Studies on starch isolated from potato subjected to various storage conditions
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Date
2017
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CCSHAU
Abstract
The present study was carried to find out the physiochemical and functional properties of starch isolated
from potatoes by various extraction methods, from different varieties and after subjecting the tubers to various
postharvest and storage conditions. The fresh potato tubers of variety Kufri Bahar were used for extraction of
starch by various extraction methods viz., T1= Control (Ambient Water-30°C), T2 = Cold Water-10°C, T3 = Hot Water-
60°C, T4 = NaOH-0.1%, T5 = NaOH-0.25%, T6 = SDS-ME-1%, T7 = SDS-ME-2%, T8 = Propanol-water (3:1 w/v), T9 =
Na-bisulphite-0.1%, T10 = Na-bisulphite-1.7%, T11 = Na-hypochlorite (5.25%), T12 = Protease (0.01%), T13 = Cellulase
(0.15%) and T14 = Combined treatment (T5 + T7 + T11 + T13). The starch extracted by various methods was analysed for
different physiochemical and functional characteristics and T14 (Combined treatment) was found to be the best method,
showing significantly higher starch yield, WAC, starch purity, swelling power, solubility, light transmittance,
whiteness, trough viscosity and final viscosity; and lower amylose, phosphorus, moisture, protein, fat, ash, crude
fiber, syneresis, peak viscosity, breakdown viscosity and setback viscosity than control.
The combined method was used for extraction of starch from the fresh as well as cured potatoes of white
flesh varieties (Kufri Chipsona-4, Kufri Badshah, Kufri Pushkar, Kufri Bahar) and pink flesh variety (Kufri
Sindhuri). The starch extracted from these varieties was also analysed for starch yield, various physiochemical and
functional characteristics. Among the various varieties of potato, Kufri Chipsona-4 showed higher starch yield, water
absorption capacity, swelling power, solubility, light transmittance and peak viscosity. For all the varieties, curing
resulted in lower starch yield, amylose content, swelling power, solubility and starch whiteness value; higher
amylopectin, phosphorus content, WAC, light transmittance and peak viscosity; and non-significant changes in starch
moisture, protein, fat, crude fiber, ash content and purity.
The cured tubers of variety Kufri Chipsona-4 were subjected to sprout inhibiting treatments viz., hot
water dip treatment (57.5±0.1oC for 20 min) and isopropyl N-(3 chlorophenyl) carbamate (CIPC) treatment. The treated
potato tubers were packed either in nylon mesh bags or MAP or vacuum packaging and stored either at room temperature
(RT) (32±2oC; RH ~90%) or low temperature (LT) (12±1oC) conditions. It was observed that there was a progressive
increase in sprouting, PLW, decay loss and shriveling of potato tubers during storage, magnitude being higher at room
temperature (RT) than low temperature (LT) conditions. With increasing storage period of tubers, both at RT and LT
conditions, the extracted starch’s moisture content, fat, ash, crude fiber, amylopectin, phosphorus content, water
absorption capacity, light transmittance and peak viscosity of stored potatoes increased; while yield, purity, amylose,
swelling power, solubility, syneresis and colour whiteness value decreased. At LT storage conditions, CIPC was more
effective sprout inhibiting treatment than HWT. The effect of various sprout inhibiting treatments was found to be nonsignificant
on starch’s moisture content, protein content, fat content, crude fiber, ash content, purity, WAC and colour
whiteness values; while higher yield, amylopectin, phosphorus content, swelling power, solubility, light transmittance
and peak viscosity were observed in starch extracted from CIPC than hot water treated tubers stored at LT. The various
packaging methods did not significantly affect the moisture, fat, protein, ash, crude fiber, purity, amylose, amylopectin,
WAC, swelling power and starch whiteness values of the starch extracted from tubers stored at LT.
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