T H E J O U R N A L O F I N D U S T R I A L AiVD E N G I N E E R I N G C H E M I S T R Y
THE COMPARATIVE VALUES OF SOME ESSENTIAL OILS AS PRESERVATIVES OF STARCH SYRUPS
co K C L U S I O KS I-Oils a r e named i n t h e following in t h e order of their value as preservatives: Fresh syrups: 0.011 per cent sassafras a p p a r e n t l y equal t o 0.011 per cent star-anise; 0.011 per cent cassia: 0 . 2 2 per cent ginger. Five-week old s y r u p s : 0.11 per cent lemon: 0.11 per cent star-anise; 0.11 per cent sassafras: 0.001per cent orange. Six-week old syrups: 0 . 2 2 per cent lemon: 0 . 0 2 2 orange. Six a n d one-half-month old syrups: 0 . 0 2 2 per cent cassia; 0 . 2 2 per cent sassafras (apparently equal t o 0 . 0 4 j per cent star-anise); 0 . 2 2 per cent lemon. a-Ginger is a poor preservative. Syrups containing this oil fermented a few months after t h e y were made. TABLEV-SASSAFRAS, STAR-ANISE. LEMOXA N D ORANGECOMPARED Specific Gravity of Syrups, 1.2563 a t 20° C. One Thirty-second of a Fleischmann's Yeast Cake in 1 Fluid Temperature of Incubator, 30-3 1 O C.
Per cent of oil
Per cent gas
....... ......
......
.....
........ .......
.
10 & 2 20 & 100
10 & 100 8- 23 & 5 8; 100
-
in days
Series 5a 8 mos old Per cent gas
80 & 100 32 & 40 None O & 43
Syrup
Sp. gr. 8 mos old Per cent gas
7 11 1,259
1/1
PEXNYROYAL COMPARED
Per cent of oil
Oil
Cassia.. . . . . 1.2568
/
12 4 8 12 i
11 5 7 5 i 4
c 0 sc L us10 N s I-That lemon as a preservative is superior t o s t a r anise a n d sassafras so far as t h e withstanding of t h e above fermentation test on t h e freshly mixed syrups is concerned. (See conclusion N o . I , Table I V a n d , also, t h e following conclusion No. 4) 2-That there is little difference between t h e preservative powers of star-anise a n d sassafras, t h e l a t t e r , however, appearing t o be a trifle t h e better. 3-That orange is inferior t o star-anise. sassafras a n d lemon as a preservative. 4-Syrups containing lemon resist fermentation much more when j u s t mixed t h a n t h e y do after t h e y have been k e p t for some time. As pointed o u t before, t h i s tendency of t h e old syrups containing oils t o l e r m e n t m a y be due t o a n increase in t h e fermentability of t h e syrups brought about b y inversion. PHILADELPHIA
AXD
of a Fleischmann's Yeast Cake in 5 0 Cc. of Syrup Temperature of Incubator, 32O C. Specific Gravity of Syrup, 1.243 a t 20' C. 1/16
Time Days
7
80 & 100 in 2 days
80 8: 100 111 & 1 20 & 30 8 & 10 85 & 100 55 & 60
USED--A measured a m o u n t of magic or Fleischmann's yeast was thoroughly mixed with a measured a m o u n t of s y r u p . Portions of t h e s y r u p mere t h e n p u t i n t w o fermentation t u b e s a n d kept i n a n incubator a t a constant temperature. T h e percentage of gas was noted once each d a y . Where only one percentage is s t a t e d in t h e following tables, t h e duplicate t u b e contained t h e s a m e a m o u n t of gas. T h e kind a n d a m o u n t s of yeast a n d s y r u p a n d t h e temperature are s t a t e d i n each table. T H E O I L S USED-The essential oils, purchased from t h e most reputable firms, were analyzed by us a n d found t o be pure. T H E S Y R U P S u s E D - T h e oils were mixed with g j per cent alcohol-one volume of oil t o g of t h e alcohol. T h e oils i n this form were t h e n thoroughly mixed with t h e s y r u p in t h e proportions desired. K a r o Corn Syrup" &'as used, all tests being made on syrups from t h e s a m e can.
/
12 4 7 11 None in 10 days
10
Received October 17, 1913
THE FERMEXTATION TEST
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