Gaurav Rajauria
University College Dublin
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Featured researches published by Gaurav Rajauria.
International Journal of Analytical Chemistry | 2013
Gaurav Rajauria; Nissreen Abu-Ghannam
Seaweeds are important sources of carotenoids, and numerous studies have shown the beneficial effects of these pigments on human health. In the present study, Himanthalia elongata brown seaweed was extracted with a mixture of low polarity solvents, and the crude extract was separated using analytical thin-layer chromatography (TLC). The separated compounds were tested for their potential antioxidant capacity and antimicrobial activity against Listeria monocytogenes bacteria using TLC bioautography approach. For bio-autography, the coloured band on TLC chromatogram was visualized after spraying with DPPH and triphenyl-tetrazolium chloride reagents which screen antioxidant and antimicrobial compounds, respectively, and only one active compound was screened on the TLC plate. Preliminary identification of this active compound was done by comparing its colour and R f (retention factor) value with the authentic fucoxanthin standard. Further, the active compound was purified using preparative TLC. This purified compound showed a strong antioxidant (EC50: 14.8 ± 1.27 µg/mL) and antimicrobial (inhibition zone: 10.27 mm, 25 µg compound/disc) activities, which were examined by DPPH scavenging and agar disc-diffusion bioassay, respectively. The bioactivity shown by the purified compound was almost similar to the fucoxanthin standard. The characteristic UV-visible and FT-IR spectra of the purified active compound completely matched with the standard. Hence, the main active compound in H. elongata was identified as fucoxanthin.
Food and Bioprocess Technology | 2012
Shilpi Gupta; Sabrina Cox; Gaurav Rajauria; Amit K. Jaiswal; Nissreen Abu-Ghannam
The possibility of using extracts from brown seaweed, Himanthalia elongata, as a natural antimicrobial agent for food preservation is presented. The effect of different concentrations of seaweed extract on the growth kinetics of four common food spoilage (Pseudomonas aeruginosa and Enterococcus faecalis) and food pathogenic microorganisms (Listeria monocytogenes and Salmonella abony) was examined. Seaweed extract at a concentration of 6% inhibited the growth of all four of the studied organisms. Lower concentrations of seaweed extract prolonged the lag phase and reduced both the exponential growth rate and final population densities of the culture. Suitability of three kinetic models, Baranyi–Roberts, modified Gompertz and logistic, for describing the growth/survival of organisms in the presence of different concentrations of the extract, was evaluated. Root mean square error (RMSE) and correlation coefficient (R2) were used to evaluate the model performance. The R2 value was greater than 0.95 for most of the cases indicating that the models could provide a good fitting to the experimental data. The RMSE and residual sum of squares were very low for all the three models, and no significant difference was observed in the goodness of fit between the three models as indicated by the F test.
Food Research International | 2017
M. García-Vaquero; Gaurav Rajauria; J. V. O'Doherty; T. Sweeney
Polysaccharides obtained from macroalgae have promising prospects and could contribute greatly to the future of a marine based bio-economy. Specifically, laminarin and fucoidan from brown macroalgae have a wide variety of potential industrial applications including functional foods and nutraceuticals, due to their broad range of biological activities. These beneficial biological activities are related to the chemical composition and structure of the macroalgal polysaccharides. The molecular weight, monosaccharide composition and sulphate content of these polysaccharides could be influenced by both macroalgal biology (i.e. variations in polysaccharide composition due to macroalgae species and their biological cycle) and different extraction/purification techniques employed to obtain polysaccharide enriched products (i.e. de-sulphation or fragmentation of sulphated polysaccharides). This review focuses on the extraction and purification methods for the macroalgal polysaccharides laminarin and fucoidan used in the recent literature. The application of innovative extraction technologies (such as ultrasound, microwave and enzyme-assisted extractions), as well as new purification techniques (i.e. membrane separation), are also discussed together with the challenges concerning molecule structure-function relationship and macroalgal variability.
Food Research International | 2017
Gaurav Rajauria; Barry Foley; Nissreen Abu-Ghannam
This study explored Himanthalia elongata brown seaweed as a potential source of dietary fucoxanthin which is a promising medicinal and nutritional ingredient. The seaweed was extracted with low polarity solvents (n-hexane, diethyl ether, and chloroform) and the crude extract was purified with preparative thin layer chromatography (P-TLC). Identification, quantification and structure elucidation of purified compounds was performed by LC-DAD-ESI-MS and NMR (1H and 13C). P-TLC led purification yielded 18.6mg/g fucoxanthin with 97% of purity based on the calibration curve, in single-step purification. LC-ESI-MS (parent ion at m/z 641 [M+H-H2O]+) and NMR spectra confirmed that the purified band contained all-trans-fucoxanthin as the major compound. Purified fucoxanthin exhibited statistically similar (p>0.05) DPPH scavenging capacity (EC50: 12.9μg/mL) while the FRAP value (15.2μg trolox equivalent) was recorded lower (p<0.05) than the commercial fucoxanthin. The promising results of fucoxanthin purity, recovery and activity suggested that H. elongata seaweed has potential to be exploited as an alternate source for commercial fucoxanthin production.
Functional Ingredients from Algae for Foods and Nutraceuticals | 2013
Nissreen Abu-Ghannam; Gaurav Rajauria
Abstract: Micro and macro algae (seaweeds) represent a vastly under-utilized renewable resource characterized as being rich in a range of biological activities. In this chapter the focus will be primarily on antimicrobials extracted from seaweeds for possible applications in the food industry to enhance food safety and quality. The chapter initially outlines the effects of environmental and extraction conditions on influencing the efficacy of seaweed antimicrobials and in this regard highlights the importance of standardization of the methodologies employed. It then describes various antimicrobial susceptibility tests and the efficacy of seaweed extract on bacteria associated with food deterioration.
Botanica Marina | 2012
Shilpi Gupta; Nissreen Abu-Ghannam; Gaurav Rajauria
Abstract Probiotic fermentation was conducted on two species of edible Irish brown seaweeds, Saccharina latissima and Laminaria digitata as a sole source of nutrition for the bacteria. Seaweeds were heat treated followed by fermentation with the probiotic Lactobacillus rhamnosus. Kinetics of cell growth, acid production, and sugar consumption were examined. The effects of heating and fermentation on the changes in total phenolic content (TPC), total flavonoid content (TFC), and antioxidant activity were also monitored. Lactobacillus rhamnosus grew well on both the seaweed species and reached nearly 10 log cfu ml-1 after 16–24 h of fermentation; however, the specific growth rate was 1.5 times higher on S. latissima. Lactic acid was the major product of the fermentation, followed by acetic acid. Heat treatment resulted in a 50–64.4% reduction in TPC and TFC for both the seaweeds concomitant with a leaching of phytochemicals into the water used for heating. Subsequently, fermentation resulted in 28% and 37.6% increases in the TPC and 1.18- and 2.04-fold increases in TFC for S. latissima and Lam. digitata, respectively, with a simultaneous increase in the antioxidant activity as well. Changes in the TPC and TFC were represented by zero-, first-, or second-order kinetic models. Fourier transform infrared analysis of the seaweeds as well as the broth revealed the presence of polyphenolic signals at different ranges.
Journal of Pharmaceutical and Biomedical Analysis | 2018
Gaurav Rajauria
Graphical abstract Figure. No Caption available. HighlightsOptimization and validation of RP‐HPLC‐DAD method for seaweed polyphenols.Validation was based on calibration curve, linearity, LOD, LOQ and precision.7 polyphenols were identified by LC‐DAD‐ESI–MS/MS in Himanthalia elongata seaweed.Phloroglucinol was the major polyphenol followed by gallic acid in H. elongata.Purified fraction showed 146.9% higher antioxidant activity than the ascorbic acid. ABSTRACT A simple reverse phase‐high performance liquid chromatography (RP–HPLC) coupled to a diode array detector (DAD) and negative ion electrospray mass spectrometer (ESI–MS) method was developed for simultaneous identification and quantification of phenolic antioxidants in seaweed. The proposed method was validated in terms of linearity, limits of detection (LOD), limits of quantification (LOQ), recovery and intermediate precision. The calibration curves were linear with correlation coefficient ranging from 0.9909 to 0.9997 while the values of LOD (0.26–0.82 mg/L), LOQ (0.77–2.50 mg/L), recovery (≥97.2%) and precision in terms of retention time (%RSD ≤2.27) and peak area (% RSD ≤5.11) were satisfactory. Brown seaweed Himanthalia elongata used in this study was extracted with 60% methanol and the crude extract was cleaned with SPE (Solid Phase Extraction) cartridge. HPLC‐DAD‐MS/MS analysis of the SPE fraction allowed the identification of 7 phenolic compounds comprising phlorotannins, hydroxybenzoic acid, hydroxycinnamic acid and flavonols subclasses of polyphenols. Quantitative analysis of these compounds revealed the presence of phloroglucinol (394.1 ± 4.33 &mgr;g/g), gallic acid (96.3 ± 3.12 &mgr;g/g), chlorogenic acid (38.8 ± 1.94 &mgr;g/g), caffeic acid (44.4 ± 2.72 &mgr;g/g), ferulic acid (17.6 ± 0.85 &mgr;g/g), myricetin (8.6 ± 0.85 &mgr;g/g) and quercetin (4.2 ± 0.15 &mgr;g/g), in the extract. The SPE fraction were tested for antioxidant capacity which were significantly (P < 0.05) higher (EC50; 14.5 ± 0.57 mg/g) than the ascorbic acid (EC50; 35.8 ± 0.59 mg/g) and the crude extract (EC50; 46.3 ± 0.48 mg/g). The occurrence of all these phenolic antioxidant compounds in H. elongata extract suggested that the developed method is sensitive enough and reproducible and could be used for qualitative and quantitative assessment of polyphenols in seaweed.
Meat Science | 2017
Sarah K. Duffy; J. V. O'Doherty; Gaurav Rajauria; Louise C. Clarke; Kevin D. Cashman; Aoife Hayes; M.N. O'Grady; Joseph P. Kerry; A. K. Kelly
This study investigated the effects of cholecalciferol (vitamin D₃) supplementation on beef vitamin D activity, beef tenderness and sensory attributes. Thirty heifers were randomly allocated to one of three finishing dietary treatments [(T1) basal diet+0IU vitamin D₃; (T2) basal diet+2000IU vitamin D₃; and (T3) basal diet+4000IU vitamin D₃] for a 30day period pre-slaughter. Vitamin D₃ supplementation linearly increased serum 25-hydroxyvitamin D₃ (25-OH-D3) concentrations (R2=0.48), Longissimus thoracis (LT) total vitamin D activity (R2=0.78) as well as individually vitamin D₃ (R2=0.84) and 25-OH-D₃ (R2=0.75). The highest vitamin D₃ inclusion diet (T3) had a 42% increase (P<0.001) in LT vitamin D activity compared to the intermediate diet (T2) and a 145% increase over the lowest level diet (T1). Vitamin D₃ supplementation decreased LT shear (P<0.05) force values after 14days chilling. Sensory parameters were not affected (P>0.05). In conclusion, through short-term vitamin D₃ supplementation of cattle diets, beef vitamin D activity can successfully be enhanced.
Seaweed Sustainability#R##N#Food and Non-Food Applications | 2015
Gaurav Rajauria; Lynn Cornish; Francesco Ometto; Flower E. Msuya; Raffaella Villa
Abstract Algae are a diverse group of photosynthetic organisms that can easily grow in marine, fresh-, and wastewater environments. About 90% of marine plants are algae that efficiently convert carbon dioxide into sugars and oxygen, hence being responsible for more than 50% of the global carbon fixation and oxygen production. There are more than 200,000 different algal species, but only approximately 200 species are currently used worldwide in different sectors. Since algae produce a wide range of metabolites such as lipids (oil), proteins, carbohydrates (sugars), carotenoid pigments, minerals, vitamins, and bioactive polyphenols, they have been used as food, feed, and fertilizers for centuries. Recently, their potential for making ethanol or biodiesel has projected them as living-cell factories for the production of biofuels and various beneficial bioactives used in pharmaceuticals and cosmetics. This chapter outlines the potential of algae for food, feed, and fuel applications along with the importance of algal strain selection for individual applications.
Food Chemistry | 2018
Sarah K. Duffy; J. V. O'Doherty; Gaurav Rajauria; Louise C. Clarke; Aoife Hayes; Kirsten G. Dowling; M.N. O'Grady; Joseph P. Kerry; Jette Jakobsen; Kevin D. Cashman; A. K. Kelly
This study investigates dietary fortification of heifer feeds with cholecalciferol and ergocalciferol sources and effects on beef total vitamin D activity, vitamer, respective 25-hydroxymetabolite contents, and meat quality. Thirty heifers were allocated to one of three dietary treatments [(1) basal diet + 4000 IU of vitamin D3 (Vit D3); (2) basal diet + 4000 IU of vitamin D2 (Vit D2); and (3) basal diet + 4000 IU of vitamin D2-enriched mushrooms (Mushroom D2)] for a 30 day pre-slaughter period. Supplementation of heifer diets with Vit D3 yielded higher (p < 0.001) Longissimus thoracis (LT) total vitamin D activity (by 38-56%; p < 0.05) and serum 25-OH-D concentration (by 20-36%; p < 0.05), compared to that from Vit D2 and Mushroom D2 supplemented animals. Irrespective of vitamin D source, carcass characteristics, sensory and meat quality parameter were unaffected (p > 0.05) by the dietary treatments. In conclusion, vitamin D3 biofortification of cattle diets is the most efficacious way to enhance total beef vitamin D activity.