• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 105
  • 32
  • 19
  • 17
  • 7
  • 6
  • 6
  • 3
  • 1
  • 1
  • 1
  • Tagged with
  • 259
  • 36
  • 23
  • 21
  • 19
  • 18
  • 18
  • 16
  • 13
  • 13
  • 12
  • 12
  • 12
  • 12
  • 12
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
181

Stellar populations in the Green Pea galaxy J1457+2232 : Study of possible age gradients by using highly resolved HST broad band imaging of the Green Peagalaxy SDSS-J145735.13+223201.8 at redshift 0.15.

Malmgren, Jan January 2019 (has links)
Abstract In this report I present a study of possible age gradients in the Green Pea galaxy J145735.13+223201.8 to be able to conclude if there is an extended star forming history in such a galaxy. Data are coming from two different sources, highly resolved images in four different wavelengths of stars in the galaxy, and of nebular gas in a narrow band Ha Balmer line filter, from the Hubble Space Telescope (HST), as well as spectral line information from the Sloan Digital Sky Survey (SDSS). I compare the observations with stellar population models from two different libraries, Yggdrasil and Starburst99. Due to the highly resolved images from HST this is one of the first studies of spatially resolved stellar populations in a Green Pea galaxy. With the help from these spatially resolved images it was possible to study star clumps independently from each other. This would not be possible when using only data from SDSS. In this way it was possible to conclude an age difference between the centre of the galaxy and its outskirts. I found that the galaxy has an age gradient at a confidence level greater than 95%.
182

Carotenóides e composição centesimal de ervilhas (Pisum sativum L.) cruas e processadas / Carotenoids and centesimal composition of raw and cooked peas (Pisum sativum L.)

Carvalho, Otilia Teixeira de 10 September 2007 (has links)
A ervilha é um dos alimentos mais produzidos no mundo e, conseqüentemente, tem uma grande importância para a nutrição humana, sendo comercializada sob várias formas: fresca, seca, congelada e enlatada, necessitando de cozimento antes de ser consumida. Sendo assim, podem ocorrer alterações em sua composição durante esses processamentos. O presente trabalho teve como objetivos avaliar as mudanças ocorridas devido ao processamento na composição centesimal e no perfil de carotenóides em ervilhas frescas (tortas - com vagem comestível - e em grão), secas e enlatadas e relacionar esses dados com sua origem e safra. Foram analisados seis lotes de ervilhas tortas provenientes de duas regiões produtoras (cruas e cozidas por 5 minutos), três lotes de ervilhas frescas (cruas e cozidas por 7 minutos), dois lotes de ervilhas enlatadas (processadas e sua matéria-prima) e três lotes de ervilhas secas (cruas e cozidas por 35 minutos). A umidade em ervilhas tortas diferiu entre safras e regiões produtoras e em ervilhas em grão, aumentou após o cozimento em duas amostras e variou entre safras. O cozimento ocasionou perdas nos teores de Resíduo Mineral Fixo (RMF) em ervilhas em grão e secas. Em ervilhas enlatadas, o processamento causou aumento da umidade e RMF, devido à incorporação de água e sais. Os carotenóides encontrados foram a luteína, o β-caroteno e traços de violaxantina. O perfil de carotenóides em ervilhas tortas, em grão e secas não se alterou após o cozimento, já o enlatamento revelou um aumento aparente no teor de luteína em apenas um dos lotes estudados. Os teores de luteína e β-caroteno variaram entre as diferentes épocas de coleta de ervilhas tortas, em grão e secas, porém não foi observada variação entre as duas regiões produtoras de ervilhas tortas. Os teores de luteína variaram entre as matérias-primas dos diferentes fornecedores de ervilhas enlatadas. Apenas o β-caroteno possui atividade pró-vitamínica A, porém está presente em quantidade insuficiente para fazer das ervilhas fontes desse nutriente. / Pea is one of the world\'s most produced foods and therefore has great importance for human nutrition, being commercialized under different conditions: fresh, dried, frozen and canned, and further cooking is needed before being consumed. As a result, processing can cause some changes in its composition. The aim of the present work was to evaluate the changes in the centesimal composition and carotenoids profile of garden peas, snow peas, dry peas and canned peas due to processing and to compare these data according to geographic origin and crop. Six batches of snow peas from two different regions (raw and cooked for 5 min), three batches of garden peas (raw and cooked for 7 min), two batches of canned peas (processed and raw material) and three batches of dry peas (raw and cooked for 35 min) were analyzed. Water content in snow peas differed between crops and region and, in garden peas, it increased after cooking and varied between crops. Cooking caused losses in the ash content of garden and dry peas. In canned peas, processing increased water and ash contents due to absorption of water and salt. Lutein, β-carotene and traces of violaxanthin were identified in all samples. Carotenoids profile of snow, garden and dry peas did not change after cooking while canning caused an apparent increase in lutein contents only in one batch. Snow, garden and dry peas showed differences in lutein and β-carotene amount due to crops, though different regions revealed not to influence snow peas carotenoids content. The raw material from two suppliers of canned peas differed in their content of lutein. Only β-carotene is a pro-vitamin A carotenoid, however it was found in such small quantities that peas can not be considered source of this nutrient.
183

Textural, Color and Sensory Attributes of Fruits and Vegetables Dried Using Electric Forced-Air and Solar Dehydrators

Crossen, Edward Wayne 01 March 2017 (has links)
Direct sun drying is one of the oldest methods of food preservation. A drying method that utilizes solar energy while minimizing negative aspects of sun drying is a solar dryer. However, research about the quality characteristics of fruits and vegetables dried using a solar dryer compared to a traditional dryer is lacking. To measure this, apple, tomato and carrot slices, and grape halves and whole peas were prepared and dried using either a solar or FA dehydrator (FA), Consumer liking was measured using two sensory panels that asked panelists 9-point hedonic questions between like products. Quality differences were analyzed using a TA.XT2 texture analyzer. Color was measured using a Hunterlab colorimeter. There were no significant differences in consumer liking (p<0.05) between drying methods for any fruits and vegetables with regards to overall acceptability. Grapes, tomatoes and carrots all had significant differences in consumer liking with regards to appearance, which correlates well with observed differences in a* values. Consumers liked the aroma of solar-dried peas significantly more. The texture of FA grapes was liked significantly more than their solar counterparts, which likely contributed to consumers significantly ranking the FA grapes higher than their solar counterparts when asked to rank which one they prefer.
184

Associative phase separation in admixtures of pea protein isolates with gum Arabic and a canola protein isolate with i-carrageenan and alginate

Klassen, Darlene Renae 28 June 2010
The overall goal of this thesis is to better understand mechanisms governing associative phase separation within admixtures of plant proteins (e.g., pea and canola) and anionic polysaccharides (e.g., gum Arabic, alginate or é-carrageenan). The process involves the electrostatic attraction between two biopolymers of opposing charges, and typically results in the formation of both soluble and insoluble complexes during an acidic pH titration. If successful, polysaccharides could be triggered to coat the proteins surface to give novel, and hopefully improved functionality as ingredients for food and biomaterials.<p> In the first study, the effect of protein enrichment and pH on the formation of soluble and insoluble complexes in admixtures of pea legumin (Lg) and vicilin (Vn) isolates with gum Arabic (GA) was investigated by turbidimetric, surface charge and fluorometric measurements. The solubility of the protein isolates and mixed biopolymer systems was also studied as a function of pH. Enrichment of the crude Lg and Vn isolates by low pressure liquid chromatography led to a shift towards higher pHs at the onset of soluble complex formation in the presence of GA for both protein isolates, whereas the onset of insoluble complex formation was unaffected. Complexation of the Lg (or Vn) isolates with GA resulted in a shift in the pH where neutrality (zeta potential = 0 mV) occurred to lower pH values, relative to the Lg (or Vn) isolates alone. In the case of the enriched Vn isloate, changes to its tertiary structure were observed by fluorometry upon complexation with GA, whereas no changes were found for the enriched Lg isolate. Complexation of Lg and Vn isolates with GA also had little effect on their solubilities relative to protein alone solutions.<p> In the second study, the formation of soluble and insoluble complexes, and the nature of their interactions as determined by optical density analysis, were investigated in admixtures of canola protein isolate (CPI) and anionic polysaccharides (alginate and é-carrageenan) as a function of pH and biopolymer weight mixing ratio. The solubilities of formed complexes were also investigated versus protein alone. In both CPI-polysaccharide systems, critical pH associated with the onset of soluble and insoluble complexes shifted to higher pHs as the mixing ratios increased from 1:1 to 20:1 (CPI:polysaccharide), and then became constant. There complexes formed primarily through electrostatic attractive forces with secondary stabilization by hydrogen bonding. The solubilities of the CPI-alginate complexes were significantly enhanced relative to CPI alone or CPI-é-carrageenan, which were similar.
185

Determining optimum plant population densities for three annual green manure crops under weedy and weed-free conditions

Lawley, Yvonne 22 December 2004
Green manure crops are critical to maintaining soil fertility in organic cropping systems. However, little research has been conducted to address their contribution to weed control. Indianhead black lentil (Lens culinaris Medikus), AC Green Fix chickling vetch (Lathyrus sativus L.), and Trapper field pea (Pisum sativum L.) are legumes developed for use as annual green manure crops in the Northern Great Plains. Currently, no plant population density recommendations exist for these three species when grown as green manure crops under weedy conditions. The objective of this research was to determine the yield-density response of these three species under weedy and weedy-free conditions and to develop plant population density recommendations for use as annual green manure crops. Each species was grown at five plant population densities (10, 24, 64, 160, and 400 plants m-2) with weedy and weed-free treatments. Wild oat (Avena fatua L.) and wild mustard (Brassica kaber (D.C.) L.C. Wheeler) were planted in weedy treatments to supplement the natural weed community. Biomass samples and soil moisture measurements were taken at early bud and full bloom to simulate when these crops would be terminated. Biomass samples from the early bud stage were analysed for total nitrogen content. Green manure biomass production for all species was lower under weedy conditions. Weed biomass in weedy treatments decreased with increasing green manure plant population density for all species. Trapper field pea was the most competitive crop while Indianhead black lentil was the least competitive. Although total plot biomass differed among species and green manure crop density, changes in soil moisture levels were not greatly affected. No significant difference in total nitrogen concentration was found among green manure species. Differences in total nitrogen accumulation occurred because of differences in biomass production. Marginal cost analysis based on green manure seed costs and their nitrogen contribution to the value of subsequent wheat crop yield were used to determine optimum plant population densities. Under weedy conditions field pea and black lentil should be planted at densities of 49-78 and 223-300 plants m-2, respectively. Under weed-free conditions plant population densities for field pea and black lentil could be reduced to 45-60 and 184-223 plants m-2, respectively. No profitable plant population density was determined for chickling vetch when assuming a lower nitrogen contribution under both weedy and weed-free conditions. However, when assuming a higher nitrogen contribution, a profitable plant population density for chickling vetch of 24 plants m-2 was determined under weedy conditions and 32 plants m-2 under weed-free conditions.
186

Determining optimum plant population densities for three annual green manure crops under weedy and weed-free conditions

Lawley, Yvonne 22 December 2004 (has links)
Green manure crops are critical to maintaining soil fertility in organic cropping systems. However, little research has been conducted to address their contribution to weed control. Indianhead black lentil (Lens culinaris Medikus), AC Green Fix chickling vetch (Lathyrus sativus L.), and Trapper field pea (Pisum sativum L.) are legumes developed for use as annual green manure crops in the Northern Great Plains. Currently, no plant population density recommendations exist for these three species when grown as green manure crops under weedy conditions. The objective of this research was to determine the yield-density response of these three species under weedy and weedy-free conditions and to develop plant population density recommendations for use as annual green manure crops. Each species was grown at five plant population densities (10, 24, 64, 160, and 400 plants m-2) with weedy and weed-free treatments. Wild oat (Avena fatua L.) and wild mustard (Brassica kaber (D.C.) L.C. Wheeler) were planted in weedy treatments to supplement the natural weed community. Biomass samples and soil moisture measurements were taken at early bud and full bloom to simulate when these crops would be terminated. Biomass samples from the early bud stage were analysed for total nitrogen content. Green manure biomass production for all species was lower under weedy conditions. Weed biomass in weedy treatments decreased with increasing green manure plant population density for all species. Trapper field pea was the most competitive crop while Indianhead black lentil was the least competitive. Although total plot biomass differed among species and green manure crop density, changes in soil moisture levels were not greatly affected. No significant difference in total nitrogen concentration was found among green manure species. Differences in total nitrogen accumulation occurred because of differences in biomass production. Marginal cost analysis based on green manure seed costs and their nitrogen contribution to the value of subsequent wheat crop yield were used to determine optimum plant population densities. Under weedy conditions field pea and black lentil should be planted at densities of 49-78 and 223-300 plants m-2, respectively. Under weed-free conditions plant population densities for field pea and black lentil could be reduced to 45-60 and 184-223 plants m-2, respectively. No profitable plant population density was determined for chickling vetch when assuming a lower nitrogen contribution under both weedy and weed-free conditions. However, when assuming a higher nitrogen contribution, a profitable plant population density for chickling vetch of 24 plants m-2 was determined under weedy conditions and 32 plants m-2 under weed-free conditions.
187

Associative phase separation in admixtures of pea protein isolates with gum Arabic and a canola protein isolate with i-carrageenan and alginate

Klassen, Darlene Renae 28 June 2010 (has links)
The overall goal of this thesis is to better understand mechanisms governing associative phase separation within admixtures of plant proteins (e.g., pea and canola) and anionic polysaccharides (e.g., gum Arabic, alginate or é-carrageenan). The process involves the electrostatic attraction between two biopolymers of opposing charges, and typically results in the formation of both soluble and insoluble complexes during an acidic pH titration. If successful, polysaccharides could be triggered to coat the proteins surface to give novel, and hopefully improved functionality as ingredients for food and biomaterials.<p> In the first study, the effect of protein enrichment and pH on the formation of soluble and insoluble complexes in admixtures of pea legumin (Lg) and vicilin (Vn) isolates with gum Arabic (GA) was investigated by turbidimetric, surface charge and fluorometric measurements. The solubility of the protein isolates and mixed biopolymer systems was also studied as a function of pH. Enrichment of the crude Lg and Vn isolates by low pressure liquid chromatography led to a shift towards higher pHs at the onset of soluble complex formation in the presence of GA for both protein isolates, whereas the onset of insoluble complex formation was unaffected. Complexation of the Lg (or Vn) isolates with GA resulted in a shift in the pH where neutrality (zeta potential = 0 mV) occurred to lower pH values, relative to the Lg (or Vn) isolates alone. In the case of the enriched Vn isloate, changes to its tertiary structure were observed by fluorometry upon complexation with GA, whereas no changes were found for the enriched Lg isolate. Complexation of Lg and Vn isolates with GA also had little effect on their solubilities relative to protein alone solutions.<p> In the second study, the formation of soluble and insoluble complexes, and the nature of their interactions as determined by optical density analysis, were investigated in admixtures of canola protein isolate (CPI) and anionic polysaccharides (alginate and é-carrageenan) as a function of pH and biopolymer weight mixing ratio. The solubilities of formed complexes were also investigated versus protein alone. In both CPI-polysaccharide systems, critical pH associated with the onset of soluble and insoluble complexes shifted to higher pHs as the mixing ratios increased from 1:1 to 20:1 (CPI:polysaccharide), and then became constant. There complexes formed primarily through electrostatic attractive forces with secondary stabilization by hydrogen bonding. The solubilities of the CPI-alginate complexes were significantly enhanced relative to CPI alone or CPI-é-carrageenan, which were similar.
188

Harmfulness of field pea (Pisum sativum L.) fungal diseases, their prevention and control / Sėjamojo žirnio (Pisum sativum L.) grybinių ligų žalingumas, jų prevencija ir kontrolė

Česnulevičienė, Rūta 23 November 2012 (has links)
Research objective and experimental tasks. The study was designed to explore the incidence and severity of root and foot rots and ascochyta blight in field pea crops and to identify the measures and practices for the prevention and control of the diseases caused by the pathogens of Ascochyta complex. Experimental tasks: - To identify the susceptibility of various field pea varieties to root and foot rots and ascochyta blight under different agro-ecological conditions. - To establish the effect of meteorological factors on the severity of root and foot rots and ascochyta blight in field pea crops. - To determine the frequency of detection of pathogens of Ascochyta complex on various pea varieties. - To estimate the feasibility of control of the diseases caused by the pathogens of Ascochyta complex using seed treatment and fungicide application. - To assess the impact of seed treatment and fungicide application on field pea productivity and yield components. - To study the possible side-effect of the chemical seed treatment on the microflora of pea rhizosphere and soil. / Tyrimų tikslas ir uždaviniai. Tyrimais siekta ištirti šaknų, pašaknio puvinių ir askochitozės išplitimą bei žalingumą sėjamojo žirnio pasėliuose, nustatyti Ascochyta komplekso patogenų sukeliamų ligų prevencijos ir kontrolės priemones. Tyrimų uždaviniai: - Nustatyti įvairių sėjamojo žirnio veislių jautrumą šaknų, pašaknio puviniams ir askochitozei skirtingomis agroekologinėmis sąlygomis. - Nustatyti meteorologinių faktorių įtaką šaknų, pašaknio puvinių ir askochitozės intensyvumui žirniuose. - Nustatyti Ascochyta komplekso patogenų aptikimo dažnį ant įvairių veislių žirnių. - Įvertinti Ascochyta komplekso patogenų sukeliamų ligų kontrolės galimybę naudojant beicus ir fungicidus. - Įvertinti beicų ir fungicidų įtaką žirnių derlingumui ir derliaus komponentams. - Ištirti galimą cheminių beicų šalutinį poveikį žirnių rizosferos bei dirvožemio mikroflorai.
189

Pea protein - volatile compound interactions: effects of binding, heat and extraction on protein functionality

Tiessen-Dyck, Melissa 19 August 2014 (has links)
Binding of volatile flavour compounds to plant proteins is known to be an issue, particularly for developers of flavoured gluten-free snacks made with pea protein. This project used a model system to describe the effects of extraction and heat on the binding of hexanal (Hex), hexyl acetate (HxAc) and 2-octanone (2-Oct) to pea protein isolate and to evaluate any resulting change in protein functionality.
190

Iron bioavailability in low phytate pea

2014 April 1900 (has links)
Field pea (Pisum sativum L.) seeds have high nutritional value but also contain phytate which can inhibit the absorption and utilization of nutrients. Phytate is the main storage form of phosphorus in the seeds but chelates Fe, Zn and some other micronutrients and is not well digested by monogastrics. Peas with pigmented seed coats contain polyphenols which also have anti-nutritional properties. To increase the nutritional value of field pea seeds, two low phytate lines (1-150-81 and 1-2347-144) containing higher inorganic phosphorus concentration (IN-P) and lower phytate-phosphorus concentration (PA-P) than the normal phytate varieties were developed from CDC Bronco in previous research. The objectives of this research were 1) to determine the effect of genotype and environment on iron bioavailability in a set of five pea varieties differing in phytate concentration and iron concentration using in vitro digestion/Caco-2 cell culture bioassay; 2) to determine the effect of seed coats on iron bioavailability by testing whole seeds compared to dehulled seeds in varieties differing in seed coat pigmentation using in vitro digestion/Caco-2 cell culture bioassay; 3) to determine the inheritance of iron bioavailability in field pea by evaluating recombinant inbred lines differing in phytate concentration using in vitro digestion/Caco-2 cell culture bioassay; 4) to determine the effects of pea with the low phytate trait on body weight and hemoglobin concentration of chickens. Iron concentration (FECON) did not differ significantly between normal and low phytate varieties. Iron bioavailability (FEBIO) of the two low-phytate lines was 1.4 to 1.9 times higher than that of the three normal phytate varieties, and growing environment also had a significant effect on FEBIO. Peas with pigmented seed coats contained 7 times lower FEBIO than peas with non-pigmented seed coat. The removal of the seed coat increased the FEBIO in peas with pigmented seed coat 5 to 6 times. From previous research on PR-15 recombinant inbred lines (RILs) which were developed from a cross between low phytate line 1-2347-144 and a normal phytate variety CDC Meadow, it was found that PA-P was controlled by a single gene. FEBIO, in this study, was also found to follow a bimodal frequency distribution, characteristic of single gene control, and it was highly correlated with PA-P in the PR-15 lines. In vivo studies were used to evaluate iron absorption of chickens fed with low and normal phytate pea diets. The diets containing the low-phytate pea lines had no significant effect on chicken body weight and hemoglobin level, compared with the diets containing normal phytate pea varieties. An unexpected high FECON was discovered in the diets that was traced to the ingredients of limestone and dicalcium-phosphate which likely affected the experimental results.

Page generated in 0.045 seconds