EFFECT OF WATER UPTAKE ON AMORPHOUS INULIN

PROPERTIES

INTRODUCTIONInulin is a natural storage

carbohydrate mainly found inplants from the Asteraceae family. It is not a simple molecule, but a mixture of linear oligo- and/or polysaccharides composed of

(2 1)-β-D-fructofuranan of various lengths, ended by a terminal a-D-glucopyranosyl group

For now, commercial inulin is mainly extracted from chicory root

and is available as a spray-dried powder product

GLASS TRANSITION TEMPERATURE ( TG )

The glass transition is a property of only the amorphous portion of a semi-crystalline solid . The crystalline portion remains crystalline during the glass transition.At a low temperature the amorphous regions of a polymer are in the glassy state it generally will be hard and rigid .If the polymer is heated it will reach its Tg The polymer now is in its rubbery state. That the polymer are lends softness and flexibility.

MODULATED DIFFERENTIAL SCANINGCALORIMETRY (MDSC)

Differential scanning calorimetry (DSC) is a thermal analysis technique which has been used for more than two decades to measure the temperatures and heat flows associated with transitions in materials as a function of time and temperature .Such measurements about physical and chemical changes that involve endothermic or exothermic processes,or changes in heat capacity.

WIDE-ANGLE X-RAY SCATTERING (WAXS)

WAXS has been used to study the structural properties of polymer electrolytes containing silver ions. The WAXS spectra of pure poly and poly showed two broad amorphous peaks. The first of these peaks was assigned to the interchain distance, and the second peak was assigned to the distance between the pendant groups of the polymer chains.

OBJECTIVE

The aim of this study was to determine the physical changes of theamorphous inulin powder at different water contents. The physicalparameters investigated were the glass transition temperature (Tg) and the crystallinity index.

MATERIALS AND METHODSSample preparation

chicory rootsextraction

dispersed in distilled water at 95 0C

spray-dried

inlet air 230 0C outlet air 120 0C.air flow were 2l/ h and 2 bars

Dehydration in P2O5

( for one week )Storage in desiccators

METHODS

Volumetric Karl Fischer Titration

Wide Angle X-ray Scattering

Modulated Differential Scanning Calorimetry

Temperature-Resolved Wide Angle X-ray Scattering

Stereomicroscopy

For determined total warter content.

RESULTS AND DISCUSSION Development of crystallization

118.9

917.2

16.9

15.7

0.9

16.3

15.7

RESULTS AND DISCUSSION ( CON )

Thermal properties

Fig. 3. MDSC total heat flow using (a) non-hermetic aluminium pans of amorphousinulin containing (1) 0.9, (2) 8.6, (3) 13.6, (4) 14.8, (5) 15.7, (6) 16.3 and (7) 18.9 g water/100 g dry inulin. (b) Hermetic aluminium pans of amorphous inulin containing (1) 0.9,(2) 8.6, (3) 13.6, (4) 14.8, (5) 15.7, (6) 16.3 and (7) 16.9 g water/100 g dry inulin.

118.9

9

16.3

15.7

13.6

8.6

14.8

0.9

118.9

9

16.3

15.7

13.6

8.6

14.8

0.9

118.9

9

16.3

15.7

13.6

14.8

Fig. 4. Glass transition temperature–water content relationship (Tg–water contentstate diagram). Zones I and II delimited amorphous in the glassy or rubbery state,respectively, while zone III characterized crystallized inulin.

Thermal properties ( Con )

PowderedAmorphous state

Sticky still amorphous

Crystallized state

RESULTS AND DISCUSSION ( CON ) Understanding the thermal property change

Fig. 5. Temperature-Resolved Wide Angle X-ray Scattering patterns of inulin containing 18.8 g water/100 g dry inulin. Darker colours correspond to higher intensities.MDSC onset (145 C) and endset (165 C) temperatures of the endothermic peaks are represented by vertical lines.

Fig. 6. Evolution of the crystallinity index of crystallized amorphous inulin during heating at 1.5 C min1, determined from Temperature-Resolved WideAngle X-ray Scattering. MDSC onset (145 C) and endset (165 C) temperature of theendothermic peaks are represented by vertical lines.

Fig. 6. Evolution of the crystallinity index of crystallized amorphous inulin during heating at 1.5 C min1, determined from Temperature-Resolved WideAngle X-ray Scattering. MDSC onset (145 C) and endset (165 C) temperature of theendothermic peaks are represented by vertical lines.

CONCLUSIONThe effect of water uptake during storage on

amorphous inulin properties has been investigated. Water content, crystallinity indexes,thermal properties and glass transition temperature evolution permitted the understanding of the physical and behavioural changes of the amorphous material. The Tg–water content state diagram allowed us to point out three zones. Zone I was the plasticization effect of water on Tg with inulin in a powdered amorphous state. The defined zone II was an intermediate state between glassy amorphous and crystallized inulin, with some macroscopic and thermal property changes. In zone III, the product crystallized,

caked and no glass transition was observed. An endothermic peakappeared at the initial glass transition, which was attributed to themelting of inulin crystals, as confirmed by Temperature-Resolved Wide Angle X-ray Scattering.

THANK FOR THE ATTENTION

REFERENCE Se bastien N. Ronkart , Michel Paquot , Christian

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P. S. Gill, S. R. Sauerbrunn and M. Reading. MODULATED DIFFERENTIAL SCANNING CALORIMETRY. Journal of Thermal Analysis, Vol. 40 (1993) 931-939

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