June, c g 2 0
T H E J O U R N A L OF I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y
EXAMINATION OF FATTY Acms-Part of t h e acid obtained from the resin-oil separation was used t o study t h e properties of the oils used in t h e manufacture of the varnish. T h e estimation of China wood oil was made according t o the method given by the author,l a n d t h e calculations were based on t h e d a t a given in the same article. Eisenschiml’s hexabromide test2 for fish oils was used for t h e detection of Menhaden oil. DISCUSSION
The only seeming contradiction appears in t h e service test data, where some varnishes otherwise good show up badly. However, i t will be noted t h a t no varnish held up well on the north library doors, and if t h e results on these places are omitted, the results are in good agreement. T h e relationships of the values for viscosity, sponge, surface, a n d elasticity t o the service tests are apparent. These values for Nos. I and 3 are quite conclusive. The high rosin and resin-oil ratio in No. 1 1 suggest some limits, even if lack of more evidence prevents us from making it definite. The complete results of tests and analyses on Nos. 1 1 , 12, a n d 13 will be given in our next paper, along with the interior varnishes. The sample of No. I O was too small for more tests, being a small sample sent in only for panel tests. A C K N 0 W L E D G M E KT
Many of the physical tests and some of the analytical work were performed under the author’s direction by Mr. Vernon Ladd, an assistant in this department. THE DETERIORATION OF CUBAN RAW SUGARS IN STORAGE By Nicholas Kopeloff and H. 2. E. Perkins LOUISIANA SUGAREXPERIXENT STATION, NEWORLEANS,LA. Received January 29, 1920
The deterioration of manufactured sugars has been the subject of considerable investigation and has presented a number of interesting aspects, commercial as well as scientific. These have been considered in detail in another c ~ n n e c t i o n and , ~ i t will suffice t o state t h a t many investigators have advanced evidence which proves t h a t the loss in sucrose content which manufactured sugar undergoes on storage is due in a large measure t o microbiological activities. It was in the hope of throwing some light on this phase of the problem t h a t the following experiment was undertaken. While much valuable d a t a may be found giving the analyses of sugars which have undergone deterioration, or those artificially inoculated for t h a t purpose, there has not come t o our notice any study based on t h e concomitant bacteriological and chemical analyses of sugar when stored under normal conditions, and which might be regarded as representative of large quantities of sixhilarly stored sugar. Two 320-lb. bags of each of three different “marks” of Cuban raw sugar representing a n aggregate of Tms JOURNAL, 11 (1919). 121.
* Ibid., 2 (1910). 43.
8 Louisiana Sugar Experiment Station, Bulletin 166; THISJOURNAL, 12 (1924), 256.
555
approximately 5 5 8 6 tons of sugar, were analyzed chemically and bacteriologically a t t h e beginning of t h e storage period, and again in a n identical manner a t t h e end of I a n d 5 . 5 mo., respectively. Each bag was sampled as follows: A “long” trier was run in three places through the middle for the entire length of the bag. Two samples were drawn from each hole, and all mixed thoroughly on a sterile glazed paper, the composite being taken as representative of the contents of the middle of the bag. The usual precautions in bacteriological technique, against contamination of trier, mixing, etc., were observed by the use of alcohol. The bag was thenskinned in two places; t h a t is, the sugar a t the surface just inside the bag was taken. Three samples were taken from each of these two holes, and after being thoroughly mixed were considered representative of the surface contents of the bag. All the holes thus made were immediately sewed up, except the hole always made b y the official sampler with a short trier. These samples were analyzed chemically a t once and a portion collected for bacteriological analysis in sterile containers. These were platted on Kopeloff’s agar1 in three dilutions. The averages given in t h e succeeding tables represent triplicate determinations of each dilution. The bags were piled in 2 rows of 3 each (the lowest ones resting on the floor) and 2 burlap sacks thrown over the sides t o approximate normal storage conditions as nearly as possible. Analyses were made a t the end of I , 4.25, and 5 . 5 mo., respectively. A second series of bags was similarly obtained and analyzed the same way. These bags, however, represented only two marks-but were triplicate bags, one mark (G) being taken from the top of the vessel where the bags had been heated, the other mark (C) taken from the bottom of the vessel, two bags having been “stained” and another not “stained.” The chemical and bacteriological analyses of all samples are presented in Table I and summarized in Tables I11 and IV. Table I1 gives the conditions of humidity and temperature which obtained through this incubation period. Certain important generalizations may be deduced from the above data, among them the fact t h a t there is a loss in polarization in all samples examined which were held for 5 . 5 mo. There is also a loss in polarization in practically all samples held one month or longer, and again in moisture content. The loss in polarization in each instance has generally been accompanied b y a gain in reducing sugars, indicating t h a t t h e loss is due t o true inversion due t o microbiological agencies. It will be remembered t h a t Browne2 has pointed o u t t h a t “the average Cuban sugar of 96 per cent sucrose would deteriorate if stored in New York for one year t o 9 5 and if stored in Cuba t o 94 per cent sucrose,” which calculated a t 1916 prices would amount t o $1,150,929. This large figure would have t o be increased a t current prices and production, From Tables I t o I11 i t will be seen in one case t h a t there has been a loss of over 9.0 per cent, while there are three instances of a loss of more t h a n 8.0 per cent. 1 LOC. 2
&.
THISJOURNAL, 10 (1918). 178.
*
T H E J O U R N A L OF I N D U S T R I A L A N D ENGINEERING C H E M I S T R Y
556
TABLE I-CHEMICAL NAME Description B Light
B
BACTERIOLOGICAL ANALYSES OF CUBANRAW SUGARS IN STORAGE Part MoisGain in Factor of Loss ture R. S. in R. S. of No. Date Pol. in Pol. Per cent Per cent Per cent Ash Bag Safety 1 Mid.1 96.4 1.38 0.62 5/7 0.54 0.38 97.0 6/10 1.07 0:01 0.63 0.36 10/21 88.0 8:4 2.65 3.57 4.19 0.22 1s Sur.1 97.0 0.62 1.47 0.49 :$YO 96.8 0:i 1.15 0:66 0.76 0.36 10/21 94.2 2.8 1.66 1.51 0.89 0.29 2 Mid. 93.8 1.88 0 : a0 1.26 0.30 :$YO 94.0 1.75 1.26 0.29 10/21 93.9 1.80 1.12 0.30 Sur. 2s 93.5 2.10 1.49 0.32 94.0 1.76 1.41 0.30 10/21 92.5 1:O 2.54 1.84 o:is 0.34 3 Mid. 93.8 1.61 2.24 5/7 0.45 0.26 6/10 93.0 0:b 1.44 2.84 0:;o 0.21 10/21 84.5 9.3 3.03 6.25 4.01 0.20 3s 5/7 Sur. 96.9 1.10 0.78 0.36 6/10 92.5 4:i 4.03 1.55 0:?7 0.54 10/21 88.0 8.9 2.92 5.69 4.91 0.24 Mid. 4 95.0 1.34 0:i5 2.21 0.27 :$YO 94.4 0:; 1 .os o:i2 2.53 0.20 10/21 87.3 7.7 2.94 3.74 5.95 0.23 4s Sur. 96.9 0.94 5/7 0.80 0.30 6/10 1:; 95.3 1.20 2.29 1149 0.26 10/21 91.3 5.6 2.25 3.76 2.96 0.26 5 Mid. 95.3 1.71 0.75 5/7 0.63 0.36 6/10 0:i 95.0 1.31 0:is 1.23 0.26 10/21 94.5 0.8 1.73 0.84 1.59 0.31 5s Sur. 95.8 1.45 1.22 5/7 0.35 6/10 95.9 0.90 1.14 0.22 10/21 90.5 5:i 2.81 3.71 1 :49 0.30 6 Mid. 96.0 1.60 0.64 5/7 0 : 55 0.40 6/10 96.0 1.20 0:;s 1.02 0.30 10/21 91.1 4:9 2.21 3.49 4.13 0.25 6s Sur. 96.8 1.16 0.61 5/7 0.36 6/10 97.0 0.85 0.92 o:ii 0.28 10/21 89.8 7:o 3.00 5.55 0.30 4.94 7 Mid. 6/13 96.1 1.63 0.56 0.42 10/21 93.8 2:i 1.85 1:97 2.53 0.30 7s Sur. 6/13 96.8 1.06 0.65 0.33 10/21 6:j 2.75 90.3 3:i4 4.19 0.28 8 Mid. 6/13 96.2 1.74 0.58 Oa46 10/21 93.5 2:; 1.92 2.53 1.95 0.30 8s Sur. 6/13 95.0 1.24 1.23 0.30 10/21 94.5 1:4 2.20 1.44 o:i1 0.40 9 Mid. 6/13 96.7 1.15 0.67 0.35 10/21 93.2 3:5 1.88 1 :86 2.53 0.27 9s Sur. 6/13 96.9 0.80 0.97 0.26 10/21 88.5 814 6.25 3.40 5128 0.30 10 Mid. 6/13 94.8 1.67 1.43 0.32 10/21 94.5 0 :i 1.60 1.70 O:i7 0.29 1 os Sur. 6/13 94.4 1.62 1.22 0.29 10/21 94.0 0:4 0:86 2.71 2.08 0.45 11 Mid. 6/13 95.8 1.23 1.46 0.30 10/21 89.8 6;O 2.73 2:92 4.38 0.27 11s Sur. 6/13 96.6 1.00 1.02 0.23 10/21 93.6 3:o 2.35 2.48 1:46 0.37 12 Mid. 6/13 96.6 1.21 0.66 0,.28 10/21 94.0 2:; 1.89 1:io 1.96 0.32 Sur. 12s 6/13 96.6 0.95 0.87 0.22 10/21 94.0 2:6 2.07 0:83 1.70 0.35 Negligible amount.
.. ....
....
.... ..
.. ..
M
Wet
..
.. .. .. .. .. .. .. *.
.. ..
Average
KJ
*... *... ..
Wet
..
..
.. ..
Average
G
.. .. .. ..
.. .. ..
.. ..
.. .... .. .. ..
Heated in top of vessel
.. .. .... ..
C
Stained in bottom of vessel
C
Not stained in bottom of vessel
1
Mid. = Middle.
2
Sur. = Surface.
*
The economic importance of such data is too obvious t o require amplification. The total numbers of microorganisms responsible for this deterioration must needs vary considerably because of t h e difficulty in such a n experiment of controlling the many variable factors which might have a n influence on the microorganisms. However, it may be observed t h a t in all bags heated in t h e t o p of t h e vessel during transit, or held in t h e bottom of t h e vessel, there was a decided increase in t h e number of microorganisms. As a rule t h e per cent of molds increased during t h e longer storage period, b u t not in one month. I n general, there were more microorganisms in t h e middle t h a n a t t h e surface of the bag, as might readily be expected, since those a t t h e periphery were more subject t o a drying-out process. A correlation between numbers of microorganisms and deterioration was discernible where there was a heavy initial infection or a noteworthy rapid increase in t h e number of microorganisms. The factor of safety or moisture ratio, which is calculated b y the formula
M.
R. =
12,
No. 6
AND
..
Dark
Vol.
Moisture Io0 - Polarization'
is in most instances over 0.35, in 6 of t h e instances 0.30 or more, in 4 of the instances over 0 . 2 7 , and in t h e
.. .. .. .. .. .. .. .. .. .. .. .. ..
No. Mic. per Molds G. Per cent 550 200,000 12,500 463 2,500 11,500 5' 480 6 19,000 4,250 7 1,034 2, 23,000 17,250 2 77,000 19,000 17,500 4,305 3,000 7,250 4, 38,035 50,000 33,500 1 4,018 2; 55,000 8,500 1,547 3, 1,700 22,000 12 251 800 11,500 16 508 20,500 16,000 1 1,040 3, 870 8,000 135 350,000 275 80,000 285 6,000 170 250,000 90 5,500 190 8,500 2,250 25,000 80,000 135,000 80 75,000 ;x 550 95,000 5,000 75,500 40,000 135,000
'51*
'4,
*
*
*
' 5* * *
* *
* * *
* * * *
* *
* *
* **
* * * * * ** *
** *
*
remaining 4 instances 0.22 or over. From t h e evidence advanced by other investigators it might be expected t h a t practically all of these sugars are unsafe, although t h e general consensus of opinion seems t o place t h e limit for t h e factor of safety at about 0.30. From t h e standpoint of mold infection i t was found t h a t even sugar with a lower factor of safety was unsafe, when sufficiently infected, and this would likewise seem t o be t h e case where other microorganisms were concerned, as in t h e above instances, which represent about one-third of t h e samples under observation. TABLE11-TEMPERATURSA N D RELATIVEHUMIDITIES A T NEW ORLEANS, LA., MAY TO OCTOBER 1919 Relative ---Temperature F. MONTH Humiditv Max. Min. Mean 85.04 May . . . . . . . . . . . 7 5 64.00 88.00 J u n e . . . . . . . . . . . 77 69.00 91 .OO 71.80 J u l y . . . . . . . . . . . 77 91.50 August.. . . . . . . . 79 72.90 88.10 September. 67 68.10 90.00 October.. . . . . . . 75 67.00
----
.....
....
AVERAGE
_-
-
75
88.90
68.50
80.47
From t h e work done with molds it was concluded t h a t with moisture ratios over 0.20, only I O O mold spores per gram were sufficient t o cause deterioration. Since bacteria are, as a rule, somewhat smaller t h a n mold spores it might be expected t h a t a somewhat larger number of bacteria would be required t o produce the same degree of deterioration. Therefore if there
June,
T H E J O U R N A L OF I N D U S T R I A L A N D ENGINEERING C H E M I S T R Y
1920
TABLE111-DIFFERENCES BETWEEN SUCCESSIVE S A M P I . I N G S DescripNAME tion Part Date pol. ’ Moist. R . S. F.5. Mic. Molds B Light Mid. 6/10 + 10/21 Sur. 6/10 10/21 B Dark Mid. 6/10 (+) (-) 10/21 (-) (+) Sur. 6/10 + 10/21 + M Wet Mid. 6/10 10/21 Sur. 6/10 10/21 Av. Mid. 6/10 .. 10/21 Sur. 6/10 10/21 ,. ..
+ -
+ -
Wet
U
Mid. Sur.
A v.
Mid. Sur.
G
Heated
C
Heated
C
Moist
+ Increase sampling. ( )
6/10
10/21 6/10 10/21 6/10
-
.. +
.+. + +++ + +++ ++ + +
+ +
+
-
+ ++ ++
+ + + + -
10/21 6/10 10/21 Mid. 10/21 Sur. 10/21 Mid. 10/21 Sur. 10/21 Mid. 10/21 Sur. 10/21 Mid 10/21 - (--) Sur. 10/21 Mid. 10/21 f Sur. 10/21 Mid. 10/21 f Sur. 10/21 Mid. 10/21 + Sur. 10/21 .over previous sampling. - N O Questionable.
+++ ++ +
-
--
+ +++ -+
-+ -- + + + + ++ ++ . + + . + ++ -$ +- + . : + - - +++ ++ +- + + . ++ +- + + . + + + . ++ + - + + .
-
+ ---+ -+ ++ --
+
+ -
::
- .. -+ .
.. .. . .. ... .. ....
+ + + + + ++ + + . ... + ++increase ++ over + + previous . . .. f
were more t h a n I O O bacteria a t moisture ratios or factors of safety greater t h a n 0 . 2 0 , deterioration might be expected. T h a t such is actually the case may be seen from Table IV, for here we find t h a t deterioration TABLEIV-SUMMARY
DF-
No, NAME scription G
9s 65
M N ha
Av.’ Wet Wet Av.
B G U M
Light A;.‘ Av. St.
U
35 3 4 1 7s 6
45 11 7 8 9 5s 11s 12
C G G
G U C
C B C U C B
1s 10s 5 12s 2s 10
C G B
8s
2
... ...
W&
St. Unst.
Light St. Wet Unst. Dark St.
.. . Dark
Part Bag Of
SHOWING MAGNITUDE O F DETBRIORATION Deterioration not Gain
R.s. Loss Factor
Sur. Sur. Sur. Mid, Mid.
cent Per 5.28 4.94 4.91 4.01 3.74
Pol. in Safety Of 8.4 0.26 7.0 0.36 8.9 0.36 9.3 0.26 7.7 0.27
Mid. Sur. Mid. Sur. Mid. Mid. Mid. Mid. Sur. Sur. Mid.
3.57 3.54 3.49 2.96 2.92 1.97 1.95 1.86 1.49 1.46 1.30
8.4 6.5 4.9 5.6
Sur. Sur. Mid. Sur. Sur. Mid. Mid. Mid.
0.89 0.86 0.84 0.83 0.35 0.27 0.21
,.
6.0
2.3 2.7 3.5 5.3 3.0 2.6
Deterio- from Predicted F.s. No. ration but from Micro. predicted No. of per G. o r ~ ~ ~ 190 1,040 .. 4,305 77,000 38,035
$:g + + -
0.38 550 0.28 80,000 0.40 508 0.30 4,018 0.30 80 0.42 135 285 0.46 0.35 90 0.35 ’ 251 0.23 550 0.28 5,000
2.8 0.49
463
0 . 4 0.29 75,000
0.8 2.6 1.0 0.3 1.4
...
0.36 1,547 0.22 40,000 0.32 1,034 0.32 2,250 0.30 170 0.30 480
+ 4-
+ + + + + + -
4-
+ + + +
+ + +. . .... .. .. ..
+ i: +
.. *.
*. *.
occurs with factors of safety from 0 . 2 2 t o 0 . 2 9 , and the microorganisms responsible vary in number from 190 t o 80,oc)o per gram. It is especially significant t h a t t h e five largest numbers of microorganisms caused deterioration a t factors of safety below 0.30. Brownel has shown t h a t the explanation for this phenomenon is t h a t t h e factor of safety becomes lower and consequently unreliable where deterioration is already in progress. This leads t o a n important commercial application; namely, next t o eliminating deterioration it is of importance to predict the keeping quality of a sugar. It has been worked out empirically and scientifically t h a t deterioration may be predicted12 in 1 LOG. Cil. f
Louisiana Sugar Experiment Station, Bulletin 162.
557
sugars with a factor of safety greater than 0.30, and this is used as the basis for the next t o last column of Table IV. I n the final column, however, is included a prediction of deterioration based not on the factor of safety (for this is below 0.30) but on the number of microorganisms per gram. T h a t is, with factors of safety above 0 . 2 0 , upward of I O O microorganisms per gram would be expected t o cause deterioration. While i t is not possible t o predict deterioration from the total number of microorganisms as confidently as in the case of mold infection, the parallel seems very striking and further experiments now in progress will form the basis for verification. ’ TABLEV-SUGARS RANKED ACCORDING TO DETERIORATION Most Most Least Least Deterioration Deterioration Deterioration Deterioration b y Bag in Bag ORDER NAME by Bag in Bag Average Middle I M Wet Surface Surface .... Middle 2 G .... Wet Surface 3 u Average Surface Dark Surface 4 B Light Middle Unstained, (Middle) 5 c Stained (Surface) (Surface) (Middle)
In Table V the sugars under investigation have been ranked in order of greatest deterioration. This ranking was arrived a t by evaluation from the complete list in Table IV, and making the proper averages. I n this way it is possible t o tell a t a glance t h a t the greatest deterioration occurred in the C L M , sugar, ) followed in order by “ G , , , t(u,,,“B,”and
