SEATTLE TECHNOL06 1CAL Lf.BCRt,TOOFlY

UNITED STATES DEPARTMENT OF THE INTERIOR FISH AND WILDLIFE SERVICE

METABOLISM STUDIES WITH ALGIN

AND GELATIN

RESEARCH REPORT No. 4

/ /

UNITED STATES DEPARTMENT OF TIlE INTERIOR Harold L. Ickes. Secretary

FISH AND WILDLIFE SERVICE Ira N. Gabrielson. Director

Research Report No.4

METABOLISM STUDIES WITH

ALGIN AND GELATIN

By

HUGO W. NILSON and J. M. LEMON

UNITED STATES

GOVERNMDrr PRINTING OFFICE

WASHINGTON: 1942

For .. Ie by the Superintendent of Document.. W .. hington. D. C. • - - • • • - • • • • • • Price 5 cent.

ABSTRACT

LGL ', u ~ult of ul~illic Ilcid f'xtmet, d from kf'lp, tllid gf'latio, produced frolll 1I111I11ul blllle:- and ~kill , Uf(' \I cd a ... taiJilizioJ"(

aL:' nb ill th,' manufucture of ICC cn'/lllI aIld in ('flail! olhN food prodllct". ~tudll" \\t'rl' COlldllct .. d with J"(rowiIlJ"( Illale rut-- O\'cr a pl'flod of 10 \\t 'I·k .. (0 delt-f1llillf' tIll' lIutntiv "crect of the \t' 'c­(able ~1I1I1 of tll~1I1 UIlt! t h,' prfJtf'in of I(dat in.

The nppnfl'II1 dig;I "t ihillt Y of alJ.(i ll \ 'uried dir etly II it h thc It'\· I f('d. AIL!;ill wa ' utilw,t! ..tlicil'lIlly aftpr ulJ~orptlO11. t:('\utin w highly dig;etcd Irn'''pN,ti\(' of the It'v I f d, but morc food wa fl'qulrl't! pl'r UIIlt iIlCfl'tbl' III lin' weight. _ '0 haract 'ritlc ~ymp­

tom: wcrc notl'd that ('I)uld lJc attributed t o acute or chronic toxicity. B oth algin aud gelatin w 're found to bc \\ holt: llOle food .

METABOLISM STUDIES WITH ALGIN AND GELATIN By H UGO W. N ILSON, Pharmacologist, and J. M. LEMON, Technologist, Division

of Fishery I ndustries, Fish and Wildlife Service

CONTENTS

Page Page

~~ElFri~d1r::~~~i;~~~i~~ ~:::~~:::~::::::: i I f~=;~:-~~~~~~.~_~~::::~:::::::: : ::::::: :: ::: : i INTRODUCTION

Algin, a salt of alginic acid extracted from kelp, and gelatin, pro­duced from animal bones and skins, have been used for some time as stabilizing agents in t.he manufacture of ice cream and in similar food products . . In ice cream they function through certain of their col­loidal properties by affecting the size and nature of ice-crystal forma­tion during the freezing and hardening process and storage; thereby producing a smoother product. Algin also is used to a considerable extent in stabilizing chocolate milk. M embers of industries utilizing marine plan ts are particularly interested in determining some of the metabolic constants of these products.

This investigation was begun in March 1939 in the technological laboratories of the Fish and Wildlife Service. The algin and two grades of gelatin used were purchased from ice cream manufacturers. One grade was a bone gelatin of high gel strength, while the other was manufactured from skins. Gelatin manufactured from skins is used to a greater extent as a stabil izer in ice cream.

EXPERIMENTAL DATA

The algin tested was a sodium alginate product extracted from Macrocystis pyrifera, the giant kelp that grows off the coast of Cali­fornia . The product was standardized to uniform colloidal strength with sugar and dextrin and treated with phosphate to make it soluble in milk. Goodman (1935)1 reported that about 0.15 to 0.25 percent of sodium alginate produced satisfactory stabilization of ice cream. Sommer (1938) pp. 428- 433, fOlmd that 0.25 percent of sodium alginate was equal or slightly superior to 0.4 percent 225 Bloom gelatin for this purpose. Anderson , Dowd, and H elmboldt (1937) reported an im­provement in the sodium alginate mix over a gelatin mix, and that algin

I Publications referred to parenthetically by date are listed in the literature cited , p. 9. 1

448040--42

2 REISE ARCH REPORT 4, FI'SIH A!N'D WI'LDLlFE' SERVICE

as a stabilizer produced an ice cream with a smoother and creamier melt down.

Chemically, sodium alginate consists of the sodium salt of poly­merized d-mannuronic acid in which the carboxyl groups are free and all of the aldehyde groups are shielded by linkages. About 71 percent of algin with sugar and dextrin may be classed as carbo.:. hydrate, and it was incorporated into diets in replacement of part of the sugar and dextrin (tables 1 and 2) .

TABLE 1.-Compositil{'Yf4 diets used

Percent by weight

Ingredients Diet No.1 Diet Diet D iet Diet Diet Diet Diet Diet (coo· NO. 2 No.3 No.4 No.5 No.6 NO. 7 No.8 No. 9 trol)

-------1-Algio ....... _ .............. __ ._ .. ___ 5.0 10.0 20.0 30. 0 .... _._ ..... _._ ......... .. _. __ _ _ Oelatio_ .... _ .. _ .. __ ._. ___ ._ .. ____ __ .. ' __ '_' .... _. __ ... _ ......... _._ 5.0 10. 0 20. 0 30. 0 Sucrose ...... __ . ___ ._._____ 27.0 25.1 23.4 19. 1 15.8 26.0 25. 0 23.0 20.4 Dextrin,tapioca .. ________ ._ 25. 0 23. 1 21.5 17.7 14.4 23.6 23.2 20.8 19. 0 Lard_ .. ______ ____ __ ........ . 15.0 Casein, techoicaL _._._ .... . 15.0 Lactelbumin, technicaL.. _. 5.0 (I) ( I) (I) (I) (I) (I) (I) <') Brewer's yeast, dried _. ___ ._ 5.0 Wheat germ __ ....... _______ 2.0 Cod liver oiL_ .. ___________ . 2. 0 SRltmixtnre, regnlaL. ___ .__ 4.0 ____ ____ ______ . ______ __ . __ ___ ._. 4.0 4.0 4.0 4. G-Salt mixture, No. L .. _. _____ ... _ .. _ 3.3 .5 ____ _____ ._._. ___ ....... _ ...... _________ ...... .. Salt mixture, No. 2 __ .... _._ ._. ___ . _ _ .. _____ 2.0 2.0 _ .. _ ........... _ . _ .. __ . _____ ........ __ ••

Supplement value: Proteio equi .-aleot .. _____ . __ . ___ ___ ._ .. _ . ____ __ _ -_ .. ---- \ 2.0 5.0 10.0 15. 0 Carbohydrate equi va·

lent_. __ . _______ _ ......... _._ .. 3.8 7. 1 15.2 21. 8 2.4 3.8 8. 2 12.6 Mineral equi\-alent_ .... _.. ..... .5 1. 5 2.0 3.0 ------ -- ---- - --- ---. - --- - --.- ---Excessmoisture_._ ........ __ ... _ .7 1.4 2.8 4. 2 . 6 1.2 1.8 2. 4

: Same in all diets .

TABLE 2.-The composition of the algin, gelatin, and the salt mixtures used

Percent by weight

Ingredients Algin with sugar and I----~-----I----._---~---­

Oelatin Salt mixture

dextrin Ski n B one R egular No.1 N o.2

Moisture _ ... _____ ._ ..... ___ 14.0 12. 0 12.0

~ej~~~~~~_~~::~~~:::::::: _ .. ____ .. ~:~~_ -' ''-' -86:8- .. · .... 87:8· :::::::::::: :::::: :::::: :::::::::::: Ash _. _____ . __ . ___ . ___ . _ .... _ 15.0 1. 6 .2 .. _._. ____ . __ ._._. _____ ... ___ ._ . _ .. . Sucrose. ____ . __ ______ ._ .... _ 17. 0 ._. __ ...... _ .. _. _______ . .. _. __ ._._. __ .. _. ______ . . __ ._ ...... . Dextrin _________ _____ .. _.... 17.0 ... _ ........ ____________ ... ___ _ ._. ___ ... _______ .. __ ._ ... _ .. . Calcium lactate _________ .. _. _ ...... _._._._ ... _ .... _ ... _. ____ .. ____ 31. 0 M. O 65.0 Dicalcium phosphate .. _ .. .. _._ .... _ .. _ .. _ . __ .. _ .. ___ _ _ . ____ . ____ . 11. 0 ___ .... _ .. __ .... ___ ..... Dipotassium phospbate __ _ .. __ ........ _ ... ____ _ ... _. _____ _ ._ ... __ . 22. 0 ___ .. ___ . ____ .. __ ._. __ ._ Potassium chloride .... ___ .. __ _ . ___ ._._._. _ ... _._. ___ . ____ ._ ... __ _ 12.5 15.0 18.0 Sodium chloride __ ... _ .. _______ .. . __ . __ __ . ______ . ___ . __ _ ._ ..... _._ 8.0 . .. _. __ ._ .. _ .. _ ... ___ ._. Calcium carbonate. __ ._._._ . _________ ._._ . _._._. __________ . __ .. ___ 7. 0 15.0 _ .... __ . ___ _ Magnesium car bonate_ ... _. ___ ... __ .. _. ___ . ____ ... _ ... _ .... ___ .. _ 3. 0 8.0 8.0 Magnesium sulfate. ___ ._ ..... __ ___ ._. ___________ . ____ _ _ .. _ .. __ .. . _ 3.7 1. 5 ....... . ___ . Ferriccitrate .. .. _._._ ...... __ ....... _______ . ___ ...... _ .. __ _____ _ . 1.3 4.0 6. 5 Copper sulfate _____ ._. ___ . __ . __ .. __ ._ .. ___ . _. __ ._._ .. _ .. ______ ___ . . 4 1.0 1.5 M a nganese sulfate. ____ .. __ ... _._._._ ....... _. ___ . __ ._ .. ____ . ____ . .1 .5 1.0 Potassium iodide __ .... _ .. . _ ______ ___ __________ . _____ . __ . __ ._.__ __ .01 . 01 0.2

METABOLISM STUDIES WITH ALGIN AND GELATlli 3

Gelatin, a byproduct of the meat-packing industry, is a protein derived from white fibers contained in pig and calf skins, and ossein obtained from bones. Two grades were used in the experimental studies. Since gelatin is a protein, it was incorporated into the experimental diets in partial replacement of the casein and lactalbumin which supplied the protein of the basal diet. Gelatin is an incomplete protein, so enough casein and lactalbumin was included in all diets to at least approximately balance the gelatin protein. In no instance did a diet contain more than 35 percent protein. This higher level of protein has been found satisfactory for normal growth of rats in experiments in which casein was fed (Morris, Palmer, and K ennedy 1933) .

ANIMAL-FEEDING EXPERIMENTS

Male albino rats, 4 weeks old, were allotted into nine groups of six l'J>nimals each, with an average initial live weight per group of 53 to 54 g. The maximum range in individual live weight was 48 to 58 g. The animals were individually housed in screen cages that were fitted with screen floors. Food and water were fed freely and the intake of each animal was recorded. The food intake of the various groups was calculated to the equivalent dry-matter content of the· control diet, and the excess was added to the water-intake records.

Groups were allotted to be fed the control diet and diets containing approximately 5, 10, 20, and 30 percent algin with sugar and dextrin, and 5, 10, 20, and 30 percent gelatin (tables 1 and 2) . Three rats of each gelatin-fed group received hone gelatin, while the other three received skin gelatin. The data show no significant differences in response, so the results from the subgroups were summarized together in the final computation. The quantities of algin or gelatin fed were chosen arbitrarily, but the smaller amount represents about 20 times the quantity usually incorporated in ice cream.

Only one 9-week t est was originally contemplated. In order to obtain accurate apparent digestibility coefficients representing the entire period, paper towels were spread under the screen floors and the feces collected every 2 or 3 days. F eces samples from individual rats were kept in a cool place and later dried to determine the dry-matter content. Preliminary tes ts soon showed that the algin could not be readily extracted from the dried feces. Consequently another sample was collected during the tenth week for the determination of algin, total nitrogen, and dry-matter content. Data for gain in weight, and food and water requirements cover the 10-week period, while data on the apparent digestibili ty of algin and the total protein are limited to the tenth week.

Th e algin c()ntent of the feces collected during the tenth week was determined for individual rats by digesting a 3-g. sample with 10 ml. of

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Thl' tlnln in [nhll' ~ ~h()w thnt thl'rc wn~ tl mark(,!! (h, rl'n in tbe hnclt'rinIIlUl1\hl'l'" nboul Iht' h\ dfth dny. Tlll'rnt thnt lind thr u h thi. lH'riod JlOwl,d n .1Ih,l'qu!'nt higiwr hn I rinl count f the in­tf' linni f'ollll'n!., whill' Ihoqt, thnl <ii d ho\\ ul e,itillH'l' that th f d wns not proP(,r1y dig-t'_ It'd. o1l\pl tp dijf('rlntial :ludilP weI' n t mndl', hut il nppear d Ihnt tllr grnyish-blue c 100il5 Wl'rt grnm n gu­tin rods ond th ~ maU b1'owni h ('01 nil: \\' I' gram p sitiH (' (' 1.

Tllr dntn nre YrD- in('omplrtl', but nppnrl'lItl. th bnrlll'ini f) 1'a f thr intr.tinnl tract \\'0 . nn importnnt fa tor in tIl ffi 'irot utilizati n of food find in thr health of thr animal,

METABOLISM STUDIES WITH ALGIN AND GELATIl\7 5

No characteristic lesions were found during necropsy of the rats that died when fed the regular experimental diet. The mean total fecal excretion of dry matter per rat during the 10-week period was 26 g. for the control group; 35, 38, 33, and 29 g. for the groups fed algin; and 19, 24, 16, and 12 g. for the groups fed gelatin at the 5, 10, 20, and 30 p ercent levels. The dry-matter content of the feces varied from 57 to 78 percent.

The data in table 4 show that the rats of all groups except those fed the 30 percent level of gelatin grew rather uniformly, although, only the rats fed the 5 and 10 percent levels of algin grew as well as the control group.

TABLE 3.-A study of the bacterial flora in the contents of the intestinal tracts of rats f ed a diet that contained 20 percent agar prior to June 7

Bacterial count in millions per gram

Rat number and Date diet fed Small Cecum intestine

20 percent agar : 12L _________ ___ June 23 3.3 10

117 ___ _______ ___ July 5 1. 5 9 :10 percent algin: 125 __________ ___ June 11 2.1 628

124 _____ ________ June 15 4.4 21 123 _____________ June 19 .2 3

118 ___________ __ June 23 3.0 14

120 _____ ________ ___ do ____ _ ___________________ _

122 ________ ____ _ 126 ___ _____ _____ JJuunnee 2276 1----.--16--.0-- 14

Remarks

The intestines were fairl y well filled with food. The ceeum was small and compact. Grayish-blue colonies.

Do.

All grayish·blue colonies. Ahout 3 times as much food in intestines as for rat

No. 125 . Grayish-blue and brown colonies. The intestines coutaiup.d very li ttle food , but the

cecum contained considerable solid food . Grayish­blUe and brown colonies .

The iutestines WerE filled with what appeared to be algin. The cecum was quite large and well fill ed wit,b a grecnish material. Grayish·blue and brown colonies.

Killed because he was obviously sick. H e did uot have any foo d in the cecum or intestines.

Died No food was found in the cecnm or intestines. The intestines were fill ed with an algin·like substance.

Grayish-blue, brown, and a few wbite colonies.

TABLE 4.-Daily gain in weight of rats for the lO-week period

Group dcslgnation Number of Mean daily Coeffici ent of Mean d iffer- Percent Icvel survivors gain variation ence from of t control

Grams Percel1t Groms ControL ____ ____________________ _ 6 3.99 13 -------------- ------------- -

4 3.72 20 0.27 (I) 4 3.53 9 . 46 (')

Algin: 5 percent ___________________ _ 10 percent. _________________ _ 20 percent. _________________ _ 4 2.98 9 1. 01 4 30 percent. _________ __ ______ _ 4 2.20 21 1. 79 1

Gelatin: 5 pcrcent. __________________ _ 6 3.31 5 . 68 5 10 r erccnt. __ __ _____________ _ 6 3. 10 11 .89 2 20 percent. ____________ _____ _ 6 2.22 10 1.77 < 1 30 percent _________________ _ _ 6 ,99 31 3.00 < 1

I Nonsignifi cant difference.

The data in table 5 are interesting since they show that none of the rats fed algin required more food per gram gain in weight than the control rats. The greater variability of food requirement for the rats

6 REISE ARCH REPORT 4, FIS!H AlND WILDLIFE SERVICE

fed 30 percent algin (coefficient of variation equals 17 p rcent) , and the smaller number of animal , made th difference from control of 0.85 g. insignificant. This finding need not be empha ized, inc what happens wben the lower I vels arc fed is f greater importanc from the standpoin t of stabilizrl's in food. The groups f d gelatin all r equired more food pel' gram gain than did the control rats. Th re was no effect of increa ing level on the apparent digestibility of the dry matter of the diet, and til Jiet were dige ted surpri ingly well in all instn nce .

The wa ter requiremrnt per gram gain in weight varie a may be expec ted (table 6). It i intere t ing to note that the rat fed the 5 and 10 pern'nt level of both algin and gelatin required about the arne amount of water per gram gain in weight a the control group.

Those freI th e greater level of either material bowed a higher require­ment wh ieh may be explained, at lea t in part , by the decreased growth rate. The mean, free-choIce water con ump tion for the 10-week period was roughly 1,400 g. for the control group; 1,525, 1,450, 1,750, and 2,000 g. for the algin-fed rats; and 1,300, 1,275, 1,300, and 950 g. for t he gelatin-fed rats.

TABLE 5.-Food required per gram ga in in weight and the apparent digestibility of dry molter for the lO-week period

Group designation

Cont roL ....................... . .\Ig' n:

5 percent. . ................. . 10 pcrcent. .... . .....••...•.. 20 perccnt ..................• 30 percen t. .....•...••..••...

Ge latin : 5 percent. . ................. . 10 percent. ................. . 20 percent. . ..... . ...... .. .. . 30 percent . . ... ... ........ '"

I Non·significant difference.

M ean food required

Gra= 3.00

3.30 3.22 3.34 3. 5

3.31 3.54 4. 17 6.71

Coefficient of variation

PtTcent 6

11 8 8

17

4 9

16 17

M ean difference

from control

Gram, --- ----- -- ----

0.30 .22 .34

5

.31

.54 1.17 3. 71

M ean Percent level apparent

of t di~estibility of dry matter

PtTcent -- -- -- ------- - 96.6

(I~ 94.6 (I 94. (I) 94.8 <I) 94.4

3 97. 2 2 96.5 1 97. 1

< 1 97.0

TABLE 6.-WateT required per gram gain in weight fOT the 10·week period

Group designation

Control .......... ... .................. . Algin :

5 percent .. ........................ . 10 percen1. ..... ........... .. . .. .. .• 2tl percen 1. ............ .. . . .... .... . 30 percen1. ... .......... . .......... .

Gelatin: . 5 percent. . . .. .............. .. ..... . 10 percent ...... ....... .. ... . .. .. .. . 20 percent ....... ... .... ... ........ . 30 percent .............. ..... ...... .

I Nonsignificant difference.

M ean water required

Grams 4.91

6. 22 5.94 8.64

13.24

5. 67 5. 98 8.29

14. 33

Coeffi cient of variation

Percent 18

26 8

25 8

17 9

10 21

Mean difference Percent level from control of t

Grams ----. _---- - - --.- - - - - - - - - ---- ._--

1. 31 <I) 1.03 <I) 3. 73 5 8.33 < 1

.76 f) I. 07 I) 3.38 < 1 9.42 < 1

METABOLISM STUDIES WITH ALGIN AND GELATIN 7

The tenth week served as a feces-collection period in order to de­termine the digestibility of the algin and the total crude protein of the -control diet and those containing gelatin. Some variation in apparent ,digestibility may be due to the fact that the food-intake data were taken.fro~ the period in which the feces were collected, and day-to­day fluctuations in food intake and feces excretion would have a greater effect during a period of 1 week than for a longer period. This factor may be responsible for part of the rather large coefficients of variation of 79 and 27 percent for the groups fed 5 and 10 percent algin ,diets (table 7) .

. The dat~ in table 7 show an increasing apparent digestibility of the algin w ith' increasing level in the diet. There was a statistically sig­nificant difference in every case. Either there was an adaptation of the intestinal tract to use a greater amount of the algin in the higher levels in order to conserve food supply, or the micro-organisms re­sponsible for digestion grew better in the intestinal contents containing the higher levels of algin. The algin after digestion was apparently well utili~ed ',by the animal, since the data in table 5 show no sig­nificantly greater amount of food required per gram gain in weight as the algin content of the diet increased from 0 to 30 percent, Appar­-ehtly the algin has considerable nutritive value and can be efficiently utiliz~d when properly digested.

, ,

", r j , TA;BLE 7.-Apparent digestibility of algin for a i-week period

Qroup designation I

Mean a)lparenti Coefficient of Mcan difference Percent level digestIbility variation within series of t

. ' .

Algin: Percent Percent Percent 5 percent__ _____ ___ ___________ ____ __ 3.0 79 ________ ____ _____ ____ _______ ___ _ 10 percenL__________________ __ ____ 35. 9 27 32. 9 < 1 20 pereent_______________________ ___ 63.4 7 60.4 < 1 30 percenL_____ ______________ _____ 88.3 3 85.3 < 1

: ~g g~~:bL~I:~ ::: : : : :::::::: : : ::: : :~::::: : ::::::: :::::::::::::::: ---------- - 27 ~ 5 - -- ----- ------- -2 30 percenL ___ ___ ______________ __ ___ _______ __ _______ ____ __ __ ________ 52.4 < 1 20 pcreent ___ ______ ~ ________ ___ ______ ______ ___ __ -___ -___ __ ____ ____________ ____ __ _____ _____ _____ ____ _ 30 percen~- -- - - - - - - ------- - --- ------ _______ __ ______ _ ___ _______ ____ __ 24.9 < 1

The ,data in table 8 show a very uniform apparent digestibility of the total pr.otein of the control diet and the diets containing increasing levels , of gelatin. The coefficients of variation were very small, indicating a high degree of uniformity. Apparently the gelatin was very digestible irrespective of the level fed, but the data in table 5 indicate a significantly higher quantity of food required per gram gain in weight when the gelatin was added to the diet and when the level of gelatin in the diet was increased_

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h,' Illllnll\" ,"ullll ' (J( tlH' III till' linltl 11Im!-

lllhilizt'l ill fOlld (lmdurt ,111'1'1111 l ' ll( Lhpi" ph) i!'11 I 111'"11 .\I tholwl. th(' 1I11triti\I' \ lilli ' of tIll' PI' Iud ur .. IIf !'!'l)lIdllr_" imp r­tll(\("', bot It 111"1' \\ 1.,,11' (HilI' , ' \\\ II ru III 'IWI! III 'Ill-(,,,I j!nJUp di I ~OOIl uft. ' r hl'ill~ fl ,d Lhl ' dil'l I hut ,"dy (11' 'uti\ 1·1" !f.ll \\ fOr' (oullIl on II( crop .. )" TIll ' I(n i, O( fIllld .. n 'u ollHbly I i (u('(ory!.! in in WI iJ!h , Thl' ~. l u t ill-f.,d flit-. ~n '" III II 19'11ilil'UI1t1y 111\\ I'r rul,' llwn th .. r.on I' J flit-. Illld [I ' /jlllrt ' " Ill(lrt' fOlld )wr ~rurn 'llilt in \\ ,i,."t, but Idl Ii,' I. '1'1", grollp f, 'd th!' c'olltml did, IIwl thl' (' 1I1lbilH I 'Will' \ hirh h d pn' \' ioll Iy \1I "' 1l (. ,d tIll' ,i und I () P"f!' 'fit 11'\ ,I of ulr·in Ilr ,!'('llllin w r f. ,d till' ,i p, 'n ','nl 1('\', ,1 of Ill!,!illllllcl I!l'lutill lind hI' 'l!r IIlp 11I1\" bl" n C' IlIlIII"I1'" 011" 11I'r1I1I1'nl for 0\ "1':2 yl'll , 1 putt. \\ I'r linlllly till t Plll'l1111llllill HlId l1lnt.~IIHI11 tllinor , (" ·pt I n t fl d 111 in liil'd ( r-01\111'.\" I'mhol, /lI nllt! Illlolh .. r of p J' ihll' dir,1' tl\ t' iii tllrb,Bl r inll'.,lilllll infectioll ,

~r all'lllhino ntt \\ ith IIIl n\ l'mg., inilinllino \\ fed il\di\' idllHII~' for (lilt' 10-\\ I'('k IH'ri HI on 1\ 'ontrol did, uppl In n d "ilb ,i, Ill, :2(), Hlld :~ 1 p 'n '('nl of nIt Yin \\ itlt . U"t r null Ii ,· trin nn ,i, In, ~(l, Hlld :H1jH'('(' 'Ilt IIf (!1,lHtlll. Th( upp rellt dig(' lihility r tll algin l'Hngl'd from :1 10 ' perc 'nt, d p ndill~ upon till I,v I {('d, Tb

nppnn'nl digl".;tibility of 11." lotnl prot in of III Ii '\ ' vnricd from abollt • ' t) 9~ per ('nl. I {lt h fOllnd to Ill' I\'hol('s m [nod",

Trn mnlr rat of . imilnr inili al wight, bu W'orr latrr f d thr b , nl dirt ('nit r pitlr d th p('!'c nt of algin wiLli tWllr an I d xtrin. ing thr 10-wrok p ri J. Thr ny r t O'r d ily g. of food an I .04 0', of wat r w I' r quir weight.

METABOLISM STUDIES WITH ALGIN AND GE LATIN 9

LITERATURE CITED

ANDERSON, E. 0.; DOWD, L. R.; and H ELII1BOLDT, H. 1937. Sodium alginate as a stabilizer for ice cream. I ce Cream Rev. 20 (11);

88-91 GOODMAN, CLARK.

1935. Technical cont rol of ice cream with sodium alginate. I ce Cream Rev. 18 (7); 42-48, illus.

SOMMER, H UG O H. 1938. The theory and practice of ice cream making, 3d ed . 639 pp., illus.

MORRSI, H. P.; PALMER, L. S. ; and KENNEDY, CORNELIA. 1933. F undamental food requi rements for the growth of the rat. VII. An

experimental st.udy of inheritance as a factor infl uencing food utili­zation in the rat. Minn. Agr. Exp. Sta. Tech. Bull. 92 :1-56, illus.

o