endogenous enzymes, the useful life of many foods can be increased by
storage at low temperatures. Though this has been known since anti-
quity, one of the earliest recorded experiments was conducted by the
English natural philosopher Francis Bacon who in 1626 stopped his
coach in Highgate in order to fill a chicken carcass with snow to confirm
that it delayed putrefaction. This experiment is less notable for its results,
which had no immediate practical consequences, than for its regrettable
outcome. As a result of his exertions in the snow, it is claimed Bacon
caught a cold which led to his death shortly after.
Using low temperatures to preserve food was only practicable where
ice was naturally available. As early as the 11th century BC the Chinese
had developed ice houses as a means of storing ice through the summer
months, and these became a common feature of large houses in Europe
and North America in the 17th and 18th centuries. By the 19th century,
the cutting and transporting of natural ice had become a substantial
industry in areas blessed with a freezing climate.
Mechanical methods of refrigeration and ice making were first pat-
ented in the 1830s. These were based on the cooling produced by the
vaporization of refrigerant liquids, originally ether but later liquid am-
monia. Much early development work was done in Australia where there
was considerable impetus to find a way of transporting the abundant
cheap meat available locally to European population centres. At the 1872
Melbourne Exhibition, Joseph Harrison exhibited an ‘ice house’ which
kept beef and mutton carcasses in good condition long enough for some
of it to be eaten at a public luncheon the following year. This banquet
was to send off a steamship to London carrying 20 tons of frozen mutton
and beef packed in tanks cooled by ice and salt. Unfortunately it was an
inauspicious start, during passage through the tropics the ice melted and
most of the meat had been thrown overboard before the ship reached
London. Chilled rather than frozen meat had however already been
successfully shipped the shorter distance from North America to Europe
and by the end of the century techniques had been refined to the extent
that shipping chilled and frozen meat from North and South America
and Australia to Europe was a large and profitable enterprise.
Since then, use of chilling and freezing has extended to a much wider
range of perishable foods and to such an extent that refrigeration is now
arguably the technology of paramount importance to the food industry.
4.4.1 Chill Storage
Chilled foods are those foods stored at temperatures near, but above
their freezing point, typically 0–5 1 C. This commodity area has shown a
massive increase in recent years as traditional chilled products such as
fresh meat and fish and dairy products have been joined by a huge
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