure cooking system.

BCH Pilot Plant Trial – Steak Pie Filling with Gravy & Thickener

The pilot equipment is provided with scraped surface agitation, steam jacket and injection, complete with the facility to vacuum transfer & cool a wide range of sauces to below 5°C. Please contact us for more details.

BCH (Rochdale) Limited, Spring Place, Millfold, Whitworth, Lancashire, UK, OL12 8DN

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Registered in England Number: 10415909