Thermal degradation of 1-amino-1-deoxyketoses and their role in flavour development : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Food Technology at Massey University

the permission of the Author.

THE��L DEGRADATION OF 1 -AMIN0- 1 -DEOXYKETOSES AND THEIR ROLE IN FLAVOUR DEVELOPMENT

A The s i s

p re s ente d i n parti^al ful fi lment o f the re qui rements fo r the degree o f

Do c to r o f Phi l o so phy i n Foo d Te chno l o gy a t Mas s e y University.

by

Edward John Birch March , 1 98 1 .

ABSTRACT

Sugars undergo carame l i s a tion re a c tions a t

rel a ti v e l y high tempera ture s bu t when amino compound s are pre s e n t , Ma i l l ard bro wning re a c tions are p o s s ibl e and the s e o c cur under l e s s s evere condi ti o n s . The re a c ti o n condi ti o ns and the b a s i c chara c te r o f the ami no compound s de te rmi ne the range o f flavour compo unds fo rme d . The fi rs t s tep during Mai l l ard browning i s the condens a ti o n o f a redu c i ng sugar wi th an ami ne to fo rm a gl yco syl amine and thi s compound may then undergo the Amadori rearrangement to fo rm a

1 - ami no - 1 -deo xyke to s e .

The pyro l y s i s o f two 1 - amino - 1 -deo xyke to s e s ( 1 - deoxy- 1 -gl ycino-D- fru c to s e and 1 -�- alanino - 1 - d e o xy- D­

fruc to s e ) wa s s tudi ed in thi s inve s tiga ti on to

examine the i r p a r ti c i p a ti o n i n a l o w energy route to aroma form a ti o n . Thermal anal ysi s and para l l e l c hem i c a l i nve s tiga tions showe d tha t the fo rma tion o f the s e Amadori compounds f a c ili ta te s the the rmal

degrada t i o n o f the i r sugar and amino a c i d mo i e ti e s . In addi t i o n incre a s e d quanti ti e s o f vari ous a roma c ompo und s are p ro duc ed , compared wi th the con trol s . I n parti cul a r , the toxi c comp o und pro to anemonin i s form e d and a degra d a tion pa thway l e adi ng to i ts pro du c ti o n i s propo s e d .

Mo s t o f the wo rk i nvolving the e l u c i da ti o n o f degra d a ti o n pa thways duri ng M a i l l ard bro wning h ave i nvo l v e d s tudi e s in aque o u s s ys tems . Browning reacti ons b e twe en gluco s e and amino a c i d s we re al so o b s e rved during h e a ting i n the dry- s ta te in thi s s tudy.

The s e re a c tions are very vigorous o nce i ni t i a ted and thi s pre c l uded th e s tudy of a gluco se p lu s ami no a c i d contro l b y the te chniques u s e d to s tudy the pyro l ys i s o f the 1 - amino - 1 -de o xyketo ses . Such re ac ti o ns o ccur

a t temp e ra ture s b e l o w tho s e requi red for the the rmal degrada t i o n of the corre sponding Amado ri rearrangem e n t compound thus que s t i oning the invo lvement o f the s e compound s i n the l o we s t ene rgy thermo l ys i s p a thway i n the ab s e n c e o f mo i s ture . The re sul ts o f experimen t s de signe d t o i nve s ti gate the ro l e o f Amadori c ompo und s during the browni ng o f sugar-amino acid sys t ems i n the dry- s t a t e demons tra ted however that the re a c t i o n s

reported t o o c cur i n aqueous sys t ems c a n a l so a c c o un t fo r the d ry- s ta t e p ro c e s s e s a t t empera ture s up un t i l the spont aneous de c ompo si tion o f the 1 - ami no- 1 -deoxy- ke t o s e c an o c cur. Tha t the 1 - amino- 1 -d e o xyke to s e d o e s no t brown by i t s e l f o r i n the pre sence o f gl uco s e a s readi ly a s a gl u co s e plus amino a c i d sys tem i s

pre sumabl y a ba s i c i ty e ffe c t . The s tronger ba s e ^{the amino a c i d) may p romo te a s o l id- s tate eno l i s a t i on o f the gl uco s e and hence ini t i a t e browning a t a som ewha t l ower t emp era ture . The re sul t s o f the s e exp eri m e n t s al so demo n s tra t e t h e s tabi l i ty o f the 1 - amino- 1 -d e o xy­

ke to s e s and show that the i r form a ti o n i s no t a r a t e ­ l imi ting s t ep duri ng browning.

I n the thi rd s e c tion or thi s the s i s the e ff e c t o f changing the ami ne mo i e ty on the degrada t i on p a t t e rn o f 1 - amino - 1 -deoxyke to s e s i s a s s e s s e d .

Previ ous re search h a s indi c a t e d tha t gluco s e by i t sel f and Ama do ri compounds fo rmed from we ak p rimary ba s e s degrade vi a an ini t i al 1 , 2 eno l i s a t ion s tep t o f o rm mainly 2- furaldehydes and pyrro l e deriva tives whi l e

1 - amino - 1 -deoxyke to s e s containing a s trong ba s i c

mo i e ty (u sual l y fo rmed from a s e condary ba s e) d e grade vi a a 2 , 3 eno l i n t ermedi a t e and give ri s e to fragrant

caramel aroma compounds . Several 1 -ami no - 1 -deox y-

ke to s e s we re prepared us ing primary and s e condary b a s e s cove rin g a range o f pkb val ue s . The s e c ompound s were pyro l y s e d and thei r de compo s i ti o n chara c t e ri s t i c s

moni tored by thermal anal y s i s me thods . Paral l e l

i i i

anal ys i s o f the vo l a ti l e s produc e d and a compa ri son o f the re sul ts from previous inve s tiga tions gene ral l y e ndo rsed the repo r ted hypo th e se s o n the degrada ti o n o f Amadori compo unds . I t was found tha t the s tru c ture o f the b a s e and funq ti o nal groups pre s en t influen c e d the degrada ti o n phenomena ^as wel l a s the basi ci ty . The thermal d e c ompo s i ti on o f amino acid - derive d Amado ri compo und s fo r ins tance , d i d no t fi t i n to the p a ttern o f tha t ob s e rved fo r 1 - am i no- 1 -deoxyke to s e s derived from o ther ba s e s . The amino a c i d i nfluen c e s the degrada ti o n tra i t s by promo ti ng 1 , 2 eno l i s a ti o n and charri ng ra ther than aiding 2 , 3 eno l i s a ti o n s i mi l ar to ba s e s o f comparabl e pkb .

ACKNOWLEDGMENTS

The au thor thanks hi s sup e rvi s o rs , Pro fe s s o r E . L . Ri chards and D r ^{J .} Leli evre (Department o f Fo o d Te chno l ogy , M a s s e y Universi ty} and Dr G . B . Rus s e l l

(Appl i ed Bi o chemi s try Divi s i o n , DSIR) f o r the i r s ugge s ti ons and i n tere s t throughou t thi s s tudy and h e l p in fo rmul a ti ng and cons tru c tive c ri ti que o f the m anu s cri p t.

The autho r e xp re s s e s hi s appre c i a ti o n to the fo l l o wing p e rsons fo r the i r a s si s tance and couns e l :

Pro f R . Ho dge s (Chemi s try Departme nt , Ma s s ey Uni versi ty} fo r di s cu s sions on ma s s s p e c trome try.

Dr R . No rri s (D3i ry Research Ins ti tu te) for h e l p and advi c e o n a s pe c ts o f di ffere n ti al s canning

c a l o rime try .

Mr D . E . Rogers and Dr N . Mi l e s tone (Chemi s try Divi sio n , DSIR) for running thermogravime try and d e riva tive the rmogravi me try sampl e s .

Pro f A . Campbe l l and s taff (Chemi stry Departmen t , Otago Universi ty) fo r el emental analys e s .

Dr G . Midwi n t e r (Chemi s try Departmen t , Ma s s ey Unive rsi ty) fo r amino acid analys e s .

V

Abs tr a c t

Acknowl edgment s Li s t o f Tabl e s Li s t o f Figure s INTRODUCTION

Tabl e o f C ontents

I . 1 The invo lvement o f Amado ri c ompounds i n non-enzymi c browning - a revi ew

Page

ii

V

ix

X

1 I . 1 . 1 The na ture o f non- enzymi c browning 1 I . 1 . 2 The chemi s try o f non-enzymi c browning 1

I. 1 . 2 . 1 C aram el i s a tion I . 1 . 2 . 2 Mai l l ard browning

I . 1 . 3 Evi dence for the involvement o f

1 2 Amado ri c ompounds in Mai l l ard browni ng 4 I . 2 S cope o f thi s inve s ti ga tion

I . 3 Exp erimen t al appro ach for s tudying the the rmal de grada t i o n of carbohydra t e s PART A

A . 1 Summary

A . 2 I ntroduc t i o n

A. 3 The rmal ana l ys i s b y d . s . c . , t . g. and d . t . g.

A . 3 . 1 Exp e ri mental

A . 3 . 1 . 1 Amad o ri c ompo unds A. 3 . 1 . 2 The rmal analysis A . 3 . 2 Re sul t s and di s cus sion

A . 4 Analysi s o f d e c ompo s i tion produc t s from the 1 -amino - 1 -deoxyke to s e s and contro l s A . 4 . 1 Pyro l ys i s cond i t i ons

A . 4 . 2 Exp e rimen tal A . 4 . 2 . 1 Pyrolys i s

A . 4. 2 . 2 Gas chroma t o graphy

A . 4 . 2 . 3 Gas chromatography - mas s sp e c trome try

A . 4 . 3 Re sul t s and d i s cu s s i on

7 9

1 1 1 2 1 3 1 3 1 3 1 3 1 4 2 2 2 2 2 2 2 2 2 2 23 2 3

A. 5 The fo rma t i o n o f pro to anemonin A. 5 . 1 Introduc t i on

A. 5 . 2 Experimental

A . 5 . 2 . 1 Pro t o anemoni n

A. 5 . 2 . 2 3-deoxy-D-e ry thro-hexo sul o s e A. 5 . 2 . 3 Rad i o a c tive 1 -�-alanino- 1 -

deo xy-D- fru c t o s e s

A. 5 . 2 . 4 Pyro l ys i s , g. c . , g. c . -m . s . A . 5 . 2 . 5 Mea surement o f radi o a c tive

p ro to anemonin

A. 5 . 3 Re sul t s and di s cu s s i on

PART B

B . 1 Summary

B. 2 Intro duc t i o n

B . ) Evi denc e for the forma tion o f compounds i n sugar-amino a c i d o n heat ing i n the dry- s t a t e B. ). 1 Expe rimental

B . ). 2 Re sul t s and di s cu s s i on

Amado ri sys tems

B. 4 Obs erva t i ons on the ra te o f browning o f model sys tems i n the dry- s t a t e in ho t o i l , where one component i s mo l t en B . 4 . 1 Introdu c t i on

B. 4 . 2 Expe riment a l

B. 4 . 3 Re sul t s and di s cus s i on

B. 5 S tudy o f the i nvolvement o f 1 -�-al ani no- 1 -deoxy-D- fru c to s e in the l o we s t energy rout e to p ro du c t forma t i o n during the browning o f a gluco se-�-al anine mix ture

Page 29 29 29 29 3 1 3 1 3 1 3 1 3 2

3 7 38 40 40 40 4 2 4 2 4 2 4 2

i n the dry- s t a t e 46

B. 5 . 1 Introdu c t i on 46

B. 5 . 2 Experim ental 4 6

B . 5 . 2 . 1 Browning re a c t i ons 46

B . 5 . 2 . 2 Gluc o s e analys i s

B. 5 . 2 . 3 Analys i s o f � - a l anine and 1 -� ­ al anino- 1 -deoxy-D- fructo s e B . 5 . 3 Re sul t s a nd di s cus sion

4 7 47 4 8

v i i

PART C

c. 1 Summary

C . 2 Introduc tion

.

C. 3 The rmal anal ys i s by d . s . c . , t. g. and

d. t. g.

C . 3 . 1 Experiment al

c. 3 . 1 . 1 Amado ri c ompo und s c . 3 . 1 . 2 The rmal analys i s C . 3 . 2 Re sul t s and d i s cu s s i on

c. 4 Ana lysi s o f pyro lysi s produc t s from the 1 - amino- 1 -d e o xyfruc t o s e s

C . 4 . 1 Exp erimental

c . 4 . 2 Re sults and di s cu s s i on APPENDI CES

A 1 Pyro lysi s p ro c edures

A 1 . 1 Pyrolys i s uni t d e s i gn

A 1 . 2 Opera t i o n o f the pyrolys i s uni t and de fini t i on o f ma s s bal anc e fra c t i on s A2 Prep ara tion o f Amado ri c ompound s

A2 . 1 Synthe t i c p ro c edure s A2 . 2 Infrared sp e c tra

A3 C o l o urime tri c analys i s of Bro wning rea c t i on mi x ture s

REFERENCES

Page

63 64 69 69 69 70 70 80 80 80

96 96 97 99 99 1 0 3 1 07 1 1 1

Tabl e A. 1 A . 2

A. 4

B. 1

C . l c . 2 C . 3 c. 4 C. 5 c. 6 C . 7

c. 8

Li s t o£ Tabl e s

Page Pyro l ysi s pro du c t s from Amadori

c ompound s and contro l s 24

Vo l a t i l e o rgani c pyrolys i s pro du c t s

£rom 1 -deoxy- 1 -gl ycino-D-£ruc to s e

and 1 -� - a l anino - 1 -deoxy-D-fru c t o s e 2 7 , 28 Pyro l ys i s pro du c t s from 3-deoxy-D-

e rythro-hexo sul o s e a t 1 95 °/1 5 min 3 3 Incorpora tion o f radi o a c tivi ty

i n t o pyro lysi s produc ts of 1 -� ­

a l anino- 1 -deoxy-D- fru c t o s e s derived

£rom gl u c o s e l abel l e d a t vari ous

p o s i t i ons 35

Fo rma t i on of 1 -deoxy- 1 -glyc ino-D- f ru c t o s e from gluco s e plus gly c i ne

mixture s heated in the dry-s t a t e 4 1 R a t e o f browning o f vari ous sys tems

in paraffin 4 3

Phys i c al da ta f o r amine s under s tudy 78 Pyrolys i s produ c t s from the 1 - amino -

1 -deoxyfruc t o s e s a t 250°/1 5 min 8 1 Pyrolys i s produ c t s from 1 -deoxy- 1 -

p ro l i no-D-fru c t o s e under vari ous

the rmal t rea tment s ( 1 5 min dura ti o n) 84 Vo l a t i l e o rgani c pyro l ysi s pro duc t s

from 1 -deoxy- 1 -mo rpho l ino-D- fru c t o s e 86 Vo l a t i l e o rgani c pyro lysi s produ c t s

from 1 -deoxy- 1 -p- t o l ui dino-D-

fruc t o s e 87

Vo l a t i l e o rgani c pyro lys i s produc t s from 1 -deoxy- 1 -dibenzyl amino-D-

f ru c t o s e 88

Vo l a t i l e o rgani c pyro lys i s produ c t s from 1 -d e o xy- 1 -pro l i no-D- fru c to s e and

1 -deoxz- 1 -N-me thyl ani l ino-D- fru c t o s e

at 250 /1 5 min _. 89

General re l a t i onship be tween the b as i c mo i e ty o f 1 -amino - 1 -deoxyfruc to s e s and

the observed pyrol ys i s produc t s 95

ix

Li s t o f' F i gure s

Intro du c t i o n Fi g I . 1

Fi g I . 2

Part A Fi g ^A. 1

Fig A. 2 Fi g A. 3

Fig A. 4

Fig A . 5 Fi g A . 6 Part B Fi g B . 1 Fig B . 2 Fig B . 3

Fig B. 4 Fi g B. 5

Forma tion o f' Amadori compounds

Sugge s ted scheme f'or the produc t i o n o f' melano i d i n s in a n aldo s e- amino sys tem

Dif'f'eren t i al s canning cal o rime tri c curve s f'o r 1 -d eoxy- 1 -glycino-D­

f'ru c t o s e and contro l s

Thermogravime tri c analys i s curves f'or 1 -deo xy- 1 -glycino-D-f'ruc t o s e and contro l s

The rmogravime tric and de riva tive thermogravime t ri c curve s f'o r 1 -deoxy- 1 -gl y c ino-D- f'ru c to s e , heating ra t e 0 . 5°/min

Kine ti c tran s fo rma t i on o f' the t . g.

curve f'o r 1 -d eoxy- 1 -glycino-D­

f'ru c to s e , he a ting ra t e 4°/min Kine t i c t rans fo rma t ion o f' the t . g.

curve f'o r 1 -d e oxy- 1 -glycino-D­

f'ruc to s e , he a t ing ra t e 0 . 5° /min Pathway of' p ro toanemonin fo rm a t i o n

Browning rou t e f'o r sugars and primary amino acids

Progre s s of' the browning re a c t i on be t�een gl u c o s e and � - al anine a t

1 20 i n the s o l i d s ta t e

Progre s s o f' the browning re ac t i o n be twe en glu c o s e and � -alanine in

the p res ence o f' 1 -� -al ani no - 1 -o deoxy-D- f'ru c to s e a t 1 20 in the_

s o l i d s ta t e

Progre s s o f' the browning reac ti o n be tween glu c o s e and � -alani ne a t

1 50° i n the s o l i d s t ate

Pro gre s s o f' the browning rea c ti on be twe e n gluco s e and � -al anine i n

the p re s en c e o f' 1 -�-alanino- 1 -o deoxy-D-f' ru c to s e a t 1 50 in the s o l i d s ta t e

Page

3 6

1 5 1 6

1 8 20 2 1 30

45 4 9

5 0 5 1

5 2

Fi g B. 6 Fi g B . 7 Fi g B . 8 Fig B. 9 Fi g B. 1 0

Fig B . 1 1 Fi g B . 1 2 Fi g B. 1 3

Fig B . 1 4

Part C Fi g c . 1 Fig c . 2 F i g c . 3 Fig C. 4 Fig C. 5 Fi g c . 6 F i g C. 7 Fi g c . s

Di s appearanc e o f gluco s e during ₀ browning a t 1 20 in the solid s ta t e Di s appe aran c e o f gluco s e during ₀ browning a t 1 50 i n the solid s ta t e Change o f absorbance during

browning � t 1 20°

Change o f abs o rbance during browning a t 1 50°

u.v. spe c trum o f browning produc t s from gluco s e and � -al anine a t 1 20°

i n the s o l i d s tate

WeiBht l o s s e s duri ng browning a t 1 20 i n the s o l i d s tate

We i§ht l o s s e s during bro wning a t 1 50 i n the s o l i d s tate

Rel a ti onshi p be twe en the di s appe ar­

ance o f gluco s e and �-alanine during browning a t 1 20° in the s o l i d s t ate

Fi rs t o rder pl o t fo r the di sapp e a ra^{n c}e o f �-al ani ne during bro wning o f

gluco se + �- a lanine ( 1 : 1 ) a t 1 20° i n the s o l i d s t^ate .

Degradation o f monoke toseami ne s vi a 1 , 2 eno l i s a t i on

De grada tion o f monoke to seami ne s vi a 2 , 3 eno l i s a t i o n

Thermogram for the de compo s i t i o n o f 1 -deoxy- 1 -p ro l ino-D- fructo s e

Thermogram for the de c ompo s i t i o n o f 1 -deoxy- 1 -morpho l ino-D-fruc to s e Thermogram f o r the decompo s i t i o n o f

1 -deoxy- 1 -p- tolui dino-D-fru c to s e . Thermogram for the de compo s i t i o n o f

1 -deoxy- 1 -N-me thyl ani l ino-D­

fru c to s e

Thermogram fo r the decompo s i t i o n o f 1 -deoxy- 1 - dibenzyl ami no-D- fruc to s e T. g. and d . t . g. curve s for the de compo si t i on o f p i peridine-hexo s e ­ reduc tone

x i

Page 5 4 5 4

5 7 5 8 6 1 6 1

62

62

66 7 1 7 2 73 74 75 77

Fig C . 9

Fig C . 1 0

Fi g C . 1 1

App endi c e s Fi g A 2 . 1 Fig A 3 . 1

Fi g A 3 . 2

Rel a t i o nship be twe en bas i ci ty o f amine subs t i tuent and residue

remai ning a t 400° from the pyro lysi s o f 1 - ami no- 1 -deoxy- 2-fru c to s e s

Re l a ti onship be twe en ba s i ci ty o f amine substi tuent and de compo si t i on t emp era ture o f 1 -amino - 1 -deoxy-2- fru c t o s e s

Pro p o sed decomp o s i t i o n re a c t i ons o f 1 -de oxy- 1 -morpho l i no-D- fruc t o s e

I . R . spec tra o f Amado ri compound s Change o f abso rbanc e wi th time for a 1 -� -al anino - 1 -deoxy-D- fruc t o s e determina t i o n a t 5 74 nm

C ompari son be tween ^u.v. and T . M . s . me thod s for moni t o ring 1 -�-al ani no -

1 -d eoxy-D- fru c t o s e l eve l s during browni ng

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1 1 0