I N D V S T R I A L A X D ENGINEERING CHE-MIXTRY
'780
hydrogen-ion concentration due to the buffer effect of other substances in solution. Fellenberg2 mentions the fact that the viscosity of pectins decreases with decreasing methoxyl content. In this connection it may be of interest to note that the acid pectin extracts of high jellying power had greater viscosity than did autoclave extracts in which the jellying properties were greatly reduced.
CONCLUSION The true explanation for the discrepancies which have been pointed out involves a knowledge of the pectin bodies both as regards their constitution and their colloidal nature, which a t present is not available.
Vol. 15, 9 0 . 8
As a result of unfinished tests with purified pectins, the writers concluded that quantitative relations in sugar-pectinacid gels cannot be correctly interpreted, nor can any great advance be made in the study of the colloidal properties of these solutions until there are available for careful experimentation pectins of a high degree of purity and of welldefined composition. When the relation of jellying power to composition is.once established, a very satisfactory method of estimating effective pectin content, based upon jellying power, can be developed. Such a method, to be capable of general application, will require an accurate device for measuring gel strength under carefully standardized conditions.
Jellying of Sorghum Sirup' Effect of Malt Diastase upon the Filtration of Sorghum Juice By Sidney F. Sherwood OFFICE OF SUGAR PLANT
INVESTIGATIONS,
BUREAUO F
PLANT
INDUSTRY, WASHINGTON, D. C.
T
Starch seems to be largely responsible f o r the jellying of sorghum The following sirups were HE cause of jellying sirup and for the extreme dificulty i n filtering sorghum juice, espeprepared from juice from of sorghum sirup, a characteristic well cially after it has been heated. Preliminary treatment of the juice Silver Top, Folger's Early, known to manufacturers, with malt diastase greatly increases the rate of filtration and preSugar Drip, Early Rose, has not yet been explained. oents the 'j'ellying" of the finished sirup. Early Amber, and Red Amber sorghum, grown a t Although much of the sirup Arlington Farm, Va., in produced seems to have no jellying characteristics, jellying may occur a t any time, 1922. The quantity of starch in the juice was not deterordinarily becoming manifest either immediately after the mined, but all the juices gave a positive reaction with iodine, finished sirup has become cold or after the cold sirup has and when preserved with mercuric chloride and allowed to setbeen stored for some time. Jellied sirup varies from a tle exhibited in the settlings a starch layer or band. The slightly slimy material to a gelatinous semisolid resembling tables are based upon nine series of determinations and the ordinary table jelly prepared from fruit juices. Sirup of this results are in entire agreement with similar investigations character is highly unsatisfactory to both the dealer and made in previous seasons. the consumer. SIRUPA-Approximately 900 cc. of juice plus 1 ounce of kieselMany of the sirups made from different varieties of sweet guhr (3 per cent by weight), heated to 98" C., and filtered a t sorghum in connection with some breeding experiments and once. SIRUPB-Approximately 900 cc. of juice plus 1 ounce of kieselvarietal tests on sweet sorghums conducted by this laboratory stirred, and filtered a t once without heating. (project in charge of H. B. Cowgill, agronomist, under the guhr, SIRUPC-Approximately 900 cc. of juice heated t p 98' C., direction of C. 0. Townsend, pathologist in charge of office), cooled to 40' C., 10 cc. of malt extract added, permitted to stand had a jelly-like consistency. The starch content of 15 for 1hour, 1 ounce of kieselguhr added, and filtered at once. SIRUPD-Approximately 900 cc. of juice heated t o 98" C., samples of juice expressed from 15 varieties of sorghum cooled to 40" C., 10 cc. of malt extract added, permitted to stand a t maturity varied from 0.142 per cent (1.3 pounds per 100gal- for 1 hour, 1 ounce of kieselguhr added, heated to 98" C., and lon of juice) to 0.852 per cent (7.8 pounds per 100 gallon), with filtered a t once. SIRUPE-Identical with Sirup D, except that 20 cc. of malt an average of 0.366 per cent (3.3 pounds per 100 gallon).2 Starch seems to be largely responsible for the jellying pro- extract was used. pensity and for the extreme difficulty hitherto experienced The rate of filtration of these juices is shown in Fig. 1. in filtering sorghum juice, especially after it has been heated. Apparently, pseliminary treatment of the juice The effect of the diastase upon starch in the juice was inwith small quantities of malt diastase greatly increases the vestigated further by adding ordinary cornstarch to juice obrate of filtration and prevents jellying. tained from Early Rose and Red Amber sorghum. Starch was added at the rate of 15 grams per gallon (3.3 pounds per EXPERIMENTAL 100 gallon), the average of the figures given for starch conFreshly ground malt was mixed with water in the proportion tent of normal sorghum juice. Some of this juice was of 26 grams to 200 cc., stirred frequently during 1 hour, and treated with kieselguhr and with malt extract in the followfiltered through filter paper. The resulting extract was per- ing proportions: fectly clear. A Buchner funnel, 6 inches in diameter, was fitSIRUPF-Approximately 900 cc. of juice, heated to 98" C., ted with a single thickness of closely woven cotton cloth, which t o 40"C., permitted to stand for 1 hour, 1 ounce of kieselwas then faced with a layer of kieselguhr approximately 2 cooled guhr added (3 per cent by weight), heated to 98" C., and filtered mm. thick. The juice was kept thoroughly stirred while a t once. SIRUPG-Approximately 900 cc. of juice, heated to 98' C., being poured bn the filter, so as to build up an even cake, and cooled to 40" C., 20 cc. of malt extract added, permitted t o stand vacuum was maintained at a closely constant rate for all for 1 hour, 1 ounce of kieselguhr added, heated to 98" C., and runs. filtered a t once. 1 2
Received March 3, 1923. THISJOURNAL, 16, 727 (1923).
The rate of filtration of these juices is shown in Fig. 2.
IA'D CSTRIAL AiYD EIVGIAiEERILVGCHEMISTRY
August, 1923
The remarkable effect of t,reatment with malt extract upon the rate of filtration of sorghum juice is shown in Figs. 1 and 2. Direct filtration of unheated juice to which kieselguhr had been added gave an average of 285 cc. filtrate in 2 minutes, and 515 cc. in 5 minutes. The heated juice E D
DO0 I
€ D
,c-
/ ,I
,
I
---
I , Lo--
/
'---A
-
A
,
I 0
I
3
2
4
5
Mlnuies FIG. 1
gave an average of 90 cc. of filtrate in 5 minutes. In both cases filtration practically stopped after 5 minutes. It may be said that the heated juice refused to filter. Juice that had been treated with malt diastase filtered readily, giving an average of 800 cc. of filtrate in less than 2 minutes. The filtration continued a t a satisfactory rate. Treating ordinary sorghum juice with malt extract is as satisfactory at the rate of 10 cc. of extract to 900 cc. of juice (equivalent to approximately 1 gallon of extract to 100 gallons of juice) as a t the raie of 20 cc. to 900 cc. (Juices D and E.) When starch was added, the untreated juice refused to filter (Fig. 2 ) . The tyeated juice filtered readily (average of 800 cc. of filtrate in 2 minutes) and continued to filter beyond 12 minutes although at a slower rate. At the end of 12 minutes the filter cake was "4 inch thick. I n every case, whether or not the juice had been treated with malt extract, the filtrates had a light amber color and were perfectly clear and brilliant.
'781
The sirups prepared from the filtrates from the treated juice presented a marked contrast to those from the raw juice. All were smooth and free floning; none were slimy or gelatinous. This was true also of the sirup from the juice containing added starch, although one such sirup contained a few minute, transparent,. gummy particles. I t is probable that the starch in the original juice plus that added made such a large total that either the malt extract or the period of time was insufficient for its complete conversion. None of the sirups showed indications of jellying or sliminess after 4 months storage a t room temperature. The color of the sirup was practically identical with that of the sirups from corresponding original raw juice. Several of them were perfectly clear but most of them were slightly cloudy. The degree of cloudiness, however, was markedly less than that of the corresponding sirup from original raw juice, and no particles of suspended material appeared. The clouding did not take place until the liquid had been reduced nearly to finished sirup. Probably it was due to the decomposition of certain constituents a t the higher temperature that prevails in boiling the thick sirup. Possibly this cloudiness could be avoided by a lime clarification immediately after treatment with the malt extract or by filtration of the nearly finished sirups. The investigation was directed particularly to the jellying, however, and this point was not investigated. There was no appreciable difference in taste or flavor of sirup from treated and untreated juice. Sucrose and reducing sugars calculated to a water-free basis, determined in several sirups, are reported in Table I. TABLE I-COMPOSITION Sucrose (Clerget) Samplea
1R I M 2R 2 M 3R 3 M
4R
4 M
Average R a
% 60.61 61.96 60.86 25.21 72.47 42.79 66.17 66.26
. ...
O F S I R U P O N \.T'ATER-FREE BASIS
Reducing Sugars (as I n v e r t Sugar)
% 24.99 25.23 24.89 60,09 17.20 46.54 21.96 22.88
....
1M .... ..., R, sirup direct f r o m original r a w juice;
filtered juice.
T o t a l Siiyars (Sucrose plus I n v e r t )
% 55.60 87.19 85.74 85.30 89.67 8 Q .33 86.13 89.14 87.29 87.74 M , sirup from treated a n d
EFFECT OF TREATMEKT ON SIRUP All tbe experimental sirups were made by direct open-pan evaporation of the filtrates. Control or check samples were prepared from portions of the original raw juice. The process followed was similar to the one ordinarily used in the commercial production of sorghum sirup-a simple, direct, open-pan evaporation by rapid boiling, without the use of clarifiers or filtration, and removal of scums by simple skimming. The raw juice gave the usual copious quantities of green and yellowish scums. A particularly noteworthy characteristic of the boiling of the filtrates was that no scums were formed. When the sirup had become very dense, the usual small quantity of foam characteristics of the boiling of any high-density sugar sirup was evolved. The treatment resulted in the entire removal of the scum-forming constituents of the juice. It is unnecessary to give in detail the characteristics of the sirups prepared. None of those from the raw juice were perfectly clear, and most of them were cloudy and contained specks and particles of suspended material. The color varied from light to very dark amber. Some were smooth and free flowing, while others had a marked slimy or gelatinous consistency. Those prepared directly from raw juice containing added starch were extremely gelatinous and contained transparent, gummy, lumpy masses.
Minutes FIG.2
There is no appreciable difference in the amount of total sugars in the sirup. No exDlanation is offered for the marked in;ersion that occurred in-the case of Samples 2 and 3, al-
INDUSTRIAL A N D ENGINEERING CHEMISTRY
782
though it may have been due to the effect of natural acidity of the juice. It is highly advantageous from the standpoint of sirup production, because the presence of invert sugar retards, and when present in sufficient quantity, prevents crystallization of sucrose. For purposes of sirup production, it would seem to be desirable t o select or breed varieties of sorghum, the juice
Vol. 15, No. 8
from which contains minimum quantities of starch a t maturity. However, the ease of filtration of the juice, the elimination of jellying of the sirup resulting from treatment with malt diastase, and the elimination of scum-forming constituents by filtration, indicate that the process may be applied with great advantage to the commercial production of sorghum sirup.
Suitability of Various Solvents for Extracting Vanilla Beans' Part
I
By J. B. Wilson and J. W. Sale WATER
W
ITH the advent Of prohibition and "le
AND
BEVERAGE LABORATORY, BUREAUOF CHEMISTRY, WASHINGTON, D.
Because of the restrictions on the use of alcohol which have followed prohibition, and the consequent substitution of other solvents for extraction of flavors, some preliminary work has been done to de-
c. 500-cc. flasks and covered with 200 cc. of solvent. The solvents used were " and 95 per cent isopropyl ether, acetone, and
termine whether or not these alcohol substitutes produce the same placing Of restrictions On the purchase and use Of amount and kind of extracts as those prepared f r o m ethyl alcohol. This investigation was limited to several varieties of vanilla and the interIn est has been manifested in tonka beans, and the solvents selected were isopropyl alcohol, ether, acetone, and carbon tetrachloride, to be compared with ethyl alcohol. One series Of 'perations the the Of Other than for The results show that the alcoholic solvents are much superior f r o m beans mTere with the standpoint of quantity of extraction, the carbon tetrachloride grams Of potassium carbonthe manufacture Of ins and flaVors) and ate and then extracted with in being the poorest i n this respect. I t is possible, however, that a 65 per cent ethyl alcohol. the reduction Of the Wanpreliminary extraction with ether or carbon tetrachloride followed tity Of which by a weak alcoholic solution m a y be found practicable. Work on The characters of vanilla extracts made is used' The United States the analysis of the final extracts i s still i n progress. Department of Agriculture, with 65 and 95 per cent ethyl alcohol and with alkain Circular 136, defines a flavoring extract as "a solution in ethyl alcohol of proper line 65 per cent ethyl alcohol are quite well known, so that strength of the sapid and odorous principles derived from these solvents were used as standards with which to compare an aromatic plant, or parts of the plant, with or without the characters of the extractive matters obtained with the its coloring matter, and conforms in name to the plant used other solvents. Isopropyl alcohol, ether, acetone, and carbon in its preparation." It is further held, under the Federal tetrachloride were selected, because they are available in large Food and Drugs Act,* that "nonalcoholic flavoring products quantities and have sufficiently low boiling points so that they may be labeled with the term 'flavor,' provided they contain can be removed from the extracted matters a t a low temperathe same kinds and proportions of flavoring ingredients ture under reduced pressure without affecting the quality of as are required by the Department's definitions and stand- the oleoresins. Moreover, their cost is reasonable when it is ards for extracts," and provided they comply with pertain considered that they can be recovered and used over and other requirements. Therefore, when oleoresins or flavors over again. The flasks containing the beans and solvents are prepared with solvents other than ethyl alcohol of proper were closed with rubber stoppers and covered with tinfoil. strength, the question immediately arises as to whether or The finely cut beans were macerated in the solvents for not the oleoresin or the finished flavor has "the same kinds five days or more with frequent mixing, and then separated and proportions of ingredients" as the oleoresins and flavor- from the supernatant liquids by decantation, placed in a ing extracts prepared with ethyl alcohol of proper strength. percolator, and drained, fresh solvent being poured over the It is obvious that considerable information on this question beans to make the volume of the extract up to 200 cc. Two can be obtained by $he analysis of extracts and flavors made additional portions of 25 cc. each of fresh solvent were used by extracting beans, roots, etc., with various solvents. Lab- to wash the beans. A second extraction was conducted in oratory work along this line covering vanilla and tonka beans a similar manner except that the solvents were kept in conwas started in the fall of 1922, and there are submitted here- tact with the beans for 4 weeks or more. There were thus with some preliminary data which are being supplemented obtained forty-eight solutions. The solvents were removed by further laboratory work. The important question of from all the solutions obtained from the two extractions, the toxicity of the solvents was outside the scope of this except those containing 65 per cent alcohol, at a temperature of not over 70" C., and a pressure of 100 to 25 mm. The investigation. quantities of extractive matter obtained are set forth in GEKERAL PROCEDURE I. The various vanilla beans which had been pracTable beans A quantity Of 'Iexican,Bourbon, and Tahiti tically exhausted with 95 per cent ethyl alcohol, isopropyl and Of tonka beans secured from a importing alcohol, ether, acetone, and carbon tetrachloride, were house, cut to about ' 1 4 inch in length With scissors, placed dried in the air and then subjected to the action of in a wooden and divided by Of a 95 per cent ethyl alcohol for 2 weeks and the quantity of meat chopper' One portions were placed in extractive matter determined after removal of the solvent 1 Presented before the Division of Agricultural and Food Chemistry at the temperatureand pressure noted above. These results at the 65th Meeting of the American Chemicaf Society, New Haven, Conn., are set forth also in Table I. The tonka beans, which had April 2 to 7, 1923. 2 Service and Regulatory Announcement, Chemistry, 28, Item 391. been practically exhausted with the solvents just enum-
'
