Cooking technique solves the problem of scale-up

A completely different cooking technique is now available for producing cooked foods that retain the taste, texture, colour and nutritional performance of 'home cooked' foods.

A completely different cooking technique is now available for producing cooked foods that retain the taste, texture, colour and nutritional performance of 'home cooked' foods.

This system, known as the PDX Sonic 25, has been developed by Pursuit Dynamics and it also offers several other advantages to food processors.

Pursuit Dynamics Head of Technical Sales, Stuart Rigby explains "Development chefs do an excellent job of creating new cooked foods with high standards of taste, texture and nutritional performance, but the problem has always been to scale-up the process without compromising these characteristics.

Compared with saucepans used in development kitchens, industrial-scale steam-jacketed kettles have a lower temperature differential that results in a slower rate of heating.

If quantified in terms of cook values (or Co numbers), the optimum for a particular product - achievable in a saucepan - might be 20-30, whereas the full-scale plant would typically only achieve 100 or more, with correspondingly lower qualities.

Scraped surface heat exchangers are sometimes cited as a better alternative to kettles, though they are significantly more complex, expensive and difficult to clean, and they deliver only a marginal improvement.

However, the PDX Sonic 25 enables Co to be accumulated as fast and in as controllable a manner as in a saucepan.

For example, trials have shown that a 120kg batch of smooth curry sauce takes six minutes to mix and cook with a PDX Sonic 25, which compares with around one hour using conventional technologies.

Significantly, the process will not damage even the most delicate particulates and, unlike conventional methods of steam injection with high thermal gradients, thermal shock is reduced and cook-on eliminated.

As a result, food quality is maintained whilst cleaning times are reduced.

As the product flows through the PDX Sonic 25, additional ingredients can be entrained virtually instantaneously, so each can achieve its own optimum Co value, and mixing is extremely even, despite the short timescales.

Tests have also shown that the PDX Sonic 25 cooks-out starches instantly at 70C without a 10 minute dwell time saving time and cost.

Steam is introduced into a special annular conditioning chamber that is wrapped around the core of the PDX unit.

From here, it is expanded into the process fluid at speeds exceeding 1000m/s.

The combination of this momentum transfer and the controlled collapse of the steam sees the process fluid accelerated to over 2 times the speed of sound in a supersonic and gaseous phase until the condensation shockwave.

This supersonic phase is highly energetic and causes the simultaneous mixing, homogenisation, heating and pumping actions to take place.

A vital aspect of the technology is that this supersonic region can be controlled enabling different conditions to be set e.g homogenisation or alternatively low shear to ensure particulate integrity.

Flow rates and temperature rise can also be controlled.

Importantly the geometry of the technology enables this to happen with no constrictions or moving parts.

With such a fast, versatile, easily cleaned, scaleable system, food processors can benefit from substantially increased productivity.

But a further major attraction is the ability to produce recipes and qualities that are simply not feasible using conventional technologies.

For more information about the PDX Sonic 25, or to discuss particular applications and arrange for a pilot plant demonstration or trial, please contact Pursuit Dynamics.

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