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THE RHEOLOGY OF BUTTER
A thesis presented
in partial fulfillment of the requirements for the degree
of Doctor of Philosophy in Food Technology
at
Massey Pniversity.
Michelle Harnett
1989.
i i
Abstract.
A para l l e l p l at e vi s co e l a s t omet e r was b ui l t t o per form creep c o mp l i ance t e s t s on b utter and re l ated fat s . C reep movement w a s me a s ured with a l i near di s p l acement t r ans d ucer and
r e c o rded by a data l ogger de s i gned and b ui l t f o r c reep c o mp l i ance expe r iment at i on .
A t emperat ure o f 1 0 °C was ma i n t a i ned b y p l a cing the par a l l e l p l at e v i s c o e l a s t ome t e r in a re f rigerated i n c ubat o r .
A s e r i e s o f pre l iminary expe r i ment s e s t ab l i shed the creep r e sponse w a s l inear and that t he dire ct i o n in wh i ch s ome s amp l e s we re sheared was cr i t i c a l . The d urat i on o f creep c o mp l i ance t e st ing was a l s o f o und to a f fe ct r e s ul t s .
C r eep behavi o ur o f b utter wa s a s s umed t o be v i s c o e l a st i c ( b a s e d o n p revi o us st udies ) and was mode l led w i t h a
g e n e ra l i z ed Ke lvin mode l . El a s t i c and v i s c o us parame ters were f i t t e d to the dat a by a Marqua dt non- l i near l e a s t squares c urve a l g o r ithm . Cont i n uo us ret ardat i o n spect r a we re f o und by p l ot t ing
L(�)aga i n s t ln t ime . Data wh i ch had been both
s moothed and di f fe rent i ated by the met ho ds of S av i t z ky and G o l a y
(1964)showed evidence o f the e xi s t ence o f three or f o u�
m a in g r o up s o f ret ardat i on mechan i sms .
O n remova l o f s t re s s a fter c r e ep comp l i ance t e s t ing a part i a l r e c ove ry o f st rain w a s ob s e rved, howeve r , s amp l e s fai l ed t o r ec ove r a s m uch a s p redi cted b y v i s co e l a s t i c t h e o r y . A s e cond c reep / recovery cycle re s ulted in a respon s e s s im i l a r in
m a gn i t ude to the f i r s t recove r y . All fat produ c t s tested
s h owed the s ame pat t e rn of response o n repe ated creep / recove ry c y c l ing .
An expl anat i o n , ba s e d on the behavi o r o f p o l yme r s , was put
f o rward t o exp l a i n t he ob s e rved pat t e rn o f r e s p on s e . The
i ii
c r y s t a l network was t h o ught t o a l i gn i n the direct i on in whi ch s t r e s s was app l i e d . The format i o n o f new ' bonds ' was t hen
t h o ught to l o c k the network i n i t s ' new p o s i t i on .
A n umbe r o f s amp l e s were rewo r ke d , The c re ep c urve seen on creep/ re c ove ry cyc l i ng o f rewo r k e d s amp l e s was s im i l a r in s hape to t h at s e en for t he o r i g i n a l s amp l e s . Howeve r , the c urve s were t hree to f o ur t im e s great e r than tho s e s een f o r t he o r i g i n a l s amp l e s . I n gen e ra l , creep re spon s e wa s f o und t o b e inve r s e l y prop o rt i on a l t o h a rdne s s .
The ret ardat i on spect ra o f reworked s amp l e s di f fe r e d from t h o s e s e en for the o r i ginal s amp l e s in s eve ral way s . The spect ra we r e smoothe r , the b ul k o f the spectra had moved t o s h o rt e r t ime s and t he y were l a rger than those seen for the o r i g inal s amp l e s .
A s urve y o f s e a s on a l b ut t e r s amp l e s was a l s o unde rt aken . C reep c omp l i ance paramet e r s were f o und t o corre l ate we l l w i t h
s e ct i l i t y h a rdne s s a n d s o l i d . fat c ontent .
•
i v
Aim of Study.
The a ims o f t h i s work a r e :
a ) T o s t udy t h e rhe o l og i ca l prope rt i e s o f but t e r a n d re lat e d f a t p r o d uct s by a creep comp l i ance metho d .
b ) T o gain a c l earer unde r s t anding o f the re l at i onship between rhe o l o g i c a l pr opert i e s , c omp o s i t i on and s t r uct ure o f b ut t e r and r e l ated product s .
c ) T o us e t h i s knowledge t o improve the rhe o l o g i c a l prope r t i e s
o f b ut t e r .
V
Acknowledgments.
I am i ndebt ed t o my s upervi s o r s D r . M . W . T ay l o r , D r .
J.L e L i evre , D r . R . Lambert and D r . R . Norr i s , who s e adv i c e and s upport wa s grat e fu l l y rece ived . I am a l s o i ndebt ed to the New Z e a l and D a i r y Re s e a r c h I n s t i t ute who funded t he pro j ect in the f o rm o f a re s e a r ch contract . In addi t i on I wou l d l i ke to thank A l a s t a i r MacGibbon , Trevor B i s s e l l and othe r membe rs o f the Mi l k fat S e ct i on , New Z e a l and D a i r y Re s e arch I n st i tute f o r t he i r ide a s a n d d i s cu s s i on . I nva l u ab l e techn i ca l a s s i st ance was rende red by t he t e chn i c a l s t a f f of t he F o o d Techn o l ogy D ep a rtment , Ma s s e y Unive r s i t y and by the Da i ry Pr odu c t s D eve l opment Cent re s t a f f , N e w Z e a l and D a i ry Re s e a rch
I n s t i t ute . F i n a l l y , thanks to TD f o r moving to Pa lme rs to n
N o rt h .
List of Contents.
AB S TRACT . i i
A IM . iv
ACKNOWLEDGE MENT S . v
C HAP TER ONE : AN INTRODUCT ION IN THREE PARTS . P a rt A : Rhe o l ogy .
lA . l . Int r oduct ion .
1 A . 2 . S t re s s and s t r a i n .
1A . 3 . S o l i ds , l i qu ids , p l a s t i c s . 1A . 4 . V i s c oe l a st i c s .
1A . 5 . Me chan i c a l mode l l i ng . 1A . 6 . Fundame nt a l t e st ing .
1A . 6 . 1 . Stat i c t e st ing . 1A . 6 . 2 . Dynam i c t e s t ing:
1A . 7 . Emp i r i c a l t e s t ing .
P a rt B : Me a s u rement o f the rhe o l og i c a l paramet e r s o f b ut t e r 1 1 1 1 2
7
7 10 10 19 2 2
and marg a r i n e . 23
l B . l . Int roduct i on . 2 3
1B . 2 . Fundame nt a l t e chn i que s . 2 3
1 B . 2 . 1 . Creep comp l i ance . 2 3
1 B . 2 . 2 . Cont i nuous she a r . 1 B . 2 . 3 . Dynam i c t e s t ing .
1 B . 3 . Emp i r i c a l and imitat ive t e s t i ng . 1 B . 3 . 1 . Sect i l i t y ha rdne s s .
1 B . 3 . 2 . E xt ru s i on . 1 B . 3 . 3 . Comp r e s s i o n . 1 B . 3 . 4 . Pene t r omet ry .
1 B . 3 . 5 . Spreadab i l i t y s i mu l at i on . P a rt C : But t e r and margar ine .
lC . l . I n t roduct i on . 1 C . 2 . Butter
34
3 7
4 1
4 1
4 3
4 5
4 7
5 0
5 1
5 1
5 1
1 C . 2 . 1 . Manu f acture . 1 C . 2 . 2 . S t rut u re .
1 C . 2 . 3 . F act o rs af fect ing rhe o l ogy . 1 C . 3 . Marg ari ne
1 C . 3 . 1 . Man u f acture . 1 C . 3 . 2 . S t ru t u re .
1 C . 3 . 3 . F act o rs af fect ing rhe ology . 1 C . 4 . Ammi x but t e r .
1 C . 4 . 1 . Man u f acture . 1 C . 4 . 2 . S t ruture .
1 C . 4 . 3 . F act o rs af fect ing rhe o l ogy . 1 C . 5 . A ft e rw ard .
C HAP TER TWO : MATERIALS .
2 . 1 . But t e r f rom comme rc i al dai ry fact o ri e s . 2 . 1 . 1 . C omme rc i al s amp l e i dent i f i c at i on .
5 1 5 4 5 5 6 2 6 2 6 6 6 7 7 2 7 3 7 3 7 5 7 8
7 9 7 9 7 9 2 . 2 . B ut t e r m ade u s ing di f fe rent c re am c o o l ing te chn iques . 7 9 2 . 3 . Butt e r and anhydrous product s made f rom the s ame f at . 8 0
2 . 4 . Rewo rk in g . 8 3
2 . 5 . S t o rage . 8 4
C HAP TER T HRE E : E S TABL I S HED ME T HOD S . 3 . 1 . E xt ract i o n o f mi l k f at .
3 . 2 . S e ct i l i t y h ardn e s s . 3 . 3 . F at t y ac i d c ompo s i t ion . 3 . 4 . T ri g l y c e ri de comp o s i t i on .
8 5 8 5 8 5 8 6 8 8 3 . 5 . S o l i d f at content by nu c l e ar magnet i c re s o n an c e . 8 8 3 . 6 . S o l i d f at cont ent by di f fe re nt i al s c anning c al o rimet ry . 8 9 3 . 7 . C omp ari s on o f nuc l e ar magnet i c re s o n ance and di f f e rent i al s c an n i ng c al o rimet ry .
C HAP TER FOUR : CREEP CO MP L I ANCE ME T HOD . 4 . 1 . The i n s t rument .
4 . 2 . Temp e rat u re ' cont ro l .
4 . 3 . The d at a c o l l e ct i on s y stem .
4 . 4 . S amp l e p rep arat i on , l o ading and runn i ng . 4 . 5 . Re c ove ry and l o ad c yc l i ng .
4 . 6 . D at a an al y s i s .
9 0
9 2
9 2
9 4
9 6
10 0
10 3
1 0 3
4 . 6 . 1 . C reep curve s . 10 3
4 . 6 . 2 . Re coverey . 114
4 . 6 . 3 . P re s e nt a t i on o f re s u l t s . 1 1 4
4 . 6 . 4 . Re tardat i o n spect r a .
1174 . 7 . P re l im i n a r y exper iment s . 12 9
4 . 7 . 1 . L in e a r i t y . 12 9
4 . 7 . 2 . O r i en t at i o n . 12 3
4 . 7 . 3 . Repe at ab i l i t y . 141
C HAP T ER F IVE: LARG E D EFORMAT ION T EST ING. 149
5 . 1 . I nt roduct i on . 149
5 . 2 . Expe r ime nt a l me th od . 15 2
5 . 3 . Expe r i men t a l and r e s u l t s . 15 3
5 . 4 . D i s cus s i on . 16 3
5 . 5 . Concl u s i o n . 17 2
5 . 6 . Trad it i on a l s e ct i l i t y ha rdne s s t e s ti n g vs . l a rge
de f o rmat i on t e s t ing . 17 2
C HAP T ER S I X : AN INTROD UCT I ON TO CREEP CO MP L IANC E EXP ER I MENTAT I ON .
P a rt A
6A . 1. Exper ime nt a l . 6A . 2 . Re su l t s . 6A . 3 . D i s cu s s i o n .
P a rt B : But t e r s manu factured u s i n g di ffer ent cream c o o l ing t e chn i que s .
6B . l . Expe r i me nt a l . 6B . 2 . Re s u l t s . 6B . 3 . D i s cu s s i on .
C HAP T ER S EVEN : T HEORY . 7 . 1. I n t roduct i o n . 7 . 2 . Load c y c l ing .
7 . 2 . 1 . Expe rime nt a l . 7 . 2 . 2 . Re s u l t s . 7 . 2 . 3 . D i s cu s s i on . 7 . 3 . Rework i n g .
17 4 1 7 ·4 17 4 17 4 17 6
17 8 17 8 17 8 17 9
18 1
18 1
18 1
18 1
18 1
19 1
19 4
7 . 3 . 1 . Expe r i me nt a l . 1 9 4
7 . 3 . 2 . Re sult s . 1 9 4
7 . 3 . 3 . D i s cu s s i on . 2 0 4
7 . 4 . Deve l opment o f a theory t o e xpl a i n ob s e rved behavi our . 2 0 6
7 . 4 . 1 . I nt r oductory comment s . 2 0 6
7 . 4 . 2 . Theory A . 2 0 6
7 . 4 . 3 . Theory B . 2 0 8
Chapt e r E i ght : But t e r and Anhydrous P r oduct s made from the
S ame F at . 2 1 3
8 . 1 . I nt rodu ct i on . 2 1 3
8 . 2 . Expe r iment a l . 2 1 3
8 . 3 . Re s u l t s . 2 1 4
8 . 3 . 1 . Sect i l i t y hardne s s and sol id fat cont ent . 2 1 4
8 . 3 . 2 . Creep comp l i an ce . 2 2 9
8 . 4 . D i s c u s s i on . 2 3 5
8 . 4 . 1 . Compo s i t i on 2 3 5
8 . 4 . 2 . Reworking . 2 4 2
C HAP TER N I NE : SEAS ONAL TREND S I N FRI T Z AND AMMI X BUT TE R . 2 4 5
P a r t A : E s t ab l i shed method s . 2 45
9A . 1 . I nt roduct i on . 2 4 5
9A . 2 . Exper iment a l . 2 4 5
9A . 3 . Re s u l t s and di s cu s s i on . 2 46
9A . 3 . 1 . Sect i l it y h a rdne s s . 2 4 6
9A . 3 . 2 . S o l i d fat content . 2 46
9A . 3 . 3 . Compar i s on between s e ct i l i t y ha rdne s s and s o l i d
f a t cont ent . 2 5 1
9A . 3 . 4 . D i f fe rent i a l s canning ca l o r imet ry . 2 5 5
9A . 3 . 5 . Fatty a c i d compo s i t i on . 2 5 6
9A . 3 . 6 . T r i g l y c e r i de c ompo s i t i i on . 2 6 1 9A . 4 . C o n c lu s i on .
P a r t B : C reep comp l i ance . 9 B . 1 . Exp e r iment a l .
9 B . 2 . Re s u l t s . 9 B . 3 . D i s cu s s i o n . 9 B . 4 . C on c l u s i on .
2 6 4
2 6 5
2 6 5
2 6 5
2 7 1
2 7 2
C HAP TER TEN : GENERAL D I S CU S S ION .
1 0 . 1 . D eve l opement o f the c reep comp l i ance method . 1 0 . 1. 1. Equ i pment .
10 . 1. 2 . D a t a C o l l e ct i on . 10 . 1 . 3 . Tempe rature Contr o l . 1 0 . 1 . 4 . Ac curacy .
1 0 . 2 . D at a ana l y s i s .
10 . 2 . 1. The V i s c oe l a s t i c Mode l . 10 . 2 . 2 Dat a Ana l y s i s .
10 . 2 . 3 . Ret a rdat i o n Spectra .
10 . 2 . 4 . App rop r i atene s s o f t he Mode l . 1 0 . 3 . P re l iminary Exper iment s .
10 . 3 . 1. L i n e a r i t y .
1 0 . 3 . 2 . Durat i o n o f E xper iment . 10 . 3 . 3 . O r i e nt a t i on o f Samp l e . 10 . 4 . Load Cyc l i ng .
1 0 . 5 . P r oduct s made from t he same fat . 1 0 . 6 Rewo rked pr oduct s .
10 . 7 . S e a s o n a l s u rvey .
1 0 . 8 . Conc l u s i on and fut ure work . AP P END I X 1 : Compu t e r P r ograms .
2 7 4 2 7 4 2 7 4 2 7 4 2 7 5 2 7 5 2 7 6 2 7 6 2 7 7 2 7 8 2 7 8 2 7 9 2 7 9 2 8 0 2 8 2 2 8 4 2 8 9 2 9 0 2 9 1 2 9 3 2 9 6 AP P END I X 2 : Non- l i n e a r Le a s t Square s Cu rve F i t t ing Re s u l t s . 3 13
APP END I X 3 : D i f fe rent i a l S c ann ing C a l o r imetry Me l t i ng The rmo grams , 19 8 5 - 19 8 6 S e a s on .
REFERENCE S .
3 42
3 5 6
List of Tables.
Table 1 . 1 : Creep r e s u l t s report ed by var ious worker s . 2 6
Table 1 . 2 : Re sults r epor t ed b y D a v i s ( 1 9 73 ) us ing a var iety o f r heological
met hods . 2 9
Table 1 .3 : Compar i s on o f the results r epor ted by S hama and S herman ( 1 9 7 0 )
and Gupta a nd D eMan ( 1 9 8 5 ) . 3 1
Table 2 . 1 . Pr oduct ion conditions used i n the manufactur e o f butt er and
anhydr ou s pr oduct s from the s an e milk fa t . 8 2
Table 2 . 2: Product temper atur e s r ecorded dur ing pr oduct ion of butter and
a nhydr o u s pr oduc t s from the same milk fa t . 8 2
Table 3 . 1 : Compo s i t i on o f standard a� hydr ous mi lk fa t . 8 7 Table 3 . 2: Norma l iz ing factor s f or fat t y acid we ight per centage s , relat ive
to c 16 : o· 8 7
Table 4 . 1: The e f fect o f var y i�g the n umb er of exponent i a l terms used i n f it t ing dat a to the pr e f i ned mode l . (Sample TUI A ugu st ' 86 , 1 0° C . ) 1 1 0 Table 4 . 2 : P ar ameter s f itted t o cr eep c ompl iance dat a by two met hods , e xponen t i a l pee l ing and non-l inear c�rve f itt ing . 1 13 Table 4 . 3 : A compar i s on o f retardat ion t imes calculated by a lea s t sq uares c ur ve f i t t ing pr ogr am ( NONLIN ) and tak en from conti nuous r e t arda t ion
s pe c tr a, F igur e s 4 . 2 0 and 4 . 2 2 . 1 2 8
Table 4 . 4: S tr a in r e sponses obser ved o n the applicat ion o f s tr e s s . 13 1 Table 4 . 5 : Cr eep compl iance par ameter s f ound for one s ample on t he
app li c a t ion o f dif fer ent str e s s e s . 13 1
Table 4 . 6 : Cr eep compl iance parameter s obt a ined fr om patted Fr itz butt er s
s he ar e d i n t he thr ee poss ible direction s . 13 4
Table 4 . 7 : Recover y dat a f or the butter TUI Apr i l ' 8 7 . 13 6
Table 4 . 8: Cr eep comp l i a nce par ameter s obt a ined from patted Fr itz butter s
shear e d i n two direct ions . 13 6
Table 4 . 9 : Cr eep compl iance par ametr s obta ined from unpatted Fr i tz but ter s
s h e ar e d i n two dir ect ions . 13 8
Table 4 . 1 0 : Cr eep comp l i ance par ameter s f i t ted t o cr eep curves obser v ed for
t he butter TT Januar
y
, 1 9 8 6 . 1 4 4Table 4 . 1 1: Creep c ompl iance par ameter s f itted t o cr eep cur ve s obser ved for
t he butter TT Apr i l , 1 9 8 6 . 1 4 7
Table 5 . 1 : P er centage s o l id fat determined by NMR and tr adit ional sect i l ity h ar
dri
e s s values a t 1 0°C for butt er s used in large de f orma t ion t e s t ing . 1 5 4Table 5 . 2 : An e xample o f dat a reco rded by the Perkin E lme r dat a s ta t io n
dur i ng la rge de fo rmatio n tes t ing . 16 1
Table 5 . 3 : Compariso n o f s e c t i l i t y h a rdness tes t ing ( t radi t io n a l ) with s he a r t es t ing .
Table 5 . 4: S e c t i lity hardness res u l ts ( C R Analys e r ) .
16 4 16 4
Table 5 . 5: The fit o f v a r io us mo dels to shear speed vs . fo rce data fo und at 5 , 1 0 a nd 1 5° C fo r fo ur s amples express ed as co rre lat io n co e f f i c ients . 16 9 Table 6 . 1 : Rheo lo gical pa rameters fo und fo r creep and reco v ery experiments
o f d i f fe ring length . 1 7 5
Table 6 . 2 : Sect i lity hardness v a lues a t 1 0°C fo und fo r but t e rs manufactured f ro m c ream s ub j ected to di f fe rent c re am coo l ing t e chniq u es . 1 8 0 Tab l e 6 . 3 : C reep compl iance pa ramete rs f itted to t he c reep res po nse o f but t e rs manufactured fro m c ream s ub j ected to di f fe rent c ream coo l ing
techniq ues . 1 8 0
Table 7 . 1 : Sect i l ity ha rdness es and so l id fat co ntents o f s e lected
det e rmined at 1 0° C . 1 83
Table 7 . 2 : C reep compl iance parame t e rs fo r s amp les co l lected t h ro ughout the yea r . 1 8 7
Table 7 . 3 : Ov e r a l l creep respo ns e d isp layed by s amples co l lected thro ugho ut
t he yea r . 1 8 8
Table 7 . 4 : Co r relat io n co e f f ic ients fo und b etween v a r io us c reep comp l i ance pa rame t e rs and sect i lity ha rdness fo r s amples o f butte r co llected
t h ro ughout t he yea r . 1 8 9
Table 7 . 5: Creep compliance pa rame t e rs f itted to o riginal and rewo rked
but t e r pa i rs . 1 9 5
Table 7 . 6: P e rcent age changes s een i n creep respo nse o n t he rewo rking o f
but t e r s amp les . 1 9 7
Table 7 . 7 : P e cent age change fo und i n s elect ed pa ramet e rs o n compa ring f i rs t
and s e co nd c reep respo ns es . 1 9 7
Table 7 . 8: Ret a rda t io n t imes found fo r o rigianl and rewo rked but t e rs . 2 0 3
Table 8 . 1: S e c t i lity h a rdness res u l ts , 1 0° C . 2 1 5 Table 8 . 2 : So l id fat co ntents as det e rmined by NMR . 2 1 5 Table 8 . 3 Creep compliance parame t e rs fo r o r igina l and rewo rked s amples o f but t e r , plas t i c ized milkfat and a mi l k f a t /o i l blend man u f a c t u red f rom t he
s ame fat so urce . 2 2 0
Table 8 . 4: Co r relat io n co e ff i c ients found between v a r io us c reep comp l iance pa r amet e rs and sect i l i t y h a rdness' fo r o rigina l and rewo rked but t e rs ,
p l a st ic ized milk f at and milk fat/ o i l blend m anufact u red f rom th e s ame f at . 2 2 1 Table 8 . 5 : Pe rcent age ch anges seen i n various param et e r s go ing f rom
o r iginal t o rewo rk ed .
Table 8 . 6 : Comparison o f second c reep response with the f i r st c reep response .
23 1
233 Table 9 . 1 : The sect i l it y h a rdness o f s amples o f patted butte r det e rmined at
1 0° C . 2 4 7
Table 9 . 2: Pe rcent age soli d fat a s det ermined by NMR for s amples o f milk fat
ext racted f rom F r itz butt e r . 2 4 9
Table 9 . 3: P e rcent age s o l id fat a s det e rmined b y NMR for s amples o f milk fat
ext racted f rom �� ix butt e r . 2 5 0
Table 9 . 4 : Fatt y acid comp o s it ion o f F ritz b utt e r s col lect ed dur ing the
1 9 8 5 - 1 9 8 6 season . 2 57
Table 9 . 5 : Fatt y acid compos s iton o f Amm ix butt e r s collect ed du r i ng th e
1 9 8 5 - 1 9 8 6 season . 2 5 8
Tab le 9 . 6 : Trigly ce ride com po s it ion o f F r itz b utt e rs collected du ring th e
1 9 8 5 - 1 9 8 6 season . 2 6 2
Table 9 . 7 : Triglycer ide compo sit ion of Amm ix butt e rs c o l le cted dur i ng th e
1 9 8 5 - 1 9 8 6 season . 2 63
Table 9 . 8 : Creep com pl iance paramet e rs f itted t o butters . 2 67 Table 9 . 9: Co rrelat ion coe f f ic ient s found between sect i l it y h a rdne s s a nd s o l id f at content and c reep compl iance paramet e rs for a numbe r o f b utt e rs .
2 6 9 Table 9 . 1 0 : C reep com p l iance par amet e r s f o r samples c o l lect ed th rough out
the yea r . 2 7 0
List of Figures.
F igure 1 . 1: Rate o f sh ea r vs . sh ear for a Bingh am plast i c . 6
Figu re 1 . 2: Stan da rd rh eological m ode ls : a) Hookean s p r in g , b) Newt on ian
da shpot , c ) St Ven ant glide r . 8
F i gure 1 . 3: Rh eological m odel s: a) B ingh am plast i c , b ) Max wel l un it , c)
Kelvin un it and d) , Burgers m ode l . 9
F i gu re 1 . 4: Typic a l c reep an d recove ry curve for a p l a st ic f at . 1 3
Figure 1 . 5 : A m ode l c reep cu rve . 1 4
F igure 1 . 6: The generalized Kelvin m odel . 16
Figu re 1 . 7: St re s s re spon s e t o s in uso ida l st rain . 2 1 Figure 1 . 8: Creep parameters repo rted by G upt a an d D eMan ( 1 9 8 5 ) plotted
again st force used . 3 3
Figure 1 . 9: Th e m odif ied Bin gh am body . 36
Figu re 1 . 1 0: a) Th e Vis cous -Max we l l -Bin gh am mode l (D e in e r and He ldman, 1 9 86) , b) st uct u r a l applicat i on of the m ode l . 3 9 Figure 1 . 1 1: Th e P a s i lac HCT 2 cont in uous butt e rm ak e r . 5 3
Figure 1 . 1 2: D i f f e rent ial scann in g calorim et ry m e lt in g th e rm og r am o f a
F r itz butt e r . 5 7
Figure 1 . 1 3: D iagram of a sect ion th rough a sc raped s u rface h e at exchange r . 6 4 Figure 1 . 1 4: Cont in uous soft m a rga rin e p roduct ion ( E r i ks on, 1 9 8 5) . 6 5
F igure 1 . 1 5: D i f f e rent i a l s cann in g c a l o r im et ry m e lt in g th e rm ogram o f a
t ab le m a rgarine . 6 9
Figure 1 . 16: Th e Amm ix proce s s . 7 4
F igure 1 . 1 7: D i f f e rent i a l scann in g c a l o r im et ry m e lt in g the rm ogram of an
Amm ix b utte r. 7 7
F igure 2 . 1: P lant con f igurat i on used in the m an u fa ct u re o f butt e r an d
anhydrous product s f rom t he smae f at . 8 1
F igure 4 . 1: The pa rallel p l at e viscoelast ometer . 9 3
F igure 4 . 2 : D i f fe rent ial s c ann in g c a l o r im et ry m e lt in g t h e rm ogram
i l lust rat in g the c hanges in s o l id fat content with tem pe r ature at 1 0 and
1 5oC . 9 5
F i gu re 4 . 3 : Fluct u at i on in tem pe rat ure obse rved ove r
�
f o rt y hour period . 9 7F igure 4 . 4: D at a collect ion syst em . 9 8 F igure 4 . 5: Ch a rt recorde r t race seen on pe r f o rming a c reep compl iance
expe r iment . 9 9
F igure 4 .6: P lan and s ide views o f th e s ample cutt e r . 1 0 1
F igure 4 . 7: A c reep and recove ry curve . 1 0 4
F igure 4 . 8 : A c reep compl iance curve sh owing ext rapo l at ion back t o 0 t ime . 1 06 F igu re 4 . 9: Ln Q plotted aga inst t ime sh owing th e st r a ight l ine port ion of
th e graph ext rapo lated to 0 . 1 0 8
F igure 4 . 1 0 : Creep and recove ry curve s sh owing inst a nt aneous comp l iance, th e s um o f comp l i ances recovered and th e un recovered st r a i n . 1 1 5
F igure 4 . 1 1: Re sult presentat ion b y th e curve f itt ing p rogram NONLIN . 1 16
F igure 4 . 12 : An ideal cont inuous ret a rdat ion spect rum c a lculated for the
s ample MAN May 1 9 8 7 . 1 1 9
F igure 4 . 13 : Ret a rdat ion spect rum found f o r the sample MAN May 1 9 8 7 us ing
raw dat a . 1 2 0
Figure 4 . 1 4 : Cont inuous reta rdat ion spect rum found f o r MAN May 1 9 8 7 a fter
smooth ing raw dat a . 122
F igure 4 . 1 5 : Th e ideal cont inuous ret a rdat ion spect rum found f o r MAN May
1 9 8 7 a ft e r smooth ing . 122
F igure 4 . 16: Th e cont inuous ret a rdat ion spect rum found f o r MAN May 1 9 8 7
a ft e r d i f f e rent iat ing th e raw dat a . 123
F igure 4 . 1 7: Th e ideal cont inuous ret a rdat ion spect u rm f ound f o r MAN May 1 9 8 7 a ft e r diffe rent iat ing according t o the meth od o f S az itz ky and Go lay
( 1 96 4) . 123
F igure 4 . 1 8: Th e ideal cont inuous ret a rdat ion spect u rm f ound f o r MP� May 1 9 8 7 a ft e r a 13 point cubic d i f f e rent iat ion . 1 2 4 F igure 4 . 1 9 : Th e ideal cont inuous ret a rdat ion spect u rm f ound f o r MAN May 1 9 8 7 a ft e r a 7 point qua rt i c d i f f e rent iat ion . 1 2 4
F igure 4 . 2 0 : The cont inuous ret a rdat ion spect u rm found f o r MAN May 1 9 8 7 a ft e r smooth ing and d i f f e rent iat ing according t o the meth od o f S avitz ky and
Golay ( 1 96 4) . 1 2 5
F igure 4 . 2 1 : Th e ide a l cont inuous ret a rdat ion specturm found for MAN May 1 9 8 7 a ft e r smooth ing and di f fe rent iat ing according to th e meth od o f
Savitz ky a nd G o l a y ( 1 96 4 ) . 1 2 5
F igure 4 . 2 2 : The cont inuous ret a rdat i o n spect u rm found f o r MAN Apr i l 1 9 8 7 a ft e r smooth ing and di f fe rent iat ing �c c ording t o the meth od o f S avitz ky and
Golay . 1 26
F igure 4 . 2 3: The ideal cont in uous ret a rdat ion s pecturm foun d f o r MAN April 1 9 8 7 a ft e r smoot h in g and di fferent i at in g according to t he method of
S avitzk y an d Golay ( 1 9 6 4) . 1 2 6
F igure 4 . 2 4: Th ree dimen s ion a l axes imposed on a pat o f butt e r . 1 3 3 Figure 4 . 2 5: Ope rat in g prin c iples o f t he S ig FD 1 4 0 patt e r . 1 3 9
F igure 4 . 2 6 : Creep complian ce curve s foun d f o r t he samp le T T Jan ua ry ' 8 6 . 1 4 3 Figure 4 . 2 7: Creep compl ian ce curves foun d f o r the samp le T T Ap r i l ' 8 6 . 1 4 5 Figure 5 . 1 : Front an d s ide views o f t he apparat us att a c hed t o t he c R
An a lyser used for shea r test ing . 1 5 1
Figure 5 . 2: Force vs . shear speed f o r t he sample TUI Februa ry 1 9 8 7 . 1 5 5 Figure 5 . 3 : Force v s . s hea r speed f o r t he samp le MAN MAy 1 9 8 7 . 1 56 Figure 5 . 4 : Force vs . shear speed f o r t he sample TT Februa ry 1 9 8 7 . 157 Figure 5 . 5 : Force vs . s hear speed f o r t he s ample TT M a rch 1 9 8 7 . 1 5 8 Figure 5 . 6: Shear fa i lu re st res s plotted aga in st tempe rat ure . 16 0 Figure 5 . 7 : St ress vs . distance moved by the p robe . 16 2 F igure 5 . 8 : Fo rce vs . s hear speed f o r both she a r te st in g an d sect i l it y
h a rdn e s s t e st ing, sample MAN May 1 9 8 7 . 165
Figure 5 . 9: Force vs . s hear speed f o r bot h shea r test ing an d sect i l it y
ha rdn e s s test ing, sample T T Ma rch 1 9 8 7 . 166
F igure 7 . 1 : Typical c reep complian ce curve seen on repeat edly applyin g an d
removin g st res s . 1 8 4
Figure 7 . 2: Cont in uous reta rdat ion spect ra foun d for t h e butt e r TUI Apr i l 1 9 8 7, a ) f i r st c reep respon se, b ) , s econ d c reep respon se . 1 8 5 Figure 7 . 3: Cont inuous ret ardat ion spect ra foun d for t he butte r T T March 1 9 8 7, a ) f i r st c reep respon se, b ) , secon d c reep respon se . 1 86
F igure 7 . 4: Fi rst and secon d c reep c u rves obse r ved f o r the but e r TUI Ma rch
1 9 8 7 . 1 9 2
F igu re 7 . 5: Cont inuous reta rdat i on s pect ra foun d for t he butt e r TUI Ma rch 1 9 8 7, a ) f i r st c reep_ re spon se, b ) , s e c on d c reep respon s e . 1 9 9
F igure 7 . 6: Cont inuous reta rdat ion spect ra f o un d for t he butte r T T Feb . 1 9 8 7, a ) f i r st c reep respon se, b ) , s e cond c reep respon se . 2 0 0 F igure 7 . 7: Cont inuous ret a rdat ion spect ra foun d for t he reworked butter TUI Ma rch 1 9 8 7, a) f i r st c reep respon se, b ) , secon d c reep respon se . 2 0 1
F igure 7 . 8 : Cont i nuous ret a rdat ion spect ra foun d f o r the rewo rked butt e r TT Feb . 1 9 8 7, a) f i r st c reep response, b) , secon d c reep re sponse . 2 0 2
F igure 8 . la : Di f f e rent i a l s c a nn ing c a l o r imetry m e lt in g th e rm ogram found for
o ri g in a l plast i c ized m i l kfat . 2 16
F i gu re 8 . l a : D i f fe rent i a l s c a nn i ng c a l o r imetry m e lt ing therm ogram found for
rewo rked plast ic ized m i l kf at . 2 1 7
F igu re 8 . 2 a : D i f ferent ia l s c a nn ing c a l o r imetry m e lt ing the rmogram found for
o r i g in a l m i lkfat/ o i l blend . 2 1 8
Figure 8 . 2b : D i f ferent ia l s c ann ing c a l o r im etry m elt ing th e rm ogram found for
rewo rked m i lkfat/ o i l blend . 2 1 9
Figure 8 . 3 : Cont in uous ret a rdat i on spect ra found for p l a st ic ized m i lkfat : a) i n it ial creep respon se, b) secon d c reep re spon se . 2 2 3 Figu re 8 . 4 : Cont inuous ret a rdat ion spect ra found for butt e r : a)
c reep respon se, b) secon d c reep respon se .
in it i a l 2 2 4 Figure 8 . 5: Cont in uous ret a rdat ion spect ra found fo r m i lk fat/ o i l bl en d : a) init i a l creep re spon se, b) second c reep re spon se . 2 25 F igure 8 . 6 : Cont in uous ret a rdat ion spect ra found f o r rewo rked p l a st ic ized m i l k f at: a) init ia l c reep re spon se, b) second creep respon se . 2 26
F igure 8 . 7 : Cont in uous ret a rdat i on spect ra found for reewo rked butt er: a) in it ia l creep respon s e, b) second c reep respon se . 2 2 7 Figure 8 . 8: Cont in uous ret a rdat ion s pect ra found f o r reworked m i lkf at/ o i l blend : a) init ia l c reep response, b) secon d creep respon se . 2 2 8
Figure 9 . 1 : The variat ion o f sect il it y h a rdness w ith season . 2 4 8 Figu re 9 . 2 : Th e variat ion o f pe rcent age s o l id fat with season . 2 5 2
Figure 9 . 3 : Solid f at cont ent plott ed aga i n st sect i l it y h a rdne s s showing l in e s of best f it for a l l s amples and F r itz and Amm ix butt e r s sepa rate ly .
2 5 3
Figure 9 . 4 : D i f fe rent ial s cann ing c a l o r im et ry m e lt ing th e rm og ram s found for
Oct ober an d Decemb e r Amm ix butt e r s 2 5 5
F igure 9 . 5 : We ight pe recent age s o f c 16: 0 and c 1 8 : l f o r F r itz and Amm ix butt e r s col lected ove r th e ' 8 5 - ' 86 s e a s o n . 2 5 9
F igure 1 0 . 1 : A c reep a nd recove ry curve . 2 8 1
F igure 1 0 . 2 : Typical c reep com p li a nce cu rve seen on repeatedly applyin g and
rem o ving st re s s . 2 8 5
Figure 1 0 . 3 : P roposed rheological m odel s t o represent th e c reep compliance
beh aviour of butt e r . 2 8 8
