ASHRAE Journal - February 2014 - 74

COLUMN REFRIGERATION APPLICATIONS

Rattling the Chain

Andy Pearson

see where the switch from controlled to uncontrolled
cold chain happens. I have often met people who prefer
One of the nice things about working in
to buy fresh meat and freeze it at home in their garage
refrigeration (as opposed to being a rocket chest freezer because they think fresh quality is better.
They look bemused when I ask whether they would prescientist or a brain surgeon) is there are
bits of the job that everybody can relate to. fer their meat frozen by amateurs or professionals.
The level of food waste in the western world is quite
I have found over the years that it is the ice staggering, ranging in estimates from 25% to over 50%
rink projects I have worked on that deliver of what is harvested. Some of that waste is inevitable -
the highest recognition factor with people not everyone eats their potato skins or apple cores - but
in many cases it is avoidable. At first sight it seems that
outside the industry.
most of the waste occurs in the second half of the chain
You would think the food distribution chain would gener- and there is certainly great scope for waste reduction
ate a similar response since we are all regular users, but it
through good housekeeping.
is surprising how little people know about what happens
However, there is also great scope for improvement in the
to food before it reaches the shelves of the
I said "cold chain," you crazy fool! first half through clever use of refrigeration
supermarket or the local shop. It still amazes
techniques. For example, in some sophistime a distribution center the size of two football
cated markets vegetables are rapidly chilled
fields can be completely filled with chilled proas soon as they are harvested by placing them
duce and empty again within a 24-hour cycle
inside huge vacuum chambers while still in the
and yet the food temperature does not vary by
field. The evaporation of water sprayed onto
more than a couple of degrees.
the crop pulls the temperature down and gives
The produce arrived at the center from all
a significant increase to product shelf life, perover the world, and when it leaves it may travel hundreds ceived quality and price. This could have a transformational
of miles before it is sold to a consumer, all within the same effect on producers if it were applied in third world fields as
tight temperature band. This is an engineering miracle of well as first world ones, but there is no point incurring this
teamwork, international cooperation and technical skill.
operating expense if the next link in the chain is broken
The distribution network for perishable food is comand the product still spoils before it gets to market.
monly called "the cold chain," and it stretches from the
The third world challenge is first to ensure that there is
point at which the crop is harvested (or milked, killed
a continuous chain, including the point of sale, and then
or caught) through to the moment that it is taken out
to extend product life and quality to increase value and
of your refrigerator to be eaten. This can be readily
reduce wastage. Refrigeration is a critical process throughdivided into two halves; the controlled cold chain and
out that chain. Without refrigeration modern city life would
the uncontrolled cold chain. The controlled cold chain
not be possible. As we work through the challenges of global
is subjected to very strict regulations on food hygiene,
population growth, the increase of mega-cities and shorttemperature control and elapsed time. This may take
ages of fresh water and electrical power it is imperative
the food from the field (or dairy, abattoir or sea) through that we pay close attention to the science of refrigeration.
several stages of storage, transport, storage, processThe changes necessary to get the cold chain working more
ing, storage, transport, storage, more transport, more
effectively and more efficiently will not just happen; they
storage and finally display. Then, the produce is picked
need to be carefully planned and properly implemented
from the shelf, wheeled round the supermarket for a bit, for long-term success. We need to shout this from the roofpacked into the trunk of a car, left on the kitchen table
tops-loudly and often. Get out there and rattle the chain.
for a bit and finally put into the refrigerator. It is easy to
Andy Pearson, Ph.D., C.Eng., is group engineering director at Star Refrigeration in Glasgow, U.K.
BY ANDY PEARSON, PH.D., C.ENG., MEMBER ASHRAE

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