lent to %lo%of malt. Recent reports from other laborstoriea, EBEARCH wasbegunnearlg ten yeamagoin the biophysiincluding those of Zier, Rosenblatt, and Liebmann (IO),IIaO cal chemistry Laboratories at Iowa &ate College in an atand Jump (J), F'igman and Blair (4), and Roberts. Laufer, Stewtempt to find a satisfactory amylolytic material which c o u l d s e r v e a s a n a l t e ~ t e t o ~ t f o r s a o c ~ f ~ g&, ~ ~ rand h Saletan @), have confirmed the findings at Iowa State College. in the alcoholic fermentation of grains. Known wurces of amylThe results upon which the published favorable reports for 88es other than the cared grains, notably certain species and mold bran are based were obtained from laboratory experiments strains of fungi and bacteria, were investigated. As a result of pnly, except for the.pilot plant tests reported by Beresford this work Underkofler, F h r , and & h m e (9)in 1939suggested theuseofmoldbranprep~bygmwingsel~strsjnsofAaper- and Cbristemn (1). Large-male tests of mold bran in an induk trial grain alcohol plant had to await the availability of mold ~Uus~meonmoist.sbteriliEed wheat bran. A similarsuggegtion bran in tonnage quantities. The purpose of this paper is to rehad been made many yesrs previously by Takamine (8). but his port the results of industrial-scaleteatsof mold bran in the alcohol suggestion bad led to no Large-acale developments in the alcohol plant of the F m Crops Rocassing Corporation during the early industry. Hao, Fulmer, and Underkofler (3)reported comparative months of 1945. testson the saccharifyingability of mold bran preparations pmFor the production of the mold bran u d in the plant teste, d u d by twenty-seven strains of molds; they found that strains two semicommercial units were constructed,each with a capacity ofAspergillus ayure, R M z ~ p u s d e and k ~ Rhisopvs o r y m gave of about one ton of hished product per day. The first of these the best results. Becaw of better cultural chsnroteristica the units provided for the growth of the mold during incubation in strains of AspergiUus ayure were found to be preferable. Tbe cells with for& aeration through the thick layers of inoculsted s t a b of the application of microbial ensymeb to alcoholic ferbran. In the second unit the mold wae grown on the bran on mentation ww reviewed by Underkofler (7) and by Underkofler trays placed in specially ventilated incubation rooms. At the anddFulmer(8)in194!2mdld. completion of the incubation period in either unit the mold Fmm the results obtained at Iowa State College, the conclubran was dried by n stream of warm, dry air to a moisture wnsion wae reached that, when malt and mold bran are used under tent of about 12%. to be stored until required for w in the optimum conditions for each, the alcohol yield8 obtained are alcohol plant. Both units were opated continuowly over essentislly the samb, h d upon total dry matter going into the periods of several months and simultaneously for much of that p m s s . with apparently a eJight advantage for the mold bran. time. Experience showed that the tray unit wae simpler in o p The mount of mold brm required for satisfadmy saochsrifiostion of 'the grain starch ww found to be considerably lesa than I Preaent sdd-. baa State College, Am-. Io-. *PreaentIddms. Mold Bran Comeany, Inc.. Esda Gmve. lo-. that required for malt, 2.54% mold bran giving results equivs-
I .
October, 1946
INDUSTRIAL AND ENGINEERING CHEMISTRY
eration and gave a more uniform final mold bran of high amylolytic activity. This system wa.s subsequently adapted for installation in a plant at Eagle Grove, Iowa, for the production of mold bran on a commercial scale. The mold bran was tested for use in saccharifying grnin mashes for alcoholic fermentation on the full plant scale in three usages: for the preparation of plant yeast, culture mashes, as the sole saccharifying agent for plant fermenter mashes, and in combination with malt for saccharification,of plant fermenter mashes. MOLD BRAN IN YEAST CULTURE MASHES
981
plant mash was withdrawn into the yeast tub, and mold bran was added instead of supplemental malt. The time required for the lactic souring was found to be reduccd for the mashes containing mold bran. The soured mash was sterilized, cooled, and inoculated with the yeast. After the usual growth period of 14 hours the culture had about 200 million yeast cells per ml., and the yeast cells under microscopic examination were larger and showed higher viability (by the methylene blue staining technique) than had previously been considered normal. The rcplacement of 7200 pounds of supplemental malt by 2000 pounds of mold bran gave such excellent results in the early trink that this procedure was adopted as standard practice for this plant. The time required for the lactic souring operation was decreased t o half the time required with the all-malt mashes; more rapid growth of yeast and higher yeast cell counts were obtained, and, moreover, fermenters inoculated with the yeast cultures grown on mash containing mold bran showed better alcohol yields. The latter point is shown in Table 11, which gives yield data for the plant by weeks for the first six months
Mold bran had previously been used in laboratory yeast culture mashes with exccllent results at Iowa State College, the University of Idaho, and the t-niversity of Sebraska. We t.herefore decided to t r y replacing supplemerital malt by mold hran in yeast culture mashes. The common method for preparing yeast cultures for the purpose of inoculating the fermenters in a grain alcohol plant involves the following_ general steps: (a) withdrawal of plant grain _ mash into yeast tubs, ( h ) addition of supplemental malt, (c) inoculation n-ith and growth of lactic acid bacteria to incrt,ase the acidity and thus: lower arge plant-scale teqts of mold bran in three usages as saccharifying agent the pH, ( d ) sterilization by heatin the alcoholic fermentation of grains are reported. Replacement of ing, ( e ) inoculation with yeast, and supplemental malt by mold bran in the make-up of plant yeast culture (f) groivth of the yeast. I n testinz mashe3 resulted in shortening the period required for lactic souring, in higher the use oi mold bran in the plant yeast yeast counts, and in somewhat higher alcohol ?ields from plant fermenters culture mashes, only the second step inoculated from such yeast cultures. The alerage alcohol yield from six plant was changed-that is, mold bran was fermenters in which the mashes were saccharified with about 4% mold bran added in place of supplemental malt. was approximately 2940 higher than the alerage yield during the same period Since the specific procedures emfrom fermenters in which the mashes were saccharified with malt. The a+erployed for carrying out these general age alcohol yield from seben plant fermenters in which the mashes were sacdteps vary from one plant t o ancharified with mixtures of mold bran and malt were slightly higher than the other, the details of the operations as average jield during the same period from fermenters in which the mashes carried out in this plant' are sumwere saccharified with malt alone. A consideration of the economics shows marizcd in Table I. Also the yeast' that mold bran has a considerably greater value than malt, and its general culture mashes containing mold bran use in the industry should result in apprecianle sa+ings.N-Photographs are compared with the conventional used to illustrate this paper were hindly supplied by TIold Bran Company. mashes in which no mold bran was employed. The procedures used in the Omaha plant xere, briefly, as follows: The yeast t u b was steamed Blowing Dried Spore Culture into Cooker to Inoculate Cooked Bran for one hour at 200-212" F. (93100" C.) just before filling. Khile the tub vias hot it was filled with plant mash a t 142" F. (61" C.). Supplemental malt was then added, the mash was soured (by means of a lactic culture), sterilized, cooled, and inoculatcd with yeast (Table I). At the time of inoculation with yeast the density of the centrifugate from the mash was about, 21" Balling. After growth for 14 hours the density dropped to about 13-14" Balling, and the yeast count was about 100 million cells per ml. The culture was then cooled t o 60" F. (16' C.) and held a t this temperature unt 1 completely used. The first use of the yeast culture was a t about 14 hours. One yeast t u b was used for the inoculation of seven fermenters over a period of 24 hours. The procedures employed when mold bran was used in the yeast culture mashes were the same except that a slightly larger volume of
L
982
INDUSTRIAL AND ENGINEERING CHEMISTRY
of the year 1945. The average number of fermenters distilled each week was forty-four; the actual numbers for a specific meek were from thirty-eight t o fifty-one fermenters. For convenience the alcohol yield data are expressed in Table I1 in two ways- in terms of proof gallons, as usually employed in a distillery, and in terms of gallons of 190-proof alcohol, more familiar to others. The yield data in Table I1 and other tables of this paper are analytical yields and were calculated to the standard bushel, nhich in this plant represents 56 pounds of mixed grain with an average moisture content of 12%. Moisture contents of the grains processed are highly variable; all results must be calculated to a standard moisture basis if yield data are to be compared.
TABLE I. PLANT YEASTCULTURES Conventional Yeast Mash Plant mash withdrawn into yeast tubs Vol. plant mash per t u b , gal. Concn., gal./bu. Wt. of total grain, Ib. Grain, 70 Malt 70 Tern;. of mash, O F.
19,800 25 44,352 91 9 142
19,200 25 43,008 91 9 142
Additions t o plant mash in yeast tubs, Ib Extra malt Mold bran Diammonium phosphate Ammonium sulfate
n
7,200 0 34
2,000 34 34
20 128 80 12
0 128 80 6
1,000 190 80 1,000
1,000 190 80 1,000
22 50.208 78 22 0 19,800
24 46,352 87.1 8.6 4.3 19,800
34
Processing operations in yeast tubs Holding time a t 152' F., mi?. Temp. of lactic incubation, F. Vol. lactic culture added, gal. Time for souring t o pH 4.0 h r Mash withdrawn for yeast 'inoculum tanks, gal. Temp. of 90-min. pasteurization, ' F. Setting temp., O F. Yeast inoculation, gal. Compn. of final yeast cultures Concn gal./hu Wt. of'kotal g r a k lb. Grain % h\lait '% Moldbran, % Final yeast culture vol., gal.
Mold Bran Yeast Mash
Culturing and use of yeast cultures Temp. during active yeast growth controlled e F. ... - below. .. Yeaat cell couni after 14 h r millions/ml. Holding temp. after 14 hr., "F. Age a t first fermenter inoculation, hr. No. of fermenters inoculated from each yeast t u b Age a t last fermenter inoculation, hr. Vol. of yeast culture for each 1.30,000-gal. fermenter, gal.
__
86 100 60 14
86 200 60 14
7 36
7 36
2,800
2,800
~
TABLE 11. EFFECT OF MOLDBRANIN YEASTCULTURE MASHES i?
Maah Bill, Period
Milo
Jan. 1-7 , '
8-14 15-17
L2; 29EFeb. 4
Feb. 5-11 12-18 19-25 26-Mar. 4 Mar. 5-11 12-18 19-25
M a y 7-13 14-20 21-27
33.46 8',25
6
Corn Malt 7.44 9.77 10.40 10.71 23.55 9.88 9.88 23.55 8.63 32.23 38.42 , 8.18
hlold brann
0
0 0 0.11 0.10 0.11
.4lcohol Yield/ Standard Bu. 190Proof, Proof, gal. gal. 4.67 2.46 4.78 2.52 4.75 2.50 5.24 2.76 5.41 2.85 5.47 2.88
57.27 82.68 90.93 90.16
9.17 8.94 8.90 9.66
0.10 0.13 O,l7 0.18
5.38 5.20 5.04 5.04
2.83 2.74 2.65 2.65
5.52 3.95
. ..
90.05 90.34 84.99 86.65
9.10 9.44 9.30 9.24
0 0.22 0.19 0.16
4.87 5.08 5.26 5.25
2.56 2.67 2.77 2.76
5.60 11.69 2.83 1.43 0.73
85.17 79.19 87.98 89.44 90.18
9.13 8.90 9.02 8.98 8.93
0.10 0.22 0.11 0.15 0.16
5.23 5.08 5.02 5.23 5 24
2.75 2.67 2.64 2.75 2.i6
... ,
..
0.85
26-Apr. 1
Apr. 2-8 9-15 '16-22 23-29 30-May
82.69 78.89 66.57 66.57 59.04 53.29
70
0.71 3.32
90.04 9.14 0.11 5.19 2.73 87.53 9.00 0.16 5.17 2.72 91.17 8.67 0.16 5.01 2.63 2&June 3 2 . 1 4 89.05 8.72 0.09 5.18 2.73 I, Mold bran ,used in plant yeast culture mashes, approximately 2000 pounds per day instead of 7200 pounds of malt.
...
Vol. 38, No. 10
Alcohol yields in any alcohol plant vary somewhat from fermenter to fermenter, from day to day, and from week t o week. Such variations are due to differences in kinds of grain and grain quality and to variability in operations. The yield data of .Table I1 manifest these deviations. However, the d a t a indicate improved yields of alcohol in the plant when mold bran was used instead of extra malt in the yeast culture mashes. During the first seventeen days of the year, when only malt was used in the yeast culture mashes, the average alcohol yield was 4.75 proof gallons (2.50 gallons of 190-proof alcohol) per standard bushel. The average yields immediately improved (Table 11) from the time it became the practice to use mold bran in the yeast cnlture mashes. I t was probable in this plant (where operating conditions and grain bills were changed frequently) that other factors besides use of mold bran in the yeast culture mashes might have been partly responsible for the improved alcohol yiclds; also, the average yields showed some decrease as the use of milo in the mesh bills was discontinued in favor of soft corn. Consequently it wae deemed advisable to discontinue the use of mold bran in the yeast culture mashes for a time as a check. The average yield for thie clicck period during the week of March 5-11, while extra malt znd no mold bran was used ill the makeup of the yeast mashes, !vas slightly lower than that during the preceding week and during the following week, with mold bran in the yeast culture mashes. When other factors of irregular operation, ivhich might have affected yields, were considered, the conclusion was drawn that the minimum yield increase caused by the regular use of mold bran in the yeast culture mashes was about 2'3. Even assuming no yield iiicrease, the use of mold bran represenled a considerable monetary saving, and simplified arid speeded up operations in the plant yeasting department. MOLD BRAN AS SOLE SACCHARIFYING AGENT
During LIarch and April, 1945, six full plant fermenters were set i n the alcohol plant in which the only saccharifying agent eniploped x a s mold bran (Table IIIA). Although laboratory tests showed that, in general, less than 4% of good mold bran is adequate, the percentage of mold bran used in the plant fermenter mashes was kept at about 4% to ensure adequacy. Table 111-4 presents data on the companion malt fermenters set just before and just after each mold bran fermenter, and the averages of all the malt fermenters for March and April. 'These fermenters were inoculated with yeast cultures groivn on mashes containing mold bran. The grain employed in the fermenter mashes vas corn, and the regular plant operating procedures rvere adhered to in all cases. The grain was ground and made into a slurry at 110' F. (43"C.) of 15 gallons of liquid per bushel of grain. During passage through precookers the slurry \vas heated to about 150" F. (66" C.) by direct steam injection and was thvn cooked in continuous pipe cookers for about 5 minutes a t 330" F. (166" C.) under 120 pounds gage pressure. The cooked mash was flashed through two-pressure-reducing vessels, t h e . first at 16 pounds gage pressure and the second under vacuum, to reduce the mash telnperature to 170" F. (77" C.). At this point a slurry of the appropriate concentration of saccharifying agent in cold water was mixed continuously into the stream of hot mash so that the resulting temperature was 142" F. (61" (3.). After a holding period of about 2 minutes at this temperature the mash was pumped through coolers and entered the fermenter a t about 82" F. (28" C.). A period of about 3 hours was required to fill menter of 130,000gallons and yeast was pumped into the er 30 minutes after beginning the fill. During thefermentation the temperature was controlled to a maximum of 95" F. (35' C.) by continuous circulation of the mash through external coolers. The mushes as fermented contained about 20% of thin stillage, had a concentration of about 30 gallons per bushel (22.4
.. .
.
~.@xNQA.), an initialpH of about 5.2, and initial titratable acidity of about 2.7 ml. of 0.1 N solution per 10 mL of maah. The ferinentation pwiod was 48 hours from the t me of yeasting in dl -that is, all fermentemwere dropped to the hssr. stills in regulsr oyole at the W o w period4thougb the maahea saccharified with mold bran usually had reached the maximum alcohol content after about 40 hours. Exact codusions are dif6eult to draw fmm the results of single fermentersbecause of variationsin gain, operating conditih, and other factow which change fmm fermenter to fermenter. The yield8 obtained frbm the f-ters in which the maahea were saooharified with mold bran were (bereforecotegssed withthose obtained from the malt fermentere set just before and just after 4 moldbran fermenter. Of the six meld bran fermentarn, one (WF-12) gave a slightly lower yield than the companion malt fermenters, two (418F-17 and 475-F-4) gave almost the asme yielda 8. the averages for +e companion malt fermentera, end the other three (362-F-9,MO-F-S, and 671-F-2) (lave appreciablyhigher yielda than the companion malt fermenters (Table IIIA). The average aloobo1 yield from all six mold bran fermenters w8. 6.84 proof gallons (2.76 g&w of 19O-proof alcohol) per stand& bushel. The average yield for the companion d t fermenters wan 6.12 pmof gnllona (2.70 gallons of leO-prwf alcohol) per bushel; for all the malt fermenters for Marah and April the yield w y 5.11 proof gaUons (2.69 gdons of 19O-pmof al@& per bu&$;, "heseligured indiorite that the yerage yield in t6e plant fiom fermentas in which the. maah was saochsri6ed by mold hran WBB about 2% ,higher than the .average yield during the name, 'meqteq in which the mash w q malt. Certainly yields can be ~xpec& to.be at le& as gmd when'mold bran i n substituted &I# e I y f o r m a l t i n ~ + h o l w t . ~. ' '
.
.
i
,' -
,
.*:,.:
8..
t I .
:~
,,,, C O M P I N A T I O N S O F M O W1B .1, R A N ~ M A L T
~evioua IaGratory temarch *owed t h s t . d t and mold bran amybshsvesupplemental action but that, w h , h e two rue .usedtogether, the unounta of each required cannot be pwlioted on the bnsis of a linear relation. During April and
cI-3
984
INDUSTRIAL AND ENGINEERING CHEMISTRY
TABLE111.
CO~lPARI~OX OF RESULTSFROM FERNESTERS OF CORX 11.4SH ShCCHARIFIED WITH V A R I O V S .LGESTS
"0
Fermenter
Date
Yaccharifving Ageni
8. ~ A C C H A R I F I C A T I O NW I T H 361-F-7 (3/5) 12. 4 malt 362-F-9 (3/5) 3 9 mold bran 9 , 0 malt 363-F-13 (3/51 417-F-15 (3/14) 10.6malt 418-F-17 3 9 mold bran 419.F-2 9 . 1 malt 474-F.6 ( 3 / 2 3 ) 9 . 4 malt 475-3-4 ( 3 / 2 3 ) 4 . 0 mold bran (3123) 9 . 8 malt 476.3-8 (4,'lj 8 . 7 malt 539-F-7 240-F-9 (1(1, 4 . 1 moldbran ,241-F 13 (4/1) 9.7malt 8.8malt 604-F-14 (4111) 605-F-12 (1ill) 1 Omoldbran 9 7malt (4111) 606-F-16 8 . 9 malt 670.h' 17 (4121) 6il-F-2 (4121) 4 . 8 mold lirmi (4;21) 10 1 niult 672-F-6
Final Acidity, $11. 0.1 N per 10 All, Beer
>larch av.
av.
B.
708-F-6 715-F-18 716-F-1 717-F-5 761-F-2 762-F-6 763-F-4 769-F-I 8 770-F-1 771-F-5 841-F-18 842-F-1 843-F-3 901-F-13 902-F-11 903-F-15 904-F-17
:,;;
2 63
2 2 2 2
78 61 73 03
3 5
5 19 3.38 5 23
2' 77 2 c14 2 7ti
9 . 3 ma!t
4 8
5 10
2 68
9 .0malt
5 0
5.12
3.8 4 9 4 4
5 3 5 1
AIALT A S D 31OLD
+
+ +
+
+
+ +
5.00
BR.AN> I I X T l X E i l
2 70 A S D TYITH
0.7
5.00
2.63
2.9 3.5 3.2
5.43 4.96 5.51
2 86
3,5 3.9
5,36 5.32 5.37
2 82 2.80 2.83
4.1
5.02 5.35
2 64 2.81
3.2
3.7
2 01
2.90
3.5
5.43
2.536
4.7 3.8 4.4
S,18 5.18 5.25
2.73 2.73 2.76
4.5 4.9 5.2
5.55 5.26 4.95
2.92 2.77 2.61
5.0
5.12
2.70
4.9 6.0
5.18 5.16
2.73 2 . 72
5.0
5.12
2,iO
4.9
5.18
2.73
Of the seven fermenters in which the mashes were saccharified by combinations of malt and mold bran, three (716-F-1,762-F-6, and 770-F-1) gave slightly lower alcohol yields than the averages for the companion malt fermenters set just before and just after, whereas the other four gave higher yields than the companion malt fermenters. The average alcohol yield from a11 seven of the fermenters saccharified with malt and mold bran mixtures was 5.26 proof gallons (2.77 gallons of 190-proof alcohol) per standard bushel. The average yield for the companion fermenters saccharified entirely with malt was 5.23 proof gallons (2.75 gallons of 190-proof alcohol) per bushel, and that of all of the malt fermenters for April and May was 5.15 proof gallons (2.71 gallons of 190-proof alcohol) per Spreading Inoculated
Bran on Incubation Trays
RESULTSO F PLASTSVALB TEST^ 70.
s o . of Fernienrerj 299 817 6 12
7 12
+;G
mold br
,'
cy
.
Saccharif\-ing A g e n t in Fermenter Ma,hra 10 malt 9 10 malt in
9-10 malt
+
3.9-6.2 innlt 2.20.9 mold hran 0 to 10 malt
OF
MOLDBRAN
h v . Alcohol Yield/ Standard Bu. 190-
Saccharif) irig Ament in Y e a ? [ Proof, CGlture >lashes 931. 2 2 malt 4.77 8 . 6 malt 4.3 mold hrnn i 17 8 . 6 m< 1 . 3 fi~r>l,! hran ,X2$ 8. 6 malt 4 . 3 mold bran i l i 8 . 0 ni'ilt 4 . 3 mold [>ran .> " f i 8.!i n i n l i T 4 . 3 molil oran 5.23
+ +
+ +
Proof, gal. 2.61
2.72 2.76 2.71
~
2 , 77
2.75
2 8.2 2 93
2 ti3 2 68 2 01 2 72
X~L ALONE T 10.8 malt (4/26) 4 . 0 malt 1.6 mold bran (4/26) 8. 7 malt (4/28) 9 . 0 malt (4/28) 6 . 2 malt 0.9 mold bran (4128) 9 . 0 malt (5/4) 9 8malt i6/4) 3 . 9 malt 1.7 mold bran (5/4) 9 . 0 malt (5/5) 10. 1 malt (.5/5) fi 2 malt 1.0 mold hran (6/5i 8.4malt (5/17) 9 2 malt (5/17) 5 1 malt 2.2 mold hran (5/17) 8 . 6 malt ( 5 / 2 5 ) 1 0 . 5 malt ( 5 / 2 5 ) 4 . 1 malt 1.6 mold bran ( 5 / 2 5 ) 4 . 3 malt 1.6 mold bran (5/25) 9 . 2 malt April (av.) 9 , 0 malt May (av.) 8 . 9 malt
(4/26)
;;
2.71
2 72 2.53 2.59
.i1 0 4 96 5 11:
SACCHARIFICATION W I T H
706-F-17 707-F-2
BRAXA S D 11.4LT 5 3 5.13 4 1 5.16 4.9 4.81 5.4 1.92 3 4 5 00 3.8 5 28 6.6 5.34 4 3 3 19 7 7 5.04 5 0
>IOLD
ti$i:j
April
Alcohol Yield,' Standard Bu. 190Proof, Proof, gal. gal.
TABLE IV.
Vol. 38, No. 10
T h i v figurc.i indicate ahout thi, s:irne or n slightly higher yivld in thc, p l m t from fermcmters sacchnrificd lvith malt :incl mold h r m cornbiri:Ltions, :E compared r i t h the average yii,ld tlrii,iiig the same period for fermenter niuslins sacvharified with malt alone. buslwl.
:iyixrqy
DISCUSSION
The rebults given in detail, which iverc obtained in the fullscde tests of mold bran in the alcohol plant in the three usages, mw avcragcd and arc presented in Table Il-, The data in the t,vble show the actual average analytical yields obtained in the Omaha plant. The average yield obtained from 299 fermenters inoculated with conventional yeast cultures containing malt was about 8% lovxr than the average yield obtained from 847 fermenters inoculated with yeast cultures containing mold bran; however, it is believed that the difference, at least in considerable part, was due to other factors. In the main the fermenters inoculated with yenst cultures containing mold bran were run a t a little later period when plant equipment was functioning somewhat better and plant operations Lvere a little smoother. It is certain, however, that use of mold bran in the yeast culture mashes improved the yields somewhat; the mold bran \vas particularly valuable in the Omaha plant because it simplified and speeded up operations in the yeasting department. I n each of the usages of mold bran tested (Table IV) the data indicate slightly better alcohol yields in the plant when this agent was employed. The tests confirm the previous laboratory reports and prove conclusively that mold bran is entirely satisfactory for use on the plant scale in that it results in yields of
INDUSTRIAL AND ENGINEERING CHEMISTRY
October, 1946
alcohol a t least as good as those obtained with malt; furthermore, the amount of mold bran required is considerably less than the malt requirement. S o difficulties were experienced in any of the distillery operations a t Omaha when mold bran was substituted for malt, either Tvholly or in part. No changes were necessary in the regular plant routine or in the operating conditions. It is probable, however, that slight changes in procedures or operating conditions would be necessary or advisable in certain alcohol plants for the satisfactory use of the mold bran. This is because the mold amylases differ from malt amylases in some eharacteristirs, such as thermal stability, rates of liquefaction, and saccharification of starch. During the war pcriod alcohol of industrial quality \yas produced in the Omaha plant. The quality of the industrial alcohol produced with mold bran \vas fully as good as that produced v i t h malt. Since the end of the war the Omaha plant has been producing pure neutral spirits; no differences in alcohol quality can be detected either by chemical tests or organoleptic teststaste and odor-when the fermenter mashes contain mold bran. The main question, then, in the continued and expanding use of mold bran in the alcoholic fermentation industry, is one of economics, arid it is of interest to calculate the value of the mold bran in comparison with malt. From the practical standpoint, as well as for purposes of calculation, it is convenient to assume that the alcohol yields are identical when either malt or mold I)ran are employed. Khen 2000 pounds of mold bran are used to replace 7200 pounds of malt (costing 4.8 cents per pound) in the makeup of yeast culture mashes, the value of the mold bran may be calculated as follows: 2000 z = 7200 X 4.8 x = 17 cents per pound
where z
=
value of mold bran
\\-hen mold bran is used as the sole saccharifying agent for fermenter mashes, its value may be calculated as follows:
ax
A
bm =
cy
- din
n-liere a = mold bran used, b = grain used with mold bran, yo c = maltused, yo d = grain used with malt, C; z = value of mold bran, cents per pound ni = cost of grain, cents per pound y = cost of malt, cents per pound This equation permits calculation of thc value of mold bran undcr usual conditions of variation in mash bills, or of grain and malt prices. For instance, comparing a mash bill Containing 470 mold bran and 967, corn with one containing 1070 malt and 90% corn, and taking the present prices of 4.8 cents per pound for malt and 2 cents per pound for corn, the value of mold bran is
985
Freshly Incubated 3lold Bran Flowing into Drying Bins
where a b c d e z ?J
in
= mold bran used,
70
malt used in combination xith the mold bran, ri = grain used with the mold bran and malt' mixture, Yo = malt used alone, % = grain used with malt alone, % = value of mold bran, cents per pound = cost of malt, cents per pound = cost of grain, cents per pound
=
L-sing this equation and comparing a mash bill containing 1.6% mold bran, 4s malt, and 94.494 corn with one containing 109; malt and 90% corn, a t present prices of 4.8 cents per pound for malt and 2 cents per pound for com, the calculated value for the mold bran is 12.5 cents per pound. With the same mash bills, and with prewar prices of malt at 3 cents per pound and corn at 1 cent per pound, the calculated value for the mold bran is 8.5 cent,s per pound. The economics of using mold bran in saccharification of starchy mashes for the production of industrial alcohol are, therefore, definitely favorable. Experience in a commercial plant at Eagle Grove, Iolva, now producing 10 tons of mold bran per day, showed that mold bran can be produced for sale with a profit a t figures n-ell below those calculated as shown here for the equivalent value of mold bran as compared with malt. Grain alcohol manufacturers could produce their own mold bran and their own malt. In the past distillers preferred to purchase the malt and will probably prefer to purchase mold bran as well. The general use of mold bran should result in a distinct saving in cost of ra\v material. for grain alcohol manufacture. LITERATURE CITED
+ (96 X 2)z == (10 X 4.8) + (90 X 2) 9 cents per pound
(1) Beresford, H., and Christensen, L. M., Idaho A g r . Espt. Atri. BuU. 241 (1941). : 2 ) Hao, L. C., Fuhner, E. I., and Underkofler, L. A., ISD. ESG.
Under pren-ar conditions, 1%-ithmalt a t 3 cents per pound anti corn a t 1 cent per pound, the value of mold bran, calculated from the equation, is 6 cents per pound. Because of the supplemental and sparing action of mold amylases used in combination with malt amylases, mold bran has a greater value xvhen it is used in mixture x i t h malt than when it is used alone. Again assuming identical yields from mashes saccharified entirely with malt and those saccharified with mold bran and malt mixtures, the value of the mold bran ma>-be calculated from the follo~vingequation:
cHEM..35,814 (1943). 13) Hao, L. C., and Jump, J. A , Ibid., 37, 521 (1945). (4) Pigman, W. K., and Blair, AI. G., Div. of Sugar Cliem. and Tech., 107th Meeting of A.C.S., Cleveland, 1944. ( 5 ) Roberts, M.,Laufer, S.,Stewart, E. D., and Saletan. L. T., ISD.EYG.CHEM.,36, 811 (1944). (6) Takamine, K., Ihid.. 6 , 824 (1914). (7) Underkofler, L. A., Brexers Digest, 17,S o . 12, 29 (1942). (8) Underkofler, L. .1.,and Fulmer, E. I., Chronica Botan., 7, 420 (1943). (9) Underkofler, L. &4., Fulmer, E. I . , and Schoene, L., ISD. ENG. CHEM., 31, 734 (1939). (10) Ziffer, J., Rosenblatt, M., and Liebmann, A. J., Div. of Ind. and Eng. Chem., 106th Meeting of A.C.S., Pittsburgh, 1943.
4%
ax
+ by + cm = d y + em
PRESENTED before the Division of hgricultural and Food Chemistry a t t h e 109th Meeting of the AMERICASCHEUICAL SOCIETY, Atlantic City, N J
