62 BULLETIN 1370, U. S. DEPARTMENT OF AGRICULTURE 
addition of acids, prolonged heating during concentration of juice 
to sirup, or allowing the cane or juice to undergo slight fermentation, — 
impair either the flavor or the color of the sirup, or both. Addin 
acid to sirup made from mature cane imparts the objectionable ei 
uality characteristic of sirup made from green cane. None of 
cedure can not be used for a product which is to be sold as pure cane 
sirup. | 
The invertase process is the most satisfactory method for increasing 
the proportion of invert sugar in cane sirup in order to prevent 
crystallization. It may be used during the process of concentrating 
the juice to sirup, or it may be applied to the finished sirup at a | 
central receiving, canning, and marketing plant. 
Cane juice is sweet because it contains in solution cane sugar, | 
with some invert sugar. The proportion of cane sugar is usually 
much higher than the proportion of invert sugar, but equal weights 
of cane sugar and invert sugar have practically the same degree of | 
sweetness. Invert sugar is not a simple sugar, but a mixture of 
two sugars, dextrose and fructose, in equal proportion. It is widely 
distributed in nature, and is the principal constituent of honey. 
The production of honey by bees is a good example of the effect 
produced when the invertase process is used in manufacturing cane 
sirup. The sweet substance that the bees collect from plants and 
flowers consists essentially of sucrose, which is the chemical term for 
cane or beet sugar. Bees convert this sugar into invert sugar. The 
use of invertase in cane-sirup manufacture accomplishes the same 
transformation; it converts part of the cane sugar into invert sugar, 
which is just as sweet and wholesome as cane sugar but sugars or 
crystallizes much less readily. 
Invertase is chemically classified as an enzyme. As the cheapest 
and most available material from which to prepare it is yeast, the 
water extract of yeast, suitably prepared, is generally termed inver- 
tase. Invertase is a yellowish-brown liquid, with a rather peculiar 
but not disagreeable odor and taste. It is not a chemical, in the 
ordinary meaning of this term. Because of the extremely small 
proportion added to sirup, moreover, it can not be detected in the 
sirup by either odor or flavor. 
USE OF INVERTASE DURING MANUFACTURE OF SIRUP 
Atter skimming or clarifying the cane juice from the mill in the cus- | 
tomary manner, evaporation is continued until the density of the sirup, | 
when quickly tested while still very hot, corresponds to 20° Baumé 
(35.8° Brix), which is equivalent to approximately 24° Baumé (43.1° 
Brix) at ordinary temperature. Sirup at this stage is about two- 
thirds evaporated and is termed ‘‘semisirup.’”? Upon reaching this 
density, the semisirup is collected in a tank large enough to hold — 
the entire day’s output. When a continuous evaporator is used, © 
the flow of juice should be adjusted so that the required density © 
is obtained when the semisirup has reached the finishing end of the 
evaporator. The juice, therefore, must flow into the evaporator | 
faster than would be necessary in case it were evaporated to finished 
sirup 1n one operation. 
T 
‘he required quantity of invertase is now added to the semisirup. | 
As invertase is destroyed at fairly high temperatures, the semisirup | 
these methods of treatment can be recommended. Crystallization | 
may be prevented by mixing the sirup with glucose, but this pro- | 
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