INVESTIGADORES
LEON Alberto Edel
congresos y reuniones científicas
Título:
Effects of damaged starch on aging of wheat starch gels
Autor/es:
BARRERA, G. N.; LEÓN, A. E.; RIBOTTA, P. D.
Lugar:
Santiago
Reunión:
Congreso; II Conferencia Latinoamericana de Cereales ICC; 2011
Institución organizadora:
ICC
Resumen:
Granular integrity of the
starch can be affected by the mechanical action of the wheat milling process
thus producing what is called damaged starch (Hoseney, 1994). Starch damage
profoundly changes starch granular and polymer structures which influences
rheological and functional properties (Faridi, 1990). Damaged starch has the
ability to absorb more water than native granules, native wheat starch can
absorb between 39% and 87% its weight in water, while damaged starch between
200% and 430% (Berton, et al 2002). The molecular interactions after cooling of
the gelatinized starch have been called retrogradation. It is known that the
starch retrogradation is controlled by the water present during aging; however,
little evidence about the effect of damaged starch content on amylopectin
retrogradation process has been published. The objective of this work was to evaluate
the effect of damaged starch (DS) on the aging of wheat starch gels. Native wheat starch
(Sigma Aldrich) was milled in a mill disk in order to cause a greater rupture
of starch granules. Four samples, with 3.8, 8.4, 12.9 and 23.8% DS content were
prepared mixing partially damaged wheat starch and native wheat starch. The kinetic of
starch recrystallization was evaluated by differential scanning calorimetry
(DSC) according to the Avrami model at different storage times (0, 2, 3, 6, 8, 10
and 15 days). The rate constants (k),
that represent
crystal growth, and the Avrami exponents (n),
that describing
the type of crystal growth, were obtained by fitting of retrogradation enthalpy experimental
data. Texture properties
of wheat starch gels were studied by texture profile analysis (TPA) at 0, 7 and
14 days.Gel
hardness, springiness and chewiness were determined. Gel syneresis was
evaluated at 0, 7 and 14 storage days. The results showed that retrogadation
enthalpy (ΔHr) increased significantly by the increment of DS at all storage
times. DS content affected significantly kinetics of amylopectin retrogradation,
k and n for the starch samples were modified by DS content. The n values decreased and the k values increased by effect of DS. Therefore,
DS has an effect on the nucleation process of starch recrystallisation and on the
crystal growth rate. Starch gels hardness, springiness and chewiness at 0 and 7
days of storage were not influenced by DS. However, the increments of DS
produced gels with lower hardness, springiness and chewiness at 14 days of
storage. These texture profile parameters were significantly reduced by DS
effects.Water separation of the gels decreased significantly with DS increments at 0 and 7 storage times, however, DS
effect was not significant at 14 days. The decrease in syneresis could
be attributed to changes in the characteristics of the pastes formed and to the
characteristics of the interactions developed in the system.