S e p t . . 191 j
T H E J O C R S A L O F I - V D I ' S T R I A L AiVD E,VGIiYEERING C H E M I S T R Y
t h e device a means is provided t h a t can be k e p t ready for use i n t h e laboratory a n d t h a t permits t h e successive determination of solids a n d f a t of milk a n d t h e direct determination of t h e solids-not-fat, t h u s effecting a very considerable saving of time on t h e p a r t of t h e analyst. CHSMICAL
LABORATORY,
CITY
DEPARTMEKT OF HEALTH YORK
OF N E W
THE DETERMINATION OF FAT I N ICE CREAM BY THE BABCOCK METHOD By C . A . 4.U T T
773
f a t column i n t h e neck of t h e bottle. Whirl z minutes. R e a d from t h e b o t t o m of t h e fat column t o t h e ext r e m e t o p of t h e meniscus a n d multiply t h e reading b y 2. If a centrifuge without a heating device has been used. t h e bottle should be held in water at 5 j O C. for I O minutes before reading. Chalk, powdered calcium carbonate or t a l c rubbed on t h e g r a d u a t e d neck of t h e bottle facilitates reading t h e f a t column. A few examples will illustrate t h e value of t h e method:
-
Ice cream mixture containing P e r cent b u t t e r fat f o u n d Butter , ' S o . Thickener f a t (VC) A B C D
Per cent
Av.
Dit7 Per cent
16.45
0.15
Received J u n e 14, 1915
T h e determination of f a t in ice cream b y t h e B a b cock method is simple, desirable, a n d accurate, if properly conducted. I n this laboratory t h e hydrochloric-acetic acid method has not been found satisfactory in most cases. If much g u m thickener, gelat i n e , or condensed milk, has been a d d e d , a white precipitate comes up i n t h e neck of t h e bottle o n t h e last addition of water. obscuring t h e f a t column. t h u s preventing a n accurate reading. T h e following m e t h o d , making use of a mixture of sulfuric a n d acetic acids, was des;eloped i n this laborat o r y . I t has been i n use over a year a n d has given excellent results on commercial ice cream. I t has also been checked against ice cream mixtures of knon-n f a t content. Since developing t h e method t h e a u t h o r has been told t h a t t h e r e is such a method i n existence b u t he has been unable t o locate i t . T h e details are offered for what t h e y m a y be worth. PROCEDURE
sAauLE-Warm t h e sample t o 40' C. a n d mix b y pouring a n d stirring. If the f a t has separated, a few granules of powdered sodium h y droxide may be necessary t o aid in t h e emulsification. B--wEIGHISG-~T'eigh 9 grams of t h e well-mixed sample i n t o :a I O per cent Babcock milk bottle. A pipette, with a large outlet, b u t sufficiently small t o fit i n t h e neck of t h e bottle, is desirable. S e a r l y t h e required a m o u n t can be added t o t h e bottle b y bloviing a n d t h e remainder b y dropping. C---THE B A B C O C K PRocEss-Make u p a mixture of equal p a r t s b y volume of commercial sulfuric acid (sp. gr. 1.83) a n d glacial acetic acid.' -4110~t h i s mixture t o cool before using. A d d 1 2 t o I j cc. of t h i s mixture t o t h e ice cream in t h e Babcock bottle a t a b o u t t h e same t e m p e r a t u r e . Shake t h e mixture, using a r o t a r y motion. Place t h e bottle in a s t e a m b a t h or hot waterl a n d h e a t with occasional shaking until it t u r n s a d a r k chocolate color. Remove t h e bottle from t h e s t e a m b a t h a n d allow i t t o s t a n d I O minutes. Place in a centrifuge (preferably a s t e a m centrifuge) a n d whirl I O minutes. Shake t h e bottle again, using a whirling motion. Fill to t h e neck with hot water a n d mix. A precipitate sometimes forms on t h e addition of hot water. This can usually be destroyed b y adding a fen- cc. of t h e acid mixture. Whirl 3 minutes a n d a d d boiling water t o bring t h e .+--MIXING
'
6 Condensed milk andgelatin
16.40
16.40
16.60
16.40
S U M bl A R Y
T h e method as outlined, using a mixture of sulfuric a n d acetic acids, gives good results i n t h e determination of f a t in ice cream. Checks were obtained i n ice cream mixtures made u p according t o various formulas within from 0.04 t o 0 . I j per cent of t h e a m o u n t occurring in t h e mixtures. T h e above method has been i n constant use for over a year i n t h i s laboratory a n d uniformly good results have been obtained on commercial samples of ice cream. FOOD LABORATORY,
STATE AGRICULTCRAL COLLEGE
MAKHATT.4W,
KAWSAS
BETTER BREAD BY MEANS OF NATURAL LACTIC ACID' By ARSOLD WAHL
THE
\Ye use Grasselli Chemical Co. glacial acetic acid, 99.5 per cent strictly c. P.
16.60
HISTORICAL
Corup-Besanez made t h e first experiments in 1 8 4 7 ~ t o demonstrate t h e presence of a proteolytic enzyme. These results were published in t h e Berichte a n d later confirmed b y t h e work of K e ~ m e i s t e r . ~ Langley i n 1886 found t h a t pepsin which is secreted b y t h e glands of t h e stomach as a pepsinogen needs a specific acid t o activate i t , which acid he shom~edwas hydrochloric. R . K a h l in 1 8 9 3 ~pointed o u t t h a t similar t o t h e manner in which starch is dissolved during t h e mashing process a n d b y means of diastase converted i n t o dextrine. iso-maltose a n d maltose, so t h e insoluble proteins of barley, partially during malting b u t more extensively during mashing, are b y means of peptase, a proteolytic enzyme of malt a n d a counterpart t o pepsin. converted into three different proteins: albumoses, peptones a n d amides, t h e process of peptonization progressing as long a s t h e mash is held a t a t e m p e r a t u r e favorable t o t h e operation of t h e peptic enzyme. Silson showed in 1 9 0 3 ~a n d again in 1 9 0 4 ~ t h a t t h e peptonizing of proteins b y peptase was dependent t o some extent on t h e acidity of t h e mash. H e ex-
'
Presented a t t h e 5 1 s t Meeting of t h e American Cht-mica1 Society, S e w Orleans. March 31 t o April 3 , 1915. 2 Ber.. 7 (1847), 1478; 8 (18753, 1510; 9 (18i6). 673. =Imer. Brewers' Rev., 7 , 185, 201. I b i d . , 7, 185, 201. 6 Ibid , 17, 294-7. 8 I b i d . . 18, 294-7.
7 74
T H E J O U R N A L OF I N D U S T R I A L A N D E X G I N E E R I N G C H E M I S T R Y
pressed t h e view t h a t t h e germ a n d endosperm of t h e barley does n o t contain free enzymes i n sufficient q u a n t i t y t o m a k e germination possible, a n d t h a t t h e enzymes a r e set free b y chemical action of t h e acids produced b y t h e living bacteria of t h e barley corn, which bacteria, i n exchange for t h e soluble carboh y d r a t e s a n d proteins extracted b y t h e steeping water from t h e barley, send back i n t o t h e germ a n d endos p e r m t h e lactic acid which dissolves t h e insoluble proteins a n d t h e r e b y sets free t h e enzymes. R . W a h l i n I 9 I 2l published extensive researches on t h e proteolytic enzyme of malt, in which he showed conclusively t h a t t h e peptic enzyme contained i n malt becomes active t h r o u g h liberation b y bacterial acidity. T h e researches of H. L. White2 bear o u t t h e fact t h a t acid extracts of b r a n when added t o t h e dough i n breadmaking effects a n improvement in t h e bread. T h e a u t h o r s p e n t t h e s u m m e r of 1914 s t u d y i n g i n Copenhagen, D e n m a r k , with D r . S. P. L. Sorensen a n d Dr. H. Jessen Hansen i n t h e Carlsberg Laboratories of Biological Research, i n order t o become thoroughly familiar with Dr. Sorensen’s3 method of measuring t h e concentration of hydrogen ions a n d t h e researches of Dr. H. Jessen Hansen i n applying t h e principles of t h i s science t o extracts of flour. D r . H . Jessen H a n s e n showed, i n 1 9 1 1 , ~t h a t a definite relation exists between t h e concentration of hydrogen ions of water e x t r a c t s of flour a n d i t s baking value. Prof. L. D. Bushwells gave a n address in 1915 showing t h a t acids a d d e d t o t h e dough h a v e certain germicidal tendencies therein. SCOPE O F PRESEXT ISVESTIGATION
T h e investigation here described is concerned mainly with t h e improvement of bread a s influenced b y t h e presence of lactic acid produced b y Bacillus Delbruecki. N o details of operation are given, it being m y intention t o publish t h e m a t some later d a t e . T h e scope of t h e work f r o m t h e results of which m y conclusions were reached included: I-The investigation of t h e effect of various kinds a n d concentrations of acids i n breadmaking when a d d e d t o t h e dough. 2-The investigation of t h e effect in breadmaking of t h e various lactic acids produced b y different microorganisms when a d d e d i n various concentrations to t h e dough. 3-Researches on t h e diastasis a n d peptonization of t h e s t a r c h a n d proteins contained i n t h e flour as influenced b y t h e n a t u r a l lactic acid produced b y Bacillus Delbruecki. 4-The investigation o f t h e influence of this bacterial lactic acid on t h e basic phosphates a n d insoluble proteins of flour. 5-Researches t o determine t h e value of t h e products of t h e flour made soluble b y bacterial lactic acid a s nourishment for bakers’ yeast. 1
Communication 8th Intern. Congress App. Chem., XIV, 215
2
THISJOURNAL, 5 (1913). 990.
a Meddelelser Carlsberg Labor., 1909, Vol. 8. 4
6
Comfit. rend., Carlsberg Labor., 1911, Vol. 10. Bakers’ W e e k l y , Vol. XXXII, No. 8.
Vol. 7 , NO. 9
6-Researches on t h e effect of various acids on t h e mucilaginous coating surrounding t h e yeast i n a n a t t e m p t t o produce a non-cluster forming yeast type. 7-The measurement of t h e hydrogen ion concentrat i o n of bacterial lactic acid e x t r a c t s of flour. 8-The investigation of bacterial lactic acid ext r a c t s of b r a n for their value as yeast food. 9-Researches on t h e bacterial lactic acid e x t r a c t s of various malted cereals for proteolytic a n d diastatic strength. DISCUSSION
T h e results of m y researches lead me t o believe t h a t t h e lactic acid produced b y a certain t y p e of lactic acid microorganism known a s Bacillus Delbruecki found i n germinating barley when a d d e d t o bread i n t h e dough stage a c t s t o liberate a n d a c t i v a t e t h e proteolytic enzymes contained in very small q u a n t i t i e s i n t h e flour, besides itself acting enzymatically i n splitting u p t h e insoluble proteins i n t o soluble p e p t o n e s a n d amino bodies. T h i s bacterial lactic acid also effects t h e solution of t h e basic phosphates a n d these soluble phosphates together with t h e soluble peptones a n d amino bodies provide t h e food required b y t h e yeast t o build u p its protoplasm, much of t h e required yeast food being contained in t h e flour i n a n u n assimilable because insoluble condition, b u t which t h e lactic acid transforms a n d makes soluble a n d assimilable. T h e acidulation does not become markedly noticeable, either i n t a s t e or otherwise, because t h e lactic acid is neutralized b y t h e alkali of t h e basic phosphates. T h e potassium, calcium a n d magnesium phosphates, which a r e present as bases, are i n t u r n changed f r o m basic t o acid phosphates. It is also t o be n o t e d t h a t t h e production of yeast food b y t h e effect of lactic acid o n t h e phosphates a n d protein substance of t h e flour aided b y t h e a c t i v a t e d proteolytic enzymes has a marked stimulating a n d invigorating effect on t h e y e a s t , whereby t h e l a t t e r is caused t o produce within a given time a much larger a m o u n t of carbonic acid gas, so t h a t i n t h e period of making bread during t h e t i m e of dough f e r m e n t a t i o n a s well a s i n t h e “proofing,” t h e gas generated is i n dependably large quantities. T h e increased nourishm e n t afforded t h e yeast with i t s resultant invigoration produces increased yeast growth a n d a c o n s t a n t t e n d e n c y t o s e p a r a t e t h e yeast i n t o individual cells a n d t h u s avoid cell aggregations, whereas if t h e individual yeast cells comprising t h e m be undisturbed o r insufficiently nourished, t h e y remain intact a n d t h r o u g h combined action of t h e aggregated cells, cause t h e production of holes i n t h e c r u m b , or a lack of uniformity i n i t s texture. T h e lactic acid itself has a tendency t o dissolve t h e mucilaginous coating s u r rounding t h e individual yeast cell membrane, which renders t h e yeast sticky a n d forms t h e non-readily dispersible cell aggregations already referred t o , t h e yeast t h u s yielding more readily t o thorough mechanical mixing with t h e dough. T h e greater volume of t h e loaf is d u e t o t h e increased distribution of t h e invigorated yeast cells combined with a larger n u m b e r of t h e l a t t e r so t h a t each particle of t h e dough becomes, as i t were, aerated,
Sept., 191j
T H E JOCRLV,lL OF I - l i D r S T R I d L A S D E S G I S E E R I S G C H E M I S T K I -
each cell being surrounded by gluten (gliadin a n d glutenin) modified b y t h e lactic acid in t h e direction of greater elasticity. Bread made b y usual methods has often t h e alkaline taste of t h e basic phosphates of t h e flour from which it was made. By the transformation of these basic phosphates, by the lactic acid. t o acid phosphates n-ith their palatable qualities. together with t h e agreeable taste of t h e lactic acid itself, a much sweeter and more pleasant flavor is imparted t o t h e resulting bread. T h e crumb of t h e bread is a t the same time rendered m-hiter b y t h e bleaching effect of t h e lactic acid on t h e bran specks. oil a n d other coloring matter of t h e flour. T h e change of t h e tribasic alkaline phosphates of calcium and magnesium t o soluble acid phosphates, a n d the partial change of t h e insoluble nitrogenous substances t o soluble peptones a n d amino bodies renders t h e bread more wholesome and more readily digestible. Iforeover, t h e acid, be i t t h e added lactic acid or t h e acid phosphate produced, has a general retarding influence on t h e development of t h e foreign ferments. or other microorganisms, t h e growth of which would tend t o produce b a d odor. discoloration. ropiness or sourness in t h e bread. T h e organisms Bczcilliis Dclbiuecki can be propagated in almost a n y media containing solublc phosphates, proteins, and sugars, such as crushed wheat, rye, corn, or t h e flours therefrom: fresh. stale, or defective b r e a d ; or b r a n . T h e organism mill not grow in milk without added sugar in t h e form of saccharose, maltose, or glucose, since t h e organism cannot ferment t h e lactose of t h e milk. When propagated in milk, whey, or similar milk products a n d t h e whole added t o t h e dough. the resulting bread is much improx-ed for reasons similar t o those given above. ; i bran mash is the most desirable propagation media, since the highly nutritious soluble phosphates a n d soluble proteins contained in relatively large quantities therein, are dissoll-ed out b y t h e acid, and are t h u s incorporated into t h e dough v h i c h adds materially t o t h e effectiveness of t h e propagated acid. This lactic liquor of a n acid strength of 1-2 per cent niay be employed with crushed wheat or rye malt flours, t h u s liberating t h e proteolytic enzyme. peptase contained in t h e malt or malt flour, which enzyme goes into solution together with t h e diastase of t h e malt flour. T h u s the acid-extracted substances of t h a t flour containing. in addition, this activated peptase a n d diastase, besides t h e free lactic acid. will, when added t o t h e dough. effect a n inversion not only in t h e protein a n d basic phosphates, b u t also of t h a t form of starch which is in a gelatinized condition. Starch, in a gelatinized condition, m a y be added coni-eniently t o the dough which t h u s provides not only for t h e yeast food that forms t h e protoplasm of t h e yeast cell, ~Lliz., amino bodies and soluble phosphate salts (potassium phosphates a n d acid phosphates) b u t also malt sugar and dextrin through the splitting u p of which into carbnn dioxide and alcohol t h e \-ita1 energy of t h e yeast necessary t o carry on its life function is
..-113
supplied. T h e malt sugar so produced and not used b y t h e yeast, adds color t o t h e bread when bnlicd, due t o the low caranielization temperature of t h e sugar. TT’hile commercial lactic acid may be tised with i n proved results in all cases, it is preferable t o L I S ~ bacterial lactic acid on account of its greater effec.ti1.cness since this acid with t h e extracti\-e substances in it! contains a much greater concentration of hydrogcm ion. upon which the effectiveness of the acid largc‘lydepends. c 0 s c I. u SI 0 s 5 I n the main it K;IS found t h a t : I-The general appearance of a loaf of l.)rentl is greatly improved by t h e use of bacterial lactic w i l l ; a larger loaf results per weight of bread with imprni-cd bloom, a n d color of crust. 11-Through t h e chemical influences of t h e b a c t e r i d acidity, there results a greater whiteness of crumb n i t h improved texture consisting of a more uniform tiistribution of t h e fermentation gas cells 1vhic.h arc> nf smaller size in augmented number. with avoidancc oi 1ar ge h ol es t h u s eliminating cr u mbl e nes s a n d prod 11 c i n g a more velvety crumb. 111-By t h e addition of bacterial lactic acid t o t h e dough there results a finer flavor a n d increased palatableness in t h e bread b y virtue of a chemicxl combination Ivith t h e phosphates of t h e flour. l h c t o its physical condition: it produces a more pleasant t a s t e , and adds zest and appetizing qualities t o the bread. I1--Bp using bacterial lactic acid produced by propagating Bacillus Delbriii2cki in a bran mash. all t h e highly nutritious extractive substances of the bran are t h u s incorporated into t h e dough, while t h e lactic acid renders soluble the proteins and hasic: phosphates of t h e flour which results in a more viholrsome product by reason of its increased cligestihility. \--The employment of bacterial lactic acid insures better bread since t h e “microbi-cidal” tend(,ncics of lactic acid check t h e growth of those undesir:ililc microorganisms which t e n d t o caiise a tlisngrec~n1)lc: taste. bad odor, ropiness and other h e a d diseases. 1-I-Bacterial lactic acid extracts of malted ccre:tls a t lon- temperatures contain in addition t h e activate11 proteolytic and diastatic enzymes, peptase, ant1 diastase, which act during dough fermentation t o cffect a partial digestion of t h e dough, t h c resulting soluble proteins. phosphates. and carbohydrates serving as a most desirable nourishment for the yeast. TII-hfilk> whey, buttermilk, a n d similar mill; products containing either added or developed hacterial lactic acid, when added t o t h e dough, also effect a similar improrement in t h e bread. YIII-Commercial lactic acid may be usetl i v i t h irnproi-ed results b u t bacterial lactic acid is preferable a n d t h a t bacterial lactic acid which is produced by t h e organism Bacilliis Delbrinecki is t h e most desiratile, since this lactic acid with t h e extractive substances in it contains a much greater concentration of hydrogen ions upon which t h e effectiveness of this acid largely depends. U‘AHLEFFICIESCY INSTITUTE FOR BAKING RESEARCH 327 S O U T H I,.%SALLES T R E E TCIIICAGO ,
