Handbook of Meat Processing

Bacon 331

can be achieved using a one - stage system by

placing the bacon in a cold room operating at

the target temperature, or, more commonly,

by a two - stage system employing a blast

freezer and a separate cold room to achieve

equilibration (Brown et al. 2003 ).

The amount and composition of the

adipose tissue can also affect the fi rmness of

the bacon to be sliced (Enser et al. 1984 ;

Shackelford et al. 1990 ; Rentfrow et al. 2003 ;

Teye et al. 2006 ), depending on the degree of

unsaturation of the component fatty acids,

which can vary widely. A high proportion of

saturated fatty acids results in adipose tissue

that is relatively fi rm, which, in turn, affects

sliceability.

Packaging

Two systems are used for packing pre -

sliced bacon: vacuum packing and modifi ed

atmosphere packing. Various studies have

shown that the cured meat pigment nitric

oxide myoglobin (NOMb) is unstable when

exposed to light and air. A major concern,

therefore, in both pack types is to exclude

oxygen, which is detrimental to the stability

of the cured meat pigment. This is quite dif-

ferent from fresh meats, where the predomi-

nant pigment, oxymyoglobin, is favored by

high oxygen concentrations.

Vacuum Packing

Twenty years ago, the majority of pre - sliced

bacon in the UK was vacuum packed.

Vacuum packing ’ s use continues but less

commonly than formerly. Packing under

vacuum extracts the air, and the package col-

lapses around the meat. Any residual oxygen

is depleted by tissue respiration, and carbon

dioxide is produced. The resulting pattern of

microbial growth is quite different from that

which occurs in air. The growth of pseudo-

monads is inhibited, while lactic acid bacte-

ria dominate and can reach high numbers

without causing objectionable spoilage.

Dry - cured bacon is drier and has a higher
meat content, about 97%, than that produced
using a brine, but the fl avor is similar in both.

Smoking

Traditional methods of smoking use natural
wood smoke generated under controlled tem-
perature and humidity conditions from hard-
woods such as oak, beech, and hickory. The
center of the product never rises above 30 ° C,
so the product remains uncooked, albeit with
an altered fl avor, odor and color due to the
action of the smoking process. Smoked bacon
accounts for approximately 25% – 30% of the
UK market (Fisher 2006 ).

Tempering and High - Speed Slicing

Most bacon is sold pre - sliced. This is
achieved using high - speed slicers operating
at 800 – 1400 revolutions per minute (i.e.,
∼ 10 – 20 revolutions per s). This requires
bacon to be sliced in a tempered (partly
frozen) condition to maximize the yield of
high - quality slices. The optimal conditions
for slicing depend on both the bacon (its tem-
perature, salt content, and the amount and
composition of the adipose tissue) and the
slicer (its design and slicing speed) (James
and Bailey 1987 ; Brown et al. 2003 ). High -
speed photography has demonstrated the
importance of correct slicing temperature. If
the temperature is too high, the bacon is too
soft and distorts when presented to the slicing
blade, resulting in a low yield of high - quality
(well - defi ned) slices. If the temperature is too
low, the bacon is more brittle and tends to
shatter, again reducing the slicing yield. The
optimal temperature varies with salt content.
For bacon containing 3% salt, the optimal
slicing temperature is about − 7 ° C (Brown
et al. 2003 ). The optimal temperature varies
because salt lowers the initial freezing point
(ifp), which, in turn, affects the ice content
and the resulting mechanical properties of the
semifrozen product. The temper temperature