May, 1 9 1 3
T H E J O U R N A L OF I N D U S T R I A L A N D EATGISEERI-VG C H E M I S T R Y
sity of Missouri, and to Mr. 0. C. Smith, of the Experiment Station, for glassblowing. MISSOURIDEPARTMENT O F FOODA N D DRUGINSPECTION COLTJMBIA
SAMPLING ICE CREAM’ B y J . 0. HALVERSOS
In a n investigation on the Modified Babcock” for testing sweetened dairy products, especially ice cream, considerable variation in the results for butter fat was a t times obtained. I t did not appear that this was caused by the tests used as it was observed in both the hlodified Babcock and the Roese-Gottlieb methods. Thus i t was necessary to investigate the factors which influence the per cept of milk fat obtained. These results are discussed in this paper. A good quality of ice cream, testing 16 t o 1 7 per cent fat, was used. This mas made in the University creamery room under the best of conditions. A fact of some importance is worth mentioning in this connection: A small amount (about a tablespoonful) of commercial ice cream powder (gum tragacanth in part) was used as a thickener in the formula for standard vanilla ice cream, given below. An intermittent Miller-Tyson Co.’s freezer, of capacity 2 0 gallons per hour, was used. This, in larger amounts, may have some effect in preventing the “churning” of fat in ice cream. However, this was not investigated. Formula for 5 gallon mix:
they obstructed the milk pipette. The freezer was examined after the day’s run. A considerable number of small lumps of churned butter forming a layer estimated at one-eighth to three-sixteenths of an inch deep were found along the edges of the revolving paddles. This layer of small lumps of butter became more marked on the last batches frozen. These small particles of fat were more noticeable a t times in the frozen cream. Thus hot weather and old cream may be more favorable for their formation than cold winter weather. These factors. however, were not studied. EFFECT
OF
N O K - U I i I F O R M I T Y O F T H E I C E CREAM
At all times the cream was carefully mixed, special care being taken t o prevent churning. All charges in each set in Table I were weighed out a t the same time. Occasionally some variation seemed due t o an unavoidable non-uniformity of the cream itself. A rich cream, as here worked viith, is liable t o churn t o a slight extent in the freezer and contain at times small lumps of butter: such were found. I n weighing out charges Paper presented a t the Annual Meeting of the American Chemical Society, Milwaukee, March, 1913. 2 “The Modified Babcock for F a t in Sweetened Dairy Products-Ice Cream,” THIS JOURNAL, 6 , 403.
TESTISG
CHARGES
TAKEN
T I M E S O N I C E CREAhI W H I C H H.kS
AT
DIFFEREKT
STOOD, A L L O W I S G
T H E CREXhI TO R I S E TO T H E T O P
Further work led to the belief that the charges were not uniform, due to the inability t o thoroughly mix the samples after standing in the cooling rooms for several days. At the temperature of 4 0 ’ to j o o F. in the cooling rooms on samples preserved with formalin, the cream in the ice-cream sample tended to rise to the top. To uniformly mix the sample in order to take charges for test.ing gave some difficulty. On sample 1 1 / 1 9 / 1 2 are shown the results of three sets of charges taken as follows (each of these was checked up by the Roese-Gottlieb method). TABLE~.--“SAMPI.IXG”ICECREAM.
SAXPLE
11,’19/12
P a t by Modified Babcock m Fat Determination RoeseStandard Direct number Gottlieb rending rending
3 0 lhs. cream a t 21 per cent 6 Ibs. sugar 60 cc. vanilla extract Small amount. ice cream powder
I n Table I , fat readings in the Modified Babcock Method, taken a t 130’ to 140’ F. with glymol, are designated ‘‘ standard readings,” while those taken a t once upon completing the test, are given as “direct readings.” Considerable variation in results at times obtained, may be caused by a non-uniformity of the ice cream itself or poor mixing after having stood several days in the cooling room. This subject therefore divides itself into three parts: I . Non-uniformity of the ice cream itself. 2. Effect of testing charges taken a t different times on ice cream samples which have stood, allowing the cream to rise to the top. 3. Method of mixing ice cream samples after having stood some time.
409
.ri
First s e t . . . . . . . . .
3 15
r6 1 7 8
Second set
r Third s e t . . . . , . . . . . . .
17.70 17.56 17.32
... . . 17 . O i
16.91
19
... ...
‘0
16.45 17.13
16.75
... __
Average. Dets . . . . . 3--17 .OS> Maximum variation 1.25 1st set (sampled at once), av. 1 7 . 4 8 2d set (sampled 1 week later), av. 16.99 3d set (sampled still later), a v . . 16.79 0.38 Max. variation, 1st s e t . . , , . . . . . 0.16 Xax. variation, 2d set. . , . . . . . . 0.73 hlax. variation, 3d set. . . . . . . . . .
l i . 10 17.10 17.20 17 .oo 17 . O O 16.15 16.30 li.10 16.80 17 .oo 16.60 16.50 16.75
__
13-16.79 1 .05 17 18 16.59 16.71 0.10 1.65 0.50
17 30 17.35 17.50 17.25 17.30 16.25 16.30 17.25 16.85 16.85 16.80 16.75 1fi.90
__
13-16.94 1.25 17.34 16 64 16.83 0.25 0.45 0.15
First Set.-Determinations one to five mere tested at once from the sample as the ice cream Fame from the freezer. Second Set.-Determinations 6 to 9 were taken I week later from the same sample, using particular care t o obtain as uniform charges as possible. Third Set.-Determinations I O to 1 3 were charges taken still later and tested. From the averages and maximum variation on each set it will be seen that when sampled at once the highest per cent of fat is obtained. Allsot h a t , in general, the variation on individual determinations was small while in the third set (determinations I O to 13) i t is observed the average per cent of fat is lower by both
T H E JOURi\’AL
410
the Roese-Gottlieb and Modified Babcock method. The maximum variation on the three sets is considerable by both methods, showing that it is somewhat more difficult to obtain as uniform results as are obtained on fresh samples unless they have been kept a t or below freezing temperature. To eliminate this difficulty as much as possible, 18-gram charges are used. The method of mixing ice cream samples after standing some time was also given careful attention. METHOD
OF
MIXISG
ICE
CREAM
SAMPLES
AFTER
STANDING SOME TIME
Ice cream samples which have been kept in a refrigerator or in cooling rooms for some time are not readily sampled for uniform charges unless some precautions are taken. This is especially necessary when the ice cream has melted somewhat and the cream risen t o the top, forming a layer. Thus to obtain a uniform charge, the author found it convenient to dip the sample jar in a pan of hot water a t about 70’ t o 80’ C. with gentle shaking, until it had approximately attained the temperature, as felt by the hand, of freshly drawn milk (98’ F.). Carefully shake and mix until of a uniform consistency. This occurs and will be shown when the mixture runs freely down the sides of the glass container and no lumps are seen. There. is danger of the fat separating and rising to the top of the sample if i t is heated too long or much above 80’ C. This condition makes uniform sampling impossible and is t o be avoided. SUMMARY I . The ice cream itself may not be perfectly uniform. This may not be noticeable except on the paddles of the freezer. The extent of “churning” in these samples was, of course, small. 2 . I n taking charges from preserved ice-cream samples which have stood in a cooler so that the cream rises, not perfectly uniform charges can be obtained. This, it appears, causes a slightly greater variation in the fat reading with a tendency to run somewhat lower. 3. The mixing of ice-cream samples should be carefully performed, especially when they have stood so t h a t the cream has risen to the top.
SOME EFFECTS OF FEEDS UPON THE PROPERTIES OF LARDS. I1 B Y C. L. HARE Received April 8, 1913
I n a former paper’ the writer described the effects of a number of different feeds upon the melting points and iodine values of lard. I n the present paper are given results obtained during the examination of more than two hundred lards produced by feeds of different kinds. The lards are from six series of feeding experiments extending over a period of five 1
THISJOURNAL, 2,
264.
5
years and have been furnished by the Department of Animal Industry of the Alabama Experiment Station. These investigations have been conducted in cooperation with Prof. Dan T. Gray, of that department. I n continuing the investigations, attention has again been confined largely t o melting points and iodine values as these are the two constants-so calledmost affected by different feeds. The feeds used have been corn, cottonseed meal, tankage, wheat shorts, cowpeas and skim-milk for certain lots, while still other lots received a pasture ration’of soy beans or peanuts ad libitum, accompanied or followed by a part ration of other feeds as indicated in the tables. I n order t o have the results comparable, the pigs throughout the experiment were selected with regard to uniformity of age, weight and breed, and all lards were rendered from the kidney fat. For purposes of convenient comparison, the results published in the first paper have been placed beside the later results. The .feeds used with each separate lot of pigs in each series are specifically set out in the tables of results. Results on the individual lards in each series have been condensed to the averages for the series and the tables show such averages. Each series represents the experimental work of one year. I t will be shown below that-within reasonable limits-the age of the pig has little effect upon the properties under consideration. The same may3 be said of the duration of the feeding test, though this is not true for all feeds. We are therefore warranted in accepting the average results as representative. Results reported on individual lards would merely multiply figures without giving additional information. I n every case melting-point determinations were made by the Wiley method while the Hanus method was used for the determination of the iodine values. Lards from corn-fed pigs constitute the bulk of the pure lard on the market and are used here as the standard for comparison of lards from other feeds. I n Table I are given results on lards from twenty corn-fed pigs. TABLE I-RATION: CORN MEAL
---
Iodine values
MISSOURI DEPARTMENT OF FOODAND DRUG INSPECTION COLUMBIA
j, NO.
1’01.
OF I N D U S T R I A L A.VD EXGINEERING C H E M I S T R Y
No. of Series lards I . . . . ...... 5 2..........5
LMelting points 42.6 43.7 3. 3 43.4 4 2 43.3 5 5 42.6 hverage of 20 lards. 43.1 Maximum . . . . . . . . . . ..45.6 Minimum . . . . . . . . . . . .. 4 0 , 5
.........
.......... ..........
~
56.92 54.05 62.65 57.01 60.94 58.08 65.04 51.50
-
Max. 58.68 56.57 64.79 57.87 65.04
Yin.
53.87 51.50 60.07 56.16 54.00
The iodine value j8.08,being the average of determinations on lards from 2 0 pigs, confirms the conclusion in the previous paper t h a t corn does not produce abnormally soft lards. The variations in the iodine values from year t o year may be possibly, though not probably, explained by variations in the composition of the corn. No analysis was made of the corn
