Lynne Wong's PhD thesis

Qin and White’s finding was confirmed in a later experiment with a stalk fibre sample,
when 10° Brix and 15° Brix sucrose solutions were used; the ratio of the contact solution
was varied from 14.0 to 25.6 (Table 4.15).
Table 4.15. Impact of ratio of contact solution to sample size on Brix-free water.
Sample Concentration of contact Ratio of contact Brix-free water/% Mean/%
sucrose solution/°Brix solution to sample
Stalk fibre 10 25.0 15.36 15.71
Stalk fibre 10 25.6 16.06
Stalk fibre 10 18.8 15.47 15.75
Stalk fibre 10 19.3 16.02
Stalk fibre 10 14.3 16.65 16.55
Stalk fibre 10 14.0 16.45
Stalk fibre 15 25.5 16.99 16.96
Stalk fibre 15 25.2 16.92
Stalk fibre 15 18.9 15.94 16.26
Stalk fibre 15 19.0 16.57
Stalk fibre 15 14.4 16.33 16.21
Stalk fibre 15 14.9 16.09
4.4.9 Contact time
The contact time was also checked, it appears that one and a half hours is sufficient to
reach equilibrium.
4.4.10 Sample fineness
According to Mangion and Player (1991), a sample in a finer state has a higher Brix-free
water value due to the increased surface area per unit mass. It was therefore decided to
reduce some fibre samples to a finer state (about 3 mm long) by using a pair of scissors,
and to carry out Brix-free water determinations before and after the operation. Results
obtained for duplicate analyses of 21 fibre samples are tabulated in Table 4.16. Statistical
analysis by the Student’s t-test showed that there was no significant difference (P = 0.89)
between the samples whether in their original or finer states. The standard error of the
mean for 21 data points is 0.547 for a mean of 12.82 on the original samples, and 0.500 for
a mean of 12.72 on finely cut samples. This shows that increased surface area does not
increase the Brix-free water value, contrary to the finding of Mangion and Player (1991).
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