Fascinating food trip through time

22 Dec 2011

Paul Skudder's Seligman Lecture delivered a fascinating selection of advances over the last 100 years covering all aspects of food processing. From raw ingredient preparation to final packaging, he captivated his audience, which included members of the Seligman family.

His lecture illustrated the revolution in food-process engineering and the major advances made since 1900. Metallurgy innovations such as aluminium welding in 1909, the invention of stainless steel by Harry Brearley in 1913 and argon arc-welding in 1946 underpinned the manufacturing of structures necessary for innovative batch and continuous food processes. For example: aluminium vessels had previously been riveted and by 1920, as many as 32 APV breweries existed with aluminium fermenting vessels.

The 1930s saw stainless steel starting to be used for food plants with the first plate heat exchanger in 1933. Richard Seligman's revolutionary invention in 1923 the plate heat exchanger (more information), was constructed from cast gunmetal!

the homogenisation of milk patented by Auguste Gaulin in 1899 was not widely accepted until after 1919. The first plant for drying milk, a Just-Hatmaker roller dryer, was introduced in 1903, but roller dryers for milk were superseded by spray driers in the 1930s. In 1938 Nestlé developed freeze drying for coffee, although this was not entirely novel, as lyophilisation of food had been practised by the Incas as early as 1400.

The first microwave
In the 1940s, high-temperature short-time processing of milk was used by several companies and was approved for pasteurisation of milk by the UK government in 1941. In 1946, microwave heating was discovered by chance by Percy Spencer of the Raytheon Company when he realised a chocolate bar had melted in his pocket when close to a magnetron. Raytheon sold its first commercial microwave oven in 1947. It was 1.67m tall, weighed 0.34 tonnes and cost $5,000.

In the 1950s and 1960s, plant automation began with the requirement for clean-in-place (CIP) systems for complex processes. Electromechanical devices (relays and cams) for timing were replaced in the 1970s and 1980s by solid-state electronics with microprocessors and programmable logic controllers. In the 1980s, various processes for improving the quality and safety of milk were introduced, such as APV's infusion heating of milk, membrane processing, and Alfa Laval's microfiltration of milk. Since the 1980s, electrical heating has found some niche applications. Ohmic heating has been used in Japan for processing high quality particulate fruits. Pulsed electric-field technology allows food to be sterilised at lower temperatures by destroying cells resulting from the expansion and contraction by the pulsed electric field.

Microbial destruction by pressure was known in the 1800s, but it wasn't until the 1990s that processing equipment, capable of producing pressures of over 7,000 bar to extend the shelf-life of products, was designed.

With continuing innovation in food engineering, the future challenges are of sustainability, and particularly minimising the impact of food processing on the environment in respect of waste, energy and water. This has led to the application of membrane technology to recover food components from waste streams and even the on-site generation of CIP and sanitisation chemicals through the electrolysis of salt.

Graham Byars

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