Baking & Snack - February 2004 - 67

INGREDIENT TECHNOLOGY

Strictly
speaking,
staling is
unavoidable,
but it can be
slowed.

An
Achievable
Goal

BY LAURIE GORTON
f only freshness were a permanent characteristic of
baked foods. But it's not, and bakers have pursued
many anti-staling methods and strategies. Among the
latest is the combination of formulation changes and
processing adjustments known as extended shelf life, or
ESL. But there's more than one way to achieve the antistaling goal.
Consumers describe the hardening of texture and
deterioration of flavor in baked foods as staling. Bakery
researchers attribute these effects chiefly to retrogradation of starch. In nature, starch molecules consist of
branched chains of glucose units and are tightly packed
into compact, hard granules. Milling exposes the starch
granules. When starch (the major component of flour)
is combined with water and heated, the granules absorb
water by binding it to the starch molecule's branches.
This swells (or gelatinizes) the starch, giving the baked
foods a tender, soft texture. On cooling, some moisture
escapes, and the texture begins to firm. Over time, additional moisture losses shrink the swollen starch chains
and granules. The starch is said to retrograde to its earlier
hard, close-packed structure. Oxidation of fats complicates the picture, principally because of its flavor effects
but also due to fat's role in mouthfeel and eating quality.
Bakers have tried many additives to inhibit or retard
the process of staling. Such materials include flour components, milk products, colloids, modified starches, dextrins, sugars, enzymes, soy flours and proteins, glycerol,
shortenings, emulsifiers, glycolipids and more.

SHORTER CHAINS. One way to reduce the effect of
retrogradation is to make the starch chains shorter. This
not only frees up more glucose molecules and shorter
polysaccharides, which exert a humectant effect, but also
limits the potential for long chains to relink and thus
form hard, crystalline regions. Bakery formulators use

enzymes to
effect this change.
Basically, an enzyme
is a biological catalyst that is not
consumed in the reaction. The enzyme catalyzes reactions until limited by lack of substrate or deactivated by
heat. Its action is highly specific, only affecting a certain
type of bond or even a bond at an exact location within
a molecule.
Although derived from larger organisms, typically
cereal or microbial sources, enzymes themselves are
proteins and are added to bakery formulas as protein,
not the organism.
Enzymes can only act on swollen starch, when its tight
structure opens up. This takes place at 130°F to 145°F. By
learning the operating temperature of a given enzyme,
a formulator can determine its potential as a staling
retardant. Fungal alpha-amylase is generally inactivated
by the time the system reaches 130°F (57°C). Bacterial
alpha-amylases reach optimum activity at 165°F to 170°F
(74°C to 77°C). About half of their activity will remain
ᮡ Encapsulation maintains the functionality of preservative ingredients
during processing.
BALCHEM ENCAPSULATES

February 2004 / BAKING & SNACK / 67

Baking & Snack - February 2004

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