Showing papers by "Central Tuber Crops Research Institute published in 2007"

Indole-3-acetic acid production and effect on sprouting of yam (Dioscorea rotundata L.) minisetts by Bacillus subtilis isolated from culturable cowdung microflora.

Abstract: Bacillus subtilis strains (CM1-CM5) isolated from culturable cowdung microflora were investigated for indole-3-acetic acid (IAA) production in nutrient broth (NB). All the strains tested produced IAA in NB; albeit in very low concentrations (0.09 n 0.37 mg/l). The addition of L-tryptophan (0.1 n 1.0 g/l) into NB substantially enhanced IAA production (6.1 n 31.5 folds) indicating that L-tryptophan was the precursor for IAA biosynthesis by these bacterial strains. Maximum IAA production was observed after 8 days of incubation (in late stationary phase of bacterial growth). The variation in IAA production was attributed to the genetic make up of these strains as evaluated by RAPD analysis of these isolates and B. subtilis type strain MTCC 441. Application of B. subtilis suspension (8 ◊1 0 9 CFU/ml) on the surface of yam (Dioscorea rotundata L.) minisetts increased the number of sprouts, roots and shoots length, root and shoot fresh weights and root: shoot ratio over those minisetts not treated with bacterial suspension. Fresh cowdung slurry treatment on yam minisetts also produced similar results as obtained with B. subtilis application.

Lactic acid fermentation of sweet potato (ipomoea batatas l.) into pickles

Abstract: Lactic acid (LA) fermentation has many benefits. It is feasible in small scale, inexpensive, and does not require additives and confers organoleptic characteristics to the foodstuff according to the habits and requirement of the consumers. Sweet potato roots were pickled by lactic fermentation by brining the cut and blanched roots in common salt (NaCl, 2-10%) solution and subsequently inoculated With a strain of Lactobacillus plantarum (MTCC 1407) for 28 days. The treatment with 8-10% brine solution was found to be the most acceptable organoleptically. The final product with 8 and 10% brine solutions had a pH of 2.9-3.0, titratable acidity of 2.9-3. 7 g/kg LA of 2.6-3.2 g/kg and starch of 58-68 g/kg on fresh weight basis. Sensory evaluation rated the sweet potato lacto-pickle acceptable based on texture, taste, aroma, flavor and aftertaste. Principal component analyses reduced the six original analytical variables to two independent components (factors), which accounted for 92% of the total variations.

Lactic Acid Fermentation of β-Carotene Rich Sweet Potato (Ipomoea batatas L.) into Lacto-juice

Abstract: Lacto-juices processed by lactic acid fermentation bring about a change in the beverage assortment for their high nutritive value, vitamins and minerals which are beneficial to human health when consumed. Sweet potato roots (non-boiled/ fully-boiled) were fermented with Lactobacillus plantarum MTCC 1407 at 28 ± 2°C for 48 h to make lacto- juice. During fermentation both analytical [pH, titratable acidity, lactic acid, starch, total sugar, reducing sugar (g/kg roots), total phenol and β-carotene (mg/kg roots)] and sensory (texture, taste, aroma, flavour and after taste) analyses of sweet potato lacto-juice were evaluated. The fermented juice was subjected to panelist evaluation for acceptability. There were no significant variations in biochemical constituents (pH, 2.2–3.3; lactic acid, 1.19–1.27 g/kg root; titratable acidity, 1.23–1.46 g/kg root, etc.) of lacto-juices prepared from non-boiled and fully-boiled sweet potato roots except β-carotene concentration [130 ± 7.5 mg/kg (fully-boiled roots) and 165 ± 8.1 mg/kg (non-boiled roots)]. The panelist evaluation scores ranged from 3–4.8 (in a hedonic scale of 1–5) from moderate liking to very much liking of sweet potato lacto-juice. Principal component analyses reduced the eight original analytical variables to three independent components (factors), which accounted for 99.9% of the total variations. Similarly, five original sensory variables were reduced to two independent components, which accounted for 83.1% of the total variations.

Alpha-amylase production by Bacillus subtilis CM3 in solid state fermentation using cassava fibrous residue.

Abstract: Central Tuber Crops Research Institute (Regional Centre), Dumuduma Housing Board, Bhubaneswar – 751019, India In extraction of starch from cassava (Manihot esculenta Crantz), one of the major solid waste released is fibrous residues which constitute 15–20% by weight of the cassava chips/tuber processed. Production of α-amylase under solid state fermentation by Bacillus subtilis CM3 has been investigated using cassava fibrous residue. Response surface methodology (RSM) was used to evaluate the effect of the main variables, i.e. incubation period, initial medium pH, moisture holding capacity and temperature on enzyme production. A full factorial Central Composite Design (CCD) was applied to study these main factors that affected α-amylase production. The experimental results showed that the optimum incubation period, initial medium pH, moisture holding capacity and temperature were 6 days, 8.0, 70% and 50 °C, respectively.

Antioxidative enzymes and isozymes analysis of taro genotypes and their implications in Phytophthora blight disease resistance.

Abstract: Assessment of the differential expression of antioxidative enzymes and their isozymes, was done in 30 day-old ex vitro raised plants of three highly resistant (DP-25, Jhankri and Duradim) and one highly susceptible (N-118) genotypes of taro [Colocasia esculenta (L.) Schott]. Antioxidative enzymes were assayed in the ex vitro plants, 7 days after inoculation with the spores (15,000 spores ml−1 water) of Phytophthora colocasiae Raciborski to induce taro leaf blight disease. Uninoculated ex vitro plants in each genotype were used as control. The activity of superoxide dismutase (SOD) and guaiacol peroxidase (GPX) increased under induced blight condition when compared with control. Increase in antioxidative enzymes was more (67–92%) in the resistant genotypes than that (21–29%) of the susceptible genotype. The zymograms of SOD and GPX in the resistant genotypes, with pathogenic infection, showed increased activity for anodal isoform of SOD and increased expression and/or induction of either POX 1 or POX 2 isoforms of GPX. In susceptible genotype, expression of the above isoforms was faint for SOD and nearly absent for GPX under both blight free and induced blight conditions. Induction and/or increased activity of particular isoform of SOD and GPX against infection of Phytophthora colocasiae in the resistant genotypes studied led to the apparent conclusion of linkage of isozyme expression with blight resistance in taro. This might be an important criterion in breeding of taro for Phytophthora leaf blight resistance.

Studies on the properties of citrate derivatives of cassava (Manihot esculenta Crantz) starch synthesized by microwave technique.

Abstract: Cassava starch citrates with degree of substitution (DS) ranging from 0.005 to 0.063 were synthesized by the microwave-assisted reaction of cassava starch with citric acid. A response surface small composite design was used to study the effect of different reaction conditions, viz. time, temperature and reagent concentration. All these variables significantly affected the substitution level in the modified starches. The DS increased with increase in the time of reaction and temperature. However, reagent concentration had a negative effect on the DS. The modified starches showed higher viscosity with lower breakdown, lower setback and higher final viscosities in comparison to native starch. Differential scanning calorimetry showed that the modified starches exhibited a decrease in gelatinization temperatures, To, Tp, Te, in comparison to native starch. However, the heat of gelatinization was not significantly affected. The citrate derivatives exhibited reduced swelling volume and enhanced water binding capacities. They were found to be less susceptible to enzyme hydrolysis than native starch. Copyright © 2007 Society of Chemical Industry

Industrial Demand for Cassava Starch in India

Abstract: Cassava (Manihot esculenta crantz) is a staple food crop cultivated in several developing countries Cassava is consumed either directly as cooked tubers or as the products prepared from cassava Cassava in India is used mainly in the human consumption, industrial and animal feed sectors In India nearly 60% of cassava is used industrially in the production of sago, starch and dry chips The presented study has clearly indicated that the future of cassava in India lies in its diversified uses in the industrial sector The projected demand is predominantly in the adhesive sector, especially in the corrugation gums and paper conversion industry, and in the paper industry The projected demand-supply gap in the industrial sector is expected to be 15 x 10 6 t of cassava tubers requiring another 750 000 ha to be brought under cassava cultivation New and potential areas in the non-traditional cassava-growing states are to be considered for area expansion

β‐Carotene‐rich sweet potato curd: production, nutritional and proximate composition

Abstract: Summary Sweet potato (SP) is an important root crop grown all over the world and consumed as a vegetable, boiled, baked or often fermented into food and beverages. A curd-like product was prepared by fermenting boiled β-carotene-rich SP puree and cow milk with curd (starter) culture (Lactobacillus bulgaricus, Streptococcus lactis, Streptococcus diacetilactis, etc.). There were not much variation in pH (3.6–3.9), titratable acidity (10–11.8 g kg−1 curd) and lactic acid (LA) (7.9–5.3 g kg−1 curd) contents in SP curd consisting different concentration of SP puree. However, curd with 12–16% SP puree was most preferred by a consumer's panellist. The addition of SP puree (12–16%) made the curd quite firm and imparted flavour, body/texture, minerals, nutrients, antidiabetic substances, β-carotene pigments (antioxidant), dietary fibres and starch (carbohydrate source). The LA bacterial counts in the curd after 18 h of fermentation having 8% and 16% SP were 7 × 107 and 14 × 107 (CFU mL−1), respectively. The consumer evaluation scores ranged from 7 to 8 (in a hedonic scale of 1–9), from moderate liking to very much liking of the SP curd, taking into consideration the sensory attributes such as colour, texture, flavour, sweetness, appearance, etc. Principal component analysis (PCA) reduced the fourteen original analytical (proximate) variables to four independent components (factors), which accounted for 97% of the total variations. Similarly, PCA analysis reduced the seven original sensory attributes to three independent components that accounted for 70% of the total variations.

Studies on the synthesis and properties of hydroxypropyl derivatives of cassava (Manihot esculenta Crantz) starch

Abstract: Cassava starch was subjected to hydroxypropylation in three different media, which included water, water in the presence of a phase transfer catalyst, and 2-propanol, all at 30 ± 2 °C for 24 h. Propylene oxide was used in four different concentrations (50, 100, 150 and 200 g kg−1 of starch dry weight). The products were characterized by determining their molar substitution (MS), structural and functional properties. The analyses were done in triplicate and the data were analyzed using the statistical package 8.01. The MS of the products ranged from 0.26 to 1.41. The MS of the hydroxypropyl derivatives were found to be higher when the reaction was carried out in the aqueous medium in the presence of tetrabutylammonium bromide, a phase transfer catalyst, when compared to the reaction in 2-propanol, which was found to be not very effective at 30 ± 2 °C. The etherification altered the granular properties of starch, as could be seen from scanning electron micrographs. Hydroxypropylation resulted in starch pastes which were stable and with higher swelling volume, solubility, light transmittance and water binding capacity as compared to native starch. The hydroxypropyl starches showed significantly lower pasting temperatures and setback viscosities. The enzyme digestibility of the derivatives was seen to decrease with increase in MS and there was a significant reduction in the syneresis of the starch pastes of hydroxypropyl derivatives. Texture profile analysis showed that hydroxypropylated starch gels exhibited higher hardness, springiness (elasticity) and gumminess and lower cohesiveness than the native starch. Copyright © 2007 Society of Chemical Industry

Arbuscular Mycorrhizal Fungi Associated with Green Gram in South India

Abstract: Field studies are necessary to understand the abundance and type of indigenous arbuscular mycorrhizal (AM) fungi present in the rhizosphere. Green gram [Phaseolus aureus Roxb. (= Vigna radiata var. radiata)] is a major pulse crop of South India. A field study was conducted to identify the AM fungi associated with green gram under field conditions in this region. The rhizosphere soil samples from these fields were analyzed for AM fungal spores. Glomus mosseae, Glomus microcarpum, Gigaspora margarita, and Scutellospora sp. were identified as the AM fungi associated with green gram. Glomus mosseae was the most frequent AM fungal associate identified in 81%, G. microcarpum and G. margarita in 24% each, and Scutellospora sp. in 5% of the soils studied. The range of distribution varied from a single species of AM fungus to three species belonging to two genera in one sample. Correlations of spore count and percentage colonization for all the AM fungi on the crop in the field, along with soil parameters like pH, N, P, and K were studied. Significant negative correlation (P < 0.01) was obtained between percentage colonization and P. The pH and N were positively correlated (P < 0.01) with K. The study indicates involvement of factors other than soil nutrients in the distribution and sporulation of AM fungi.

Wet Storage of Cassava Starch: Use of Sodium Metabisulphite and Acetic Acid and the Effect on Starch Properties

Abstract: Freshly extracted cassava starch was subjected to wet storage without any chemical treatment and also in presence of different concentrations of acetic acid and sodium metabisulphite, ranging from 0.5 to 2.0% based on the volume of starch milk. The viscosity characteristics, physicochemical properties, blue value and reducing value of the stored starch samples were studied at weekly intervals up to eight weeks of storage. Sodium metabisulphite (1 %) was effective in prolonging the storage time of starch without any microbial spoilage. No significant change was observed in the swelling volume, reducing value, viscosity and pasting properties of the starch samples up to the sixth week of storage. Storage in acetic acid (1 %) resulted in decrease in peak viscosity and increase in solubility and reducing value. However, the starch was free of microbial contamination.

Mitigation of growth retardation effect of plant defense activator, acibenzolar- S -methyl, in amaranthus plants by plant growth-promoting rhizobacteria

Abstract: Four rhizobacterial strains and acibenzolar-S-methyl (ASM), a chemical activator, which suppressed foliar blight of amaranthus (Amaranthus tricolor L.) caused by Rhizoctonia solani Kuhn were evaluated for their effect on plant growth. The experiments were performed both under sterile and non-sterile soil conditions, in the presence or absence of the pathogen. In all cases, plants treated with ASM showed significant reduction in growth, as determined by shoot length, and shoot and root dry weight when compared to other treatments. The growth retardation effect of ASM was more profound with respect to shoot length. Reduction in shoot length was least when plants were treated with a combination of the chemical activator and Pseudomonas putida 89B61 under non-sterile soil conditions in the absence of the pathogen. Both under sterile and non-sterile soil conditions, in the presence of the pathogen, reduction in shoot length due to application of ASM was diminished significantly when plants were treated with rhizobacterial strain Pseudomonas fluorescens PN026R. Combined use of plant growth-promoting rhizobacteria (PGPR) and ASM was found to be beneficial as the growth retardation effect of the plant defense activator was reduced by the growth-promoting ability of the rhizobacteria.

Sweet Potato Response to Boron Application on an Alfisols in the Subhumid Tropical Climate of India

Abstract: Splitting of sweet potato tubers because of boron (B) deficiency is a major cause of reduction in marketable tuber yield in India. Soil and plant tests are employed in this study to determine the fertilizer B requirement (FBR). Fertilizer B requirement of sweet potatos grown on an Alfisols under rainfed conditions was evaluated by two simple methods. In the first method, the relationship between B uptake and sweet potato tuber yield was utilized to find the B uptake at a given sweet potato tuber yield. This relationship was then used to find the amount of B applied for that particular uptake to set the targeted yield. In the second method, FBR was determined using the equation: FBR=(UB−U0)/BRF, where UB is B uptake at a given yield, U0 is B uptake from unfertilized soil, and BRF is the recovery of applied B. All of these parameters were determined in a field experiment with sweet potatos grown on Alfisols under rainfed conditions. The results of the study indicated a very good relation between ob...

Biological Control of Taro Leaf Blight Caused by Phytophthora colocasiae (Racib.) and Storage Losses with Rhizobacteria

Abstract: Effect of seed treatment, soil application and foliar spray of rhizobacterial cultures that were isolated from Colocasia esculenta on Phytophthora blight was studied under polyhouse and field conditions. Under polyhouse conditions, when applied as seed tuber treatment, the antagonistic rhizobactcrial cultures S1B3, S11B4, S13B5 and S23BS reduced the Phytophthora blight disease severity. In these treatments there was no disease incidence compared to control where the disease severity was 2.92 on a 0-5 disease rating scale. In soil application, when rhizobactcrial cultures S4BS, S13B5 and S23BS were used, the disease incidence was nil compared to control where disease severity was 2.83 on a 0-5 disease rating scale. Foliar application with S1B4 and S11B3 reduced the disease severity to 0-0.33 rating compared to 2.66 in control. Under field conditions, tuber treatment with S1 B3, soil application of S13B5 or foliar application with S1B4 and S11B3 reduced the disease severity and increased the yield compared to untreated pathogen-inoculated control plants. Seed treatment with S1B3 resulted in tuber yield of 255g/plant compared to 95.42g in control. Soil application with S13B5 resulted in 232.65g/plant, while in foliar application with S1B4 or S11B3, yield were 274g and 605g per plant, respectively. These treatments promoted the plant growth also. These treatments were tested in the field and it was found that application of bacteria in combination (seed treatment, soil treatment and foliar spray) helped in reducing the leaf area damaged due to blight by 41% during the first peak of the disease spread and by 28% during the second peak of the disease spread. Rhizobacteria treatment also helped in reducing the storage losses. The storage loss of tubers harvested from rhizobacteria treated plots ranged from 4.14 to 21.24% compared to 26.02 and 21.78% in fungicide treated and control plots, respectively, resulting in 18 to 36% increased yield in the field trials.