DTG and dta studies on typical sugars

55

The?mochimica Acta, 134 (1988) 55-60 Elsevier Science Publishers B.V., Amsterdam DTG AND DTA STUDIES

M* C. J.

ON TYPICAL

RA!v0S-SAKHEZ*,

F.J.

SLKX?S

REY,

MS L.

ROCRIGUEZ-MEMEZ,

F.J.

MARTIN-GIL*

47011

Spain

and

MARTIN-GIL

E.T.S.I.I.

Universidad

* Hospitales

de Valladolid,

INSALUD,

Valladolid,

Valladolid,

Spain

ABSTRACT

The

DTG and

DSC-DTA

tigation

of

reaction

temperatures

not

merely

mation

typical

to

techniques between

25aC

and

enthalpies

of

characterize

pertaining

have

sugars

to

or

the

identify

relation

been

found

and

700%.

24

to

sugars

are

substances,

between

be suitable

for

Endothermic

and

listed.

but

molecular

to

the

These

yield

inves-

exothermic data

serve

important

structure

and

infor-

thermal

behaviour.

INTRCDLCTXX

The of

present

a range

used

in

during

of

order their

foods

is

a systematic

24

sugars

and

to

obtain

data

heating.

temperature in

study

polysaccharides. concerning

operations

is and

into

DTG and the

This.information

processing and woods

investigation

changes

the

thermal

DTA-DSC

techniques

produced

important

for

understanding

behaviour were

by carbohydrates

safely

directinq

deterioration

high

phenomena

(I)

EXPERIMENTAL

All

the

formed

samples

using

were

a Perkin

supplied

Elmer

by Merck

3600

and

and

Sigma.

DTA 1700,as

Thermal

analysis

previously

was

reported

per-

(2).

RESULTS

The of

effects rimetric in

the

300% of

features

of

carbohydrates in

DTA and

CUrVeS monowere

and

The

in

calorimetric

only the

DTA effect

curves

Whereas one

more

by at

(effect II

0) is

the

were

peak

simple

is

and

sugars DTA curves,

least

two other

a slightly

different

polysaccharides

significative

polysaccharides

preceeded

water/fusion

before

tne

analyzed.

in

depending mainly

DTG,

the

comparatively the

shape rich

decomposition

endotherms,

one

to

decomposition

an early

‘endothermic

or

on the

exhibit of

inflexion

these

(Fig.1).

to

that

appears

Thermal Analysir Proc. 9th ICTA Congress, Jewakm, Israel, 21-25 Aug. 1988 0040-6031188603.50 Q 1988 Elsevier Science Publishers B.V.

above

the

(effect

combustion.

caloThus,

exotherms

corresponding

type

exothermic

loss

I). just

56 Relative and

to

their

520*20aC

can

It

is

worth

marker

while

ty

each

for

DTG curves,

noting, the

that

second

the

peak

is

shifted of

227X

to

the

sugar

di-

and

the

from

the

the

the

point

behaviour has

of

and

at

220f40%,

310f20sC

of

could

with

data described of

or

than

be more

the

236

DTG-I

among the

data

of

in

Table

1,

262%.

in

Table

In

three

the

monosaccharides,

and

(see

above),

are

the

Galactose, than

it

also

carbohydrates.

stable

the

differentiation

effects

mdnosaccharides

stability must

DTG first

polymeric

purposes. place,

ISO-

while

Dextrin,

Starch

280%.

previously

the

disaccharides thermal

of

takes

from

between above

a polymerization

as a “fingerprint’‘-proper-

decomposition

decomposed

process appears

view

Trehalose

the

is

characterization

allowing As seen

of

are

for

polymerization

temperatures,

characteristic

main

be considered

usefulness the

peak

1 are can

be concluded

reflected For

in

example,

disaccharides

Lactose

or

evaluated

the if

that

thermal

Glucose

Cellobiose,

Melibiose,

such

as

Malthe

show.

In ted

steps

DTG decomposition

carbohydrates.

differences

a higher

facts

of

thermoanalytical

species

tose

higher

oligosaccharides

and Cellulose If

is

first

linkages

family

DTG peak

.decomposition

DTG effect

particular

Whenthroughglycosidic

groups

three

be recognized.

in

like

manner,

a higher

the

higher

thermostability

sequence

Cellobiose

> Trehalose

The lower stability saccharides) Raffinose Ficoll

can

is responsible

ting points

for

Maltose

Galactose

Sucrose.

So,

over

Fructose

from

DTG-I

resuldata,

> Melibiose

Sucrose

>

the other mono-

low peak DTGI temperatures

vs. disaccharides.

a

disaccharides:

For the same reason,

Inulin

for and

than other polysaccharides.

also derived from the comparative

DTGI

and

DTGII

maxima

in the characterization

points of certain

or

of

over

for the irregular

and Melezitose

that

stability

Lactose

be established

> Lactose

decomposed earlier

1 is

of

of the Fructose moiety (204OQC below all

Other conclusions Table

thermal

thermostability

carbohydrates

are

a more

of sugars,

analysis

suitable

above all

(i)

near, or (ii)

are closely

tool

of the data in than

the

mel-

when the melting

when it deals with

hydrated compounds. Also in basis between molecular

of

effects

DTG

structure

and thermal stability,

(a) Aldoses are more stable (b) the fi-glycosidic sidic (c)

linkages

the p-14

some other relations

than Ketoses (Fig.

linkages confer (Fig.

linkages

could be demonstrated

as follows: 2).

more thermstability

than the a-glyco-

3).

are more stable

than (r-1-6, the a-l-l

and 0-14

being

in between... In the last

part of this

comnunication

the thermal behaviour above 3DOQCof

the same range of sugars and polysaccharides

early

reported

is also presented.

57 TABLE 1 Decomposition

endothermal

effects of typical effect 0

Carbohydrates

Onset

sugars

(in static air, ratelOQC/min) effect II

effect I DTGI

DTA

DTG-II QC

TG

DTA (AH)

QC (Cal/g)

*C

QC (Cal/g)

D-Ribose

90 (27)

150

189 (20)

213

279

291

D-Xylose

160 (40)

160

198 (11)

203

273

302

D-Arabinose

167 (46)

173

203

( 2)

203

275

313

L-Arabinose

164 (43)

155

195 (10)

211

263

287

D-Mannose

135 (34)

175

205 (58)

222

275

275

D-Glucose

156 (33)

192

208 (36)

227

285

321

D-Galactose

;z;sh(39,

189

200 (20)

220

285

308

L-Rhamnose .H20'

102 (49). 137 ( 5)

70 150

196 (31)

205

306

299

D-Fructose

121 (39)

149

189 (53)

180

282

267

L-Sorbose

173 (30)

170

192 (.2)

198

282

266 283

D-Trehalose .2H20

;;; (56)

94 237

214 (26)

260

297

312 317

D-Maltose .H20

121 (31) 155 ( 1)

105 205

220 (27)

252

281

315

Sucrose

DTA (AH)

QC

QC

Monosaccharides C5H1005 pentoses

C6H1206 hexoses

hexuloses

Disaccharides

and

Oligosaccharides Cl2H22011

180 (27)

215

226 (25)

238

294

294

D-Lactose .H20

150 (35)

126 228

;g; (68)

246

285

312

D-Melibiose .H20

119 ( 4) 188 (18)

85 212

223 (15)

239

305

310

236

251 (94)

245sh 262

306

317

D-Cellobiose C18H32016

D-Raffinose .5H20

91 (32) 126 (19)

52 213

233 (23)

236

316

301

D-Melesitoee .2H20

152 (34)

112 216

245 (29)

244

283

287

164 ( 2)

226

233 (13)

242

337

278

Polyeaccharides Homopolyeaccharides Inulin

58 TABLE 1 (cont.) Carbohydrates

effect 0

onset

DTA (AH)

TG

DTA (AH)

DTG I

DTA

DTG II

GC (Cal/g)

QC

QC (Cal/g)

QC

QC

QC

Dextrin

230

231 ( 7) 258 ( 5)

257sh 287

308

(345)

Starch sol.

273

273 (26)

280sh 310

330

-

Cellulose

280

-

338

310

-

Ficoll (a syntetic polymer of sucrose) -

220

-

260sh

$00

Hyaluronic acid (sodic salt)

220

effect I

Heteropolysaccharides

Fig.

1:

DTA,

Table and

the

2 summarizes respective

phenomena

tiles from We have each

DTG and TG thermograms

are

found

carbohydrate

mer effects)

for

temperatures

enthalpies

related

the

the

reaction that in their

to

for

the

togethgr

;z; (-437)

Arabinose

of

the

with

(1.a)

peaks

associated

due

398

-

and Cellulose

exothermic

the

244-254 290sh

(1.b)

to

pyrolysis

DTG effects.

These

samples vaporizationand eliminationof the vola-

zone. the

observed

particular

320 350sh

can

characterization.

DTA peaks

at

be a suitable

330-410X aid

and 44D-54OeC (together

with

the

for for-

59 TABLE 2 Decomposition

exothermal

effects of typical sugars

(in static air and at rate

of lOQC/min). Carbohydrates

effect III

effect IV

effect

combustion

DTG-III

DTA

DTA

QC

QC

QC

Cal/g

536

-1300

(279-506)

AH

(AT) QC

Monosaccharides C5H1005 pentoses

'gH12'6 hexoses

D-Ribose

335

414 481

D-Xylose

332

445

532

-1050

(273-515)

D-Arabinose

353

454

528

-1318

(275-535)

L-Arabinose

345

461

503

-1412

(263-550)

D-Mannose

357

476

525

-1476

(272-520)

D-Glucose

373

510

530

-1470

(285-586)

D-Galactose

365

471

529

-1616

(285-575)

L-Rhamnose

357 388

472

510

- 810 (306-570) -1011 (270-570)

D-Fructose

372

487

537

-1489

(282-599)

L-Sorbose

367

480

545

-1530

(282-582)

D-Trehalose .2H20

360 395

495

520

-1484 (297-599)

D-Maltose .H20

412

492

526

-1575 (280-590)

Sucrose

379

520

544

-1355 (285-665)

D-Lactose

338 413

496

530

-1525 (285-590)

D-Melibiose .H20

382

510

523

-1625 (305-600)

D-Cellobiose

374 488

496

536

-1380 (306-590)

D-Raffinose .5H20

360 420

503

520

-1255

D-Melezitose .2H20

358

484

520

-1422 (285-530)

420

565

520

Disaccharides

and

Oligosaccharides C12H22011

. Id20

C18R32016

(280-550)

Polysaccharides Homopolysaccharides Inulin

-

928

-1623

(340-596)

(235-600)

60 TABLE 2 effect III

Carbohydrates

effect IV

effect

combustion

(AT)

DTA

DTA

DTG III

QC

QC

QC

Dextrin

360

516 535

482

- 705 (308-635) -1130 (260-635)

Starch sol.

417 490

520

- 614 (330-630) -1050 (273-630)

Cellulose

352 423

AH Cal/g

QC

- 912 (305-520) - 991 (220-520)

Heteropolysaccharides Ficoll

375

Hyaluronic (sodic salt)

413

um -AnmE.

525

522

- 820 (330-590) -1315 (200-590) - 768 (350-470)

5oc

*c

Fig. 2 Thermogramfor Glucoseand Fru%ose.

-m.*c

Dtl

Fig. 3 Thermogramfor Maltoseand

Cellobiose. Finally, we

shouldunderlinethat in the largestpart of sugarsthe fusion

is associatedto the effect0 DTA, exceptin the case of anhydroussugarsCellobiose,Trehalose, Maltose,Inulin,Dextrin,Starchsoluble,whichmelt with the effectI. This fact createsa discrimination betweenthe two kindsof sugars,as far as it showsthe differentstructuralstabilityof theirpolyhydroxilicframe. REFERENCES 1 1.1. Ziderman,K.S. Gregorskiand t&Friedman,Thermochim. Acta 114 (1987)109 2 M.L. Rodriguez-Mendez, F.J. Rey, J. Martin-Gil and F.J. 9th ICTA,Jerusalem,

1988.

Martin-Gil,Proc.