Rearrangement of Milk Fat as a Means for Adjusting Hardness of Butterlike Products1

7/28/2019 Rearrangement of Milk Fat as a Means for Adjusting Hardness of Butterlike Products1

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R EA R R A N G E MEN T O F MILK F A T A S A MEA N S F O R A D J U S TIN GH A R D N E S S O F B U T T E R L I K E P R O D U C T S ~

J. B. MICKLE, R. L. VON GUNTEN, AND R. D. MORRISONDepartments of Dairying and Mathelnatics, Oklahoma State University, Stillwater

SUMMARYMilk fat was rearranged using selected times, temperatures, and catalystconcentrations, and the resulting fat was made into a semisolid product resem-bling butter. Hardnes s of the produc t was measured at 7-10 C and fomld todecrease with increased catalyst concentrations, but to increase with increasedtime. A 50 5% reduc tion in hardness could generall y be accomplished withcatalyst concentrations of 1-2%. Statistical analysis indicated that catalystconcentr ation had more influence on hardness than did reaction time or tem-perat ure. This catalyst effect was related to the formatio n of diglycerides

whose emulsif ying propert ies part iall y explained the decreased butt er hardness.

A report from this laboratory (8) indicatedthat butterlike spreads crystallized from inter-esterified (re arra nged) nfilk fat were softerthan similar spreads containing untreated milkfat. Riel's data (10) also indicated that re-arrangement extended the plastic range of nfilkfat. Work by DeMan (4, 5) an d Weihe (12),however, showed that rearranged milk fat washarder than untreated fat. Rearranged milkfat contained more high-melting -point glycer-ides (HMG) and formed smaller crystals uponsolidification than did untreated control fats(5). When usi ng sodium methoxide (NaOCH~) 2as the catalyst, nmno- and diglycerides may beformed as a by-product of rearrangement.Braun (3), therefore, recommended low cata-lyst concentrations to avoid excessive fattyacid losses.The net effect of rearrangement on butterspreadability was obscure, particularly in viewof the apparently conflicting data from differ-ent laboratories. It was thought, therefore,that additional information could be obtained ifthe effect of each reaction condition (time,temperature, and catalyst concentration) wereevaluated.

EXPERIMENTAL PROCEDUREIn the first series of trials, the effects ofthree reaction conditions (time, temperature,and catalyst) were evaluated with a randombalance experimen tal design. Reaction timesranged from 5 to 55 min in 5-rain intervals,Received for publication August 9, 1962.* Supported in part by funds from the AmericanDairy Association.~Fisher Scientific Co., St. Louis, Missouri.

tempera tures range d f rom 40 to 90, in 10 Cincrements, and catalyst (NaOCH~) concen-tra tions from 0.5 to 5.0% of the fat. Of the660 possible combinations of time, temperature,and catalyst, 31 were chosen at random, and 12of these 31 combinations were duplicated atrandom. Milk fat for these trial s was obtainedfrom a single churning of unsalted, sweet creambutte r stored at --15 C unti l used. As needed,portions of the butter were melted, then thedry milk fat decanted and filtered.

The reaction was conducted under a nitro-gen atmosphere, to avoid oxidative flavor de-teriorat ion. At the end of the trea tment periodthe catalyst was inactivated with an excess of'acetic acid and the fat was washed three timeswith water. The fat was then neutrali zed withan 8% NaOH solution and deodorized withsteam at 55-60 C and 150 mm Hg pressure for8 to 12 hr (2). Wat er and NaCl were thenadded to the deodorized fat and the mixturewhich eontained 80% fat, 2% NaC1, and 18%H_oO was crystallized to a p rod uct resemblingbutter by cooling, with egitation, from 80 to15-20 C in 4-5 rain. The special labora tory ap-paratus used has been described previously(S). The effect of the process on the finishedproduct was evaluated by measuring hardnessat 7-10 C with a consistency meter simil ar tothe one described by Kapsalis et al. (6). Thedata were analyzed as a fo ur-dime nsional sur-face representing butter hardness as affectedby each of the three reaction conditions.

A second series of experiments was designedto compare the effects of selected reaction con-ditions on butter hardness and the ratios ofmono-, di-, and triglycerides formed during re-arrang ement. The mono-, di-, and triglycerides1357


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1358 J. B. 3[1CKLE, R. L. VON GUNTEN, AND R. D. MORRISON

w e r e se pa r a t e d by F l o r i s i l c o l unm c hr o ma t o g- T ime- ,i,r a p h y , a n d g a s - li q u i d c h r o m a t o g r a p h y ( G L C ) . . . . . .w a s u s e d t o a n a l y z e t h e d i - a n d t r i g l y c e r i d ef r a c t i o u s . T h e c o l u m n o f t h e G L C i n s t r u m e n t :~w a s p a c k e d w i t h 2 0 % d i e t h y l e n e g l y c o l s u e - ~,~es~-qe i na t e on a c i d - w a she d 60- 80 me sh c h r omosor b~V and the sapo ni f ied fa t ty ac ids wer e meth - H0,d,,$,y l a t e d b e f o r e a n a l y si s , u s i n g t h e p r o c e d u r e o f qS m i t h { 1 1 ). C o o l i n g c u r v e s w e r e d e t e r m i n e do n 2 0 - m l a l i q u o t s o f r e a r r a n g e d a n d u n t r e a t e ds a m p l e s o f m i l k f a t . T h e f a t w a s p l a c ed i n adoub l e - w a l l e d t e s t t ube c oo l e d i n a d r y - i c ee t h a n o l b a t h a t a r a t e o f a p p r o x i m a t e l y 2 C / Time-ui.r a in . ~ ' I e a su r e me n t s o f f a t t e m pe r a t u r e s ( a e - 0 s~ c o ; : t y , tc u r a t e t o 0 . 1 C ) w e r e o b t a i n e d w i t h a t h e r m i s t o ra t t a c h e d to a W h e a t s t o n e b r i d g e - g a l v a n o m e t e r Time-Uin.c i rcui t , o

F l a v o r s o f t h e b u t t e r l i k e p r o d u c t s w e r e e v a l - 0ou a t e d b y a t a s t e p a n e l c o m p o s e d o f 1 1 w o m e n .E a c h p a n e l m e m b e r r a n k e d t w o c o d e d s a m p l e s ~o' S 'd"**s-~a t e a c h t a s t i n g pe r i od , one c on t a i n i ng r e - ~oa r r a n g e d m i l k f a t a n d t h e o t h e r , a c o n t r o l, c o n - .o,d.eee bot a i n i n g u n t r e a t e d m i l k f a t . T h e j u d g e s w e r e 0a s k e d t o r a n k t h e s a m p l e s a c c o r d i n g t o t a s t ep r e f e r e n c e s o n l y. T h e s am p l e s w e r e s t o r e d a t- - 1 5 C u n t i l u s e d ( l t o 8 w k } , b u t w e r e t e m -pe r e d a t 7 t o 10 C be f o r e t a s t e e va l ua t i on . Th i s Time - Min.p a i r e d - c o m p a r i s o n t y p e d e s ig n w a s r e p e a t e d 215 ~ ~ 0 ~ ~ ~e i g h t t i m e s a n d t h e p o o l e d d a t a w e r e e v a l u a t e ds t a t i s t i c a l l y .

~ZSULTS _a~D nlSe['SSIOXT h e d a t a i n v o l v e d a f o u r - d i m e n s i o n a l s u r -

f a c e , pa r t s o f w h i c h a r e show n i n a s e r i e s o ft h r e e - d i m e n s i o n a l d r a w i n g s ( F i g u r e 1 ). T h e s es u r f a c e s i n d i c a t e d t h a t t h e b u t t e r l i k e s p r e a d sb e c a m e s o f t e r a s c a t a l y s t c o n c e n t r a t i o n s i n -c r e a s e d w i t h i n th e r a n g e o f 0 .5 to 5 . 0 % . T h es u r f a c e s w e r e s a d d l e - s h a p e d w i t h r e s p e c t t ot i m e a n d t e m p e r a t u r e a n d t h e i r s h a p e w a sm o d i f i e d s o m e w h a t b y c h a n g e s i n t h e c a t a l y s tc o n c e n t r a t i o n . T h e r e w a s a g e n e r a l t e n d e n c yf o r t h e b u t t e r l i k e s p r e a d s t o b e c o m e h a r d e ra s t h e r e a c t i o n t i m e i n c r e as e d . A t t h e h i g h e rc a t a l y s t c o n c e n t r a t io n s a n d l o w e r t e m p e r a t u r e s ,h o w e v e r , t h e s p r e a d s b e c a m e s o f t e r w i t h i n -c r e a s e d t i m e , u n t i l a m i n i n m m h a r d n e s s v a l u ew a s r e a c h e d , a f t e r w h i c h h a r d n e s s i n c r e a s e dw i t h in c r e a s e d ti m e . T h e s e m i n i m u m v a l u e sf o r m e d a t r o u g h i n t h e s u r f a c e w h i c h e x t e n d e dd i a g o n a l l y a c r o s s i t. T h e e q u a t i o n f o r t h e f o u rd i m e n s i o n a l s u r f a c e w a s : Y = 5 3 3 . 8 12 - -6 .242M - t- 5 .155T - - 164.197C q- 0 .063M ~ - -0 .086T ~ + 13.538C ~ + 0 .121 MT - - 1 . 0 1 0 M e +

a An aerograph Hi -F i M odel 600, Wi lkens In-stru men t & l~eseareh, Inc. , Wal nu t C reek, Cali-f o r n i a .

800?00600Hord~ees- 50040 0300200I00

60 50 40 30 2 0 1090 ~Time- Mm.5.0 % Cofolysf

Time - Nin~^ =^ "1 30 20 I0"--]--'--] 8001 ~,oo"--'~--~ 600

i ~ 5OO.o,~=_o1 T '~- I - ' ~ 3 0 05 ~ 0 4 2 0

mOO0

FI6. 1 . Sur faces represen t ing the inf luence ofr e a r r a nge me n t r e a c t i on t i me a nd t e mpe r a t u r e a tse lec ted ca ta lys t concent ra t ions on the hardnessof but te r l ike produc ts .

0 . 4 3 7 T C , w h e r e Y = h a r d n e s s o f t h e b u t t e r l i k ep r o d u c t i n g r a m s , M = r e a c t i o n t im e in m i n -u t es . T = r e a c t i o n t e m p e r a t u r e i n C , a n dC = c a t a l ys t c onc e n t r a t i on i n pe r c e n t. Th i se qua t i on c ou l d be use d t o c a l c u l a t e spe c i f i cp o i n t s o u t h e s u r f a c e i t r e p r e s e n t e d o r t o d e -t e r m i n e t h e r e a c t i o n c o n d i t i o n s n e c e s s a r y t oo b t a i n a g i v e n h a r d n e s s v a l u e . I n g e n e r a l ,h a r d n e s s r e d u c t i o n s o f 4 5 - 5 5 % w e r e o b t a i n edw i t h 1 - 2 ~ c a ta l y st .


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R EA R R A N G EMEN T O F MILK FA T 1359

TABLE 1Influence of time, temperature, and catalystconcentration on a rearrangement reactionas it affects the hardness of butterlikeproducts

Analysis of varianceSource d.f. M.S.Mean 1 3,173,157

Linear effectsTime 1 13,573 5.0 "~Temperature 1 32,067 11.8 bCatalyst 1 640,528 234.8 b

Quandratic effectsTime 1 19,672 7.2 ~Temperature ] ] 2,320 4.5Catalyst 1 53,982 19.8 ~

Linear interactionsTime temperature 1 ]7,957 6.6 ~Time X catalyst 1 11,467 4.2Temperature X catalyst 1 1,408 0.5Lack of fit 22 40 ,893 15.0 bError (duplicates) 11 2,727" P ~ 0.05.~' P ~ 0.01.

Statistical analysis of the data (Table 1)indicated that the effects of time, temperature,and catalyst each were statistically significant(P < .05). The relative size of the F valuesindicated that of the three factors studied thecatalyst concentration had the largest singleinfluence on hardness. The effect of temper a-ture was more import ant t han time. The effectof catalyst concentration appeared to be inde-pendent of time and temperature since linearinteractions between this variable and the othertwo were not statisti cally significant (P > .05).The statistically significant (P (. 0 1 ) linearinteraction between time and temperature couldprobably be explained by the fact that thesevariables sometimes affected hardness in dif-ferent directions. The lack-of-fit term includedall those combinations of variables which hadnot been analyzed individually. This term wassignificant (P ( .0 1 ), which indicated that thereaction was affected by combinations of vari-ables in addition to those measured (i.e., time temperat ure catalyst, complex eurvilin-ear effects, etc.).

The random-balance experimental design wasan exploratory technique which determined thegeneral shape of this surface. In most eases,individual experimental variations were snmll:the average difference between hardness meas-urements, for example, was about 3%. Thetotal experimental error, however, was larger,since it represented the sum of all the indi-vidual variations. In this work, the over-all

coefficient of vari ati on was 19.2%, a reason-able value fo r a design of this type. _~[ore pre-cise predictions of hardness could have beenobtained by repeating portions of the experi-ment and changing only one variable at a time.Such data, though, would ha~,e been precise onlyfor the parti cular points they represented. Onthe other hand, the general tren~lg determinedby. the ra ndom-balance design should be validunder most circumstances.

These findings of this work agree with thedata of others (4, 5, 12), since hardness in-creased with time at low catalyst concentra-tions. The catalyst effect, however, was so largein relation to the effects of time and tempera-ture, that when the catalyst concentration wasincreased 0.5% or more, a softer butter wasproduced at nearly all times and temperatures.Similar observations were previously reportedfrom this laborato~' (8).

The changes in the fat which accompanied(and perhaps caused) the changes in hardnesswere of interest. The increase of hardness wi thtime had previously been studied by DeMan(4, 5) and attributed to the formation of HMG.The catalyst effect could possibly have been ex-plained by the formation of diglyeerides dur-ing the reaction and it was of interest to relatethe amounts of these compounds formed duringrearr ange ment to changes in hardness. Table 2

TABLE 2Glyceride comp(~sition and hardness of butterlikeproducts containing rearranged anduntreated milk fats

Reaction Con-conditions trol ~ Experimental% Catalyst 0 0.1 2.5Temperature ( C ) .... 40 40Time (~*~b~utes) . . . . 60 60

% Glyceride composition of fatTri- 94 93 80Di- 5 6 18Mono- 1 1 2Butter hardness ( g ) 1,380 1,240 170.% Softer than control .... 10 88

Control sample containing untreated milk fat.

presents typical data obtained under differentreaction conditions. When 0.1% catalyst wasused and the reacti on was conducted at 40 Cfor I hr, the butter made from the rearrangedfat was about 10% softer than the controlsample which contained untreated fat. In thiscase, the increase in diglyceride content of therearranged fat was negligible. When 2.5%


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1360 J B. MICKIA~. R. I ,. VON GUNT EN, AND R. I). MOR RIS ON

catalyst was used under the same time andtemperature conditions, the butter made fromrearranged fat was 88% softer than the con-trol. This reduction in hardness was accom-panied by an increase in the diglyeeride con-tent of the rearranged fat.

Cooling curves indicated no difference be-tween the HMG content of the control fat andthe rearranged fat when using 0.1% catalyst.The cooling curves also indicated that the sam-ple rearranged with 2.5% catalyst containedmore HMG t han did the control. The crystalli-zation of this fraction began at a temperature2 C higher th an that of the control sample.Melting points of simple diglycerides have beenreported to be higher than their correspondingtriglycerides (2); thus, the increase in tI3IGmight have been accounted for by the increaseddiglyeeride content of the rearranged fat.

This increase in HMG was contrary to whatone might have expected, since it has beenshown that an increase in ttMG is sometimesassociated with harde r fat (4, 5). Therefore,an effort was made to determine whether theemulsifying properties of the diglyeerides pro-duced would account for the reduction in hard-ness which accompanied the increased diglyc-eride content. To do this, the effect of addedenmlsifiers was tested, using two conunereiallyavailable products. When 10 or 15% Atmos150' was added, there was a linfit (about 35%)to the decrease in hardness which could beaffected by the addition of enmlsifier (Table 3).The additi on of 15% Tween 21 ' caused a 76%reducti on in the hardness of the butter. Thislatter enmlsifier was liquid at room tempera-ture, whereas the Atmos 150 was solid. Whe nthis 76% reduction was compared to the 36%caused by 15% Atmos 150, it appeared thatthe physical characteristics or chemical com-position of the emulsifier nmst have had a sub-stantial effect upon the hardness of the butter.On the other hand, the addition of 15% Tween21 did not cause as great a reduction in hard-ness (Table 3) as had 12% of additionalnat ura l diglyeerides (Table 2). Thus, the Tween21 was not as effective in reducing hardness aswere the natural glyeerides formed duringrearrangement.GLC analysis of the control fats and thediglycerides from rearranged fats indicatedfat ty acid compositions were the same for both~Mono- and diglyeerides, crystalline at 21C,Atlas Powder Co., Wihnington, Delaware.Polyoxyethylene sorbitan monolaurate, a liquidat 21 C, Atlas Chenfieal Co., Wilmingtou, Dela-ware.

TABLE 3Hardness of butter containing added emulsifiersButterEmulsifier hardness

(%Description (%) (g) softer)0 1,630Atmos 150 ~ 10 1,060 3515 1,050 360 1,290Tween 21 b 10 760 4115 310 76

Edible mono- and diglyeerides, Atlas PowderCo., Wihnington, Delaware.b Polyoxyethylene sorbitan monolaurate, AtlasPowder Co., Wihnington, Delaware.

fats. These values all were similar to thosereported by Smith (11). Thus, the rearrange-ment reaction appeared to have been random inthis ease and differences in fatty acid composi-tion of the glyee14des resulting from rearrange-ment did not appear to have been the cause forthe softer butter. The Atmos and Tween addedto some of the fat were not primarily diglyeer-ides and this might have accounted for part ofthe difference when the effects of these sub-stances were compared to the effects of thediglycerides formed during rearrangement.The feasibility of rearrangement as a com-mercial practice will depend, among otherthings, on the availability of suitable equip-ment. When diglycerides were produced byrearrangement fatty acids were released--manyof them as sodimn soaps. In eonunereial prac-tice, this saponifieation could be prevented byadding glycerol to the reaction mixture or thefatty acids could be recovered per se by one ofseveral available procedures (2).

Another consideration of commercial impor-tance is the taste of the final product. Kaps aliset al. (6) and Riel (9) have published datawhich indicated desirable ranges of spreadabil-ity and hardness. These data indicated that thehardness of some nfilk fats would have to bereduced more than 50% to produce butter witha desirable spreadability over a wide tempera-ture range. Such a reduction in hardness couldbe accomplished by adding commercially avail-able enmlsifiers to the butter. However, a 50%reduction in hardness would require more than1% of added emulsifier, a level which mightcause undesirable flavors in the bu tte r (7).The product resulting from rearrangement hadan intense metallic flavor, but this flavor wasremoved by the refining processes employed inthis study. The taste panel found no statis-


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REARRANGEMENT OF MILK FAT 136 1

tically signifi cant differ ences (P < 0.05) be-tween the samples containing refined rearra ngedmilk fat and control samples, even after 8 wkof storage. Weihe also has reporte d acceptableflavor in rearranged milk fat af ter i t was re-fined (12).

ACKNOWLEDG~IENTSThe authors are indebted to tIazel Baker,Barbara Chandler, Betty Christians, Mary Malkus,and Mary Leidigh, who helped prepare and ana-lyze the samples.

REFERENCES(1) B.~ILEY, A. E. Mel ting and Solidif icationof Fats. Interscience Publ. Inc., New York.1950.(2) BAILEY,A. E. Industri al Oil and Fat Prod-ucts. 2nd ed. Inters cienee Publ. Inc., NewYork. 1951.(3) BRAUN, W. Q. Intere sterif icatio n of E dibleOils. J. Am. Oil Chem. Soc., 37: 598. 1960.(4) DEMAN, J. M. Physi cal Proper ties of MilkI~at. I. Influence of Chemical Modificati on.J. Da iry Research, 28: 81. 1961.(5) DEMAN, J. M. Physic al Pro pert ies of MilkFat. II. Some Factor s Influencing Crystal-

lizat ion. J. Dai ry Research, 28: 117. 1961.(6) KAPSALIS, J. G., BETSCHER, J. J. , KglSTOF-FERSE~, T., AND GOULD, I. A. Ef fe ct ofChemical Additives on the Spreading Qual-ity of Butter. I. The Consistency of Butteras Determined by Mechanical and ConsumerPanel Evaluation Methods. J. Dairy Sci.,43: 1560. 1960.(7 ) KAPSALIS, 5. G., KRISTOFFERSEN, T. , GOULD,I. A., AND BETSCttEg, J. J. Ef fe ct of Chem-ical Additives on the Spreading Qualityof Butter. II. Laboratory and Pla nt Churn-ings. J. Dai ry Sci., 46: 107. 1963.(8) MICKLE, J. B. Chan ging the MolecularStructure of Milk Fat as a Means of Im-proving the Spreadability of Butter. Okla-homa Agr. Expt. S ta., Bull. T-83. 1960.(9) R mL, R. R. Specifieatio~s for the S preada-bilit y of Butter. J. Dairy Sci., 43: 1224.1960.(10) RIEL, 1~. R. Dil atomet ric Behav ior and Othe rPropert ies of Modified Milk Fats. J. DairySci. , 44: 1168. 1961.(11) SMITH, L. W. Quanti tative F at ty Acid Anal-)-sis of Milk F at by Gas-Liquid Chromatog-raphy . J. Da iry Sci., 44: 607. 1961.(12) WEmE, H. D. Inter ester ified Butteroi].J. Dair y Sci., 44: 944. 1961.

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Rearrangement of Milk Fat as a Means for Adjusting Hardness of Butterlike Products1