STUDIES ON POST-HARVEST INVERSION OF SUCROSE IN DIFFERENT VARIETIES OF SUGARCANE (Saccharum officinarum L
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Date
2001
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MPKV, UNIVERSITY LIBRARY RAHURI
Abstract
The relative susceptibility / resistance to post harvest
inversion varies significantly among varieties due to genetic variability.
The rate of moisture loss differs due to differing protection offered
against evaporation by the stem characteristics of genotypes. Therefore,
eight released and two promising varieties of sugarcane developed at the
Central Sugarcane Research Station, Padegaon were evaluated for their
relative performance to post harvest inversion The matured canes of
these varieties were kept for storage/ staling for ten days under field
conditions during the month of November (Average maximum
temperature 31.1 °C and average minimum temperature 16.3 °C,
average morning RH 92.2 % and average evening RH 45.1 %). The
post harvest deterioration was mainly assessed on the basis of loss of
cane weight, sucrose, purity, CCS and increase in reducing sugars.
The loss in cane weight (%) increased gradually with lapse
of time. Variety Co-86032 suffered a maximum loss in cane weight
(21.27 %) while the variety CoM-7125 showed a minimum loss in cane
weight (11.68 %) after 240 h of staling. The purity of the juice (which
denotes percentage ratio of sucrose to total soluble solids) decreased
significantly after 72 h. The decrease in purity was maximum in variety
Co-92020 (39.38 %) and minimum in variety CoM-7125 (15.18 %)
Enzymatic inversion which continues even after harvest caused
reduction in sucrose per cent with concomitant increase in the level of
reducing sugars. Reducing sugars in juice being important parameter
for determining the extent of deterioration of stale cane was estimated
by both Fehling and Nelson methods. Significant varietal variation was
noticed. A maximum reduction in sucrose (23.03 %) was recorded in
cultivar Co-92020 with 17 fold increase in the level of reducing sugar
content. Variety CoM-7125 and Co-86032 suffered a minimum sucrose
loss of 7 per cent with increase in the level of reducing sugars by 2.16
fold and 4.16 fold respectively. In general, it appeared that, varieties
CoM-7125, Co-7527 and Co-7219 were relatively tolerant to post
harvest inversion. Variety Co-86032 and CoC-671 which are widely
cultivated were moderately tolerant, whereas varieties Co-92020, CoM88121
andMS-92121 are relatively susceptible.
Juice analysis of top, middle and bottom portion of canes of
Co-92020 (susceptible) and CoM-7125 (resistant) along with Co-86032
at an interval of 6 hours revealed significant differences. The ratio of
sucrose (bottom / top) was more (1.96) in CoM-7125 and less (1.24) in
Co-92020. In Co-92020 the ratio of reducing sugars (top / bottom) was
6.95 as against 2.44 in CoM-7125. The analysis of juice for invertase
activity revealed difference. Activity of both acid and neutral invertases
increased with time of staling and the Acid/ Neutral invertase activity
ratio was more in Co-92020 and less in CoM-7125.
It is suggested that beside losses in cane weight, purity and
increase in reducing sugar content, the ratio of reducing sugars (top /
bottom) and ratio of sucrose (bottom/ top) along with A/N ratio should
be determined for assessing the relative performance of genotypes for
post harvest inversion.
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