L4 KOTE O N ATAUM PHOSPIIATE BAKISG POIVDERS.
'l'lie poiiit of view from which healthfulness or unhealtlifulness has been predicated for the combinations usually employed as. lenvening agents has been shifted considerably during the last few years. The innin contention has been, a n d continues to be, i i i regard to the advisability of alumilia compouuds in such food products, but the positions assumed by both advocates and opponents have been not only modified, but on some points rerersed. It will bo coiiceded, we think, tliat much of adverse opinion in regard to the employment of burut alum in baking powders lias arisen from confusion concerning two very distinct purposes for wliich ;tloni has been used. I t s peculiar nctioii upon flour produeiiig a whiter a n d lighter bread from inferior and in some c:wx unsalable flour than could otllcrwiac Le obtained, early led to its adoption in EngIt~11dmid on the Coiitineiit, for the purpose of enhancing the value of brcad products beyond tlicir legitimate value. It was t h u s a fr:tud upon the consumer, calling for ttnd being met by legislative restriction : nor should it be forgotten that the alum was added to t h e bi-cad as crystallized alum possessing, when in the bread, all t h e properties of that salt, and being extracted therefrom in large proportion by water. I n t h o use of alum in baking powder the conditions arc entirely changed ; the powder being used by the buyer, the purpose for which legislative interference was first invoked is n o longer a fitctor :tnd from :I sanitary point of view the questioii is 110 longer
XOTE O H ALUM I'HOSPHATE B l K I N Q POWDERS
453
centered on alum as such, bot on*hydrate and phosphate of alumina, I n the celebrated Xorlolk baking powder case (Analyst 4, page 231) it was contended that the phosphate of alnmina was entirely insoluble in the human system, that thus the flour was deprived of its phosphatic constituents by the alumina in the powder forming iusoluble residues, and on that account alum baking powders should be condemned. With the advent of acid phosphate of lime as used in combination with burnt alum for liberating the carbonic acid of sodium bicarbonate such objections were forestalled, since much more phosphoric acid was introduced than could possibly be removed from the flour. The reversal of opinion to which we alluded was now taking place and statements and calcnlatio~~s made were based upon t h e assnmption that all of the alumina left in the residues of bread and biscuit was taken up in the system, whereas i t had been claimed before that they were insoluble. Direct experimentation made on a typical phosphate and alum composition seemed, however, to be a t variance with sucli assumptions since in the nearest approach possible to the actual conditions the factor arrived at for the solubility of residues from phosphate and alum powders i n the mouth and stomach was found to be & to '0 of the alumina present (Pitkin, Journal American Chem.
Soc. 9, 11. 27). The consideration of the effect of the residues from the various powders upon digestion now began to be taken up, and much attention was bestowed upon that aspect of the question in the various State Boards of Health and Government reports. Some comparative figures on the action of the various combinations have been published (Pitkill, Journal Am. Chemical Soc., Vol. 12, 8) which seem to indicate that, in albuminoid digestion a t least, there is little difference between the action of residues from cream of tartar and alum phosphate powders, while sour milk and soda also seems to exercise an almost identical inhibitory action. T h e basis upon which these results were obtained was a comparison of residues from neutralization of the same quantities of sodium bicarbonate-in other words, equal leavening equivalents of the residues were employed.
In glancing over a late Government h i J O r t (Food and Food Adulterants. Part 5th, Bulletin KO. 13, p, > ; 5 ) we firid the fol1on.ing table :
~-_____-
.-
___ -
.-- .-.___ -- .
I’oivders. ..
Tartrate - - .
-
~
,
--
-.
.
..
-.
...
’
I’otnl residue o f the weight of
Chemicals used. Per cent.
.
Phosphate - - - -
--___
_ ~ ._
Ca,.i~orlic I’w c r n t .
. . .
~
..
~
.
16.
104
2.2. 2’;. 17.
1.2:;
. . .
.
Alum .- ...- .- . . - .- 12s Alum and l’liosphate . 111 -. _____ ___ -4s will Gc seen at a glance the alum and the pliosplmte powders give t h e l w s t residue per unit of gas evolved, while the alnm and pIiosl’11;ttc combinutioli is credited with tlie greatest perceiittbge of rcsiduc t o cmbonio acid. Wlien it is remembered that, it is upoii the amount ;is well as upon the c11ar:icter of residurs that :Ittentioil is now ~1)e~iiiIly dircctcd, i t is obvious tliat the mtio i s :t rnatt,er of 110 little importance. O n e a o u l d nnturnlly suppose that snch n conibini~tioii 1)owder would bo soniewliat intermediate in its leavening actioii llutweeii the two clnsses to wliicli it is related. Looking over t h e report to see upon w11:1t data the figurcs quot,cd WVIX: obtaiiied we find, p. 5;1 : “:I c i i w j i i wliich tlie cliaracter of t,lic powder appears t o be improved I)! sucli niixiug, Iiowever, is iurnislicd by tlie alum i111d 1’ 11os 121l i t t po \v d e r F. This combination seems t o be a favorite one with manufiictuiwx In fact tlierc arc now comparatively few “straiglit ” alum powders in the niarkct, most of the cheaper grades being made of mixtures i i i vnrious proportions of tlie alum with w i d phosphate of lime, the rctiction it is intended to obtain is probably the followiiig : ~
(3
+ CaH,(PO,), + 4KaI-IC0, Acid phocphatc of lime.
Ailinionin aliini. 1:x
CnSO, S !I i phatc
(,r i i i n r , .
336
334
47,5
( ? I T I I p ) p Al,(SO,),
245
= A12(1’04)2 +
B1c;irbonarc of mdn.
132
284
1i G
Sulphate of al iimiiiiii ni.
Sulphate of soda.
Carbonicdiosidc.
I’hoaphulu of a1iimiiiiiiiii. 7’7
+ (KI14)2S0, + r??;a,SO, + 4C0, + 4H,O \Varer.
S O T E O S ALUM PHOSPHATE B A K I N G POWDERS.
455
On page 567 in discussing phosphate powders, 234 parts of CaH, is credited with the power of liberating 85 parts of carbon dioxide: on page 569, 4;5 parts of AI, (SO,), liberates 264 parts of carbon dioxide, but by the equation used in discussing alum phosphate powders only half enough sodiuin bicarbonate is given to the above quantities of "acid phosphate " and burnt alum to liberate the 88+264 parts of carbon dioxide which they would separately set free. We think the published analyses in the report conclusively prove that while the combination may be ' ( a favorite one with manufacturers,'' they certainly do not intcnd to obtain the reaction with which they are credited. N o such ratio is found to exist between the ingredients i n a single one of the fifteeu complete analyses of alum phosphate powders printed in the bulletin. All baking powders lose more or less carbonic acid on keeping, depending upon the amount of moisture absorbed, quantity of ('filler" present, length of time elapsing since manufacture. etc. I t wil! therefore be advisable to examine the ratios between, for instance, the sulphuric anhydride and sodium oxide (both being proportionally increased by any loss in carbonic acid gas) called for by the formula and that found in actual analysis. By the formula (SO,), corresponds to 4 K a or 2 Na,O by weight 3?0 parts of sulphuric anhydride should be found for each 124 parts of sodium oxide or the ratio of SO, to Ka,O should be more than 2.5 to 1. I n the analyses we find : So. 5510 _ _ _ _ _ _ _ S = o , 9.7'3% Na,O = 12.25% " 5511 _ _ _ _ _ _ _ " = 11.02% " = 1;?.5S$ " 5512 '' = 11.57% '' = 14.04% " 5515 _ _ _ _ _ _ " = 13.01% = 9.83s " 5516 '' = 12.26s '( = 9.21% =_13.18% " 551'7 . _ _ _ " __ ' I = 8.33% (' 5519 _ _ _ _ _ _ _ '( = 8.78d '( = 7.26% " 5520 " = 10.51% " = 11.92% " 5521 " = 11.54s = ll.?O$ " 5524 _ _ _ _ _ _ _ " = 10.14% " = lO.SC$ '' 5525 " = 8.93% " = 12.15%
(PO,)
_______
_______
_______ _______ _______
('
456
NOTE O S A L U M P H O S P H I T E HAKiXG I'O\VI)EHS:.
No. >:IO _ _ . _ :' _r_IO.*-)';$ _ "
.jO3? -
- - - .-
('
=ll,:io$
1_ _ _'*. _ =_ 10.GGG _ __ = 13.23$
4
Sa,O = lO.;;i?$ .i
(' i'
= : l.!.(i!t5 - 1
_..!.?!I;;
By averaging the above it will be seen that the p r c e n l a g e s of sodium oxide and sulphuric anhydride are practically equal, instead of corresponding t o the ratio dcmarided by tilt! formula, nor is ratio of phosphoric acid to sodium oxide 11iuc11 closer to what is demanded. There is evidently a mistaken iLssnmptio11 therefore upon which the high ratio of residue to leaveniiig power has been asserted of this class o€ powders, and the infiuerice ;ittaching to such an exhaustive report from such a M O U ~ C C ! forms D sufficient excuse, I trust, for calling attention to tlit! error.
