ASHRAE Journal - June 2020 - 70

REFRIGERATION APPLICATIONS
COLUMN

Andy Pearson

Working From Home
BY ANDY PEARSON, PH.D., C.ENG., FELLOW ASHRAE

I'm writing this from my "home ofﬁce," also known as the attic, in the midst of the
pandemic lockdown that has affected so much of the world in the last few months. I
hope that by the time you are reading it things have calmed down a bit and are getting
back to normal, but I suspect that we will be in this situation for some time to come.

ASHRAE JOURNAL

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J U N E 2020

more detail in my August 2017 column.
Putting fresh food into your freezer at home creates lots
of problems. The amount of heat to be removed in turning the water content of the food from liquid to solid is
huge compared to the heat load required to maintain a
low temperature. The typical domestic freezer struggles
to maintain temperature when overloaded this way. This
means that not only does the quality of the stuff being
frozen suffer because the freezing
process takes too long, the quality
of the stuff already being stored in
the freezer is also at risk. Meat might
become rubbery or tasteless (particularly at the surface), fruit could
turn to mush, and ice cream is likely
to be gritty and unpleasant to eat.
Here are a few tips to minimize
these effects. Keep already frozen
food separate from stuff that's
being frozen in a separate compartment or, even better, in a second freezer. Break food to
be frozen down into individual portion sizes, or even
part-portions, so that it will freeze as fast as possible,
even if this means thawing several packets for a single
meal. Pre-chill cooked food so that it is as cold as possible when it goes into the freezer and pack it with a prefrozen glycol block to minimize the load on the freezer.
Wrap all produce to eliminate moisture
loss. Best of all: buy your food from the
store frozen by professionals and get it
home and into the freezer as fast as pos- https://bit.ly/2YUre1l
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sible.
COURTESY OF STAR REFRIGERATION

One of the top news stories in the early days of lockdown was about shoppers panic buying and stockpiling what they deemed to be necessities-we now know
that civilization is powered by hand sanitizer and toilet
paper. The follow up to the initial story told of a large
increase in food waste as much of the stockpiled fresh
produce went rotten because it couldn't be used fast
enough. This was then followed by a spike in the sales of
refrigerators and chest freezers.
This got me thinking about
Leave it to the professionals.
the problems of freezing food
at home. It's generally accepted
that fresh food taken home and
put in the deep freezer gives
better quality than food that is
already frozen when you buy it.
Generally accepted, but wrong!
I have often said over the years
when people repeat this fallacy
within earshot "Would you rather
have your food frozen by professionals or amateurs?"
An industrial blast freezer is a custom-designed wind
tunnel, specially engineered to ensure maximum
velocity across products without damaging them and
ensuring that heat is removed as quickly as possibly.
Vegetables which are frozen in a ﬂuidized bed will
change phase within a few seconds ensuring that the
integrity of the cell structure is maintained as best as
possible, and the quality of quick-frozen meat is preserved by preventing the migration of salts through
the product as the freeze-front progresses. Ice cream
is even more tricky as the "consumer experience" is
heavily dependent on the temperature-time proﬁle
through the life of the product. This was explained in

Andy Pearson, Ph.D., C.Eng., is group managing director at Star Refrigeration in Glasgow, UK.

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ASHRAE Journal - June 2020

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