Showing papers by "Central Tuber Crops Research Institute published in 2008"

Biocontrol Efficacy of Bacillus subtilis Strains Isolated from Cow Dung Against Postharvest Yam (Dioscorea rotundata L.) Pathogens

Abstract: The biocontrol potential of Bacillus subtilis isolated from cow dung microflora was investigated in vitro and in vivo against two postharvest yam pathogenic fungi, Fusarium oxysporum and Botryodiplodia theobromae. B. subtilis strains inhibited the growth of F. oxysporum and B. theobromae in vitro in liquid medium in the range of 49.3-56.6% and in solid medium in the range of 31.0-36.0%, in comparison to the corresponding growth of fungi without bacterial inoculation. The interaction between B. subtilis CM1 and F. oxysporum was also studied by scanning electron microscopy. Chitinase production was demonstrated in vitro when B. subtilis was grown in the presence of colloidal chitin as the sole carbon source in a liquid medium. In vivo study showed that B. subtilis strains inhibited the growth of fungi (F. oxysporum and B. thobromae) up to 83% in wound cavities of yam tubers.

Statistical optimization of alpha-amylase production by Streptomyces erumpens MTCC 7317 cells in calcium alginate beads using response surface methodology

Abstract: " -Amylase has a wide range of applications in starch industries, i.e. baking, brewing, distillery, etc. The "-amylase production from Streptomyces erumpens MTCC 7317 immobilized cells was compared with that of free cells. The immobilized cells of S. erumpens in calcium alginate beads were more effective for production of "-amylase (12.2% more yield) than free cells. Response surface methodology (RSM) was used to evaluate the effect of main variables, i.e. incubation period, pH and temperature on enzyme production with immobilized cells. A full factorial Central Composite Design (CCD) was applied to study these main factors that affected "-amylase production. The experimental results showed that the optimum incubation period, pH and temperature were 36 h, 6.0 and 50∞C, respectively for immobilized cells. Repeated batch fermentation of immobilized cells in shake flasks carried out in starch-beef extract medium showed that S. erumpens cells were physiologically active on the support even after four cycles of fermentation.

Chlorophyll meter and leaf colour chart to estimate chlorophyll content, leaf colour, and yield of cassava

Abstract: A field experiment was conducted with two cassava cultivars and eight levels of nitrogen to examine the relationship between extractable chlorophyll (Chl) content of cassava leaves and both the Chl meter value (SPAD) and leaf colour chart (LCC) score. The SPAD, LCC, and Chl a+b content were influenced by leaf position, growth stage, cultivar (cv.), and N fertilization. The cvs. and N fertilization had significant effect on SPAD, LCC, and Chl a+b content of youngest fully expanded leaf (leaf 1) blade in most cases. An F-test indicated that common equations pooled across cvs., N fertilization, and growth stages could be used to describe the relationships between Chl a+b content and LCC and between SPAD and LCC, but not between SPAD and Chl a+b content. Relationships between tuber yield and SPAD, LCC, and Chl a+b content were significant (p<0.05) and positive at 30 and 60 d after planting. Thus LCC and SPAD can be used to estimate leaf Chl content which is an indicator of leaf N status.

Solid substrate fermentation of cassava fibrous residue for production of alpha-amylase, lactic acid and ethanol

Abstract: There is serious concern about the disposal of solid residues left after large scale extraction of starch from cassava Owing to the high starch content (55-65% on dry weight basis) and organic matter of these wastes, an attempt has been made to utilize it for the production of three bioproducts, ie alpha-amylase, lactic acid and ethanol in solid substrate fermentation by incubating the solid residue at different moisture holding capacity (40-80%) and incubation period (12- 60 hr for alpha-amylase, 24-144 hr for ethanol and 2-10 days for lactic acid) The highest product yield was obtained at 60% moisture holding capacity of the residue and period of incubation varied from 36 hr (alpha-amylase), 120 hr (ethanol) to 6 days (lactic acid) This study showed that the solid residues from cassava starch factories could serve as a low-cost substrate for bioproducts production

Inhibitory effect of an extract of Curcuma zedoariae on human cervical carcinoma cells

Abstract: Herbal medicine has formed the basis of health care throughout the world since the dawn of civilization. Each plant is a unique chemical factory capable of synthesizing unlimited numbers of highly complex and unusual chemical substances whose structures could otherwise escape the imagination forever. Phytomedicines have been used as a treatment for many diseases, ranging from skin disease to cancer. Most of the anticancer drugs that we use today are derived from plants. The anticancer effect of plants is due to specific phytochemicals or the complex synergistic interactions among their various constituents. The aim of the present study was to evaluate the cytotoxic properties of an extract of the Curucuma zedoariae rhizome, a plant belonging to the family Zingeberaceae, and to determine its IC50 value. Various organic extracts were isolated using Soxhlet apparatus in order of increasing solvent polarity, namely petroleum ether, ethyl acetate, acetone, and methanol. Colorimetric [3-(4,5-Dimethylthiazol-2-yl)-2,5 diphenyltetrazolium bromide] assay (MTT assay) was done to determine the cytotoxicity against human cervical carcinoma cells (He La). Acridine orange–ethidium dromide dual staining and DNA fragmentation assays were done to detect apoptotic features. Among the various extracts studied, the petroleum ether extract was found to exhibit maximum cytotoxicity against He La cells. Our results suggest that the petroleum ether extract of the Curucuma zedoariae rhizome may have potential as an anticancer agent. Further steps have to be done to purify the compound and to elucidate the antitumor activity of the extract.

Collection of plant genetic resources from Andaman and Nicobar Islands

Abstract: The Andaman and Nicobar (A&N) group of islands is immensely rich in plant biodiversity. Andaman’s native tribes are hunter-gatherers, sustaining on wild or marine food and practically do not have any cultivation. Diversity in cultivated crops is presently maintained in home gardens by settlers from the mainland and other adjoining countries. The National Bureau of Plant Genetic Resources (NBPGR) through explorations either alone or in association with CARI or with other ICAR institutes has collected 1234 accessions in 48 exploration and collection missions. Variability was collected in rice, cowpea, black gram, green gram, okra, Chinese spinach, ash gourd, taro, cucumber, pumpkin, bottle gourd, ridge gourd, bitter gourd, chilli, greater yam and coconut. Indigenous landraces are absent. The in situ conservation of the wild relatives of crops is well taken care of by a large number of protected forest reserves.

Pre-treatment effect on the nutritional and functional properties of selected cassava-based composite flours

Abstract: The low protein and lack of gluten in cassava ( Manihot esculenta Crantz) are disadvantageous for its use for product development and is overcome through the use of composite flours incorporating cereal and/or legume flours. The functionality and nutritional attributes of cassava flour were altered in the present study by pre-treatment with termamyl and green gram amylase, pre-gelatinization and subsequent blending with cereals, legumes, bran sources etc. Malting of cassava flour with termamyl followed by pre-gelatinization reduced the starch and increased the sugar content of the mixes. Pre-gelatinization had little effect on the crude protein of the mixes; nevertheless, the fat content was higher by 0.15–1.0 units. Energy content was around 1176 and 1217 KJ/100 g for the rice bran added mixes from malted cassava, which slightly increased in the respective pre-gelatinized cassava mixes. The peak viscosity of termamyl treated cassava-based flour mixes was much lower than the respective gram amylase based mixes, indicating that the latter had much less amylolytic activity than termamyl and pre-gelatinization further reduced the viscosity. The very low viscosity for the enzyme treated cassava-based mixes was due to the inability for retrogradation of the hydrolyzed starch. Significant improvement in in vitro starch digestibility (IVSD) (enhancement by 5.0–16.0 units in termamyl treatment vs 5.0–9.0 units in gram amylase treatment) was observed for the pre-gelatinized mixes. Lowest IVSD (25–29 units) was for the two bran based mixes, suggesting its use in the nutrition therapy for controlling obesity linked diseases. Industrial relevance With the development in human society, the incidence of chronic diseases like diabetes, cancer, cardiovascular problems and conditions like obesity contributing to several diseases is on the increase. This has led to an increasing awareness and research efforts on the development of functional foods, pharmafoods etc, which have wide potential application in medical nutrition therapy. The present work aims at improving the nutritional and functional attributes of cassava through fortification with cereal and/ or legume flours, bran sources etc. and through pre- treatment with enzymes to improve the functionality and reduce the energy content. The study led to the development of cassava based composite flours with low starch digestibility, high protein content and low energy content which could be effectively utilized for developing designer foods for obese and diabetic people. Enhanced digestibility of pre- gelatinized malted flours from cassava finds potential application for the development of foods for geriatric and convalescent people.

Evaluation of orange-fleshed sweet potato (Ipomoea batatas L.) genotypes for salt tolerance through shoot apex culture under in vitro NaCl mediated salinity stress conditions

Abstract: Fifteen genotypes of sweet potato were evaluated for salinity stress tolerance under in vitro NaCl mediated salinity stress conditions (MS, MS + 0.5% and MS + 1.0% NaCl). The growth parameters such as number of leaves, number of shoots, number of roots, length of plantlets and length of roots decreased significantly among the genotypes with increase in level of salinity. Of the 15 genotypes tested, six genotypes (108X1, 90/606, 90/696, CIP 8, S-30X15 and SP-61) were unable to sprout even at 0.5% NaCl and were characterized as susceptible to salt stress, three genotypes (CIP 6, 90/774 and CIP 3) which could tolerate 0.5% NaCl as moderately tolerant and six genotypes (CIP 12, CIP 13, JO 14, JP 13, SB-198/115 and Gouri) as tolerant to salinity at 1.0% NaCl. Amongst the six genotypes showing tolerance to 1.0% NaCl, the exotic genotypes––JP 13, CIP 12 and indigenous one SB-198/115 continued to exhibit significant higher values for growth parameters over the susceptible one. Based on the performance under NaCl mediated salinity stress (1.0%), the pattern of salinity tolerance in the genotypes through shoot apex culture was JP 13 > SB-198/115 > JO 14 > Gouri > CIP 12 > CIP 13. The effect of salt stress on the activity of antioxidative enzymes was studied in leaves of 8-week-old plantlets of those six genotypes, which responded at higher NaCl stress along with a susceptible genotype 90/606. In leaves of salt stressed plants, superoxide dismutase (SOD), guaiacol peroxidase (GPX) and catalase (CAT) activities increased when compared with the stress free control. The increase was more pronounced in the tolerant genotypes than that in the susceptible one. These results indicate that oxidative stress may play an important role in salt stressed sweet potato plants and that the greater protection of tolerant plants from salt induced oxidative damage results, at least in part, through the increase in the activity of antioxidant enzymes.

The genetic structure of taro: a comparison of RAPD and isozyme markers

Abstract: Germplasm characterization and evolutionary process in viable populations are important links between the conservation and utilization of plant genetic resources. Here, an investigation is made, based on molecular and biochemical techniques for assessing and exploiting the genetic variability in germplasm characterization of taro, which would be useful in plant breeding and ex situ conservation of taro plant genetic resources. Geographical differentiation and phylogenetic relationships of Indian taro, Colocasia esculenta (L.) Schott, were analyzed by random amplified polymorphic DNA (RAPD) and isozyme of seven enzyme systems with specific reference to the Muktakeshi accession, which has been to be proved resistant to taro leaf blight caused by P. colocasiae. The significant differentiations in Indian taro cultivars were clearly demonstrated by RAPD and isozyme analysis. RAPD markers showed higher values for genetic differentiation among taro cultivars and lower coefficient of variation than those obtained from isozymes. Genetic differentiation was evident in the taro accessions collected from different regions of India. It appears that when taro cultivation was introduced to a new area, only a small fraction of genetic variability in heterogeneous taro populations was transferred, possibly causing random differentiation among locally adapted taro populations. The selected primers will be useful for future genetic analysis and provide taro breeders with a genetic basis for selection of parents for crop improvement. Polymorphic markers identified in the DNA fingerprinting study will be useful for screening a segregating population, which is being generated in our laboratory aimed at developing a taro genetic linkage map.

Extracellular α-Amylase Production by Bacillus brevis MTCC 7521

Abstract: Alpha amylases have various applications in food processing industries, for example, baking, brewing and distillery industries. Studies of the Ca2+ independent α-amylase production were carried out by a strain of Bacillus brevis MTCC 7521 isolated from a brick kiln soil. The optimum temperature, pH and incubation period for amylase production were 50°C, 6.0 and 36 h, respectively. The enzyme secretion was at par in the presence of any of the carbon sources (soluble starch, cassava starch and cassava flour). B. brevis produced more amylase in presence of beef extract as nitrogen source in comparison to other organic nitrogen sources (peptone, yeast extract and casein) and asparagine, potassium nitrate, ammonium sulphate, ammonium nitrate and urea reduced the enzyme activity. The addition of Ca2+ (10–40 mM) or surfactants (Tween 20, Tween 40, Tween 60, Tween 80, and sodium lauryl sulphate at 0.02% concentration) in culture medium did not result in further improvement in the enzyme production. The purified e...

Influence of fly ash mixtures on early tree growth and physicochemical properties of soil in semi-arid tropical Alfisols

Abstract: The beneficial effects of planting mixtures comprising of fly ash at the rate of 66%, 33% and 17% by soil volume were assessed for the early growth of two economic tree species, teak (Tectona grandis) and leucaena (Leucaena leucocephala) in rainfed Semi-Arid Tropical (SAT) Alfisols in India. Measurements of tree growth were made at six monthly intervals over a 3-year period. Fly ash at 66% by soil volume of the planting pit significantly increased the diameter of teak at breast height (dbh). In leucaena, application of fly ash at 17% by soil volume was found to be effective in increasing dbh during most of the study period. Changes in soil physicochemical properties (bulk density, water retention at 0.033 and 1.5 MPa, profile moisture content, pH, soluble salt content and organic carbon) were simultaneously studied. Among these soil properties, plant available water (PAW) and organic carbon (OC) contents explained variations in diameter at breast height (dbh) in teak during most of the sampling period, while none of the soil properties significantly explained dbh in leucaena. The highest dose of fly ash applied (66% by volume) decreased bulk density (BD) and increased PAW in teak and to an extent in leucaena during the first 2 years of tree growth. Higher profile moisture content was noted in pits treated with 66% fly ash during the dry period of November (after the end of seasonal rainfall which occurred from June to October) during the first and second year after application.

Alpha-amylase production by Streptomyces erumpens MTCC 7317 in solid state fermentation using response surface methodology (RSM).

Abstract: Production of AE-amylase under solid state fermentation by Streptomyces erumpens MTCC 7317 has been investigated using different agroindustrial residues, i.e. cassava bagasse, sugarcane bagasse and wheat bran; wheat bran was found to be the best substrate. Among different nitrogen source supplemented to wheat bran, beef extract or peptone (1%) showed maximum enzyme production. Response surface methodology was used to evaluate the effect of main process parameters as incubation period (48 h), moisture holding capacity (70%), pH (7.0) and temperature (50∞C) on enzyme production by applying a full factorial central composite design. The maximum hydrolysis of soluble starch (90%) and cassava starch (75%) was obtained with the application of 4 ml (~12096 U) of S. erumpens crude enzyme after 5 h of incubation.

Statistical optimization of alpha-amylase production by probiotic Lactobacillus plantarum MTCC 1407 in submerged fermentation.

Abstract: Production and purification of "-amylase by probiotic Lactobacillus plantarum MTCC 1407 has been investigated under submerged fermentation using Mann Rogassa Sharpe medium containing (1%) soluble starch in lieu of glucose (2%) as carbon source. Response Surface Methodology was used to evaluate the effect of main variables, i.e. incubation period, pH and temperature on enzyme production. A full factorial Central Composite Design was applied to study these main factors that affected "-amylase production. The experimental results showed that the optimum incubation period, pH and temperature were 36 h, 7.0 and 35∞C, respectively. The purified enzyme (by ammonium sulphate precipitation) had a molecular mass of 75 450 Da in SDS-PAGE.

Effect of benzyl amino purine on the pathogen growth and disease development of taro leaf blight caused by phytophthora colocasiae

Abstract: SUMMARY Cytokinins are implicated in a wide variety of developmental and physiological processes in plants including host-pathogen interactions. The effect of cytokinin benzyl amino purine (BAP) on Phytophthora colocasiae mycelium growth was investigated in vitro and in planta. BAP inhibited the growth of P. colocasiae under in vitro conditions and a corresponding decrease in endo b-1,3 glucanase (EBG) activity was observed in a dose-dependent manner. The BAP mediated inhibitory effect of P. colocasiae mycelium growth was overcome by supplying the media with an external source of EBG. Results also showed that BAP has inhibitory effect on disease development in taro leading to a reduction in disease severity which correlated with increasing BAP concentrations. It is concluded that the use of BAP could be an important strategy in the control of taro leaf blight.

Influence of Lipids Isolated from Soybean Seed on Different Properties of Cassava Starch

Abstract: The effect of lipids isolated from soybean seeds on the properties of cassava starch was investigated. Both polar and non-polar lipid fractions were complexed with starch and the physicochemical and rheological properties were examined. The FTIR spectra of the complexed starches showed all the absorption bands characteristic of native starch with an extra minor peak at 2355 cm -1 . The complexes prepared using the polar lipid fraction in diethyl ether as solvent exhibited a swelling volume of 32.5 mUg compared to 36.9 mL/g for petroleum ether as solvent. A similar effect was observed with the non-polar fraction. The apparent amylose content of the complexes was found to be lowered as a result of complexation. Total and soluble amylose contents and water-binding capacity of the complexes were higher while their enzyme digestibility was noticeably lowered. The peak viscosity of the complexes was suppressed as a result of complexation. The polar layer exhibited a greater influence on the viscometric properties of the complexes with a higher breakdown ratio and hence higher stability. When compared to native starch, the percentage light transmittance of the complexes was noticeably reduced. The results indicate a considerable influence of the isolated lipid fractions on starch properties which can be useful in food and industrial applications.

Rheological characteristics of different tropical root starches

Abstract: The rheological properties of starch extracted from ten different species of tropical tuber crops were examined using a Bohlin rheometer. Suspensions with starch concentrations of 3, 4 and 5% were gelatinised at 757C and fed into the rheometer cup. A C 25 measuring system was used and the heating rate was 1.57C/min, heating schedule 75-957C, holding at 957C for 600 s, cooling to 357C at 1.57C/min, holding for 3600 s. For strain sweep tests, the range of strain used was 0-0.2% and the temperature of test was 357C. The data on viscosity, storage modulus (G0) and phase angle were obtained from the rheograms. The results indicated variability in the various properties of the different starches. However the results did not follow a definite trend. The viscosity of Colocasia starch was low while Canna edulis and yam starches had high viscosities. The storage modulus was also highest for Canna starch (70-93 Pa) for 5% and gel strength was comparatively high for Canna edulis, Dioscorea esculenta and D. rotundata starches. The phase angle values followed the pattern of G0 and all the starch pastes were found to be elastic in nature at higher concentration. The wide variability in rheological properties can be useful in different applications of tuber starches. (Less)

Genetic Diversity Analysis of Starchy Curcuma Species Using RAPD Markers

Abstract: The genetic variability in starchy Curcuma species was assessed using Random Amplified Polymorphic DNA (RAPD) technique. The RAPD pattern generated by 20 primers revealed a high degree of polymorphism. A total of 274 bands were generated of which 264 were polymorphic. All the species were separated into 3 clusters using UPGMA. C. aromatica, C. leucorrhiza, and C. brog formed a cluster within which C. longa and C. zedoaria formed a subgroup. C. harita was genetically distinct from all the other Curcuma species. Since it is difficult to distinguish different species by leaf morphology, the RAPD pattern has high utility in identification of starchy Curcuma species.

MODELING CONSUMER ACCEPTABILITY OF β‐CAROTENE RICH SWEET POTATO CURD

Abstract: Sweet potato (SP) curd prepared by co-fermenting boiled β -carotene rich SP puree, cow's milk with curd culture, was evaluated for consumer acceptability of sensory attributes. One hundred consumers from the Orissa State, India evaluated SP curd in terms of five major sensory attributes, i.e., sweetness, color, texture, aroma and general appearance on a 9-point hedonic scale. The responses were modeled through binary logistic regression to understand the sensory attributes, which govern the decision process. Color and texture were found to influence consumer acceptability. The β -carotene supplied by SP-enriched yellow color of the curd, and starch and dietary fiber enhanced the thickness of SP curd. PRACTICAL APPLICATIONS Vitamin A Deficiency (VAD) is a serious problem affecting bulk of the disadvantaged population living in the developing countries. Fortification of foods with β-carotene (precursor of vitamin A) is widely regarded as a strategy to combat VAD through natural means. Sweet potato (SP) is a secondary staple food for small and tribal farmers particularly during off-season when there is a scarcity of food grains. Curd is a popular fermented dairy product, consumed widely in the Indian subcontinent. Fortifying curd with β-carotene rich SP can enhance the nutrient content (β-carotene, minerals, etc.) as well as culinary qualities (color and texture). Besides, modeling consumer preferences help us to identify the attributes, which govern the acceptability of SP curd. Such model could be compared with the sensory panel results to understand the accuracy with which decisions are made at the laboratory level.

Texture analysis of raw and cooked tubers of short-duration lines of cassava by multivariate and fractional conversion techniques

Abstract: BACKGROUND: Cassava tubers are mainly consumed after boiling in water. Their cooking quality depends on the variety, maturity, growing conditions and physicochemical and starch properties. In this study the textural and gelatinisation characteristics of ten short-duration lines of cassava were assessed. Textural changes due to cooking were modelled by fractional conversion techniques and correlated with gelatinisation and physicochemical properties by principal component analysis. RESULTS: There was a significant variation (P < 0.05) in the textural properties of tubers and the thermal and pasting properties of flours among varieties. The degree of cooking and relative firmness of tubers were modelled by a linear equation. The thermal softening behaviour was modelled by a dual-mechanism first-order kinetic model with rate constant values ranging from 0.106 to 0.190 min−1. About 69.21% of the total variation in texture profile, gelatinisation and physicochemical parameters could be explained by the first three principal components. CONCLUSION: The results indicated that the textural and gelatinisation properties varied considerably among different varieties. However, the interaction between the components of the tubers and the structural make-up of the tuber tissues played a more important role than the physicochemical and functional properties. Copyright © 2008 Society of Chemical Industry

Effect of Sodium Dodecyl Sulphate on the Physicochemical, Thermal and Pasting Properties of Cassava Starch

Abstract: The effect of different concentrations of sodium dodecyl sulphate (SDS) on cassava starch properties after complexation and in situ addition were studied. The swelling volume of the starch-SDS complexes increased to a maximum of 100 mL/g with increase in concentration of SDS (even at 0.004 mol SDS) with a corresponding decrease in solubility. During in situ addition also, a similar but gradual behaviour was observed for swelling volume and solubility. The apparent and total amylose contents showed an irregular trend. The soluble amylose content decreased with increase in concentration of SDS. In vitro enzyme digestibility of starch-SDS complexes was significantly lowered compared to that of native starch. The water-binding capacity showed an initial decrease followed by a significant increase at higher concentrations of SDS. DSC studies showed that in addition to the gelatinisation endotherm, a peak corresponding to the melting of the starch-SDS complex was obtained in the case of in situ addition of the surfactant. The peak viscosity of starch during in situ addition of SDS exhibited a rapid increase except at the highest concentration. The peak viscosity of starch-SDS complexes underwent an initial reduction followed by a gradual increase at higher concentrations. The breakdown, setback and pasting temperature were also affected.

Yield potential and economics of elephant foot yam (Amorphophallus paeoniifolius) + greengram (Vigna radiata) intercropping system as influenced by mulching and fertilizers levels

Abstract: A field experiment was conducted for 3 years during 2003-04 to 2005-06 in acid laterite soil under rainfed conditions to assess the yield potential and economics of elephant foot yam (Amorphophallus paeoniifolius (Dennst.) Nicolson) + greengram (Vigna radiata L. R. Wilczek) intercropping under varying levels of fertilizer and mulching. Application of 2 tonnes/ha dried farmwaste as mulch increased elephant foot yam yield by 21.6% over the no mulch. However, no effect was found on greengram. Increasing the fertilizer levels beyond N:F:K @ 80:60:80 kg/ha did not increase significantly the elephant foot yam tuber yield, greengram grain yield and tuber equivalent yield. The maximum gross returns (Rs 1 07 575) was obtained with the application of N:P:K @ 120:90:120 kg/ha along with mulching. However, application of N:P:K @ 100:75: 100 kg/ha along with mulching registered higher net returns (Rs 53 785) owing to lesser cost of cultivation. Production efficiency (kg/ha/day) followed similar trends of gross returns and the maximum production efficiency (512.3 kg/ha/day) was found with the application of N:P:K @ 120:90:120 kg/ha along with mulching. The benefit : cost ratio analysis revealed that the maximum benefit : cost ratio was found with the application of N:P:K @ 80:60:80 kg/ha along with mulching (2.02).