Lynne Wong's PhD thesis

Since the extrapolated purity of molasses (M) and the purities of mixed juice (J) and sugar
(S) were known, the SJM formula of Deerr (1921) could be used to predict the portion of
the sucrose in the original material that goes to the sugar produced, after deduction of
sucrose losses in filter cake and undetermined losses. The latter is the unaccounted sucrose
loss when sucrose is extracted from cane after taking into account the sucrose losses in
bagasse, in filter cake and in molasses.
The SJM formula states that given a juice (or initial material, e.g. syrup or massecuite) of J
purity and producing a sugar of S purity with a molasses of M purity, the percentage of the
total sucrose (or pol) in the original material to go into the sugar will be
100S(J-M)/[J(S-M)]. The formula predicts the portion of the sucrose (or pol) in the
original material that goes to the sugar produced, and the remainder goes to the molasses.
No losses of any kind are taken into account in this formula.
In this experiment, sucrose losses in filter cake and undetermined losses were unknown,
and they were assumed to be 0.08 and 0.13% cane, respectively. These were the 1998
island average (Anon., 1999). When these values are compared to the 2004 values (Anon.,
2005a) of 0.08 and 0.08% cane, respectively, it can be seen that they have remained more
or less constant.
The experiment also enabled the estimation of mill extraction (or more appropriately, press
extraction, in the context in which the experiment was carried out); sucrose losses in
bagasse and in molasses, boiling house recovery and overall recovery. Mill extraction is
defined as the percent mass of pol originally present in the cane that has been extracted
into the mixed juice. Boiling house recovery is the percentage of the pol in mixed juice
that passes into the sugar produced. The product of mill extraction and boiling house
recovery is known as overall recovery.
2.1.1 Materials
For each trial of EM addition to clean cane, about 2 kg each of dry leaves, green leaves and
cane tops, and about 20 kg of cane stalks were obtained from a neighbouring sugar factory.
The cane stalks were cleaned of dry leaves, green leaves and cane tops.
1.3.1 Mercuric iodide juice preservative
This is prepared by dissolving 500 g of red mercuric iodide in a saturated aqueous solution
of potassium iodide and made up to a total volume of 1 L. The potassium iodide solution
30