guar-xantan modified mixture impact on...
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GUAR-XANTAN MODIFIED MIXTURE IMPACT
ON STARCH BASED EDIBLE FILM
PROPERTIES
D. Šuput1, V. Lazić1, S. Popović1, N. Hromiš1, L. Pezo2
1Faculty of Technology, University of Novi Sad, Serbia 2Institute of General and Physical Chemistry, University of Belgrade, Serbia
28-30 October 2014
Novi Sad, Serbia
II International Congress “Food Technology, Quality and Safety”
XVI International Symposium “Feed Technology”
INTRODUCTION
Edible films are thin layers of biopolymers that are used
for food packing. Edible films may be used to:
separate layers having different water activities
retarding water transfer
may be a barrier for O2 decreasing oil or fat oxidation
could be used as a barrier for oil uptake
used as a carrying agent for antimicrobial or
functional substances
VS
Films developed from starch are:
isotropic,
odourless,
tasteless,
colourless,
non-toxic,
biologically degradable,
thus prevent a change of taste, flavor
and appearance of food products.
Starch is one of the most frequently
used biopolymer for edible films
production due to the fact that:
it could be obtained from large
number of raw materials,
its production costs are cheap,
it is renewable and
biodegradable biopolymer that has
the ability to form films.
PLASTICIZERS ?
• Starch films application is restricted owing to the brittle nature. The brittleness of
starch materials is due to strong interactions between starch macromolecules.
• Polymeric segmental mobility can be improved by doping some hydrophilic
plasticizers, as a result of having interactions between plasticizer–starch instead
of between starch–starch.
• Glycerol is one of the most popular plasticizers due to stability and compatibility
with hydrophilic bio-polymeric packaging chain.
XANTHAN GUM?
• Xanthan gum is an extracellular
polysaccharide produced by
submerged aerobic fermentation of
pure Xanthomonas campestris culture
• Xanthan gum has ability to form highly
viscous solutions at low concentrations.
• Some authors have investigated
the effect of xanthan on swelling,
solubility and viscosity of wheat
and waxy corn starch suspensions,
and introduced chemical
modification of xanthan gum to
increase dissolution rate.
GUAR GUM?
• Guar gum is a polysaccharide
composed of the galactose and
mannose. The backbone is a linear
chain of β 1,4-linked mannose
residues to which galactose residues
are 1,6-linked at every second
mannose, forming short side-
branches.
• The largest market for guar gum is in
the food industry. In Europe, guar
gum has EU food additive code
E412.
• It is used as thickener and stabilizer,
helps maintain homogeneity and
texture, functions as a binder.
• Guar gum is economical because it
has almost eight times the water-
thickening potency of cornstarch -
only a very small quantity is needed
for producing sufficient viscosity.
MATERIALS AND METHODS
Film preparation :
STARCH (1.5%) + GLYCEROL (40%)
+
GUAR-XANTAN GUM
A – film with 0.1% added guar-xanthan gum
B – film with 0.3% added guar-xanthan gum
C - film with 0.5% added guar-xanthan gum
Mechanical properties
• Film thickness
• Tensile strength (TS)
• Elongation at break
(ASTM D882-01)
Water vapour permeability
(ASTM E 96-95)
Fourier transform spectroscopy
(ASTM D 5576)
}
RESULTS and DISCUSSION
• According to visual examination obtained films were transparent,
odourless, easy to handle. Films were not greasy or sticky. Appropriate
film formation contributed to film thickness uniformity no matter the
amount of guar-xantan modified mixture addition.
• Table 1. Starch based edible films thickness with different amount of
added guar-xantan modified mixture
Guar-xantan modified mixture addition (%)
0.1 0.3 0.5
Thickness (mm) 0.079±0.008 0.071±0.010 0.068±0.006
Mechanical properties with guar xanthan modified mixture addition improved:
TS: 0,049 N/15mm 0,009 N/15mm
EB: 5,80 % 6,90 %
Fig. 1a. TS of starch films with
different guar-xantan modified
mixture addition (N/15mm)
Fig. 1b. EB of starch films with
different guar-xantan modified
mixture addition (%)
• Regarding barrier properties, it was proved that guar-xantan modified
mixture addition negatively affected water vapour permeability.
236.35 g/m2 24h
214.33 g/m2 24h (0.5%)
205.84 g/m2 24h (0.3%)
(0.1%)
Fig. 2. Water vapour
permeability of starch
films with different guar-
xantan modified mixture
addition (g/m2 24h)
Structural properties
Fig.3. FTIR spectra of starch films with different guar-xantan modified mixture addition
FTIR spectra may be used to define molecular interactions
and some chemical components.
• An extremely broad peak appeared
between 3000 and 3600 cm-1
centered at 3300 cm-1
• The peak occurring at 1641 cm-1
• The peak at 1409 cm-1
• Peaks at 1240, 1299 and 1333 cm-1
• Peaks at 2926, 1450 and 1370 cm-1
• This is the region of hydrogen-bonded
hydroxyl groups associated with free,
inter- and intra- molecular bound
hydroxyl groups.
• is associated with the tightly bound
water present in the starch due to the
hygroscopic nature of starch.
• is related to the CH bending of CH2.
• are associated to OH bending due to
the primary or secondary alcohols.
• are ascribed to C-H stretching and
bending modes.
TQ Analyst software was used for quantitative analysis. Simple Beer's law was
performed on spectra of starch based edible films with growing amount of guar-
xantan gum.
Functional dependency, described by equation:
y=0.385x+(-0.0295)
was determined between added amount of guar xanthan modified mixture and
spectra absorption values. Calculated versus actual values showed good
correlation (R2=0.86698) for the linear function
Fig. 4. Calculated verses actual values plot for Simple Beer's law performed on spectra of
starch based edible films with growing amount guar-xanthan gum
CONCLUSION
Effort to extend shelf life and enhance food quality while reducing packaging waste
Exploration of new bio-based packaging materials (edible films)
Starch-based films: environmental appeal, low cost, flexibility and transparency.
• Obtained films: tasteless, odorless and transparent (thickness: 0.068-0.0079mm )
• Mechanical characteristics with guar-xanthan modified mixture addition improved
(TS decreased and EB increased) which enabled better film folding and handling.
• On the other hand, guar-xanthan modified mixture addition negatively affected
WVP (increased from from 205.84 g/m2 24h to 236.35 g/m2 24h with guar-xanthan
increment).
• FTIR analysis proved characteristic peaks related to starch based edible films.
Quantitative law dependency between added amount of guar xanthan modified
mixture and obtained spectra was described by equasion: y=0.385x+(-0.0295).