Abstract:
Studies were conducted at Regional Agricultural Research Station,
Pattambi and the College of Horticulture, Vellanikkara to analyse the
quantitative and qualitative changes during development and storage of coleus
tubers. During the development the total fresh biomass of the plant increased up
to 90 days after transplanting in all the varieties. The absolute growth rate was
highest between 75-90 days after transplanting. The leaf fresh biomass
increased up to 60 OAT in all the varieties and at this stage more than 50 per
cent of dry matter was present the leaves. The stem fresh biomass of stem
increased up to 120 OAT, the fresh biomass of root also increased up to 120
DA T and the rate of accumulation of root dry matter was high up to 120 OAT.
The fresh biomass of tuber and dry matter accumulation showed an increasing
trend along with maturity of tubers. The higher growth rate was between 135-
150 OAT stages. Total number of tubers, length, diameter, peel thickness and
peel percentage were found to increase with maturity of tubers. The peel colour
changed from yellowish brown to brown and the flesh colour changed from
yellowish cream to whitish cream during maturation.
The starch and polyphenol content increased with the maturity of tubers,
where as the soluble sugar increased up to 135 OAT and thereafter declined.
The nematode infested tubers showed higher sugar and polyphenol content and
lower starch content compared to non-infested one. The sensory evaluation
indicated that the overall acceptability, increased with the advancement of
maturity.
Storage behaviour of coleus tuber was assessed under different
conditions of storage. Sprouting and physiological loss in weight was lowest
under the zero energy cool chamber storage. Room temperature and pit storage
were rated next to zero energy cool chamber. The spoilage was minimum in
tubers stored under room temperature followed by zero energy cool chamber.
The starch content of tubers decreased and sugar content increased in storage.
No definite pattern was indicated in the polyphenol content during storage.
Tubers turned dark brown under low temperature storage conditions. The tubers
stored under zero energy cool chamber showed better sensory characters.
Peeled tubers could be stored for two days with minimum spoilage at 8-10°C.
Hot air oven dried product had a higher rehydration ratio and better sensory
quality compared to sun dried one.
