Agriculture Reference
In-Depth Information
pancake spread). However, viscosity in batters is
not based on gluten formation (Morris and Rose
1996). If gluten forms to any great extent in
batter-based baking systems, the resulting prod-
ucts are tough, chewy, and unacceptable to con-
sumers. Cakes, for example, should have crumb
texture that is tender and soft with little resil-
ience, a cell structure that is somewhat less defi ned
than breads but still uniform with densely packed
small cells, and for high-ratio (more sugar than
fl our) cakes a silky structure (AACC approved
method 10-90, AACC 2000; Cauvain and Young
2006).
To minimize gluten formation, the soft wheat
fl our used in batter-based products should be of
low extraction (for cakes, 60% extraction fl our,
equivalent to about 0.23% ash, is frequently
used), and of low protein content (7.0%-8.5%).
The low extraction rate minimizes the starch
damage that leads to greater water absorption and
problems with the starch gelatinization profi le
(Atwell et al., 1988). Further the reduced amounts
of bran and aleurone layer fragments in low-
extraction fl our reduce the amount of water-
unextractable arabinoxylans, which can bind 10
times their weight in water (Kulp 1968). Increased
water-unextractable arabinoxylan content leads to
competition for water between these endogenous
components and sugar as an ingredient, leading
to viscosity and textural problems in the product
and complications with formulation, handling,
and baking.
To achieve proper viscosity, batters rely partly
on small bubbles created by air incorporated at
mixing (chiefl y nitrogen) and by chemical leaven-
ing agents, which produce carbon dioxide and/or
ammonia through the reaction of acid-base leav-
ening pairs (Heidolph 1996). Greater numbers
of small bubbles increase batter viscosity both
initially and during baking. As the batter heats
during baking, the bubbles expand, creating a
light, fl uffy product. Without the viscosity pro-
vided by leavening bubbles, the batter would
become more fl uid due to heating, until starch
gelatinization occurred, deleteriously affecting
product quality. Batters therefore must be suffi -
ciently viscous to hold leavening bubbles through-
out the mixing and baking process. Since gluten
formation is minimized in high-water, low-
protein, short mixing time batters, formation of a
large carbohydrate matrix by oxidative gelation
among water-extractable arabinoxylans through
esterifi cation of ferulic acid moieties has been
suggested as the mechanism of viscosity creation
(Izydorczyk et al., 1991; Bettge and Morris
2007).
Cake fl our to be used for batters is frequently
modifi ed by chlorination or heat treatment to
enhance functionality. Chlorination reduces the
fl our pH by creation of hydrochloric acid, and
also affects proteins and starch-granule surface
lipids through oxidation. The starch becomes
more hydrophobic and gelatinizes and swells
more quickly during baking (Seguchi 1990;
Greenwell and Brock 1996). Chlorination is
decreasing in use as a fl our treatment, especially
in countries other than the US. Heat treatment,
as an alternative treatment, also increases the oxi-
dation of the fl our, providing some of the same
benefi cial changes to fl our quality (Ozawa and
Seguchi 2006).
Durum pasta
In large-scale industrial settings pasta is made
from durum semolina and water. The relatively
dry dough (water addition about 18%-25%
of dry solids; Sissons 2004) is fi rst mixed to
blend the semolina and water and hydrate the
semolina, sometimes under vacuum. The
dough is then extruded under vacuum through a
shaping die, and dried at controlled high tem-
peratures (>60 ºC), often with detailed time-tem-
perature profi les (Sissons 2004; Cubadda et al.,
2007). Fresh-pasta products, although still com-
monly made from durum semolina, are often
made with a similar sheeting process to Asian
noodles. However, this product sector is smaller
in volume than the extruded and dried pasta
sector.
Durum wheat for pasta production should be
sound, be well fi lled, and contain >75% vitreous
kernels, which is related to higher semolina yields
