R E I C H E R T - M E I S S L N U M B E R S OF B U T T E R F A T FROM C O M M E R C I A L P R O D U C T S P R O D U C E D I N K A N S A S 1

WM. D. RUTZ, W. It. MARTIN, AND C. ~-Io WHITNAI t Kansas Agrivultural gxperiment Station, Manhattan

The Reichert-Meissl number of bu t t e r fa t has been used extensively as an index of bu t t e r fa t adulterat ion. One disadvantage of using this method to detect bu t t e r fa t adul terat ion is the inherent var ia t ion in glyceride composition of but ter fa t , which results in variat ions in Reichert-Meissl numbers. There is ap- pa ren t ly some doubt as to the normal var ia t ion of Reichert-Meissl numbers of but ter fa t . An a rb i t r a ry s tandard of approximate ly 24 to 33 has been accepted for m a n y years in the Uni ted States and abroad (3, 9, 16), although evidence in the l i tera ture indicates tha t bu t t e r fa t f rom individual cows m a y have a Reiehert-Meissl number as low as 14 (8, 15) under extreme feeding or environ- mental conditions. The general ly accepted range of Reichert-Meissl numbers of bu t t e r fa t is pure ly an a rb i t r a ry s tandard and should, therefore, be evaluated under present conditions of milk production. This paper reports the results of surveys designed to establish the normal range of Reichert-Meissl numbers of bu t t e r fa t as found in commercial da i ry products in Kansas.

EXPERII~IENTAL PROCEDURE

The investigation was divided into two phases. In phase one a survey was made to determine the range of Reichert-Meissl numbers of bu t t e r fa t as found in commercial ice cream dur ing August . This t ime of year was selected because it has been repor ted tha t Reichert-Meissl numbers of bu t t e r fa t are general ly lower at that t ime than at any other period (5, 6). The second phase of the investiga- tion was a 1-year s tudy of Reiehert-Meissl numbers of commercial bu t te r pro- duced in 10 but ter-producing plants in Kansas.

Dur ing the middle of August , 169 pint samples of ice cream were collected f rom many sections of Kansas. These samples, which included all of the flavors normally found in any market , were representat ive of pract ical ly all of the ice cream manufac tu red in the state and were believed to contain representat ive late summer but ter fa t . The samples, which were collected over a 5-day period, were stored at -8 ° C. until they were analyzed. Butteroi l was p repa red f rom ice cream samples by a demulsification and churning procedure in which Minne- sota Babcock reagent was used as a demulsifying agent (11). Samples were analyzed in duplicate for their Reiehert-Meissl numbers, according to the pro- cedure of the Association of Official Agr icul tura l Chemists (2). Number 2 W h a t m a n filter pape r was used to separate the water insoluble acids f rom the

Received for publication October 28, 1954.

1 Contribution No. 230, Department of Dairy Itusbandry, and No. 509, Department of Chemistry, Kansas Agricultural Experiment Station, Manhattan.

387

3 8 8 w M . n . RUTZ ET AL

soluble acids af ter the saponified fa t had been distilled and the distillate had been tempered.

Dur ing the 1-year period 105 samples of commercial bu t te r were collected f rom 10 of the largest but ter -producing plants in Kansas. Samples were taken a t each plant at approximate ly the 15th day of each month. Wi th few exceptions, bu t te r was sampled f rom the same plants each month. Butteroi l was p repa red and Reichert-Meissl numbers were determined in duplicate, according to the official methods of the Association of Official Agr icul tura l Chemists (2).

R E S U L T S A N D DISCUSSION

The Reichert-Meissl numbers of late summer bu t t e r fa t f rom commercial ice cream ranged f rom 27.40 to 31.35 with an ar i thmetical mean Reichert-Meissl number of 29.19 (Table 1). Results indicate tha t 160 (94.6%) of 169 samples had numbers between 28.0 and 30.5. Since a f requency distr ibution curve drawn f rom these data was slightly skewed, the median Reichert-Meissl number was also determined and was found to be 29.17.

T A B L E 1 l~eiehert-Meissl number distribution of 169 samples of late summer butterfat

REIGHERT-MEISSL NO. OF % 0 F

NUMBER RANGE SAMPLES SAMPLES 0 - 2 7 . 0 0 0 27.0-27.5 I 0.6 2"~5- 28.0 2 [ 2

__28.0-28.5 19 I 1.5

28.5-29.0 55 20.7 2.9.0-29.5 70 41.4 29 .5 -30D 24 14.2

3 0 . 0 - 3 0 . 5 12 7.0 30.5-31.0 5 3.0 51.0-51.5 I 0.6

ABOVE 31.5 0 0

%OF SAMPLES

o ap. 2,0. 3,0. 40

The ar i thmetical mean Reichert-Meissl number of bu t t e r fa t f rom 105 com- mercial samples of bu t te r was 28.40, with the lowest, 27.05 and the highest, 30.10 (Figure 1). These data are sl ightly lower than those in Table 1. The bu t t e r samples were collected f rom Apri l 15, 1953, to March 15, 1954, which was a period of general drought and extreme feeding conditions in Kansas, whereas the ice cream samples were collected in a previous year when pas ture and feeding conditions were good. The peak Reichert-Meissl numbers of the but te r samples collected in Apr i l may be a t t r ibuted to winter wheat or rye pasture, but no explanation is offered for the peak Reichert-Meissl numbers in July .

These da ta are similar to ranges of Reichert-Meissl numbers repor ted previ- ously (5, 12, 13, 14). Spitzer and Epple (13) found an average Reichert-Meissl

REICHERT-D~IEISSL NUMBERS OF KANSAS BUTTERFAT 389

hi

=E - , 3 0 z ,J (/)

.~ 29

14,1 -I- ,'3, 2 8

27

. . . . HiGH NUMBER

AV. NUMBER

m - - - L O W N UMBER 7"~" s / / ~

• . . _ _ , , / \ -

2 " - ' - 9 " ~ V

e ' * ,e

l f I I I I I I i I I f

JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DE(;

:PI~. ] . Seasonal val ' iat ion of Reichert-Meissl numbers of b u t t e r f a t f rom 105 samples of commercial but ter .

number of 29.91 for 500 samples of creamery but ter produced dur ing all seasons over a 4- to 5-year period. They reported the lowest Reichert-Meissl number was 26.45 and the highest, 32.10. Cox and McDowall (5) reported an average I~eich- ert-Meissl number of 30.4 for 862 samples of New Zealand but te r fa t obtained f rom commercial but ter over a 4-year period. A definite seasonal t rend was observed. The data of Stout and Wilster (14) indicate that the Reichert-Meissl numbers of bu t te r fa t produced in three "sections of Oregon dur ing J a n u a r y varied with the type rat ion fed in each section and therefore tended to be inde- pendent of the season. The average t~eichert-Meissl number of bu t te r fa t of each of three sections where different feeding conditions existed was 27.02, 30.65, and 31.10. However, the lowest and highest numbers found in any area in the state were 26.03 and 31.45. But te r fa t having the lowest Reichert-!V[eissl values was produced in a region where alfalfa hay formed the major portion of the ration. I t is recognized that feed influences but ter fa t composition and inherent glyceride composition. There are numerous references in the l i terature about the effect of various rations on the Reichert-D£eissl number of but ter fa t (1, 4, 6, 7, 8, 12, 15). In some instances extremely low Reichert-Meissl numbers have been obtained (1, 8, 15). These were invariably caused by extreme or unusual feeding condi- tions, and f requent ly the but te r fa t samples were obtained from only a few animals. There is evidence in the l i terature that Reichert-Meissl values of butter- fat, as found in commercial dai ry products in certain states or regions, generally do not va ry so much as the present accepted range. The results reported here tend to support that evidence.

SUMMARY

During August l~eichert-Meissl numbers of but ter fa t f rom 169 samples of ice cream were determined. The arithmetical mean value was 29.19 and the range

390 WM. D. RUTZ ET .4.L

w a s 27.40 to 31.35. R e i c h e r t - M e i s s l n u m b e r s o f 160 of t h e 169 s a m p l e s ( 9 4 . 6 % ) w e r e b e t w e e n 28.00 a n d 30.50.

O v e r a 1 - y e a r p e r i o d , 105 s a m p l e s of c o m m e r c i a l b u t t e r f r o m 10 b u t t e r - p r o - d u c i n g p l a n t s i n K a n s a s w e r e a n a l y z e d . S a m p l e s w e r e c o l l e c t e d m o n t h l y . T h e a r i t h m e t i c a l m e a n R e i c h e r t - M e i s s l n u m b e r w a s 28.40 a n d t h e r a n g e w a s 27.05 to 30.10.

ACKNOWLEDGMENT

The authors wish to express their appreciation to the Dairy Division of the Kansas State Board of Agriculture for assistance in collecting the samples.

REFERENCES

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Analysis. 7th ed. A.O.A.C., Washington, D. C. 1950. (3) BAILEY, A. E. Ind~lstrial Oil and Fa t Products. 2nd ed. Interscience Publishers, Inc.,

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(9) HILDITCH, T. P. The Chen~ical Constitution of Natural Fats. 2nd ed. John Wiley & Sons, Inc. New York. 1947.

(10) HILL, O. J., AND PALHEr~, L. S. A Study of the Relation of the Feed Consumed by the Cow to the Composition of Milk Fa t and the Properties of Butter. J. Dairy Sci., 21: 529. 1938.

(11) MARTIN, W. i . , RUTZ, W. D., AND WHITNAH, C. H. Detection of Foreign Fats in Ice Cream. Proc. d5th Ann. Cony., Production and Lab. Council, Intern. Assoc. Ice Cream Mfrs., 2: 5. 1949.

(12) OVERHAN, O. R., AND GARRETT, 0. F. The Influence of Certain Balanced Rations on the Chemical and Physical Properties of Milk Fat. J. Agr. Research, 45: 51. 1932.

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(14) STOUT, R. E., AND WILSTER, G. H. Some Observations on the Iodine, Reichert-Meissl and Polenske Values of Milk Fa t Produced During the Winter in Three Sections of Oregon. J. Dairy Sci., 22: 424. 1939.

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