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)

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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).

ACKNOWLEDGMENT

This work is part of project „Osmotic dehydration of food - energy and environmental aspects of sustainable

production“, project number TR-31055 financed by Ministry of Education and Science Republic of Serbia.

THANK YOU FOR

YOUR ATTENTION!