2009_Book_FoodChemistry

742 15 Cereals and Cereal Products
15.5.2 Additives
Cysteine hydrochloride (about 0.01%) lowers
the mixing/kneading time by 15–20%
(cf. 15.4.1.4.4). The cysteine also inhibits
melanoidin build-up due to nonenzymatic browning,
and suppresses the greyish-brown pigmentation.
Addition of monoglycerides (about 0.4%)
brings about amylose and amylopectin complexing,
thereby increasing cooking strength
(cf. 15.4.4). Through competitive inhibition,
ascorbic acid prevents the action of lipoxygenase
(Fig. 15.56). Although the enzyme is
a lipoxygenase with high regio- and stereospecificity
(cf. 3.7.2.2) and only slowly cooxidizes
carotenoids, the low enzyme activity can still
destroy the pigments because pasta production
is a relatively long process. Addition of ascorbic
acid inhibits this cooxidation (Fig. 15.57).
15.5.3 Production
Pasta products are manufactured continuously by
a vacuum extruder, which consists of a mixing
trough and press segments. The vacuum is used
to retard oxidative degradation of carotenoids.
The semolina and added water (30%) and, when
necessary, egg or egg powder are mixed in a mixing
trough to form a crumb dough (diameter 1–3
Fig. 15.57. Carotenoid stability in pasta products made
of three Durum wheat cultivars as affected by added
ascorbic acid (according to Walsh et al., 1970). 1–3
wheat cv. Durum
mm), pressed at 150–200 bar into a uniform paste
and then pressed through an extruder pressure
head die to provide the familiar pasta strings.
Drying is the most demanding stage of pasta
manufacturing. The surface of a pasta product
must not be allowed to harden prior to the
interior core, otherwise cracks, fractures or bursts
develop. The freshly extruded strings are initially
dried from the outside until they are no longer
sticky, then drying is continued at 45–60 ◦ C,
either very slowly or stepwise. The moisture
content drops to 20–24% after such a predrying
process. The moisture is then allowed to equilibrate
between inner and outer parts, which brings
the content of the final dried product to 11–13%.
15.6 References
Fig. 15.56. Competitive inhibition of wheat
lipoxy-genase by ascorbic acid (according to
Walsh et al., 1970). Activity assay with linoleic
acid as a substrate (1) without, and (2) in the presence
of ascorbic acid (2 · 10 −6 mol/l)
Acker, L.: Phospholipases of cereals. In: Advances
in cereal science and technology (Ed.: Pomeranz,
Y.), Vol. VII, p. 85, American Association of Cereal
Chemists: St. Paul. Minn. 1985
Ali, M. R., D’Appolonia, B.L.: Einfluß von Roggenpentosanen
auf die Teig- und Broteigenschaften. Getreide
Mehl Brot 33, 334 (1979)
Aman, P., Graham, H.: Analysis of total and insoluble
mixed-linked (1 → 3),(1 → 4)−β-D-Glucans in
barley and oats. J. Agric. Food Chem. 35, 704 (1987)
Amend, T., Belitz, H.-D.: Gluten formation studied by
the transmission electron microscope. Z. Lebensm.
Unters. Forsch. 191, 184 (1990)
Amend, T., Belitz, H.-D.: Electron microscopic studies
on protein films from wheat and other sources at the