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 N G I N E E R I N G C H E M I S T R Y
55%
sample examined a t t h e end of the incubation period, would appear t o corroborate t h e very interesting report on deterioration of sugar in storage by Blake’ as well as t h e investigations of Browne,2 Owen,2 and others already referred to. I n general i t was found t h a t t h e deterioration was proportionally greater over t h e longer incubation period t h a n a t t h e end of one month, and this despite t h e fact t h a t t h e total number of microorganisms per gram increased disproportionately t h e first month. I n fact i t would appear t h a t rapid deterioration followed a rapid increase in t h e number of microorganisms. The authors are cognizant of t h e fact t h a t any generalizations which have been made are limited b y t h e small number of samples under consideration and apply only t o t h e conditions of the experiment. The foregoing investigation which is concerned with t h e chemical and bacteriological analyses of Cuban raw sugars under normal conditions of storage has served t o bring o u t rather clearly t h e intimate correlation between t h e composition of a sugar and its microbiological content as influencing deterioration. In this way it becomes possible t o modify t h e so-called ‘‘factor of safety rule” from t h e standpoint of microbiological infection and arrive a t a satisfactory basis for predicting t h e keeping quality of sugar. S U M MARY
I-Cuban raw sugars (with moisture ratios varying from 0 . 2 2 t o 0.49) were stored under normal conditions for 5 . 5 mo. and analyzed chemically and bacteriologically. There was a loss in polarization a t t h e end of this period, as well as a t t h e end of one month, which was generally accompanied by a gain in reducing sugars. There was a gain in moisture content a n d reduction in t h e factor of safety. 11-There was a decided increase in total number of microorganisms after one month, which could be correlated within certain limitations with deterioration. Where there was a large initial infection, deterioration was rapid. I n general there were more microorganisms in t h e middle of t h e bag t h a n at t h e surface. The per cent of molds increased over t h e longer incubation period, b u t often failed t o increase in one month. 111-A correlation between t h e number of microorganisms and t h e moisture ratio is indicated which appears t o make i t possible t o predict t h e keeping quality of a sugar. IV-Bags designated as wet, stained, or having sugar light in color, deteriorated more rapidly t h a n when drier, unstained, or dark in color. I n bags of sugar which are deteriorating rapidly, t h e surface deterioration is greatest, while in less rapid deterioration t h e middle of t h e bag seems t o undergo greater decomposition. V-Deterioration was proportionately greater over a longer incubation period t h a n in one month. A C K K 0 VI L E D G M E N T i
It is a privilege t o acknowledge the invaluable assistance of Mr. J. McFetridge, whose interest made i t 1
Louisiana Planter, 6 1 (1918), 316. crt.
2 LOC.
Vol.
12,
No. 6
possible t o carry o u t this investigation, and t h e efficient help of Mr. Salvant and his associates in t h e American Sugar Refining, Co., a t Chalmette, La. We are indebted t o Dr. C. A. Browne for his reading of t h e manuscript and constructive criticism.
JELLY By C. H. Campbell GARRETTAND Co., BROOKLYN, N.
Y.
Received December 13, 1919
Although jelly is a scientific product, i t has never been considered as such b y manufacturers. I t should be so accurate scientifically t h a t manufacturers can bring their raw materials together in t h e proper proportions and be sure t o obtain a good, reliable commercial product. To produce jelly, t h e proper proportions of acid, pectin and sugar are necessary. While much has been said as t o t h e proper amounts of acid a n d sugar, nothing has ever come t o t h e author’s attention which demands a definite percentage of pectin as t h e fundamental basis for commercial jelly manufacturing. The following results prove t h a t this is t h e only t r u e basis. It has been found t h a t : I-An excess of pectin produces a firm, tough jelly and decreases t h e amount. A pectin content of 1.2 j per cent produces a fine commercial jelly; whereas, 1.0 or 0 . 7 5 per cent of, pectin produces a delicate quality resembIing homemade jelly. 2-An acidity of 0.3 per cent (as sulfuric acid) i s necessary t o produce a good quality, t h e minimum being 0.27 per cent and t h e maximum 0.5 per cent. 3-We know also t h a t an excess of sugar produces a soft jelly, while an insufficient amount results in a tough product. I n an endeavor t o determine t h e minimum a m o u n t of pectin necessary t o produce jelly, several series of experiments were run, varying t h e per cent of pectin used b u t keeping t h e acidity and sugar constant. T h e following results were obtained: SERIESI Original Apple Juice 1.22 Per cent Pectin
................
Volume, Gal.. 1 1.017 Specific Gravity.. Acidity (as HzSOa). Per cent.. 0.113 Sugar, per Gal . . . . 3 Ibs. 10 02. Acid (citric or
............ ..
Diluted t o 0.75 Per cent Pectin 1 1.010 0.074 3 Ibs. 10 02.
Diluted t o 0.5 Per cent Pectin 1 1,005 0.054 3 lbs. 10 02.
I5 20 220 220 12.5 12 Too soft for commercial use,. b u t fine quality 1 Acid was added t o juice t o make acidity 0.3 per cent (as HzSOa) i s each case. Cooked t o F . . . . . . . . . . . . . . . . . 220 Yield, 8 02. glasses. Quality.. Firm, 0 . K.,
....
....
SERIESI1 ORIGINAL JUICE 1.695 1 1,038 t 0.25
............
Pectin, Per cent Volume, Pint Specific G r a v i t y , , , , , , Acidity (as H Sugar, Lb.. . . Acid added cent up t o . . ....... 0 . 2 5 Cooked t o F.. ............ 222 Yield, 8 0 2 . glasses.. . . . . . . . 1 . 5 Quality.. ................. Clear b u t dark
.............. ,. ,..
-JUICE
1.3 1 1,025 0.21 0.5
DILUTEDTO1.0 0.75 0.5 1 1 1 1.020 1.016 1.012 0.16 0.14 0.5 0.5 0.5
0.3 0.3 222 221 1.5 1.5 Fine, Good 0. K.
--
0.3 0.34 222 222 1.5 1.5 Good, Toa too soft soft
June,
1920
T H E JOURRNAL O F I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y SERIESI11
ORIGINALJUICE Pectin. Per cent . . . . . . . . . . 1.62 1,020 ,Specific Gravity.. . . . . . . . . . 0 . 1I 8 Acidity, Per cent. . . . . . . . . . Sugar, Lhs. per G a l . . 4.25 7 Acid added, grams.. Cooked t o ' F . . 221 13 Yield, 8 oz. glasses.. .Quality.. . . . . . . . . . . . . . . . . Firm and stiff
DILUTEDTO1.0 0.75 1.017 1.012 ... 0.073 4.25 4.25 15 20 221 221 13 13.5 Very good Little soft
-JUICE
...... ....... ........... ......
SERIES I V
1 Per cent Pectin Base with Increased Suzar
ORIGINAL
DILUTEDTO0.75 0.5 ... 1.5 1.5 1.5 1.2 1.017 1.012 1.008 1,007 1.006 0.25 0 . 2 1 0.176 0.132 0.113 8 5 Ibs. 5 Ibs. 5 lbs. 5 Ihs. 1 02. 1 02. 1 02. 1 0 2 . 1 0 2 . Acid added, t s p l . . 1 1 1 1 1 1 219 219 219 Cooked t o F.. . . . . . . . 219 219 219 17 1 8 . 5 18 Yield, 8 0 2 . glasses 16 18 28 Quality., Very firm Firm Deli- Soft Soft Good cate 1 Teaspoonful acid (made b y dissolving 1.5 Ibs. acid per gal. water) added t o each glass, rather than cooking with juice. Juice prepared by cooking pomace 2 hrs. with 0.5 02. acid for each lb. pomace.
.....
JUICE
Pectin, P y c e n t . , .59 Volum e, tial. . . . . . . . . 1. s 1.017 Specific Gravtty., , , 0.25 Acidity Per c e n t . . Sugar a'dded, f;bs ...... 5 Ibs. ~
. .. .... .....
--JUICE
!. ?5
1.0 1.5
............
A s t h e result of these tests special attention should be called t o t h e fact t h a t , regardless of t h e per cent .of pectin i n t h e juice used, t h e same amount of jelly was obtained. T h e amount of sugar which would produce t h e best quality of jelly for commercial industries was next determined. A series of tests was run with various amounts of sugar per gallon of apple juice of a 1.25 per cent pectin content. ANALYSISOF JUICE Specific G r a v i t y . . Acidity, Per cent.. Pectin, Per cent..
............ 1.021 . . . . . . . . . . . .0.43
.............
1.30
With this juice 2 , 3, 4, 5 , 6 , 7 , 8, 9, I O , and 1 1 lbs. of sugar were used for each gallon of juice. The jelly became more delicate and sweeter as t h e amount of sugar increased. T h e lot containing 5 lbs. of sugar per gallon of juice was selected as best i n texture for commercial use, b u t t h e lot containing 6 lbs. was considered best i n flavor. T h e 9 t o 1 1 lb. batches produced a fine, delicate jelly, which is more like homemade, b u t entirely too delicate for commercial use, a n d really too sweet t o be relished. Using as a base 1.25 per cent pectin with 5 lbs. of sugar per gallon, t h e following table which can be .applied t o a n apple juice has been worked o u t : SUGAR FOR APPLE JUICE-PECTINBASE Pectin Per cent
Sugar per Gallon of Apple Juice Oz. Lbs.
Pectin Per cent 1.25 1.30 1.40 1.50 1.60 1.70 1.80 1.90 2.00 2.50 3.00
Sugar per Gallon of Apple Juice Lbs. Oz. 5.0 i:2 5.0 5.0 9.6 6.0 6.0 6:4 6.0 12.8 7.0 3.2 7.0 9.6 8.0 10.0 12.0 ..
.. ..
Since these results have been obtained, there has also been found a relationship between t h e Brix hydrometer reading of juice made from apple pomace and t h e amount of sugar t o be added per gallon of juice. For every degree Brix, use a pound of sugar. For example, if t h e juice reads 5.6" Brix, use 5.6 Ibs. of sugar for every gallon. This will produce a fine, clear jelly, which is firm and will s t a n d up under
559
almost a n y climatic conditions. A more delicate jelly can be made by increasing t h e sugar t o 1 . 2 5 lbs. per every degree Brix. T h e greater t h e amount of sugar t h e greater t h e yield. QUANTITATIVE DETERhIINATION O F PECTIN
T h e only test for pectin in use a t present is t h e alcohol precipitation method where t h e pectin is precipitated with alcohol, dissolved i n water, evaporated t o dryness, dried, weighed, burned, and re-weighed, and t h e loss in weight expressed as pectin. Most methods call for a concentration of over 5 0 per cent alcohol in testing, b u t this is hardly sufficient as t h e sugars and other soluble substances are held in t h e concentrated mass of pectin precipitated. T h e author used I O cc. of filtered juice and ISO cc. of alcohol, adding t h e juice drop b y drop from a pipette, with vigorous stirring. It was filtered immediately, dissolved in boiling distilled water, evaporated t o dryness, heated 2 hrs. a t 70' C. in vaczto, weighed, ashed, and re-weighed. T h e loss i n weight multiplied by I O equaled t h e per cent of pectin. It was not necessary t o let t h e precipitate s t a n d a n y length-of time, as no further precipitate formed. T h e precipitate could be filtered through a Gooch crucible, thereby eliminating t h e dissolving and drying, often saving about 2 hrs. i n handling. A physical indication of t h e amount and quality of t h e pectin present in t h e juice may be obtained by observing t h e precipitation of t h e pectin as t h e juice is slowly run into t h e alcohol where t h e proportion of I O cc. of juice t o from 1 5 0 t o 180 cc. alcohol is used. When t h e pectin amounts t o over one per cent i t will gather i n a cohesive gummy mass, b u t if t h e amount is less, t h e precipitate is flocculent and will not gather in a solid mass. A little care i n observing this precipitation will give a rough b u t quick check on t h e juice t o be used. T h e results obtained b y using this quantitative method of determining pectin have been so concordant t h a t they have been successfully applied t o commercial jelly manufacturing, resulting i n a n increased production and a n improved product. B y t h u s controlling t h e manufacturing of jelly from a pectin standpoint i t is possible t o obtain a more uniform product t h a n t h e average jelly manufacturer secures. ACIDITY AND ACIDIMETRY OF SOILS. III-COMPARISON OF METHODS FOR DETERMINING LIME REQUIREMENTS OF SOILS WITH HYDROGEN ELECTRODE. IV-PROPOSED METHOD FOR DETERMINATION OF LIME REQUIREMENTS O F SOILS By Henry G . Knight OKLAHOMA AGRICULTURAL AND MECHANICAL COLLEGE,STILLWATER, OKLAHOMA Received October 14, 1919
P A R T I11
Through t h e courtesy of Mr. J. W. Ames of t h e Ohio Agricultural Experiment Station fifteen samples of soil were obtained from a number of variously treated plots from one of t h e fertility sections of t h e Wooster
