Handbook of Meat Processing

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Chapter 11

Drying

Endre Zuk á l and K á lm á n Incze

Introduction

Drying is probably the most ancient way of
preservation, along with heating (cooking,
frying, etc.) and chilling or freezing. While
chilling and freezing were applicable only
seasonally or in arctic regions, drying as such
or in combination with smoking could be
practiced all over the world. This method was
of vital importance to early humans, when
fi shing and hunting were not always success-
ful and/or when the meat and fat of a large
animal was too much to be eaten within a
short period of time. Unsalted or salted dried
meat also had great importance during wars
and maritime navigation.
As a consequence of the development in
general, meat processing (drying) began to
be done at a larger scale, and simple ways of
“ conditioning ” were worked out and gradu-
ally improved. Good dried meat products
were also made before air conditioning.
Naturally, the process needed “ conditioning ”
at that time, too, but this process had other
names. The drying rooms had big doors
and windows, and the air conditions were
regulated by opening and closing the doors
and windows according to the daily outside
temperature and humidity. The water loss
of the product was examined by touch, and
then eventually, on the basis of color, shape,
and fl exibility of slices. This procedure
needed a lot of experience, and it was still
not always precise and well - founded enough.
That is why there was a strong demand
for the classical salami - drying specialist

( “ salami - masters ” ), who had high prestige

and earnings.

Basis of Drying

During drying, water is removed as vapor.

Thus:

• the activity of microorganisms decreases
  because the portion of water they can
  utilize decreases, and this in turn means the
  shelf life of the product increases


• the mass and volume of product decreases


• the texture will be harder


• aroma compounds develop during longer
  processes, mainly in nonheated products
  By means of these changes, meat products
  can be manufactured, stressing and improv-
  ing the favorable texture of raw meat and
  developing products with extraordinary
  attributes.

The Effect of Preservation

The pressure of water vapor will be constant

in the closed space around the material. This

pressure is lower or equal to vapor pressure

above pure water at the same temperature.

The numerical expression of this is the water

activity (a w ):

a water pressure above the material

water pressure above t

w=

hhe pure water

Microorganisms cannot grow below their

specifi c a w (Table 11.1 .) (IFT/FDA 2003 ;

Leistner and R ö del 1976 ; Mossel 1971 ).