36
(4) For measuring liquid sample
containing insoluble solids
(Simultaneous analysis of
insoluble solids, sugar and
water)
When solution containing insoluble
solids is measured for Refractive Index,
only the Refractive Index of the
solution except the insoluble
ࠉ
solids is
measured. For example, assume that
sweetened and jellied bean paste is
measured and the refractometer reads
Brix70% for it. If the sample of the
sweetened and jellied bean paste
contains bean jam at a rate of 20% in
weight, the Brix value of the whole
sample is regarded as 56%. Explaining
in detail, if weight of the sweetened
and jellied bean paste is 100g, the
weight of insoluble ingredient(s) is 20g,
weight of sugar is 56g and that of
water is 24g. The total weight of the
solution
excluding
the
insoluble
ingredients is 80g, which includes 56g
of
sugar
besides
24g of water.
Therefore, the refractometer reads the
sugar content of solution as Brix70%.
As the above example suggests,
samples containing much insoluble
ingredients require the most careful
attention to the measured values.
Simultaneous analysis of solids, sugar
and water contained in bean jam.
a)
b)
c)
11. Matters that require attention to Abbe Refractometer
c)-1
c)-2
c)-3
Directly measure a sample of bean jam
for Brix(%) and note the measured
value as "A".
Mash and knead the bean jam well, and
dissolve it in water of the same weight
well. Measure this solution for Brix(%)
and note down the measured value as
"B".
With known "A" and "B" calculate the
weight percent of insoluble solids, sugar
and water respectively according to the
following equations.
ە
Weight percent of insoluble
solids:
ە
Weight percent of sugar:
ە
Weight percent of water:
100 (1
㸫ࠉࠉࠉࠉ
)
㸣
B
A
㸫
B
AB
A
㸫
B
㸣
B(100
㸫
A)
A
㸫
B
㸣
