The 19th Gums & Stabilisers for the Food Industry Conference: Hydrocolloid MultifunctionalityBigels are complex biphasic gels, composed by the mixture of organogel and hydrogel.
These systems have been exploited mainly due to their ability to act as vehicle for hydrophilic
and lipophilic simultaneously, being very attractive for food, pharmaceutical and cosmetic
applications. However, despite the increasing number of publications concerning the
production and use of bigels in recent years,
to our knowledge
there are no papers
evaluating the effects of process conditions on their
properties.
Thus, the aim of this work
was
evaluating
the influence of the process variables
on particle size, mechanical and
rheological properties
through multivariate analysis. For this purpose, organogelator and
hydrocolloid concentration, organogel:hydrogel ratio and mixing speed were
evaluated.
At first, gellan gum hy
drogels (1 % -1,5 % w/w) and glycerol monostearate
and high oleic sunflower oil
organogels (5 % –15 % w/w) were produced separately by solubilization at 80
ºC during 30 min. After gelation, they were mixed in a mechanica
l stirrer at determined speed
for 10 min. Bigels produced were evaluated through microscopy, rheological (frequency
sweeps) and mechanical properties (spreadability, consistency, adhesiveness and
cohesiveness). According to principal component analysis (PCA),
the reduction of the
analysis to a bivariate dimension
was satisfactory. The first component (horizontal axis)
explained almost 58 % and the second (vertical axis) 20 % of th
e variability found in
measured data.
From the projection of variables,
it was
possible to confirm that
consistency
and spreadability of bigels are well correlated. These variable were
mainly responsible for
the variability of data along the horizontal axis
as well as complex modulus (G*) that was
positively correlated to them. On the other hand, tan delta (G ́ ́/G ́) and adhesiveness were
negatively correlated with these variables. The second component was explained mainly by
cohesiveness and particle size distribution that were
oppositely correlated.
These
correlations
were
in agreement with structural arrangement of the bigels. In general, small
particle size led to more cohesive systems, with higher viscous modulus (higher tan delta
values) and consequently adhesiveness. On the other hand, higher complex modulus is
related to stronger structures, which means higher consistency and spreadability. From the
cases and variable overlapping
it was possible to evaluate that the main variables were
mixing speed and organogel:hydrogel ratio. Moreover, different
groups were distinguished according to organogel:hydrogel ratio.
However, it can be observed that there were
synergistic effects among the other variables
, which also influenced the physicochemical
properties of the bigels and were responsible for the other 20% of variability. Thus, different physicochemical properties can be obtained by tuning the parameters involved in the bigels production process. Softer or harder gels, with higher or lower spreadability, bigger or
smaller particles size distribution can be produced depending on the desired final product
and applicationPortuguese
Foundation
for Science
and
Technology
(FCT)
under
the
scope
of
the
strategic
funding
of
UID/BIO/04469/2013
unit
and
COMPETE 2020 (POCI-01-0145-FEDER-006684)
and
BioTecNorte
operation
(NORTE
-
01
-
0145
-
FEDER
-
000004
)
funded
by
the
European
Regional
Development
Fund
under
the
scope
of
Norte
2020
-
Programa
Operacional
Regional
do
Norte
.
This
study
was
also
supported
by
the
Portuguese
Foundation
for
Science
and
Technology
(FCT)
under
the
scope
of
the
Project
RECI/BBB-EBI/0179/2012(FCOMP-01-0124-FEDER-027462)info:eu-repo/semantics/publishedVersio
