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Parvathy P.C.,Central Tuber Crops Research Institute Sreekariyam | Jyothi A.N.,Central Tuber Crops Research Institute Sreekariyam
Starch/Staerke | Year: 2012

Superabsorbent polymers (SAPs) were prepared from cassava starch by graft copolymerization of acrylamide on to starch using ceric ammonium nitrate (CAN) as free radical initiator, followed by alkali saponification. The reaction parameters such as concentration of acrylamide, concentration of CAN, temperature, and duration of polymerization reaction were optimized for maximum water absorbency using a 4-factor 3-level Box-Behnken design. The highest values of percentage grafting and absorbency obtained were 174.8% and 425.2 g/g, respectively. The polymers were characterized by determination of grafting efficiency, N-content, acrylamide content, FTIR analysis, SEM and XRD analyses. Thermogravimetric analysis (TG) showed that the SAP has higher thermal stability. The rate of water absorbency and the swelling behaviour of the SAP under different conditions of pH, and different salts were determined. The de-swelling pattern of the hydrogels over different time durations was also determined. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Kumar S.N.,Central Tuber Crops Research Institute Sreekariyam | Nambisan B.,Central Tuber Crops Research Institute Sreekariyam
Applied Biochemistry and Biotechnology | Year: 2014

The present study aimed to investigate antifungal activity of a stilbene and diketopiperazine compounds against plant pathogenic fungi, including Phytophthora capsici, P. colocasiae, Botrytis cinerea and Colletotrichum gloeosporioides. Minimal inhibition concentrations (MIC) and minimal fungicidal concentrations (MFC) of stilbenes and diketopiperazines for each fungus were determined using microplate method. Best activity was recorded by stilbenes against P. capsici and P. colocasiae. All four test compounds were effective in inhibiting different stages of the life cycle of test fungi. Stilbenes were more effective than diketopiperazines in inhibiting mycelial growth and inhibiting different stages of the life cycle of P. capsici and P. colocasiae. Rupture of released zoospores induced by stilbenes was reduced by addition of 100 mM glucose. The effects of stilbenes on mycelial growth and zoospore release, but not zoospore rupture, were reduced largely when pH value was above 7. In addition, stilbenes were investigated for its antifungal stability against Phytophthora sp. The results showed that stilbenes maintained strong fungistatic activity over a wide pH range (pH 4-9) and temperature range (70-120 C). The compound stilbenes exhibited strong and stable broad-spectrum antifungal activity, and had a significant fungicidal effect on fungal cells. Results from prebiocontrol evaluations performed to date are probably useful in the search for alternative approaches to controlling serious plant pathogens. © 2013 Springer Science+Business Media New York.

Angel G.R.,Central Tuber Crops Research Institute Sreekariyam | Vimala B.,Central Tuber Crops Research Institute Sreekariyam | Nambisan B.,Central Tuber Crops Research Institute Sreekariyam
International Journal of Pharmacognosy and Phytochemical Research | Year: 2012

Rhizomes and leaves of five underutilized Curcuma species viz. C. aeruginosa, C. brog, C. malabarica, C. rakthakanta and C. sylvatica were evaluated for total phenolic content, flavonoids and antioxidant activity. The total phenols in methanolic extracts of rhizomes ranged from 210 to 700 mg gallic acid equivalents/100g and in leaves from 840 to 1480 mg/100g. Flavonoid content in leaves ranged from 270 to 380 mg epicatechin equivalents/100 g dw. The leaves of all species had higher content of phenolics, DPPH radical scavenging activity and ferric reducing power as compared to rhizomes. There was good correlation between the phenol content and antioxidant activity in rhizomes, but not in leaves. The results of the study highlighted the potential of these unutilized Curcuma species (rhizomes and leaves) as a rich source of antioxidants for food and health.

Jyothi A.N.,Central Tuber Crops Research Institute Sreekariyam | Sajeev M.S.,Central Tuber Crops Research Institute Sreekariyam | Sreekumar J.,Central Tuber Crops Research Institute Sreekariyam
Starch/Staerke | Year: 2011

Cassava, sweet potato and arrowroot starches were hydrothermally modified by ANN under different conditions of temperature, moisture and time duration of treatment and the properties are compared. ANN brought about changes in swelling volume, solubility, gelatinization and rheological properties. The three starches behaved differently after the treatment. All the three tuber starches showed decrease in swelling volume after ANN treatment. The solubility decreased for cassava starch, whereas it slightly increased for majority of annealed sweet potato starches and significantly increased for arrowroot starch. For cassava starch, there was a decrease in peak viscosity, but for the other two starches, it increased after ANN. Differential scanning calorimetric studies showed that ANN resulted in a narrowing of DSC patterns for all the starches. The effect of ANN on the dynamic rheological properties was found to depend up on the source of starch. The modification resulted in increased gel hardness, gumminess, adhesiveness and decreased springiness for the starch gels. Tuber starches became less susceptible to enzyme action after ANN. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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