4 MODERNS U G AREFINERY ~
Sugar Industries
over t h e other European NTIL recent countries in the industry. The centuries, p r i c e fell from 2 shillings per man’s chief pound in the thirteenth century sweet food had been honey. Its to 4 pence per pound in the replacement by cane sugar besixteenth century. gan in the Far East, when India early developed sugar cane as the source of sweets, and AlexEarly American Period ander’s soldiers in 327 B. c. disWhile we are this year celecovered its excellence. From brating the tercentenary of the India the cane’s culture passed introduction of chemical industo Persia; the Arabs and the try into the American Colonies, Saracens took it t o the Mediwe cannot include the sugar interranean countries in the Middle dustry literally in that group Ages; and Columbus and his for a few years yet, for in 1635 followers brought it to Cuba and the West Indies. Diego Velast h e Colonies were importing quez introduced its culture when their sugar from the West Inhe settled a colony a t Baracoa, dies and consuming it in the WILLIAM D. HORNE Cuba, in 1511, and by 1650 it had form of savory m u s c o v a d o . Beech Creek, Pa. been introduced into all the West I n 1 6 6 1 , h o w e v e r , we have Indian islands. At the same time records of rum being distilled it had spread to all parts of tropion a small scale in New London. Conn., from West Indian molasses, and in 1735, just two cal America, and in 1794 to Louisiana. At this period the centuries ago, the first important distillery for making rum method of making crystallized sugar from the cane had advanced to the stage of crushing the cane between vertical from molasses was built a t Medford, Mass. The country’s rigorous climate and the colonists’ vigorous lives evidently wooden rollers, evaporating and skimming the limed juice in predisposed them to a keen appreciation of this beverage, for open kettles over wood fires, and setting the thickened massea t the time of the Revolution there are said t o have been no mite aside to crystallize and drain in conical or other containers. Efforts a t improving the quality of this crude sugar less than four thousand stills in the Colonies. As early as were made all along the line and, beginning in 500 A . D. a t 1689 there was a sugar refinery in New York City, and in 1730 Kicholas Bayard erected a sugar refinery on Wall Street, bedhwaz and Jondisapur in Persia, it was refined into such a tween William and Nassau Streets, where his imported expert superior form as t o give rise to its importation in ever-increasing quantities into Europe, where it was iconsidered a made the single- and double-refined loaf sugar of his day, luxury and brought a high price. This led the Venetian crushed sugar, brown sugar, and a form of rock candy. The Government to offer a prize of 100,000 crowns f9r the disStuarts built a refinery in 1732, and Johnvan Contandt another covery of a way to refine sugar. The prize was won by a in 1750. Peter Livingstonin 1754 erected a refinery on Liberty citizen of Venice in 1470 and, from that time on, refining was Street. Others followed so that by 1795 Xew York, Philaextensively carried on in that city. In the sixteenth century delphia, and Boston were refining 1,200,000 pounds of sugar Antwerp became the main refining center of Europe. Engyearly, about 2 per cent of the entire amount (60,000,000 land began refining in 1544 and gradually gained supremacy pounds) which was consumed annually. In 1805 the firm of
of the
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OYO
cmni IBIXY
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polariscope jwt 100 year* i q q ~ . Tlii.: instriiiiient exercised the lienfhcbal infiimic,e upon tlie iridiiitry tlmiuglr affording :I quick aiid easy control over tire increasing quantities of matorinl iiandlcd and the growing complcxit,y oE operatirim. Daring 1.liis period of rapid expansioni owing to tire clieapening (if sugar and growing' popular appreciation of its iiidis~iensdiility,clierriical control of raw factory arid oE refiiriiig grew more prevalent, a i d a g d ? d mealtli of clieniical literat i r e iwxanir available. Analytical metliods were devised arid perfected, new procedures arid proc aiid e1aLor:ite syxteiiis of scientific aipe hi 1834 &ngress published its firsst f;overmiient Industrial Cliernical Report, erit,itled "Maniiul on the Cultivation of the Sugar Cane arid tire F:ibrir:ation atid Itefinenieiit oE Siigar," by Henjamin Silliinan, Sr., \vlro Erom 1802 to 1853 was professor of chemistry a t Yale. In 1868, C. 1'. Chandler, a,bout three years after lie Irad couperated \&SI Tliomas Eglciton in establishing the Scliool of Mines of Colomhin College, became consultirig chemist to tlie Rootli and Edgar sugar refinery, West arid King Streets, S e w York. At that tiiire tlrerc were twenty-seven sugar refineries in the city, averagitig about 30 tons daily capacity. Among iitlier things, Chandler, with R.icketts, devised t,he inetliod of high-temperature plarimtion ior the estimation of the amount of commercial glucose in cane sugar, molasses, etc. Later F. G . Wieclimarin (if Columbia became consultant to Ravemeyer and Elder and contributed to sugar literature Iris exeellent book rm "Sugar Analysis," in 1890: About nine yearsearlier, .J. H. Tucker had poblislied his "Manual of Sugar Analysis" whicli also wax a fine guide iri tire same subject. Preeminent in t h i s field and gratefully ilpgreciated are the works of Wiley, Spcncer, Bryan, Brwiie, and Zer1)an The growth of the sugar industry was phenomenal; 1,ooiriana's prodiictirm clinrbed from 13,101 tons in 1823 to 235,85(i in 18il a t the out1)riv.k of the Civil War arid reached its apar of 355,330 totis i n 1904. The country's tutal conxiimption rose from 30,000 t.ons in 178.5 to 500,000 at Civil War time rind to 2,486,228in 1!100. Tile per capita consumpthni wits 18.2 p o n d s annurilly, in 1860; (j5.2 pmuds in 1900; 109.3 pounds at tlic iunirnit in 1926; arid 90.71 pounds in 1884, vi.hicli iireaiis a total for contiriental T.'nited States, last year, ,,f 5,134,746i long tons, worth about, $474,220,000. iiiost
RAW
Sln:a,, 1'rr.e
h. aiid I). Naveiiieycr, expcriencr:d iir t,Ix (;cririm~i r i e t l i d . c ~ f sirgar refining, licgari ojierati(iiic :it tlie r i m OS 87 Vandiiiii Street, in a little liiiilding 25 X 40 feet iii W. F.and F.C. Ilnreirieyer, iii 1847suppla1 story building, 200feet long, where t h y lriid ii trtelt,irigaali:ieit~of 35 tons a day; arid iu 1861 they joined iii erectiiig on t,hc water front. in I h o k l y n the great. Ilariwiegcr arid Elder rcfinery, wliicti long possessed the reputation of heing tire largest in the world. The middle of tire riiriet.eerrth cciitiiry saw great dianges i n the world's sugar iiidiwtries because of the iiiventim aiid illtroductiirri of new Inucliinery wliicli raised the prw ruauufactiire Ermr tlie previous small-soale diiiiensmiis to those rif trim mass pnidriction. Watt's .;teain engine liad recently replared iiiaii aiid nnimal power in driving sugar rane mills. IIoward, i n England, invenl.ed in 1813. Ilemsnr iritrodriced the filt.riitioii through coltirriiia of borio black in 18:30. IZil devised tiic multiple-effect eva,gimitor iii 1843. M a t t e r first used cnrlioiiation in tlic , s m e year. I'enaulrlt's celltrifugal maoliine \vas applied to tlie purging of sugar oia Cuites by sioiiolter in 1848. hfelsen applied sirifuniiis iixide >is a decrilirrant in 1849. Needham invented the filt,er press iri 1853. Eastick in 18(j7pateiited the washing OS raw sugars (:cntrifugally in preparation for refining-in other words, affination. .And in 1880 Bocqiiin and lipinski introdirced t,lie crystallizer. Improvement of Methods
Witti tliese iiiornentous advances in t l i c cheniical engirieeriiig of the sugar industry and the enormoiis increase in quantity of niaterials liandled came corresponding responsibility and need for precision in treating organic substances so susceptible t o fermentation, caramelizatim, and meclianical losi. Fortunately the French physicist, I3iot, invented LIE
Beet Sugar hfoaiitiliie, a ~iewmitry appeared iii tire field in tire sliupe of beet sugar. It was in 1747 that Illargraff succeeded i n obtaining (i.2 per cent sugar irorn beets; arid in 1709 Acliard cstnbliilir:d tlie first beet sugar factory i n Austria. Xapoleon lrearily siilisidized tlie industry in 1"rauce in 1810 to ericwrage the prodiiotim (If domestic sugar liecause the British i h c k a d e of French ports during tlie v a r largely cut off siipply (if cane sugar. Thus the technic w w s quickly acquired arid gradually spread thriiugli Europe. The first experiments is beet sugnr manufacture in tlie United States were made in hlassachiisetts in 1830, followed by others in California, Illinois, and Wisconsin, between 1863 and 1876 eacli was a financial Eailure. But in Nvarado, California, in 1870 a new factory was biiilt and operated as a prnnounced success. In 1887 Henry Oxnard went ta IhmqJe t o study the beet sugar industry and returned to build the beet. dugar factory a t Grand Islarid, Sehr. The suceesf attending this vent.ure led to tlie.gradual and tlicn to the rapid development of beet, sugar in the United States. In the early days tlie established cane refineries bought raw heet sugar from the beet. sugar factories, but soon t.lx tecliriic in the beet, industry improved so much that the iactories turned out exaltisively white sugar OS their own. These beet factories are confined in many
sl~l"rl~Ml~l~:l~, 1935
INI~US'I.'RIALANI) f!:N(;I N lilCIt 1st: (:I1 I3M1STRY
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cases t,o an opcratiiig seaon iif aimit 100 day?, and in t , l ~ l~eginningpriiduced nn nvernge of about O I tons a day. In I898 there were iiftecii i n operation, hit the next year this number lml douhled, nml tliey increased steadily nntil i n 1920 t,licre were iiinety-sereti, prodiwing a11 average rrf 100 tons u day. In 19:3:i-.:i4 there wcrc eighty-four faobories ili , uf alirnit 172 t,mw iLverage daily capacity, prodtw
053 king t r w per aliniini. I i i i p r o v e i i ~ e r ~ tisn Refining
11, refinirix, the latcr di des of the iiint:tcmtli cciitiiry sam deferatiiiir witli t)Iom!, o icr fresh or dried, soperseded b y acid plioqiiiate of liinr. (Irystallizatiori of low n i in sugar wagons was ,still conirnonly practiced lni ginniiig to be supplaiit,ed Iry tire use of crystallisers: osniogens were applied for t i l e treatment (if lowgrade Iiert simps; filter hag-; mere st,ill generally employed; sulfurous oxide was applied to dark colored solutions; graniilatd siigar 15 hoiled rather coarser than a t present arid was RhWt, iiniversally packed in barrels. The present century has wititessed multitudinoiw refineriteiits in practically every department of the industry. Xew variet,ies of cane have saved the industry in inore miintries t,han one, where pests and disease had threatened the crop. Chishers, slircdders, and disintegrators have added to t,he efficienoy uf increasingly powerfnl mills; hydraulic pressure and eorripound inaceration have raised extraction to the limit; the varions improved strainers aiid tlie Dorr continuoiis clarifier deliver a joke yo inuch freer from sediinent aiid rxilloidal matter as to produce cleaner raw eane sugars, wide tlic Kelly, the Sweetland, and the Vallez filter pr ait,li diatmnaceous earth arid paper pulp, speed u IIydrosulfitcs OS lime and of soda have hcen introduced for iileacliing. Centrifngal niacliines have I m n improved in speed, capacity, wasliing, and discharge, mid are evert operated aiitoinatically, by electric control, throngli tiit+ eiitirr round of operations. Vacuum pans have heen p i t inider almost autoiiia.tic coiitrol. \Veinrich's decarbonizer permits the revivification of bone black, a t a lower temperatirrc than is coininonly enipkiyed in kilns, with less shrinkage of the hone st.riieture aiid ~rrthahlya b e t k r reactivation of the ear-
1,ruuon G.4Ll.E"Y
lio~i. T l i e der:oIoriaing vegetairle oarboiis, Surit, Suchar, Darco, and otiiers, lrave found rcndy applications in a number e.- and have peculiar value in certain cases. Froin 1903 to 1922 a series of pat.ents was t,aken out on the preparatioil of wliat is soroetimes termed "amiorplious" sugar, from tlie invisibility of any crystals in the product so prepared; this is found to have advantages in certain quarters. Kotable feats in clietnical engineering Iry Osborii, Ualilberg, and otliers have been accomplished in the recovery o S sugar fmrri beet nmlusscs, as well as tire recovery of potas11 frrini this aiid waste waters. lias kreeii turned t,o iisefiil account in :format.ion, by a paper-making process, into fiber hoard used for paneling, sound i n s o l a t i o n , lath, mats, and other articles. C. S. IJiidson typifies a iiuniher of Aniericaii clieniists, who have added greatly to the known constitution and reactions of various sugars and to wlioni great credit is due. Tlii tury too Ira$ Seen z riiost useful advance knowledge of color and its detenriiuation as exemplified in tlie work of Peters; of liydrw gen-ion concontratiou, its detection by indicators or electrometrically, and its relation to the sugar industry; of the dietetic value of sugar and its proper place in t.lic forid of a nation. Kot the least in this respect is tlie rapid development in the scientific Seeding of cattlearid the proper iise of cane and beet tops a.nd beet pulp as well as cane and beet mo, in rnaintaiming cattle fix work and Satg them for the market. Among the riiost noticeable recent developments in the cane sugar industry might be mentioned the tropical refining of sugar by
INDUSTRIAL AND ENGINEERING CHEMISTRY
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means of decolorizing carbons, which appears t o be on the increase; and the refining by bone black a t Hershey, Cuba, where specially prepared raw sugars are stored in bulk a t outlying plants, transported in bulk (eliminating all raw sugar bags), and, without affination, refined a t the central plant. Their nature is such as t o require only about onethird the usual bone black capacity and greatly to reduce the vacuum pan, crystallizer, and centrifugal work. These progressive steps can be utilized readily by mainland refineries having or establishing suitable tropical relations; and so what may have been considered a difficulty can really be converted into a marked technical and economic advantage. Colorless solutions of sugar, more or less inverted, are now prepared in refineries and in special establishments, for use in confectionery, preserving, and other industries, doing away with needless crystallization and redissolving. By careful filtration and other means white sugars, both cane and beet, are now produced free from thermophilic bacteria.
Cane Sugar Sirup The states bordering on the Gulf of Mexico, as well as Georgia, are the principal localities where sugar cane sirup is made. In 1922 the record amount of 41,611,000 gallons is given by the Department of Agriculture, whereas the production for 1933 is placed a t 19,106,000 gallons. This shrinkage is partly due to the ravages of mosaic disease of the cane, causing a loss of $100,000,000in recent years. Now mosaicresisting varieties of cane have been introduced in 50 per cent of the acreage of cane for sirup production and in 100 per cent of that for sugar. The same authority gives for the year 1931 the following production figures (in thousand gallons) : Cane sirup Cane molasses (as food) Sorghum sirup
14,359 5,168 17,818
Maple sirup Maple augar a8 sirup Corn sirup and mixtures
2,186 202 81,686
The method of manufacture given by Paine and Walton (Dept. Agr., Bull. 1370) may be taken as typical. The strained and settled cold cane juice is treated with sulfurous oxide to a moderate, predetermined acidity; then lime is added to bring it nearly to neutrality and the whole is brought to a boil, brushed twice, and allowed to stand 40 to 50 minutes. Dark juices may be treated with 1 to 3 per cent of decolorizing carbon. The decanted or filtered clarified juice is evaporated to 20-25' BB., again brushed, and settled 5 or 6 hours. Sodium phosphate may be added a t this point to aid sedimentation and flavor. If necessary the sedimented semi-sirup is cooled to 140" F. and treated with about 0.5 cc. invertase per gallon to invert enough sucrose to prevent crystallization on cooling. It is then concentrated to 3 3 . 5 3 4 " BB. a t boiling temperature. The evaporation must, a t least, be finished in an open kettle to insure proper flavor. Such sirup in 1933 was worth 47 cents per gallon. First molasses from the sugar factory is also sometimes treated to prevent crystallization and sold for sirup purposes. Some large buyers of such sirups collect enough for a year's supply and then blend the entire lot uniformly so as to maintain a constant color and flavor for their entire year's products.
Dextrose Dextrose was first artificially prepared by Kirchoff, a Russian chemist, in 1811, who obtained it by heating starch with acidulated water. The recognition of the importance of his discovery led to his being pensioned by his government. Its use developed rapidly. A great industry had developed by 1870 in Germany and other European countries. In 1885 Germany alone had fifty starch sugar factories, making an-
VOL. 27, NO. 9
nually 20,000 tons of sirup, 10,000 tons of hard sugar, and 1250 tons of LLcolor"or caramelized dextrose. Glucose began to be manufactured in the United States in 1872. In the manufacturing process which gradually developed, Indian corn, from which it is principally made in this country, was steeped in water containing a small amount of sulfur dioxide, t o soften it and t o control fermentation, and was passed between specially constructed rolls to tear the kernels open without breaking the germs, which were floated off from the rest of the kernels in suitable tanks of water. The main portion of the corn was next ground wet and passed over bolting cloth to separate the outside fibrous portion of the grain. The starch and gluten suspended in water and treated with enzymes to help dissolve protein?, were separated by flowing the mass slowly through long troughs, where the starch granules settled. After further washing, this starch, suspended in water a t about 18" to 22" BQ., was heated in bronze converters with about 0.1 per cent hydrochloric acid a t 40 t o 45 pounds per square inch steam pressure for a few minutes after the starch disappeared (according t o the iodine reaction). The acidity was then reduced to pH 4.8-5.2 by the addition of sodium carbonate, and the liquid was clarified by centrifugal separators and filter presses and decolorized by bone black or, later, by vegetable carbon. Next it was evaporated in a triple-effect evaporator to about 30" BB. and again decolorized, and then further concentrated in single-effect vacuum pans to about 40.5-46" BB. The glucose or corn sirup of commerce was originally the principal product of the conversion of corn; but later it was found that with a more complete hydrolysis, conducted in a 15" BB. starch suspension, and with longer heating, more dextrose and less dextrin and maltose could be produced, and that, by seeding the concentrated solution in a cooling pan and flowing upon the floor, it would set in 24 hours into a crude sugar. Later Charles Ebert developed the process of hydraulically pressing much of the mother liquor out of this mass and purifying the sugar by recrystallization. This pressed sugar was called "cerelose." Meantime, constant efforts were being made to crystallize a purer dextrose from aqueous solution and to separate it completely from the mother liquor. About 1877 Soxhlet had achieved such success in preparing a solid, though impure, grape sugar as to attract the attention of F. 0. Matthiason who brought back to this country Arno Behr, one of Soxhlet's assistants; Behr, with the cooperation of others, enabled Matthiason to establish the corn sirup and sugar industry in our Middle West. While the manufacture of liquid glucose, consisting of dextrose, dextrin, and maltose, preceded the manufacture of the solid corn sugar produced by the more complete conversion of the starch during hydrolysis, there was persistent effort, nevertheless, to develop a solid sugar; and successive inventions by Williams, Behr, Firmenich, Norton, and Soxhlet in the 1880's, Barthelemy in 1892, and Wagner in 1906 developed this art somewhat but still succeeded in producing sugar of only indifferent quality except in small experimental batches. In 1884 the glucose industry in the United States was reported by H. W. Wiley (Dept. Agr., Bull. 5) to be operating in twenty establishments in seven states with $10,000,000 invested, consuming 61,000 bushels of corn daily, employing 4575 workmen, paying annually in wages $2,058,750, consuming $13,703,000 worth of materials, and yielding a product worth $18,270,000. T h e profit was 15 per cent on the investment. A bushel of corn yielded 32 pounds of glucose, and the capacity of the twenty establishments was 609,000,000pounds of glucose per annum. Some early prejudices against this newcomer in the field became so marked as to lead t o an investigation by the Katio'iral'Academy of Sciences. In 1883 the academy issued a voluminous report with findings and opinions thoroughly en-
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TOP: CENTRIFUGAL MACHINE
CENTER: VACUUM
PAN
BOTTOM: BONEBLACK FILTERS
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INDUSTRIAL AND EIVGINEERING CHEMISTRY
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Sorghum According to the Department of Agriculture [Bull. 3 (1884)I sorghum was introduced into the United States about 1854. It appears to have developed rapidly in favor as a source of sirup. The census reports estimate that in 1859 there were 6,749,123 gallons of sirup made. During Collier's service as chief chemist t o the Department of Agriculture he did much to improve the varieties by selecting seeds from the richest stalks. Thus he raised the ratio of sucrose t o reducing sugars markedly, so that 9 per cent sucrose and 3 per cent reducing sugars might be taken as a good ayerage composition. In a bulletin published in 1930, sucrose of about 15 per cent and reducing sugars of about 2.5 per cent are indicated. The effort in the early days was persistent toward making crystallized sugar from the juice, and indeed Wiley reports in 1884 that in the preceding year a little less than one million pounds of sugar had been made. Most of the sorghum sirup made is prepared in a small way on farms, using mills driven by animal power and evaporators of very simple design; but in some instances comparatively large and well-equipped plants have been established and operated under scientific control. In one plant some 20,000 tons of sorghum cane pass through in a season, producing, beside sirup from the juice, ground cattle feed from the leaves and valuable seeds threshed from the panicles, while the bagasse is utilized in the furnaces to produce the electric energy which operates the mill. The expressed juice is defecated with lime and phosphonic acid to clarify it, malt extract to hydrolyze the dextrin and starch, decolorizing carbon to improve color and flavor, and invertase preparation to invert enough of the sucrose to prevent any subsequent graining of the sirup. An excellent commercial product results which finds ready sale. The production of sorghum sirup rose in 1920 to 49,505,000 gallons, during the post-war scarcity of sugar, and sold at a dollar a gallon; but in 1933 the Yearbook of Agriculture gives the country's production as 14,961,000gallons, selling a t 47.9 cents per gallon. Its restriction to rather local use and its relatively high cost of production will probably hold its development in check.
Maple Sugar and Sirup In the northeastern states,, particularly Vermont, New York, and Pennsylvania, tapplng maple trees in the spring has long been in vogue to obtain the sweet, thin sap. This sap contains about 3.5 per cent of sucrose and is about 95 per cent pure. When evaporated in shallow open pans, with skimming and sometimes slight defecation with lime, it yields a sirup of fine characteristic flavor; or, if carried farther t o a concrete, it yields a small-grained moist sugar of similar good flavor. This sugar is never refined, for its principal value lies in its peculiar flavor, The amount of sugar thus produced fell from 2262 tons in 1917 to 661 in 1933 (Yearbook of Agriculture for 1934, p. 482). And the maple sirup had dropped from 4,258,000 gallons in 1917 to 2,175,000 in 1933. I n 1933 the sugar had a market value of 21.5 cents per pound and the sirup brought $1.18 per gallon. At these prices there appears to be an attractive problem in the successful synthesis of the specific flavoring matter of these products.
Lactose The sugar of milk is first mentioned in literature by Fabritius Bartolettus, a physician of Mantua, who in 1628 wrote of a manna seri which he obtained by evaporating the serum of milk. The first monograph upon the physical and chemi-
VOL. 27, NO. 9
cal properties of lactose was published by Lichtenetein in 17i2, and many chemists and biologists have studied its formation, composition, and properties. Lactose is formed by a molecule each of dextrose and galactose; the evidence shows that it is built up in the mammary glands through the condensation of a pair of dextrose molecules, supplied from the liver by the blood and involving the simultaneous rearrangement of one of the dextrose molecules into the galactose structure. The splitting of lactose into dextrose and galactose during digestion has given rise t o differences of opinion as to its advantages in human diet. When fed in large quantities, it is not all split in the small intestine and thus, differently from other more readily absorbed sugars, enters the large intestine where, under the influence of Lactobacillus acidophilus, it changes the putrefactive into a fermentative environment, t o the benefit of the user, especially in some abnormal conditions of autointoxication. Lactose has long been prepared in this country from the whey of cheese and casein plants. Its maximum consumption appears t o have been reached in 1930, when 6389 tons mere made in fifteen factories and 70 tons were imported. The amounts fell off rapidly thereafter, and in 1933 there were 1913 tons made and 0.96 ton imported. It brings about 10 cents per pound, in carload lots a t the factory, and its diminishing consumption is probably attributable to its replacement, in part, by other materials in infant feeding. Whey contains only about 4 to 4.5 per cent of lactose; and since this is accompanied by relatively substantial amounts of casein, albumin, salts, and occasionally fat, it becomes a difficult matter to extract the lactose economically. In a modern method of manufacture the whey is heated with a little acetic acid to precipitate albumin, decanted or filtered, evaporated i n 2racuo to about 60 per cent solids, run into water-jacketed crystatlizers with agitators to promote crystallization, purged in centrifugals, and washed. This crude sugar, amounting to about 3.8 per cent of the weight of the whey, contains about 88 per cent of lactose. About 0.5 per cent additional crude sugar can be obtained by treating the run-off from the centrifugals in a similar manner. Refining the crude lactose is effected by dissolving, clarifying, decolorizing, with bone black or carbon, filtering, boiling down in vacuo to about 35' BB., developing the crystals if necessary, and centrifuging, washing, drying, grinding, and packing. Lactose is the least sweet and least soluble of the commercial sugars, and should find an enlarged use in various fields, if its cost of preparation were lowered.
Levulose Levulose holds an interesting position as a sugar of great potential importance. Since it is about half again as sweet as cane sugar and is extremely soluble, levulose is attractive for various industrial uses; its direct absorbability in the digestive tract gives it marked dietetic value. The difficulty of its preparation, even in sirup form, has heretofore prevented its popular use, not to mention the impossibility of preparing it in dry form commercially. All this bids fair now to change. I n recent years a t the Bureau of Standards, Bates, Jackson, Proffit, and Gillis have made fundamental studies of its solubility, analysis, and crystallization, leading to the preparation of some 200 pounds in a pilot plant and later to the designing and equipping of a semi-commercial plant with a capacity of about 1000 pounds per 24 hours. The washed tubers of Jerusalem artichokes are sliced and diffused a t 80-85" C., and the juice is slightly acidulated with sulfuric acid which converts the polysaccharides into levulose. Lime is added in slight excess, the mass filtered, the filtrate chilled to 4' C., and milk of lime added with brisk
SEPTEMBER, 1935
INDUSTRIAL AND ENGINEERING CHEMISTRY
agitation to form crystals of lime levulate. This solid portion is removed by an Oliver filter and, after suspension in water, is carbonated, precipitating carbonate of lime and leaving the levulose in solution. This solution is evaporated in uacuo to high density, seeded with crystals to grow, and later cen-
995
trifuged, washed, and dried. The result is a beautiful, white, fine-grained sugar, which is practically non-hygroscopic. RECEI\ED April 1 8 , 1 9 3 5 Presented before the Division Sugar chemistry a t the 89th Meeting of the 4merican Chemical Society. N e a York, N Y , .Ipril 22 t o 26, 1935 411 photographs reproduced by courtesy of the National Sugar Refining company of N~~ J~~~~~
Food Supply and Human Progress H. C. SHERMAN Columbia University, New York, N. Y.
HREE centuries ago, when chemical industry began in this country, American and European food supplies and food habits were modifying each other to some extent, perhaps significantly for the time being, in the rapid spread of potato culture in Europe and the consequent reduction of scurvy. But from the point of view of industrial development, or of scientific control, the general food supply situation three centuries ago was much as it had been several centuries earlier; nor was there any great change in the two centuries following. Much the largest part of the food supply of the great majority of people was produced and consumed in the same locality, and with a minimum of any other than household manipulation or technology. Sir Walter Scott’s description, in “Peverel of the Peak,” of the preparations for a very grand dinner show how nearly all of the food supplies arrived at the point of consumption in the baskets or the carts of the farmers who had raised them, or on the hoof. In even greater measure was this true in ordinary daily life and in America.
T
IF W E T U R S from the scene of three hundred (or 0 even one hundred) years ago to that of thirty years ago we meet a striking and significant change. Concentration of population into cities and extension of agriculture to more remote areas, together nith the growth of commerce and of the industrial refining and preservation of foods, had brought about a situation in which the majority of people had ceased to produce any economically important part of their own food or even to obtain it from neighbors. Most people had to buy nearly all of their food; and it came from greater and greater distances and was distributed under conditions which made it increasingly difficult for the consumer to exercise any individual control over the methods by which his food was produced and handled. Consumers also began to wonder whether the refining, preserving, coloring, and elaborations of form to which their food was being subjected might not involve undue degrees of sophistication. One result of these conditions was the pure food movement. Consumers sought to substitute for the individual control which was no longer feasible a collective control of the food supply through legislation and inspection. Just what this food legislation should involve became the subject of prolonged controversy. The passage of a federal food law in 1906, and of supporting state legislation which followed rapidly, was a triumph for those who had labored in the pure food movement, and it was also a result and an indication of the scientific and technological trend of the times. It meant (among other things) that the methods for scientific control of the food industries, as well as for the policing of their products through wholesale and retail trade, had been developed
bo a point capable of commanding the confidence of the leaders among producers, dealers, and consumers. Primarily designed for the protection of the consuming public, the food laws also function as rallying points for standardization and advance within the food industries themselves. Correspondingly, the officials who administer the food law find that they can exercise a more effective control by using more of educational than of punitive measures. And in addition to the scientific developments in the food industries and the agencies of food control, we have the farreaching and efficient forces of agricultural and food research -federal, state, and privately endowed-working constructively upon all sorts of food problems in the interest of producers and consumers alike. So thoroughly has the pure food idea been assimilated during the past quarter-century and so effectively have the principles of sanitation been applied in the production, handling, and inspection of food in recent years, that in general the consumer may now safely assume that a food product offered for sale will be: (1) What it purports on its label to be, in nature and amount. (2) Free from anything actively injurious. (3) Possessed of a nutritive value within the normal range of its commercial grade. NOT fear of injury or exploitation but intelligent use of Q nut’ritional resources for the advancement of posit,ive health or, as the Journal of the Smerican M e d i c a l Association puts it, “buoyant health as distinguished from merely passable health,” should be chiefly in our minds as we now think of food. The choice of food is as worthy of thought as it ever was, but it has become a more constructive and a more cheerful matter. The center of gravity of the problem of the relations of food to health has moved forward from sanitation to nutrition. And the nutritional problem, while it carries heavy responsibi1ity;is an inspiring one as well. The new knowledge of the past thirty years, on the nutritive values of foods and the relations of food to health through nutrition, is one of the most important scientific developments of our times. It emphasizes the fact that health is more than merely freedom from disease; and that, whatever the constitutional inheritance with which one starts, one can build to higher levels of positive or buoyant health, not only by avoidance of things that may injure hut also (and even more important) by mise choices and a sound sense of proportion in the use of ordinary wholesome foods. For the newer knowledge of nutrition has now made it quite clear that a food supply composed of wholesome articles, freely chosen according to conventional or traditional ideas or to please the individual palate, is not usually sufficient to in-
