ashu gulati | IHBT (CSIR) (original) (raw)

Papers by ashu gulati

Journal of Liquid Chromatography & Related Technologies, 2011

Indian Phytopathology, 1993

Chemistry of Natural Compounds, 2015

Abstract— This paper reports on the application of Vis-NIR spectroscopy to discriminate between s... more Abstract— This paper reports on the application of Vis-NIR spectroscopy to discriminate between seven different types of tea samples from same origin (Himalayan teas). NIR spectra were recorded by measuring the absorption spectra in the range 300– 1900nm. The spectral features of each category are reasonably differentiated in the Vis-NIR region (500-1300nm), and the spectral differences provided enough qualitative spectral information for identification. Discrimination of orthodox black teas based on their spectral data was performed by principal component analysis (PCA), a common chemometric method used for data reduction and visualisation. The results demonstrate the ability of spectroscopy techniques to differentiate between orthodox black teas manufactured at different seasons. Linear Discriminant Analysis (LDA) was used to construct the identification model based on Principal Components derived using PCA. The number of principal component factors (PCs) was optimized in the cons...

Volatile flavour components of tea flowers (Camellia sinensis) were isolated by two methods viz. ... more Volatile flavour components of tea flowers (Camellia sinensis) were isolated by two methods viz. simultaneous distillation extraction (SDE), supercritical fluid extraction (SFE), analyzed by GC and GC/MS and compared with headspace analysis (HS). The composition of the volatile components extracted by the three methods differed considerably. In SFE, phenylethanol (14.7%), linalool (7.8%), (E)-linalool oxide furanoid (3.5%), epoxy linalool (1.6%), geraniol (2.3%) and hotrienol (1.5%) were major components. m-Xylene (2.6%), (E)-linalool oxide pyranoid (5.4%), p-myrcene (5.2%), α-cadinol (4.3%) and methyl palmitate (2.9%) were major compounds isolated by SDE. 3-hexenol (2.1%) (E)-4,8-dimethyl-1, 3, 7-nonatriene (20.9%) and linalool (35.1%) are major components in headspace analysis. Pheromone germacrene D is detected in tea flowers by all the methods studied. Floral, fresh and fruity odour of tea flowers is retained by SFE as there is very little loss of heat sensitive volatiles in SFE. The flavour isolated from SFE has superior quality compared to SDE.

Journal of Food Biochemistry

beta-glucosidase was purified from the shoots of Camellia sinensis cv. Asha from Kangra valley fo... more beta-glucosidase was purified from the shoots of Camellia sinensis cv. Asha from Kangra valley following acetone precipitation, hydroxyapatite, gel filtration and ultrafiltration to apparent homogeneity. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of purified enzyme indicated a dimer with a larger subunit of similar to 63 kD and a smaller subunit of similar to 36 kD, molecular mass of similar to 99 kD. The native form was confirmed by nondenaturating polyacrylamide gel electrophoresis. Optimum pH was 6.2, optimum temperature within 45-50C. beta-glucosidase exhibited Km value of 0.16 mM and kcat of 11,000/min with the substrate p-nitrophenyl-beta-D-glucopyranoside (pNpGlc) at 37C, pH 6.2. Substrate staining with 6-bromo-2-napthyl-beta-D-glucopyranoside ruled out the possibility of any isozymic forms. The purified enzyme showed specificity toward pNpGlc and equivalent activity toward p-nitrophenyl-beta-D-fucopyranoside. The enzyme liberated geraniol, linalool, phenyletha...

b-glucosidase was purified from the shoots of Camellia sinensis cv. Asha from Kangra valley follo... more b-glucosidase was purified from the shoots of Camellia sinensis cv. Asha from Kangra valley following acetone precipitation, hydroxyapatite, gel filtration and ultrafiltration to apparent homogeneity. Sodium dodecyl sulfate– polyacrylamide gel electrophoresis of purified enzyme indicated a dimer with a larger subunit of ~63 kD and a smaller subunit of ~36 kD, molecular mass of ~99 kD. The native form was confirmed by nondenaturating polyacrylamide gel electrophoresis. Optimum pH was 6.2, optimum temperature within 45–50C. b-glucosidase exhibited Km value of 0.16 mM and kcat of 11,000/min with the substrate p-nitrophenyl-b-D-glucopyranoside (pNpGlc) at 37C, pH 6.2. Substrate staining with 6-bromo-2-napthyl-b-D-glucopyranoside ruled out the possibility of any isozymic forms. The purified enzyme showed specificity toward pNpGlc and equivalent activity toward p-nitrophenyl-b-Dfucopyranoside. The enzyme liberated geraniol, linalool, phenylethanol, benzyl alcohol on incubation with tea sh...

Plant Biology

Flavonoids are plant secondary metabolites widespread throughout the plant king- dom involved in ... more Flavonoids are plant secondary metabolites widespread throughout the plant king- dom involved in many physiological and biochemical functions. Amongst the flavo- noids, flavan-3-ols (catechin and epicatechin) are known for their direct free radical scavenging activity in vitro, but studies on their antioxidant potential and interac- tion with antioxidant enzymes in vivo are lacking. Here, the flavonoid pathway was engineered by silencing a gene encoding flavonol synthase (FLS) in tobacco to direct the flow of metabolites towards production of flavan-3-ols. FLS silencing reduced flavonol content 17–53%, while it increased catechin and epicatechin content 51– 93% and 18–27%, respectively. The silenced lines showed a significant increase in expression of genes for dihydroflavonol reductase and anthocyanidin synthase, a downstream gene towards epicatechin production, with no significant change in expression of other genes of the flavonoid pathway. Effects of accumulation of fla- van-3-o...

Five wild edible fungal species of Genus Pleurotus were collected from the different localities o... more Five wild edible fungal species of Genus Pleurotus were collected from the different localities of North West India and evaluated for the amino acid composition by using Ultra Performance Liquid Chromatography (UPLC). Five amino acids namely aspartic acid, arginine, alanine, proline and tyrosine were detected from the samples. Among theese five wild samples, aspartic acid was found maximum in Pleurotus pulmonarius (0.48 %) followed by P. sajor-caju (0.44 %), P. cystidiosus (0.42 %), P. floridanus and least was found in P. sapidus (0.37 %). Arginine was found maximum in P. sapidus (0.23 %) followed by P. floridanus (0.22 %), P. sajor-caju (0.20 %) while P. cystidiosus and P. pulmonarius contained equal percentage of this amino acid (0.19 %). Alanine was documented maximum in P. pulmonarius (0.19 %) followed by P. cystidiosus (0.18 %), P. floridanus (0.17 %), P. sajor-caju (0.12 %) and minimum was documented in P. sapidus (0.11 %). Proline was recorded maximum in P. sapidus (0.09 %) followed by P. floridanus (0.08 %), P. pulmonarius (0.06 %), P. sajor-caju (0.05 %), while minimum was recorded in P. cystidiosus (0.02 %). Tyrosine was documented maximum in P. sapidus (0.20 %) P. cystidiosus (0.18 %) followed by P. pulmonarius (0.17 %), P. sajor-caju (0.15 %) and minimum was recorded in P. floridanus (0.14 %).

Plant biology (Stuttgart, Germany), Jan 10, 2012

Flavonoids are plant secondary metabolites widespread throughout the plant kingdom involved in ma... more Flavonoids are plant secondary metabolites widespread throughout the plant kingdom involved in many physiological and biochemical functions. Amongst the flavonoids, flavan-3-ols (catechin and epicatechin) are known for their direct free radical scavenging activity in vitro, but studies on their antioxidant potential and interaction with antioxidant enzymes in vivo are lacking. Here, the flavonoid pathway was engineered by silencing a gene encoding flavonol synthase (FLS) in tobacco to direct the flow of metabolites towards production of flavan-3-ols. FLS silencing reduced flavonol content 17-53%, while it increased catechin and epicatechin content 51-93% and 18-27%, respectively. The silenced lines showed a significant increase in expression of genes for dihydroflavonol reductase and anthocyanidin synthase, a downstream gene towards epicatechin production, with no significant change in expression of other genes of the flavonoid pathway. Effects of accumulation of flavan-3-ols in FLS...

Natural product communications, 2011

Volatile flavour components of tea flowers (Camellia sinensis) were isolated by two methods viz. ... more Volatile flavour components of tea flowers (Camellia sinensis) were isolated by two methods viz. simultaneous distillation extraction (SDE), supercritical fluid extraction (SFE), analyzed by GC and GC/MS and compared with headspace analysis (HS). The composition of the volatile components extracted by the three methods differed considerably. In SFE, phenylethanol (14.7%), linalool (7.9%), (E)-linalool oxide furanoid (3.5%), epoxy linalool (1.6%), geraniol (2.3%) and hotrienol (1.5%) were major components. m-Xylene (2.6%), (E)-linalool oxide pyranoid (5.4%), p-myrcene (5.2%), alpha-cadinol (4.3%) and methyl palmitate (2.9%) were major compounds isolated by SDE. 3-hexenol (2.1%) (E)-4,8-dimethyl-1,3,7-nonatriene (20.9%) and linalool (35.1%) are major components in headspace analysis. Acetophenone and pheromone germacrene D is detected in tea flowers by all the methods studied. Floral, fresh and fruity odour of tea flowers is retained by SFE as there is very little loss of heat sensiti...

Biotechnic & Histochemistry, 2015

We investigated the applicability of catechin-specific-reagent (CSR) for histochemical evaluation... more We investigated the applicability of catechin-specific-reagent (CSR) for histochemical evaluation of catechins. The diazotized arylamine moiety in CSR reacts specifically with the A-ring of catechins to yield a golden yellow complex. This makes it highly specific for spectrophotometric quantification of catechins. Therefore, microtome cut sections of untransformed and osmotin-expressing transgenic leaves and stem of tea were stained with CSR. We found catechins in the form of golden yellow globules. The catechin globules increased in the structurally intact and highly turgid cells of osmotin expressing transgenic tea plants after stress treatment with 20% PEG; by contrast, the cells in non-transgenic plants accumulated fewer catechin globules. Spectrophotometric quantification of catechins also confirmed higher levels in transgenics compared to untransformed plants. We found elevated accumulation of catechins in stress tolerant cells of tea leaves.

Journal of Microbiology and Biotechnology, 2010

A phosphate-solubilizing bacterial strain isolated from Hippophae rhamnoides rhizosphere was iden... more A phosphate-solubilizing bacterial strain isolated from Hippophae rhamnoides rhizosphere was identified as Rahnella sp. based on its phenotypic features and 16S rRNA gene sequence. The bacterial strain showed the growth characteristics of a cold-adapted psychrotroph, with the multiple plant growth-promoting traits of inorganic and organic phosphate solubilization, 1-aminocyclopropane-1carboxylate-deaminase activity, ammonia generation, and siderophore production. The strain also produced indole-3-acetic acid, indole-3-acetaldehyde, indole-3-acetamide, indole-3-acetonitrile, indole-3-lactic acid, and indole-3pyruvic acid in tryptophan-supplemented nutrient broth. Gluconic, citric and isocitric acids were the major organic acids detected during tricalcium phosphate solubilization. A rifampicin-resistant mutant of the strain exhibited high rhizosphere competence without disturbance to the resident microbial populations in pea rhizosphere. Seed bacterization with a charcoal-based inoculum significantly increased growth in barley, chickpea, pea, and maize under the controlled environment. Microplot testing of the inoculum at two different locations in pea also showed significant increase in growth and yield. The attributes of coldtolerance, high rhizosphere competence, and broad-spectrum plant growth-promoting activity exhibited the potential of Rahnella sp. BIHB 783 for increasing agriculture productivity.

Journal of Liquid Chromatography & Related Technologies, 2015

A fast RP-HPLC-DAD method has been developed and validated for simultaneous analysis of major bio... more A fast RP-HPLC-DAD method has been developed and validated for simultaneous analysis of major bioactive constituents of tea. The collective separation of theanine, caffeine and catechins have been achived by using a new hydrophobic selective C 12 stationary phase. The separation was done without any pre-column derivatization and using simple gradient solvent system of acetonitrile and water containing 0.01% TFA.

Lecture Notes in Computer Science, 2012

Food Chemistry, 2015

The aroma constituents of Kangra orthodox black tea were isolated by simultaneous distillation ex... more The aroma constituents of Kangra orthodox black tea were isolated by simultaneous distillation extraction (SDE), supercritical fluid extraction and beverage method. The aroma-active compounds were identified using gas chromatography-olfactometry-mass spectrometry. Geraniol, linalool, (Z/E)-linalool oxides, (E)-2-hexenal, phytol, β-ionone, hotrienol, methylpyrazine and methyl salicylate were major volatile constituents in all the extracts. Minor volatile compounds in all the extracts were 2-ethyl-5-methylpyrazine, ethylpyrazine, 2-6,10,14-trimethyl-2-pentadecanone, acetylfuran, hexanoic acid, dihydroactinidiolide and (E/Z)-2,6-nonadienal. The concentrated SDE extract was fractionated into acidic, basic, water-soluble and neutral fractions. The neutral fraction was further chromatographed on a packed silica gel column eluted with pentane and diethyl ether to separate minor compounds. The aroma-active compounds identified using gas chromatography-olfactometry-mass spectrometry were 2-amylfuran, (E/Z)-2,6-nonadienal, 1-pentanol, epoxylinalool, (Z)-jasmone, 2-acetylpyrrole, farnesyl acetone, geranyl acetone, cadinol, cubenol and dihydroactinidiolide. AEDA studies showed 2-hexenal, 3-hexenol, ethylpyrazine, (Z/E)-linalool oxides, linalool, (E/Z)-2,6-nonadienal, geraniol, phenylethanol, β-ionone, hotrienol and dihydroactinidiolide to be odour active components.

Food chemistry, 2015

Recently anthocyanin-rich purple tea varieties have been developed. The quality of these new purp... more Recently anthocyanin-rich purple tea varieties have been developed. The quality of these new purple tea varieties developed in Kangra valley was assessed, and compared with the quality of tea from standard Kangra clone. Purple tea shoots (PL) recorded higher amount of polyphenols compared to standard green tea shoot (GL) while epigallocatechin gallate (EGCG) recorded higher levels in GL. Higher levels of theaflavins were recorded in orthodox black tea from purple shoots (BTP) compared to black tea (BT) made from green shoots. Both theanine and caffeine recorded higher levels in GL. Volatile flavour profiles of these teas showed qualitative and quantitative differences. Aroma extract dilution assay showed higher dilution factors in BTP than BT. Orthodox teas from purple shoots exhibited higher antioxidant activity compared to standard black tea. Strong correlation of total quality scores with aroma and infusion colour was observed. Tea from anthocyanin-rich cultivars can become speci...

Journal of Liquid Chromatography & Related Technologies, 2011

Indian Phytopathology, 1993

Chemistry of Natural Compounds, 2015

Abstract— This paper reports on the application of Vis-NIR spectroscopy to discriminate between s... more Abstract— This paper reports on the application of Vis-NIR spectroscopy to discriminate between seven different types of tea samples from same origin (Himalayan teas). NIR spectra were recorded by measuring the absorption spectra in the range 300– 1900nm. The spectral features of each category are reasonably differentiated in the Vis-NIR region (500-1300nm), and the spectral differences provided enough qualitative spectral information for identification. Discrimination of orthodox black teas based on their spectral data was performed by principal component analysis (PCA), a common chemometric method used for data reduction and visualisation. The results demonstrate the ability of spectroscopy techniques to differentiate between orthodox black teas manufactured at different seasons. Linear Discriminant Analysis (LDA) was used to construct the identification model based on Principal Components derived using PCA. The number of principal component factors (PCs) was optimized in the cons...

Volatile flavour components of tea flowers (Camellia sinensis) were isolated by two methods viz. ... more Volatile flavour components of tea flowers (Camellia sinensis) were isolated by two methods viz. simultaneous distillation extraction (SDE), supercritical fluid extraction (SFE), analyzed by GC and GC/MS and compared with headspace analysis (HS). The composition of the volatile components extracted by the three methods differed considerably. In SFE, phenylethanol (14.7%), linalool (7.8%), (E)-linalool oxide furanoid (3.5%), epoxy linalool (1.6%), geraniol (2.3%) and hotrienol (1.5%) were major components. m-Xylene (2.6%), (E)-linalool oxide pyranoid (5.4%), p-myrcene (5.2%), α-cadinol (4.3%) and methyl palmitate (2.9%) were major compounds isolated by SDE. 3-hexenol (2.1%) (E)-4,8-dimethyl-1, 3, 7-nonatriene (20.9%) and linalool (35.1%) are major components in headspace analysis. Pheromone germacrene D is detected in tea flowers by all the methods studied. Floral, fresh and fruity odour of tea flowers is retained by SFE as there is very little loss of heat sensitive volatiles in SFE. The flavour isolated from SFE has superior quality compared to SDE.

Journal of Food Biochemistry

beta-glucosidase was purified from the shoots of Camellia sinensis cv. Asha from Kangra valley fo... more beta-glucosidase was purified from the shoots of Camellia sinensis cv. Asha from Kangra valley following acetone precipitation, hydroxyapatite, gel filtration and ultrafiltration to apparent homogeneity. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of purified enzyme indicated a dimer with a larger subunit of similar to 63 kD and a smaller subunit of similar to 36 kD, molecular mass of similar to 99 kD. The native form was confirmed by nondenaturating polyacrylamide gel electrophoresis. Optimum pH was 6.2, optimum temperature within 45-50C. beta-glucosidase exhibited Km value of 0.16 mM and kcat of 11,000/min with the substrate p-nitrophenyl-beta-D-glucopyranoside (pNpGlc) at 37C, pH 6.2. Substrate staining with 6-bromo-2-napthyl-beta-D-glucopyranoside ruled out the possibility of any isozymic forms. The purified enzyme showed specificity toward pNpGlc and equivalent activity toward p-nitrophenyl-beta-D-fucopyranoside. The enzyme liberated geraniol, linalool, phenyletha...

b-glucosidase was purified from the shoots of Camellia sinensis cv. Asha from Kangra valley follo... more b-glucosidase was purified from the shoots of Camellia sinensis cv. Asha from Kangra valley following acetone precipitation, hydroxyapatite, gel filtration and ultrafiltration to apparent homogeneity. Sodium dodecyl sulfate– polyacrylamide gel electrophoresis of purified enzyme indicated a dimer with a larger subunit of ~63 kD and a smaller subunit of ~36 kD, molecular mass of ~99 kD. The native form was confirmed by nondenaturating polyacrylamide gel electrophoresis. Optimum pH was 6.2, optimum temperature within 45–50C. b-glucosidase exhibited Km value of 0.16 mM and kcat of 11,000/min with the substrate p-nitrophenyl-b-D-glucopyranoside (pNpGlc) at 37C, pH 6.2. Substrate staining with 6-bromo-2-napthyl-b-D-glucopyranoside ruled out the possibility of any isozymic forms. The purified enzyme showed specificity toward pNpGlc and equivalent activity toward p-nitrophenyl-b-Dfucopyranoside. The enzyme liberated geraniol, linalool, phenylethanol, benzyl alcohol on incubation with tea sh...

Plant Biology

Flavonoids are plant secondary metabolites widespread throughout the plant king- dom involved in ... more Flavonoids are plant secondary metabolites widespread throughout the plant king- dom involved in many physiological and biochemical functions. Amongst the flavo- noids, flavan-3-ols (catechin and epicatechin) are known for their direct free radical scavenging activity in vitro, but studies on their antioxidant potential and interac- tion with antioxidant enzymes in vivo are lacking. Here, the flavonoid pathway was engineered by silencing a gene encoding flavonol synthase (FLS) in tobacco to direct the flow of metabolites towards production of flavan-3-ols. FLS silencing reduced flavonol content 17–53%, while it increased catechin and epicatechin content 51– 93% and 18–27%, respectively. The silenced lines showed a significant increase in expression of genes for dihydroflavonol reductase and anthocyanidin synthase, a downstream gene towards epicatechin production, with no significant change in expression of other genes of the flavonoid pathway. Effects of accumulation of fla- van-3-o...

Five wild edible fungal species of Genus Pleurotus were collected from the different localities o... more Five wild edible fungal species of Genus Pleurotus were collected from the different localities of North West India and evaluated for the amino acid composition by using Ultra Performance Liquid Chromatography (UPLC). Five amino acids namely aspartic acid, arginine, alanine, proline and tyrosine were detected from the samples. Among theese five wild samples, aspartic acid was found maximum in Pleurotus pulmonarius (0.48 %) followed by P. sajor-caju (0.44 %), P. cystidiosus (0.42 %), P. floridanus and least was found in P. sapidus (0.37 %). Arginine was found maximum in P. sapidus (0.23 %) followed by P. floridanus (0.22 %), P. sajor-caju (0.20 %) while P. cystidiosus and P. pulmonarius contained equal percentage of this amino acid (0.19 %). Alanine was documented maximum in P. pulmonarius (0.19 %) followed by P. cystidiosus (0.18 %), P. floridanus (0.17 %), P. sajor-caju (0.12 %) and minimum was documented in P. sapidus (0.11 %). Proline was recorded maximum in P. sapidus (0.09 %) followed by P. floridanus (0.08 %), P. pulmonarius (0.06 %), P. sajor-caju (0.05 %), while minimum was recorded in P. cystidiosus (0.02 %). Tyrosine was documented maximum in P. sapidus (0.20 %) P. cystidiosus (0.18 %) followed by P. pulmonarius (0.17 %), P. sajor-caju (0.15 %) and minimum was recorded in P. floridanus (0.14 %).

Plant biology (Stuttgart, Germany), Jan 10, 2012

Flavonoids are plant secondary metabolites widespread throughout the plant kingdom involved in ma... more Flavonoids are plant secondary metabolites widespread throughout the plant kingdom involved in many physiological and biochemical functions. Amongst the flavonoids, flavan-3-ols (catechin and epicatechin) are known for their direct free radical scavenging activity in vitro, but studies on their antioxidant potential and interaction with antioxidant enzymes in vivo are lacking. Here, the flavonoid pathway was engineered by silencing a gene encoding flavonol synthase (FLS) in tobacco to direct the flow of metabolites towards production of flavan-3-ols. FLS silencing reduced flavonol content 17-53%, while it increased catechin and epicatechin content 51-93% and 18-27%, respectively. The silenced lines showed a significant increase in expression of genes for dihydroflavonol reductase and anthocyanidin synthase, a downstream gene towards epicatechin production, with no significant change in expression of other genes of the flavonoid pathway. Effects of accumulation of flavan-3-ols in FLS...

Natural product communications, 2011

Volatile flavour components of tea flowers (Camellia sinensis) were isolated by two methods viz. ... more Volatile flavour components of tea flowers (Camellia sinensis) were isolated by two methods viz. simultaneous distillation extraction (SDE), supercritical fluid extraction (SFE), analyzed by GC and GC/MS and compared with headspace analysis (HS). The composition of the volatile components extracted by the three methods differed considerably. In SFE, phenylethanol (14.7%), linalool (7.9%), (E)-linalool oxide furanoid (3.5%), epoxy linalool (1.6%), geraniol (2.3%) and hotrienol (1.5%) were major components. m-Xylene (2.6%), (E)-linalool oxide pyranoid (5.4%), p-myrcene (5.2%), alpha-cadinol (4.3%) and methyl palmitate (2.9%) were major compounds isolated by SDE. 3-hexenol (2.1%) (E)-4,8-dimethyl-1,3,7-nonatriene (20.9%) and linalool (35.1%) are major components in headspace analysis. Acetophenone and pheromone germacrene D is detected in tea flowers by all the methods studied. Floral, fresh and fruity odour of tea flowers is retained by SFE as there is very little loss of heat sensiti...

Biotechnic & Histochemistry, 2015

We investigated the applicability of catechin-specific-reagent (CSR) for histochemical evaluation... more We investigated the applicability of catechin-specific-reagent (CSR) for histochemical evaluation of catechins. The diazotized arylamine moiety in CSR reacts specifically with the A-ring of catechins to yield a golden yellow complex. This makes it highly specific for spectrophotometric quantification of catechins. Therefore, microtome cut sections of untransformed and osmotin-expressing transgenic leaves and stem of tea were stained with CSR. We found catechins in the form of golden yellow globules. The catechin globules increased in the structurally intact and highly turgid cells of osmotin expressing transgenic tea plants after stress treatment with 20% PEG; by contrast, the cells in non-transgenic plants accumulated fewer catechin globules. Spectrophotometric quantification of catechins also confirmed higher levels in transgenics compared to untransformed plants. We found elevated accumulation of catechins in stress tolerant cells of tea leaves.

Journal of Microbiology and Biotechnology, 2010

A phosphate-solubilizing bacterial strain isolated from Hippophae rhamnoides rhizosphere was iden... more A phosphate-solubilizing bacterial strain isolated from Hippophae rhamnoides rhizosphere was identified as Rahnella sp. based on its phenotypic features and 16S rRNA gene sequence. The bacterial strain showed the growth characteristics of a cold-adapted psychrotroph, with the multiple plant growth-promoting traits of inorganic and organic phosphate solubilization, 1-aminocyclopropane-1carboxylate-deaminase activity, ammonia generation, and siderophore production. The strain also produced indole-3-acetic acid, indole-3-acetaldehyde, indole-3-acetamide, indole-3-acetonitrile, indole-3-lactic acid, and indole-3pyruvic acid in tryptophan-supplemented nutrient broth. Gluconic, citric and isocitric acids were the major organic acids detected during tricalcium phosphate solubilization. A rifampicin-resistant mutant of the strain exhibited high rhizosphere competence without disturbance to the resident microbial populations in pea rhizosphere. Seed bacterization with a charcoal-based inoculum significantly increased growth in barley, chickpea, pea, and maize under the controlled environment. Microplot testing of the inoculum at two different locations in pea also showed significant increase in growth and yield. The attributes of coldtolerance, high rhizosphere competence, and broad-spectrum plant growth-promoting activity exhibited the potential of Rahnella sp. BIHB 783 for increasing agriculture productivity.

Journal of Liquid Chromatography & Related Technologies, 2015

A fast RP-HPLC-DAD method has been developed and validated for simultaneous analysis of major bio... more A fast RP-HPLC-DAD method has been developed and validated for simultaneous analysis of major bioactive constituents of tea. The collective separation of theanine, caffeine and catechins have been achived by using a new hydrophobic selective C 12 stationary phase. The separation was done without any pre-column derivatization and using simple gradient solvent system of acetonitrile and water containing 0.01% TFA.

Lecture Notes in Computer Science, 2012

Food Chemistry, 2015

The aroma constituents of Kangra orthodox black tea were isolated by simultaneous distillation ex... more The aroma constituents of Kangra orthodox black tea were isolated by simultaneous distillation extraction (SDE), supercritical fluid extraction and beverage method. The aroma-active compounds were identified using gas chromatography-olfactometry-mass spectrometry. Geraniol, linalool, (Z/E)-linalool oxides, (E)-2-hexenal, phytol, β-ionone, hotrienol, methylpyrazine and methyl salicylate were major volatile constituents in all the extracts. Minor volatile compounds in all the extracts were 2-ethyl-5-methylpyrazine, ethylpyrazine, 2-6,10,14-trimethyl-2-pentadecanone, acetylfuran, hexanoic acid, dihydroactinidiolide and (E/Z)-2,6-nonadienal. The concentrated SDE extract was fractionated into acidic, basic, water-soluble and neutral fractions. The neutral fraction was further chromatographed on a packed silica gel column eluted with pentane and diethyl ether to separate minor compounds. The aroma-active compounds identified using gas chromatography-olfactometry-mass spectrometry were 2-amylfuran, (E/Z)-2,6-nonadienal, 1-pentanol, epoxylinalool, (Z)-jasmone, 2-acetylpyrrole, farnesyl acetone, geranyl acetone, cadinol, cubenol and dihydroactinidiolide. AEDA studies showed 2-hexenal, 3-hexenol, ethylpyrazine, (Z/E)-linalool oxides, linalool, (E/Z)-2,6-nonadienal, geraniol, phenylethanol, β-ionone, hotrienol and dihydroactinidiolide to be odour active components.

Food chemistry, 2015

Recently anthocyanin-rich purple tea varieties have been developed. The quality of these new purp... more Recently anthocyanin-rich purple tea varieties have been developed. The quality of these new purple tea varieties developed in Kangra valley was assessed, and compared with the quality of tea from standard Kangra clone. Purple tea shoots (PL) recorded higher amount of polyphenols compared to standard green tea shoot (GL) while epigallocatechin gallate (EGCG) recorded higher levels in GL. Higher levels of theaflavins were recorded in orthodox black tea from purple shoots (BTP) compared to black tea (BT) made from green shoots. Both theanine and caffeine recorded higher levels in GL. Volatile flavour profiles of these teas showed qualitative and quantitative differences. Aroma extract dilution assay showed higher dilution factors in BTP than BT. Orthodox teas from purple shoots exhibited higher antioxidant activity compared to standard black tea. Strong correlation of total quality scores with aroma and infusion colour was observed. Tea from anthocyanin-rich cultivars can become speci...