Probe
The broccoli is subsequently maintained at a temperature between 4 and 6 deg
C. Marshalls' quality controls now include checks by probe to ensure that the required
temperatures are not exceeded. A Geneglace Ice Pack 21 machine produced 2,000 kg of flake
ice every 24 hours, which is held in a stainless steel silo. London-based AFR
Refrigeration supplied the machine.
It is essential to keep the harvested crop in prime condition during the
main broccoli-growing season. To this end,Marshalls performs rigorous quality checks on
several criteria including temperature, colour, size, and weight. Dedicated controlled
atmosphere storage rooms are designed to maintain the perfect balance between humidity and
temperature. Before the Geneglace installation, a local
supplier delivered ice to Marshalls. Production manager Steven Munn says this was far from
satisfactory. Apart from the cost, the ice was granular, and tended to congeal, making it
harder to spread evenly over the cut broccoli in the field.
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As well as its 5,500 acres in Lincolnshire, Marshalls maintains year round
continuity of supply by maintaining growing partnerships with throughout Europe and
elsewhere in the UK.
During the winter and spring seasons, Spanish broccoli is delivered by road
to Marshalls in Boston, Lincolnshire . The spanish suppliers also use Geneglace flake-ice
machines, and the broccoli leaves the Spanish plant with a coating of flake-ice, usually
packed in the major customers' own 10 kg trays.The Geneglace sub-cooled ice - which is at
-5 deg C - helps to maintain the broccoli in perfect condition for redistribution by
Marshalls from Boston to UK customers.
The cooling benefits stem from the physical properties of ice. When placed
on the warmer broccoli, the flake-ice transforms in two ways - through melting and
evaporation.
In the melting process - the change from solid to liquid - 1 kilo of ice
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absorbs 80 kilocalories fromm the broccoli adjacent ot it. This cooling
power effectively chills the product. As the melting temperature of the broccoli remains
slightly above this; avoiding any risk of over chilling.
The newling melted water evaporates and changes from liquid to water vapour.
This saturates the air around the product with moisture so that the broccoli retains its
own moisture and maintains its freshly cut appearance.
Lumps
The flake-ice, sub-cooled to a temperature of -4 deg C, is effectively dry
ice. This means that it always flows evenly over the produce in the freigth boxes without
forming lumps or waighing heavily on the broccoli.
Ice made in the Geneglace machines can be produced in very small flakes -
only 1.5 mm thick. This enables small pieces of ice to penetrate the many gaps that make
up the surface of the broccoli. As the ice melts, it creates an area of chilled water
vapour, which permeates the broccoli. in effect, the produce is then in a chilled high
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