Handling Fresh Alfalfa before Dehydration 0
J
R-ALPH E. SILKERI AVD H. H. ICING hariscis 4pricirltitrnl E x p e r i m e n t Stution, AManhattuii.hnns.
considerable interest was shall-n by operators 1x1 widely scat.tcsrcd localities, it was felt advisable to carry out the following study on tht, two procedures. T h e data were obtained in .iugust and Scpteiiiber of 1945.
Dehjdrated alfalfa meal obtained from field-chopped alfalfa contained slightly less carotene than did meal produced in the con7entional manner from long alfalfa, H hich w a s chopped just prior to the dehydration. Slightlj more than 4 R of the carotene was lost during the normall? anticipated time required to load, haul the chopped haj, and feed it into the dehjdrator. This loss wab couritered in some measure, how-eFer,by a l o w er loss of carotene during dehydration of the field-chopped haj than that noted during dehjdration of the long hay. On standing for a period of se7eral hours, the field-chopped alfalfa lost about 3% of its carotene per hour. The results indicate that field chopping does not seriouslj reduce the carotene content of alfalfa meal.
T""
COLLECTION O F SAMPLES
sua1 method of handling green alfalfa for coninirrcial dehydration uis t o cut the alfalfa with a mower and c9lcvattB it dircbctly onto a t,ruck or trailer for transportation to th(1 plant site. Tt is then pitched, or fed by automatic equipment, onto a conveyor which feeds the alfalfa into a chopper; thcrc it ip c u t into short lengths before being elevated into the d c ~ h y h t o r . T h r e has been a trend recently, hoivever, toward us(' of fic,ld equipment Tvhereby the alfalfa is chopped in the field instcwl of at the plant. Field-chopped alfalfa is produced by one or thc. ot1ir.r of the following methods: First, a regular mower, having an attachment which causes the alfalfa to fall in nindroiv-a similar tu those mnde with a side delivery rake, m a y be used for mowing. This iwcessitates a second machine which follows t h t s nio1ver, picks u p thc alfalfa from the w i n d r o y chops it, and t h i l i i i l r v a t w or b l n ~ v s tho chopped material onto a truck or trailer. T h c second procedure uses a single field machine v-hich iiiov-s thc alfalf;t dirc.c,tly, conveys it, t o a chopper, and finall- e,lttvates or b l o w the fwshly chopped material onto a truck or tr:tiler, AII auxi1i:ti.y polver unit, vihich is a n integral part of thc m:ichinc. i. used to opfrate thc choppcr. Thc second metiinti is s u p i r i o r t o the first since only one operation is involved, and the c u t matcr.i;il n t ~ v o touelit's i~ the gi~oundto collect dust and 0thi.r iowign ni:it crial. il :idvantages are advanced for using the iiel(1 c-liol)!)ing proc.cvluw. The most important factor to coii.4tlc.r is tli:it choppc'tl :ilCdt':i can be fed into the dehydrator a t R ninrt' uniiornl rat- gnoel jot) can be donrx by using a spixcial aUtoi~iatic.fectfcr.,but thc, i\-ork ~ n.ith efficiency. better product i? obcan be d o i i ~nianually taincxl whc-ii :i uniform rat r of oper:ition can be maii1t:iincd. ai111 :i given unit should produce a somen-hut greater quantity of prntiuet. Somr operators state t h a t less help is rcquircd in tlic fit,l(l whcn fic.ld chopping is done. There is also l c d ~loss of iiiat~~ri:iI during tr:iiisportation of clioppcd alfalfa than ai long alfalftt. 1-ar.iation in c:irotene content is of primary importance in any problem involving thc production of deh>-drated ulf:ilfa nical, but no attempt had heen made on tlic part of plant operators to e v d uate the two methods from the standpoint of the carotene coiltent of the final product. Since operators' opinions differed widely regarding the effect'of field chopping on alfalfa, and since Present address, The I!J.. Small Company, I n c . , Kan3as City, 110,
Field samples were collected as follows: IValking beside t'l1e firld machine, the collector picked samples .c~f the long alfalfa Ii,om the conveyor as it passed from the moiver to the choppcr; sinniltaneously, samples of the chopped material were collected as it came from the blower tube. B y this procedure sainplcs of bot,h types were obtained from identical parts of the field. The samples were placed in paper bags t o minimize evaporation during the short time required t o reach the laboratory, which vias set u p a t the plant. Samples of the chopped alfalfa. from the different loads at the plant were obtained by taking small handfulls from widely different parts of the load, the storage: pile o n the dock, or the conveyor as the alfalfa was fed into the tfehydrator. All samples of the dehydrated meal n'ere taken directly from the spout at the bagger and stored in a refrigerator in tightly covered glass jars until analyzed. A portable laboratory, which had been used throughout the sunimcr during a survey of alfalfa dehydrating plants located in thc IGtw I'allcy, was utilized in this study. PROCEDURE
.ill samples of fresh material were cut into small pieces--'/$t o /$-inchlengths-mixed well, and carefully sampled by quartering, before weighing out individual samples for determination of carotene or moisture. Five grams of the various samples of fresh alfalfa were extracted in a Waring Blendor for 5 minutes with a Foaming mixture of alcohol and Skellysolve B T h e mct'hocl has tieen described previously (4)a n d is essentially t h a t of Moore and Ely ( 3 ) as modified by Wall and Kelley (9). The total contcrits of the Blendor were transferred t o a 250-ml. P:rlennieycr flask, x-ith Skellysolve B t o rinse and wash out parlicles which did not pour out readily. Sufficient solvent was uscd SO t h a t only enough space remained t o accommodate a tight-fitting cork. Charkey and Wilgus ( 2 ) showed the necessity for protectillg alkaline ethanol extracts of alfalfa from the a1r and thc offcttivc manner in which Skellysolve may be used. T h e cornplctcly filled fiaslcs were placed immediately in a n ice chest and trarisportcd to the laboratory where the analyses were c o m p l c t d on the folloiving day. The contents of t,he Erlenmeyer flasks n-ere filtered through Biichrier. funnel and the extract transferred t o a 5Oo-nl1. scparatory funnel. Water (100 ml.) was used t o ~ 3 ~ t1h e1 oxtract a n d to remove most of the alcohol from the mist,ure:. A small portion of anhydrous sodiun ulfate was added t o prevcnt tho formation of a n emulsion, A ' r separation, the aquious 1ayc.r mas extracted three t i m w t h 35-ml. portions of Skellyaolve U. T h e cornbincd extracts Kere washed by pouring 100 Inl. of"water through the mixture, and then concentrated t o a volume of 30-40 nil. on a steam bath and dried with a small amount of ailhydrous sodium sulfate. T h e concentrate of extract was next drawn through a 2-1 mixture of Hyflo-Super-Cel a n d magnesia (Llicron No. 2611). T h e chromatogram \vas developed, and the carotenes eluted with a n approximately 5% solution of acetone in S k e k solve B. T h e eluate was made u p t o a volume of 250 ml., and the optical density measured a t 436 millimicrons with a Beckmarl ( 1 ) spectrophotometer. Carotene determinations on the samples of dehydrated meal were made by a simplified method (6) developed in this laboratory. One gram of meal \:as weighed into a 125-1111. Erlenmeyer
1163
1164
I.ong alfalfa directlj- f r o m mower
8 7
('hopped alfalfa directly from blower
i
1,orl.q alfalia after 1 h r . on dork
Vol. 39, No. 9
INDUSTRIAL AND ENGINEERING CHEMISTRY
h
l b t (if load, 9 2 I.aet oi Iciad. 8 3
('hopped :ilfalfu directly froirr blower
R h
Chopped alfalfx directly from field
1st of load. 10.9 114 load off,
Chuvtied ulfaltu afier 4.5 hr. o n dock
Ton of n i l P i0.i .' ('enter of pile. 8 . 1
29
x
L'h h
"I
?$k
2
1
RESULTS
"14,i)l10
Table. I presents tlie data \vliicti \v(,i'v otitsittcil OII the fresh alfalfa from a field \vhich \vas I , \ reptionally uniform in stand and gro\vtli, and \vas ideal for a study of this typcs. Tlic, nwitt1t.r \vas clear m i l hot. Definite hcatiny oc~rurrcd ill t h e , pile of alfalfa ivhirh stood o n t hr.
~1X.l)lIll
I
28 8
.)., , -,>
. I
?i ii
28 8 ,
.i:
411.4
99
31 ::
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,INDUSTRIAL A N D ENGINEERING CHEMISTRY
September 1947
(' ~ ~ ' O T E S S COXTENTOF
DEHPUR~TED
ALF~LFA
NEALFROU FIELD So. 2
Origin of Ikhydrared 11eal (
Carotene i n Fresh Sample, IIg./lOO G .
Dry Matter, C'
Carotene, D r y Basis, 3Ig./lOO G .
\itamin
A8
I.t-./I.h
'Iiopped alfalfa directly f r o m field
Chopped alialfa after 2 . 5 h r . on truck C'h c pped a l f alia a f t e r 4 . 5 h r on
dwk
LO>. U! Carotene during Dehydration, C,?
1165
nidi to thank \V. J. Small for the intcli,twt anti close cooperation which made this Ytutly possible. The authorl: are also indebted to \Villiani 13. Honstead and \V. G. Ychrt,itk for assistanci: in sccuring and prtJparing saiiiplos for :iiialysis, and to IT. Ci. Schrcnk ior the spectrophotomt~lric readings. This work was supported by The Kansas Industrial Development Commission.
LWER41'UR E f :ITEL> ( I ) Cary, 1 4 . H . , aiid Becknmii. :\ O . , . / . Optical Soe. Am., 31, 682 (1941) ( 2 ) ('harke>-,L. W., arid JTilgus. H . S..$11 ., I s o . K s o . ( ' H E M . , 36, 184 (1944). ( 3 ) Moore, L. .A,, and Ely, I{., IN^. I:v(,, ( ' H E M . , As.ii.. ED., 13,600 (1941). (4) Silker. R. E.. Schrenk. W.G . and ~ Kiiin. fi. H . ,
Vapor Pressure of Water Adsorbed on Dehvdrated Alfalfa T h e Fapor pressure of water adsorbed on dehbdrdted alfalfa w a s measured iu the region of 2.2 to 14.17' moicture and in the teniperature range from 17 O to 50" C. \&orption isotherms are the tSpical S-qhaped isotherm- of other similar materials. Isosterio plots of the data were rnatle h> the method of Othnier and Sawjer (6), and the ratio. het w e e n the heat of adsorption ofwater h) alfalfa meal t o the heat of taporizatioii of water at the .anie teniperature were calc*ulated. This paper Show5 that proteiu cwntent. withill the range itudied, has little effect on the Tapor p r e s u r e . Blanching the alfalfa meal prior to dehjtlratioii does r i o t appear t o d l t e r the position or shape of t h e \'il)or i)re-*urt' i iir\e*.
REC'EXT pxpei' ( 7 ) iridicatcd that a wlatioii inay exist beturc contt'nt and cai'oteiit: rc~tt~iition in dehyiiw thehi: d a t a niay make it desirable to dchy(irate' alfalfa to a known iiioistui.t, content, ini'ormation regarding vapor presswe rquilibrium data ticv>nicv iiecessary, not only for the dehydration pi'oceus, but also for purposes of dctcrmining optiniuni storage c*onclitions aiid iritlicirting type< of packaging
materials ivhich i ~ o u l dtic drsirahle. This paper therefore prwents data regardiiip th(8 i ~ i p i ~ prt'.-r sur(. of watcr adsorbed on dehydrated alfalfa and iiiclicat i+ i1.G u d u l n e s s to t h e industry. Two different commercially dehydrated alfalfa 1 1 i c 4 r aiid one' ateam-blanched sample produced in this laboratoi,~were investigated; they contained 20.1, 15.2, and 19.3Ycprotein, respectively. The blanched sample \vas prepared by placing fresh alfalfa in a steam cabinet through which live steam was passed a t atmospheric pwssure foi, 10 miriutes before the alfalfa was dehydrated.
Iloistures w~xrcadjustcti in the laboratory by iiit'aiis oi' a vacuuin ovcn lor thr ]OR. values (operated a t room tcinperaturt~)aiid a reiiiprratnrc:-ti~iniidity cabinet for the higher levels. XIoisturi. 1 1 ~ ~ :tpprosimating ~~1s 2, 3, 5 , 7 , 10, ailti 14?;, idculatrti on a dry \vcight basis, were obtained. Thc moisture contents of the samples were tleterniiiit~dby placiiig the samples in a vacuum o w n a t 100" C. f o r 2 hours. I'rcvi011s nieasui'enieiits had iiidicatcd no further loss of \wight in this type‘ of material after 2 hours. Vapor pressure nieasurt!rnr~nts art' ia\pi,cssed in terms of these determiiiations. The equilibrium vapor pressures wercy deteriiiincd by the ~uanoiiicstric method described by Makoiver (3, 5). For low prcssures (txdow 30 mni. of mercury) dibut,yl pht,haltitr was used i i i the ilianometer; for higher prrssures mewury wa+ used. For this lorvc~rtemperatures the flask containing the ssinplc was placxudin H constant tc:nipvrature water bath, and for higher tcmperat~ure,~ t lie entire unit vas plareil in a constant tc~mperaturr? air cabirier , *I) that the moisture in t h e system woulcl riot condense. Sample5 i i f approsimatcly 10 graiiis w r v usrtl. All coiinectii)ns w(m. made by means of ground glass joints and stopcocks. The techniques iif cvacuation aiid making readings ivi-re also ~iniiliirto those. described by Makower (3,5 ) . During evac-untion thc nioi?ture trap WLS coolcd to -80' C. by nw:iiis of 511 :ic~btone dry ice iiliuture. IIeaaurements were first made a t thr low ternpcraturw and then at successively higher temperature6 up to 50 O C. Pressure r t d i n g s n'w~continued for several hours, although equilibrium was apparently attained in 30 t o 45 minutcs. It, was found possible to return to lower temperatures after m:ikirig i i w:uling at a higher temperat,urcs and to repeat the previous reading within t:sperimental wror, This would indicate thin rc bility (JE the sorption priii'tw xithin the limits of the oxp(siiincnt. ~
