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Amido resistente obtido a partir de amido de leguminosas e de seus hidrolisados / Resistant starch from legumes starches and their hydrolysatesPolesi, Luis Fernando 28 August 2009 (has links)
O amido resistente (AR) é a fração do amido que não sofre a ação das enzimas digestivas, apresentando comportamento semelhante ao da fibra dietética. O objetivo do presente trabalho foi avaliar o teor e as características dos AR obtidos a partir dos amidos de ervilha e de grão-de-bico por diferentes processos de redução de massa molecular. Os amidos naturais ou gelatinizados foram submetidos a processos de hidrólise ácida (HCl 2 M por 2,5 h) ou enzimática (pululanase, 40 U/g por 10 h) previamente a um processo controle, que constou de tratamento hidrotérmico (autoclavagem a 121 °C por 30 min), refrigeração (4 °C por 24 h) e liofilização. O material produzido foi caracterizado quanto ao aspecto geral por microscopia eletrônica de varredura (MEV), teor de AR, teor de fibra dietética total (FDT), índice de absorção de água (IAA), índice de solubilidade em água (ISA), padrão de cristalinidade (difração de raios X), viscosidade (RVA - Rapid Visco Analyser) e propriedades térmicas (DSC - Differential Scanning Calorimeter). O teor de AR para o amido natural de ervilha e grãode- bico foi de 39,8 e 31,9 %, respectivamente. Nos amidos processados esse teor variou de 38,5 a 54,6 % para a ervilha e de 16,4 a 32,3 % para o grão-de-bico. Os melhores tratamentos para elevar o teor de AR foram o tratamento ácido (amido natural e gelatinizado) para o amido de ervilha e o tratamento enzimático (amido gelatinizado) para o amido de grão-de-bico. Os teores de FDT dos amidos processados de ervilha variaram de 22,9 a 37,1 % e foram superiores aos do grão-de-bico, que variaram entre 7,2 e 15,7 %. A MEV revelou a presença de grânulos inteiros ou não fragmentados nos amidos de ervilha dos diferentes tratamentos, enquanto os amidos de grão-de-bico tratados apresentaram apenas massa amorfa, sem a evidência de grânulos. Os padrões de cristalinidade dos amidos naturais foram tipo B e C, respectivamente para os amidos de ervilha e grão-de-bico, entretanto, os amidos processados de ambos apresentaram padrão do tipo B. Os amidos naturais apresentaram endotermas entre 56 e 90 °C, enquanto os amidos processados apresentaram endotermas em temperaturas superiores, entre 131 e 171 °C. A entalpia de gelat inização (H) dos amidos de ervilha processados foi superior à dos amidos de grão-de-bico. Os amidos natural e processados de ervilha, de modo geral, apresentaram viscosidade baixa (< 20 RVU) em RVA. O amido de grão-de-bico natural apresentou viscoamilograma bem definido, característico da fonte. Os amidos resistentes obtidos por hidrólise, de ambas as fontes, apresentaram redução na viscosidade em comparação com o controle. A viscosidade foi inversamente proporcional ao teor de AR nas amostras. A hidrólise e o processamento térmico promoveram o aumento no IAA e ISA dos amidos tratados. Os processos de hidrólises dos amidos de ervilha e de grão-de-bico podem elevar o teor de AR se comparados com o método controle. / Resistant starch (RS) is the fraction of starch that does not suffer the action of digestive enzymes, showing similar behavior to that of dietary fiber. The aim of this study was to evaluate the amounts and characteristics of RS obtained from chick-pea and high amylose pea starches using different processes of molecular weight reduction. The natural or pregelatinized starches were submitted to acid (2 M HCl for 2.5 h) or enzymatic (pullulanase, 40 U / g per 10 h) hydrolysis prior to a control process, which consisted of hydrothermal treatment (autoclaving at 121 ° C for 30 min), refrigeration (4 ° C for 24 h) and liophilization. The material was characterized as to the general appearance by scanning electron microscopy (SEM), RS content, total dietary fiber (TDF) content, water absorption index (WAI), water solubility index (WSI), crystallinity pattern (X-ray diffraction), viscosity (RVA - Rapid Visco Analyzer) and thermal properties (DSC - Differential Scanning Calorimeter). The RS content in pea and chick-pea natural starch was 39.8 and 31.9%, respectively. The processed starches showed contents ranging from 38.5 to 54.6% for pea and from 16.4 to 32.3% for chick-pea starch. The best treatments to raise the level of RS were the acid treatment (natural and gelatinized starch) for pea and the enzymic treatment (gelatinized starch) for chick-pea starch. The FDT amounts in processed pea starches ranged from 22.9 to 37.1% and were higher than those of chick-pea, which ranged between 7.2 and 15.7%. The photomicrographs in SEM revealed the presence of whole grains (not fragmented) in pea starches treatments, while the treated chick-pea starches showed only amorphous mass, without the evidence of granules. The cristallinity patterns of natural starches were B and C types, respectively for pea and chick-pea starch. Both processed starches, however, presented B type pattern. The natural starches showed endotherms between 56 and 90°C, while the processed starches showed endotherms at higher temperatures (131 and 171°C). The processed pea starches gelatinizati on enthalpy (H) was higher than those of processed chick-pea starches. The natural and processed pea starches, in general, showed low viscosity (<20 RVU) in RVA. The natural chick-pea starch presented viscoamylogram well defined, typical of this botanical source. The resistant starches obtained by hydrolysis showed in both sources, a decrease in viscosity compared to the control treatment. The viscosity was inversely proportional to the RS content in the samples. The hydrolysis and the thermal processing promoted an increase in WAI and WSI of treated starches. The hydrolysis process of pea and chickpea starches may raise the level of RS when compared to the control process.
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THERMAL, INTERFACIAL, AND APPLICATION PROPERTIES OF PEA PROTEIN MODIFIED WITH HIGH INTENSITY ULTRASOUNDKoosis, Aeneas 01 January 2019 (has links)
The overall objective of the study was to investigate different food ingredient conditions and ultrasound treatment on pea protein in terms of surface morphology and thermal characteristics. The motivation of this work was based on previous studies focusing on non-chemical physical modifications of plant proteins and the increasing demand for functional alternative proteins.
Ultrasonication time and amplitude, pH, protein concentration, and salt concentration all influenced the thermal and interfacial properties of pea protein. Ultrasound treatment altered the quaternary and tertiary structure of the storage protein and disrupted non-covalent bonds. The structural altercations and a reduction in particle size led to improved functionality.
For foams generated at pH 5.0 with 4% (w/v) ultrasound treated protein, the foams had acceptable capacity and stability even when high levels of sugar (5% sucrose) and salt (0.6 M) were incorporated. An acceptable angel food cake simulation can be achieved by replacing egg white with ultrasound treated pea protein. Color and loaf height were different, but similar texture profiles were achieved.
Ultrasound treatment significant improved the emulsifying capacity (up to 1.4 fold), emulsion stability, and creaming index compared to control samples (no ultrasound) over two weeks. The ultrasound treated emulsion yielded lower TBARS values, likely due to the change in exposed protein reactive groups.
These findings demonstrate that ultrasound processing is an effective nonchemical method to change the structural and physiochemical properties of pea protein. Pea protein processed with this method might allow for the functionality in a bakery, dressings, or beverage products, which is appealing to many consumers and manufacturers.
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Synbiot encapsulation employing a pea protein-alginate matrixKlemmer, Karla Jenna 29 March 2011
Probiotics and prebiotic are becoming increasingly important to consumers to alleviate issues surrounding gut health, despite the lack of definitive efficacy studies to support health claims. The addition of both probiotics and prebiotics to foods is challenging due to the harsh environmental conditions within the food itself and during transit through the gastrointestinal (GI) tract. To circumvent these challenges encapsulation technology is being explored to protect sensitive ingredients and to control their release within the lower intestines thereby maximizing the health benefiting effects. The overall goal of this research was to design a protein delivery capsule using phase separated pea protein isolate (PPI)-alginate (AL) mixtures for the entrapment of the synbiot which includes the probiotics, Bifidobacterium adolescentis, and the prebiotic, fructooligosaccharides (FOS), such that the capsule design provides highly effective protection and release within the GI tract. Research was carried out in three studies.<p>
In study 1, PPIn (native isolate) and AL interactions were studied in dilute aqueous solutions as a function of pH and biopolymer mixing ratio. Turbidimetric analysis and electrophoretic mobility during an acid titration was used to determine conditions where phase separation occurred. Critical structure forming events associated with the formation of soluble and insoluble complexes in a 1:1 PPIn-AL mixture were found to occur at pH 5.00 and 2.98, respectively, with optimal interactions occurring at pH 2.10. As the PPIn-AL ratio increased, critical pH values shifted towards higher pH until a mixing ratio between 4:1 and 8:1was reached, above which structure formation became independent of the ratios through to ratios of 20:1. Electrophoretic mobility measurements showed a similar trend, where the isoelectric point (pI) shifted from pH 4.00 (homogeneous PPIn) to pH 1.55 (1:1 PPIn-AL). As the ratio increased towards 8:1 PPIn-AL, net neutrality values shifted to higher pHs (~3.80) before becoming constant at higher ratios. Maximum coacervate formation occurred at a mixing ratio of 4:1. Based on these findings, capsule design by segregative phase separation was only used in future studies, due to the acidic nature associated with associative phase separation.<p>
In study 2, capsule formation using a native and commercial PPI was studied, and showed no difference between the two formulations during challenge experiments in simulated gastric juice (SGJ). As a result study 3 focused on optimization and characterization of capsules prepared using the commercial PPI. Capsule designs were investigated as a function of protein concentration, prebiotic level, and extrusion conditions (20 vs. 27 G needle) in order to determine protective ability for B. adolescentis within SGJ. Capsule designs were also measured in terms of protein and prebiotic retention during the encapsulation process, geometric mean diameter and size distribution, swelling behaviour and release characteristics within simulated intestinal fluids (SIF). All capsules provided adequate protection over the 2 h duration within SGJ. Capsule breakdown and release was similar for all designs within SIF, with a release mechanism believed to be tied to enzymatic degradation of the PPI material within the wall matrix and/or the amount of excessive Na+ present in the SIF. Capsule size was found to be dependent only on the needle gauge used in the extrusion process. Swelling behaviour of the capsules with SGJ was also found to be dependent only on the protein concentration, where capsules shrank once immersed in SGJ.<p>
A 2.0% PPI-0.5% AL capsule without FOS and extruded through a 20 G needle represents the best and most cost effective design for entrapping, protecting and delivering probiotic bacteria. Future work to establish the role FOS could play post-release as the entrapping probiotics colonize the GI tract, and the protective effect of the capsules wall on FOS structure during transit is recommended.
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Genetic analysis, QTL mapping and gene expression analysis of key visual quality traits affecting the market value of field peaUbayasena, Lasantha Chandana 15 April 2011
Visual quality is one of the major factors that determine the market value of field pea (Pisum sativum L.). Breeding for improved visual quality of pea seeds is currently a challenging task, because of the complexity and lack of sound genetic knowledge of the traits. The objectives of this research were to characterize the genetic basis and identify the genomic regions associated with four key visual quality traits (cotyledon bleaching in green pea, greenness in yellow pea, and seed shape and seed dimpling in both green and yellow types) in field pea. Biochemical and gene expression profiling to understand the molecular basis of post-harvest cotyledon bleaching in green pea was also addressed. Two F5:6 recombinant inbred line (RIL) populations (90 lines from Orb X CDC Striker cross, and 120 lines from Alfetta X CDC Bronco cross) were developed and evaluated for visual quality traits in two locations in Saskatchewan, Canada in 2006 and 2007. The four quality traits evaluated all displayed a continuous range of expression with moderate to high heritability. Two genetic linkage maps utilizing 224 markers (29 simple sequence repeat (SSR) (from Agrogene) and 195 amplified fragment length polymorphism (AFLP)) and 223 markers (27 SSR and 196 AFLP ) were constructed for the Orb X CDC Striker population and the Alfetta X CDC Bronco population, respectively. Multiple quantitative traits (QTL) mapping detected major QTLs on linkage group (LG) IV and LG V, as well as location- and year-specific QTLs on LG II and LG III associated with green cotyledon bleaching resistance. Nine QTLs controlling yellow seed lightness, three for yellow seed greenness, 15 for seed shape and nine for seed dimpling were detected. Among them, 5 QTLs located on LG II, LG IV and LG VII were consistent in at least two environments. The QTLs and their associated markers will be useful tools to assist pea breeding programs attempting to pyramid positive alleles for the traits. The bleaching resistant cultivar CDC Striker had a slower rate of chlorophyll degradation in cotyledons and a higher carotenoid to chlorophyll ratio in seed coats than the bleaching susceptible cultivar Orb when seed samples were exposed to high intensity light. An oligo-nucleotide microarray (Ps6kOLI1) was utilized to investigate the gene expression profiles of CDC Striker and Orb seed coats at different developmental stages. It clearly indicated that the expression of genes involved in the production and accumulation of secondary metabolites was significantly different between these cultivars. The results of both biochemical and gene expression studies suggested the bleaching resistance in CDC Striker was not due to the accumulation of chlorophyll pigments in the cotyledons, but rather due to the ability of seed coats to protect them from photooxidation. Accumulation of specific carotenoids which could bind with the reaction center protein complex more effectively and accumulation of phenolic secondary metabolites which could enhance the antioxidant properties and structural integrity of the seed coats may lead to the bleaching resistant phenotype. Therefore, breeding green pea cultivars with higher seed coat antioxidant properties would improve both visual and nutritional quality. This research has provided several insights into molecular approaches to improve field pea visual quality for food markets.
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The impact of lentil and field pea seeding rates on dinitrogen fixation and subsequent nitrogen benefits in an organic cropping systemUsukh, Boldsaikhan 15 April 2010
There is a demand for new recommendations for pulse seeding rates that will meet the needs of organic farmers. This study was conducted to determine the impact of seeding rate on N2 fixation and N accumulation in lentil and pea and to examine the impact of different seeding rates of lentil and pea on the productivity and N-uptake (i.e., N benefit) in a subsequent wheat crop.<p>
The study was performed between 2005 and 2007. Two sites were selected each year of the two-year experiment on certified organic farms in central Saskatchewan. At each location, lentil (<i>Lens culinaris</i> L.) cultivar CDC Sovereign and field pea (<i>Pisum sativum</i> L.) cultivar CDC Mozart were each seeded at five different rates. Wheat (<i>Triticum aestivum</i> L.) cultivar AC Elsa was sown as a non-fixing reference crop at a plant population density of 250 seeds m-2. In the following year, wheat was sown to assess the effect of the pulse seeding rate treatments on the succeeding crop.<p>
The pulse crop seeding rates significantly affected the quantity of N2 fixed of lentil and field pea, although %Ndfa (80 to 88% and 79 to 85% for lentil and pea, respectively) typically was unaffected by seeding rate. Yield parameters of following wheat crop were not affected by the seeding rates of the previous pulses. Typically, N contributions increased with increasing seeding rates of both lentil and pea, but there was no detectable difference in N uptake by the following wheat grown on the both pulse stubble.
The different seeding rates of organically grown lentil and field pea have impacts on the amount of N2 fixed and N contribution to the soil. However, the differences in N remaining in the soil at different seeding rates of the pulse crops were not detectable in the following wheat crop and the soil N in the following year.
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Role of green manure options in organic cropping systemsMarufu, Gift 22 June 2010
On the Canadian prairies, organic production generally includes the use of annual green manure (GrM) crops, which are terminated using tillage to add nutrients and organic matter to the soil. However, in a GrM plough-down year, farmers face loss of income. As an alternative to growing traditional GrM crops, legumes can be grown alone
or intercropped with cereals and harvested as green feed forage (GF) for use on-farm or for sale to other producers without depleting soil nitrogen (N) for the subsequent crop. We hypothesized that the GF system would have similar biomass, and N yield, and ultimately would return N into the soil. Furthermore, by intercropping a legume with a cereal, biological N2-fixation will be enhanced in the legume.<p>
Field experiments, conducted over two years, were established at Vonda and Delisle, Saskatchewan, Canada. The experiment was conducted using a randomized complete block design (RCBD) with 16 treatments and four replicates in which field pea
(<i>Pisum sativum</i> cv 40-10 silage pea), oat (<i>Avena sativa</i> L.cv AC Morgan), and triticale (X
<i>Triticosecale</i> Wittmack cv Pika) were grown alone or in combination and managed as GrM or GF. Wheat and tillage fallow served as cropped and uncropped controls, respectively. The tillage fallow-control system was tilled twice in the growing season using a small tractor disc. The intercropped oat was seeded at three densities (50, 100, and 150 plants m-2) to determine whether increasing cereal density stimulated N2-fixation in the field pea.<p>
The GrM system was sampled and incorporated (when the field pea was at full bloom) two weeks earlier than the GF system. Consequently, at both sites, all treatments in the GF system consistently yielded more dry matter and accumulated more N than treatments in the GrM system. At the Delisle site, where percent nitrogen derived from the atmosphere (%Ndfa) was compared, increasing cereal density did not increase N2-fixation in both management systems. However, pea in the GF system accumulated more
than twice the amount of N (kg ha-1) from fixation as compared to pea in the GrM system, presumably because of the longer growth period.<p>
Wheat grown following the GrM treatments produced more biomass and accumulated more N than wheat following the GF treatments. Wheat grown after the monoculture field pea as a GrM had greater
yield than all treatments. As well, the GrM system returned more N to the soil than did
the GF system. The extra two weeks of growth in the GF system resulted in the extraction of significant amounts of nutrients and probably moisture from the soil, which adversely affected yield and nutrient composition of the following wheat crop.<p>
Although organic farmers may lose income in the plough-down year, on a longterm soil sustainability basis, the GrM system is a better option than the GF system as it returns nutrients to the soil, thus providing improved plant biomass, and N accumulation of subsequent crops. However, organic farmers growing GF for hay may benefit from the increased productivity of this system on a short-term basis. Thus, farmers pursuing GF options may need to adopt other means of sustaining soil productivity on a longer term.
The tilled fallow-control system resulted in high amounts of biomass and N accumulation by the subsequent wheat crop, probably due to the fact that there were no nutrients taken up in the previous year and moisture was conserved in these treatments. However, this system may have less long-term benefits compared to the GrM regime, as no nutrients are returned through ploughing down a crop.
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Characterization and encapsulation of probiotic bacteria using a Pea-protein Alginate matrixKotikalapudi, Bhagya Lakshmi 24 September 2009
Research was undertaken to examine different <i>in vitro</i> characteristics of probiotic bacteria, including <i>Lactobacillus acidophilus</i> ATCC® 11975, <i>Bifidobacterium infantis</i> ATCC 15697D, <i>Bifidobacterium catenulatum</i> ATCC® 27675 and <i>Bifidobacterium adolescentis</i> ATCC® 15703 in order to identify suitable strain(s) for encapsulation. Under simulated gastric conditions (pH 2.0), <i>L. acidophilus</i> was the most acid-tolerant strain (D-value 10.2 ± 0.8 min), and was able to survive for 30 min; whereas, the other tested probiotics underwent a rapid (within the first 5 min at pH 2.0) 4-5 log colony forming units (cfu)/mL loss in viability. All probiotics tested were able to survive 5 h exposure to 0.3% Oxgall bile at pH 5.8. The relative ranking of probiotic adherence to Caco-2 cells was determined to be: <i>L. acidophilus</i> > <i>B. catenulatum</i> > <i>B. adolescentis</i> > <i>B. infantis</i>, which correlated with 4.5 104, 3.1 103, 2.6 101, and 1.5 101 cfu/mL associated with Caco-2 cell monolayers, respectively. The most hydrophobic probiotics included <i>L. acidophilus</i> (46.5 ± 6.1%) and B. catenulatum (65.5 ± 5.2%); their hydrophobicity were positively correlated with auto-aggregation ability. Addition of divalent cations, EDTA, and bile salts were found to affect hydrophobicity as well; for example, 0.5 mM MgCl2 resulted in a 20% increase in cell surface hydrophobicity of <i>L. acidophilus</i> from baseline levels; whereas, the addition of 0.1 and 0.5% bile salts decreased <i>L. acidophilus</i> hydrophobicity from control levels by 60 and 90%, respectively. Cell free culture supernatant of <i>L. acidophilus</i> effectively inhibited the growth of <i>Escherichia coli</i> O157:H7, and <i>Clostridium sordelli</i>. Bactericidal activity of <i>L. acidophilus</i> cell-free supernatant (the lethal factor was determined to be both heat and trypsin-resistant) against Escherichia coli O157:H7 and <i>Clostridium sordelli</i> ATCC 9714 over 24 h resulted in reductions of 5.5 and 3.5 log cfu/mL, respectively. Further examination of probiotics revealed varying degrees of resistance to the
iv antimicrobial agents ciprofloxacin (4 ìg/mL), naladixic acid (32 ìg/mL), kanamycin (64 ìg/mL) and sulfisoxazone (256 ìg/mL). Determination of carbon source utilization patterns indicated that <i>B. catenulatum</i> utilized a number of carbohydrates including -methyl-D-glucoside, D-xylose, D-cellobiose, and -D-lactose; whereas,<i>L. acidophilus, B. infantis</i>, and <i>B. adolescentis</i> utilized D-xylose. <i>Lactobacillus acidophilus</i> was ultimately selected for encapsulation in a 3 mm diameter pea protein-alginate matrix followed by <i>in vitro</i> challenge to simulated gastric conditions (pH 2.0). Encapsulation of <i>L. acidophilus</i> demonstrated a significant (P < 0.05) protective effect during the 2 h exposure to simulated acidic stomach conditions; within capsules, there was approximately 1 log cfu/mL loss in cell viability, whereas unprotected cells experienced > 6 log/mL loss in cell viability over the same period.
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Characterization and encapsulation of probiotic bacteria using a Pea-protein Alginate matrixKotikalapudi, Bhagya Lakshmi 24 September 2009 (has links)
Research was undertaken to examine different <i>in vitro</i> characteristics of probiotic bacteria, including <i>Lactobacillus acidophilus</i> ATCC® 11975, <i>Bifidobacterium infantis</i> ATCC 15697D, <i>Bifidobacterium catenulatum</i> ATCC® 27675 and <i>Bifidobacterium adolescentis</i> ATCC® 15703 in order to identify suitable strain(s) for encapsulation. Under simulated gastric conditions (pH 2.0), <i>L. acidophilus</i> was the most acid-tolerant strain (D-value 10.2 ± 0.8 min), and was able to survive for 30 min; whereas, the other tested probiotics underwent a rapid (within the first 5 min at pH 2.0) 4-5 log colony forming units (cfu)/mL loss in viability. All probiotics tested were able to survive 5 h exposure to 0.3% Oxgall bile at pH 5.8. The relative ranking of probiotic adherence to Caco-2 cells was determined to be: <i>L. acidophilus</i> > <i>B. catenulatum</i> > <i>B. adolescentis</i> > <i>B. infantis</i>, which correlated with 4.5 104, 3.1 103, 2.6 101, and 1.5 101 cfu/mL associated with Caco-2 cell monolayers, respectively. The most hydrophobic probiotics included <i>L. acidophilus</i> (46.5 ± 6.1%) and B. catenulatum (65.5 ± 5.2%); their hydrophobicity were positively correlated with auto-aggregation ability. Addition of divalent cations, EDTA, and bile salts were found to affect hydrophobicity as well; for example, 0.5 mM MgCl2 resulted in a 20% increase in cell surface hydrophobicity of <i>L. acidophilus</i> from baseline levels; whereas, the addition of 0.1 and 0.5% bile salts decreased <i>L. acidophilus</i> hydrophobicity from control levels by 60 and 90%, respectively. Cell free culture supernatant of <i>L. acidophilus</i> effectively inhibited the growth of <i>Escherichia coli</i> O157:H7, and <i>Clostridium sordelli</i>. Bactericidal activity of <i>L. acidophilus</i> cell-free supernatant (the lethal factor was determined to be both heat and trypsin-resistant) against Escherichia coli O157:H7 and <i>Clostridium sordelli</i> ATCC 9714 over 24 h resulted in reductions of 5.5 and 3.5 log cfu/mL, respectively. Further examination of probiotics revealed varying degrees of resistance to the
iv antimicrobial agents ciprofloxacin (4 ìg/mL), naladixic acid (32 ìg/mL), kanamycin (64 ìg/mL) and sulfisoxazone (256 ìg/mL). Determination of carbon source utilization patterns indicated that <i>B. catenulatum</i> utilized a number of carbohydrates including -methyl-D-glucoside, D-xylose, D-cellobiose, and -D-lactose; whereas,<i>L. acidophilus, B. infantis</i>, and <i>B. adolescentis</i> utilized D-xylose. <i>Lactobacillus acidophilus</i> was ultimately selected for encapsulation in a 3 mm diameter pea protein-alginate matrix followed by <i>in vitro</i> challenge to simulated gastric conditions (pH 2.0). Encapsulation of <i>L. acidophilus</i> demonstrated a significant (P < 0.05) protective effect during the 2 h exposure to simulated acidic stomach conditions; within capsules, there was approximately 1 log cfu/mL loss in cell viability, whereas unprotected cells experienced > 6 log/mL loss in cell viability over the same period.
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The impact of lentil and field pea seeding rates on dinitrogen fixation and subsequent nitrogen benefits in an organic cropping systemUsukh, Boldsaikhan 15 April 2010 (has links)
There is a demand for new recommendations for pulse seeding rates that will meet the needs of organic farmers. This study was conducted to determine the impact of seeding rate on N2 fixation and N accumulation in lentil and pea and to examine the impact of different seeding rates of lentil and pea on the productivity and N-uptake (i.e., N benefit) in a subsequent wheat crop.<p>
The study was performed between 2005 and 2007. Two sites were selected each year of the two-year experiment on certified organic farms in central Saskatchewan. At each location, lentil (<i>Lens culinaris</i> L.) cultivar CDC Sovereign and field pea (<i>Pisum sativum</i> L.) cultivar CDC Mozart were each seeded at five different rates. Wheat (<i>Triticum aestivum</i> L.) cultivar AC Elsa was sown as a non-fixing reference crop at a plant population density of 250 seeds m-2. In the following year, wheat was sown to assess the effect of the pulse seeding rate treatments on the succeeding crop.<p>
The pulse crop seeding rates significantly affected the quantity of N2 fixed of lentil and field pea, although %Ndfa (80 to 88% and 79 to 85% for lentil and pea, respectively) typically was unaffected by seeding rate. Yield parameters of following wheat crop were not affected by the seeding rates of the previous pulses. Typically, N contributions increased with increasing seeding rates of both lentil and pea, but there was no detectable difference in N uptake by the following wheat grown on the both pulse stubble.
The different seeding rates of organically grown lentil and field pea have impacts on the amount of N2 fixed and N contribution to the soil. However, the differences in N remaining in the soil at different seeding rates of the pulse crops were not detectable in the following wheat crop and the soil N in the following year.
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Role of green manure options in organic cropping systemsMarufu, Gift 22 June 2010 (has links)
On the Canadian prairies, organic production generally includes the use of annual green manure (GrM) crops, which are terminated using tillage to add nutrients and organic matter to the soil. However, in a GrM plough-down year, farmers face loss of income. As an alternative to growing traditional GrM crops, legumes can be grown alone
or intercropped with cereals and harvested as green feed forage (GF) for use on-farm or for sale to other producers without depleting soil nitrogen (N) for the subsequent crop. We hypothesized that the GF system would have similar biomass, and N yield, and ultimately would return N into the soil. Furthermore, by intercropping a legume with a cereal, biological N2-fixation will be enhanced in the legume.<p>
Field experiments, conducted over two years, were established at Vonda and Delisle, Saskatchewan, Canada. The experiment was conducted using a randomized complete block design (RCBD) with 16 treatments and four replicates in which field pea
(<i>Pisum sativum</i> cv 40-10 silage pea), oat (<i>Avena sativa</i> L.cv AC Morgan), and triticale (X
<i>Triticosecale</i> Wittmack cv Pika) were grown alone or in combination and managed as GrM or GF. Wheat and tillage fallow served as cropped and uncropped controls, respectively. The tillage fallow-control system was tilled twice in the growing season using a small tractor disc. The intercropped oat was seeded at three densities (50, 100, and 150 plants m-2) to determine whether increasing cereal density stimulated N2-fixation in the field pea.<p>
The GrM system was sampled and incorporated (when the field pea was at full bloom) two weeks earlier than the GF system. Consequently, at both sites, all treatments in the GF system consistently yielded more dry matter and accumulated more N than treatments in the GrM system. At the Delisle site, where percent nitrogen derived from the atmosphere (%Ndfa) was compared, increasing cereal density did not increase N2-fixation in both management systems. However, pea in the GF system accumulated more
than twice the amount of N (kg ha-1) from fixation as compared to pea in the GrM system, presumably because of the longer growth period.<p>
Wheat grown following the GrM treatments produced more biomass and accumulated more N than wheat following the GF treatments. Wheat grown after the monoculture field pea as a GrM had greater
yield than all treatments. As well, the GrM system returned more N to the soil than did
the GF system. The extra two weeks of growth in the GF system resulted in the extraction of significant amounts of nutrients and probably moisture from the soil, which adversely affected yield and nutrient composition of the following wheat crop.<p>
Although organic farmers may lose income in the plough-down year, on a longterm soil sustainability basis, the GrM system is a better option than the GF system as it returns nutrients to the soil, thus providing improved plant biomass, and N accumulation of subsequent crops. However, organic farmers growing GF for hay may benefit from the increased productivity of this system on a short-term basis. Thus, farmers pursuing GF options may need to adopt other means of sustaining soil productivity on a longer term.
The tilled fallow-control system resulted in high amounts of biomass and N accumulation by the subsequent wheat crop, probably due to the fact that there were no nutrients taken up in the previous year and moisture was conserved in these treatments. However, this system may have less long-term benefits compared to the GrM regime, as no nutrients are returned through ploughing down a crop.
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