July, 1924
INDUSTRIAL A N D ENGINEERING CHEMISTRY
Minnesota yields from 10 to 20 tons of whole cane per acre, and about 16 gallons of sirup per ton.
DESCRIPTION AND USES OF
THE
SIRUP
The sirups made during the present investigations were usually clear; only in a few cases did they become cloudy during evaporation. In color they ranged from a light amber, similar to a good grade of maple sirup, to a dark brown, similar to molasses. The viscosity of the sirups was about that of maple sirup of the same density. The flavor, of course, is difficult to describe. Many people pronounced it very similar to that of sorghum, although in the writers' opinion they were not a t all alike. Most of the samples made had a mild, agreeable flavor; less pleasing than that of high-grade sorghum, but more so than that of molasses. Some of the samples made from corn grown in soil unusually rich in nitrates and other minerals had a very disagreeable flavor as was discussed above. Such sirups are unfit €or food, but their occurrence would probably be unusual and could be predicted by watching the purity quotient of the juices, as suggested. The cornstalk sirups so far produced are not suitable for table use, but are well adapted for cooking purposes. The writers have submitted samples of the sirups to a great many individuals for use in the home; to a class in experimental cookery ; to a cafeteria for use on a large scale; to an experienced buyer of sirups and molasses; and cookies made from these sirups, from sorghum, and from molasses to several groups of people for comparison. The general opinion of these various observers was that the cornstalk sirup is equal to the best grade of sorghum and molasses, and much superior to the lower grades, for all cooking purposes. One objection was that the sirups do not impart so dark a color to the products as molasses does but such an objection probably would not be general, The flavor of the products is not so pronounced as when molasses is used, but this difference seemed to be acceptable to the great majority of the judges. From the foregoing evidence the writers consider cornstalk sirup to be a competitor of high-grade molasses and sorghum. SUMMARY I-The stalks of all varieties of sweet corn, and two varieties of field corn, gave satisfactory sirup, with the exception of Stowell's Evergreen in 1922, which contained an excessive amount of potassium nitrate. 2-The purity coefficient, solids-over-Brix, of the juice and of the sirup proved to be a very useful criterion of quality. It is suggested tentatively that any juice with a quotient of 94 or less be considered unsuitable for sirup-making. 3-Stalks a t all ages after removal of the ears made good quality of sirup. The purity did not appreciably increase as the density of the juice increased with the age of the stalks. 4-Shocking the stalks with the leaves on, or stacking them with the ears removed, for periods up to 4 days, did not affect the sirup-making qualities, although the acidity and density of the juice increased in most cases. 5-Although in the present experiments low percentages of juice were obtained, this was due more to the character of the mill than to the lack of juiciness of the stalks. 6-The titratable acidity of the juice always decreased during defecation by heat. It decreased further by the addition of kieselguhr and of activated carbon. These changes have to be taken into consideration in controlling juice acidity. Calcium hydroxide exerted almost theoretical effect in neutralizing juice acidity. 7-Activated carbons had practically no value in decolorizing cornstalk juices, and very little in removing objectionable flavor.
739
8-Kieselguhr proved to be an excellent filter aid, and the juices filtered very satisfactorily with 1 per cent of their weight of this material. 9-A brief outline of the process of manufacture recommended for commercial practice is given. It differs from the manufacture of sorghum sirup only in the treatment in the field and in the control of the acidity. 10-The smaller varieties of sweet corn yield 3 or 4 tons of stalks to the acre; the larger varieties of sweet corn and field corn, 9 to 10 tons. 11--Most varieties, allowed to stand for 2 or 3 weeks after picking the ears, yield from 11 to 12'gallons of sirup per ton of whole cane. If used a t the time of picking, the yield may be as low as 8 or 9 gallons. 12-Cornstalk sirup is usually clear, of a reddish amber color, and has a mild, agreeable flavor. It is not a table sirup, however, but a cooking sirup, with characteristics and uses very similar to those of sorghum and of molasses.
Fermentation of Natural Fruit Juices' By B. A. Dunbar and C. F. Wells SOUTH
DAKOTA STATSCOLLEGE, BROOEINGS, S. D.
N THE course of a series of calls for evidence in criminal
I
cases involving the enforcement of the liquor laws, the writers have been confronted with a need of more accurate data than they have been able to adduce, relative to Conditions under which the spontaneous fermentation of cider and other common fruit juices may take place most rapidly, of the effect upon such reaction which an addition of sugars such as glucose may produce, of the temperature conditions that accompany maximum or minimum production of alcoholic content, and of the time factors that have to do with such maximum effect. Since the admixture of foreign materials was usually found to be so varied in kind and quantity as to preclude imitation in experimentation during the period wherein freshly expressed juices could be secured, the writers have confined their work to the time rate of fermentation and the increase of alcohol content attendant upon such a fermentation as proceeds when the raw juices are allowedto ferment without addition of ferments and when more or Iess glucose is added, without the presence of yeast or other added catalysts. I n the experiments described in this paper glucose has been used, since this type of sugar has been found to be too much in evidence in unlawful production of alcoholic beverages. However, for comparative purposes, cane sugar will be used in some future experimentation.
EXPERIMENTAL Apples of the Jonathan variety and Concord grapes were thoroughly pulped and this pulp was pressed through a hand press of the screw type, whereby a juice of the concentration naturally met in such processes was obtained. These juices were a t once transferred to sterile beakers, loosely covered with cheesecloth to prevent contamination by foreign materials, and placed in electrically heated compartments having free access to the air, and maintained a t a constant temperature of 21' C. (70"F.) (withno variation greater than a fractionof 1degree) throughout theexperiment. At the end of each 24 hours the contents of each beaker were thoroughly stirred and two samples were taken for analysis-one of 50 cc. to determine alcoholic content, and one of 10 cc. which was titrated against 0.2 N sodium hydroxide to de1 Received
February 29, 1924.
INDU8TRIAL A N D ENGINEERING CHEMISTRY
740
termine acidity, phenolphthalein being used as indicator. This periodic examination of the fermenting mixtures was continued until there was no further evidence of alcohol. In order to compare the effect of more or less addition of glucose to the fermenting liquids, five fermentation cells were maintained separately to the close of the experiment. The results of the analyses are given in Table I, which covers the five fermenting masses as follows: A-3500 B-3500 glucose
cc. of pure grape juice as expressed cc. of pure grape juice plus 560 grams of commercial
C-3000
cc. of pure apple juice as expressed cc. of pure apple juice plus 280 grams commercial
0-3500 glucose E-3500 glucose
cc. of pure apple juice plus 560 grams commercial
In this table no correction has been made to cover the increased volume attending the addition of the glucose, inasmuch as this was not considered necessaryin thepresent paper.
Periods 1 2 3 4
5
6 7
8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 2s
Alcohol 0.2 N NaOH Per cent cc
Alcohol 0.2 N Per cent 0.00 0.80 1.70 4.55 6.20 6.90 8.30 8.00
7: 10 6.96 6.55 4.80 4.30 3.35 3.15 3.10 2.90 2.60 2.45 2.20 2.00 1.50 1.50 1.15 0.80 0.00
NaOH cc. 7.3 7.3 7.3 7.4 7.4 7.4 7.4 7.4 7.4 7.4 7.4 7.5 7.7 8.5 9.0 9.4 9.9 10.1 11.2 12.5 13.8 14.7 15.0 16.0 17.5 20.1
An examination of Columns C, D ,and E of the table brings out the fact that the addition of fermentable sugars affected the initial acidity, but that doubling such addition had no effect upon this increase of acidity. On the contrary, this addition results, after about half the fermentation period is passed, in decrease of acidity and in a final lowering of the same as compared with that of the unaltered juice. This problem is to be studied during the coming year. CONCLUSIONS 1-In the natural fermentation of either pure fruit juice or of that to which fermentable sugar has been added, the peak of alcoholic content was reached in from 7 to 10 days, temperature being constant a t 21" C. (70" F.). 2-No material increase of acidity was observed until the alcoholic content had reached or passed this peak. 3-Introduction of fermentable sugars retarded the oxidation of alcohol to acid-a fact already observed by other workers.
TABLE I
_____B---
____- A--N o . of 24-Hour
.
I
These data are perhaps more strikingly presented in the accompanying graphs, of which Curve A represents a composite of the matter of record in Columns A and B of Table I, and Curve C similarly composites the data of Columns C , D , and E of the same table. These graphs show a decided dissimilarity of curve form attending the work with these two types of juice, while the data for each type of juice present graphs which are markedly alike in general contour.
Vol. 16, No. 7
____--C---Alcohol 0.2 N NaOH Per cent cc.
7---
Alcohol Per cent 0.00 0.00 0.40 2.45 3.50 4.25 5.20 7.60 7.70 8.30 7.20 6.95 6.90 6.70 6.00 4.20 3.80 3.20 3.00 2.60 1.70 1.40 1.40 0.80
0.80 0.05
0.00
_____
--D 0.2 N NaOH cc. 5.7 5.7 5.7 5.9 5.9 6.2 6.4 6.5 6.6 6.7 6.8 7.2 7.3 7.8 8.2
8.5 9.1 9.5 10.0 10.5 11.0 11.8 12.5 13.0 13.6 14.3 15.8 17.2
---F---
-
Alcohol 0.i.V NaOH Per cent cc 0.00 5.7 0.00 5.7 1.10 5.7 2.45 5.9 3.80 6.0 4.25 6.2 5.80 6.3
.
8.00
8.00 8.30 7.20 7.20 6.95 6.90 6.70 6.00 4.20 3.80 3.20 3.00 2.60 1.65 1.60 1 60 0.80 0.80 0.05 0.00
6.6
6.7 6.8 6.8 7.3 7.4 8.3 8.6 9.1 9.6 10.4 11.1 11.6 12.4 13.1 13.8 14.7 16.0 16.8 18.8
19.1
To determine proper methods of reforestation in the great forests of the Pacific Northwest, the United States Department of Agriculture will establish a forest experiment station in that regjon on July 1. This station marks the latest addition in the department's plan to establish forest experiment stations in all the principal forest regions of the United States. Its work will consist of determining proper ways and means t o prevent forest destruction either by destructive logging, fire, or other agencies and to insure the perpetuation of the forests as growing crops.
