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Starch Content (starch + content)

Distribution by Scientific Domains

Life Sciences	42%
Chemistry	42%
Earth and Environmental Science	10%

Selected Abstracts

Characterizing diversity in composition and pasting properties of tuber flour in yam germplasm (Dioscorea spp.) from Southern Ethiopia

JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 10 2008
Muluneh Tamiru
Abstract BACKGROUND: Studies on composition and functional properties in germplasm collections are important in determining their diversity and suitability for food and non-food applications. The diversity in 65 yam accessions collected from Southern Ethiopia and belonging largely to a yet unknown species and to Dioscorea bulbifera L. (aerial yam) was analyzed based on protein, starch and amylose contents, and pasting properties of tuber flour, applying descriptive and multivariate statistics. RESULT: Starch content varied from 65.2% to 76.6% dry matter, while the protein content range was 6.4,13.4% dry matter. Amylose represented between 7.1% and 30.6% of the starch fraction, and was negatively correlated (P < 0.01) with starch content. UPGMA clustering and principal component analysis clearly distinguished aerial yam from those accessions with underground tubers. The first four principal components accounted for 78% of the total variability, and were highly correlated with pasting parameters. CONCLUSION: The extent of diversity detected among accessions studied showed scope for improving the crop through selection of landraces with desirable characteristics. Similar investigations on tubers grown under different environmental conditions and additional data on physicochemical properties of isolated starch will be useful in evaluating the potential of yam for food and non-food applications. Copyright © 2008 Society of Chemical Industry [source]

White-core endosperm floury endosperm-4 in rice is generated by knockout mutations in the C4 -type pyruvate orthophosphate dikinase gene (OsPPDKB)

THE PLANT JOURNAL, Issue 6 2005
Hong-Gyu Kang
Summary We have isolated a floury endosperm-4 (flo4) rice mutant with a floury-white endosperm but a normal outer portion. Scanning electron microscopic analysis revealed that this abnormal endosperm consisted of loosely packed starch granules. The mutant phenotype was generated by T-DNA insertion into the fifth intron of the OsPPDKB gene encoding pyruvate orthophosphate dikinase (PPDK). Plants containing flo4-1 produced no OsPPDKB transcript or the OsPPDKB protein in their developing kernels and leaves. We obtained two additional alleles, flo4-2 and flo4-3, that also showed the same white-core endosperm phenotype. The flo4 kernels weighed about 6% less than wild-type ones. Starch contents in both kernel types were similar, but the total protein content was slightly higher in the mutant kernels. Moreover, lipid contents were significantly increased in the flo4 kernels. Expression analyses demonstrated that the cytosolic mRNA of OsPPDKB was induced in the reproductive organs after pollination, and greatly increased until about 10 days after fertilization. This mRNA was localized mainly in the endosperm, aleurone, and scutellum of the developing kernel. Our results suggest that cytosolic PPDK functions in rice to modulate carbon metabolism during grain filling. [source]

Agronomic factors affecting the yield and quality of forage maize in Ireland: effect of sowing date and plastic film treatment

GRASS & FORAGE SCIENCE, Issue 1 2002
G. P. Keane
The objectives of these studies were to examine the effects of sowing date and plastic film on the yield and quality of forage maize (Zea mays L.) in Ireland, a marginal maize-growing area. In 1989,95, comparisons were made of maize sown through clear plastic film (PP treatment), and maize sown in the conventional manner without plastic (NP treatment), in terms of dry-matter (DM) yield and quality (cob, grain and starch contents). The PP treatment significantly increased DM yields in five years, with a mean yield increase of 3·10 t ha,1. Whole-plant DM content increased (significant in four years) by a mean of 0·15; cob content increased (significant in five years) by a mean of 0·32; grain content increased (significant in all of the three years examined) by 0·75; and starch content increased from 236 to 318 g kg,1 DM (P < 0·01) in 1995 where the plastic film treatment was used. Organic matter digestibility values were similar for both treatments in 1995. Sowing date in the April-May period had no consistent effect on DM yields, but early sowings did increase cob (significant, except in 1994), grain (significant in one (1995) of the two years tested) and starch (P < 0·05) contents (only tested in 1995). Sowing on 11 April 1995 through perforated plastic gave lower yields than the NP treatment sown on the same date, due to severe frost damage in early May. [source]

Effects of oat processing on the glycaemic and insulin responses in horses

JOURNAL OF ANIMAL PHYSIOLOGY AND NUTRITION, Issue 3-4 2003
I. Vervuert
Summary This study was conducted to evaluate the effects of different oat processing techniques on the plasma glucose and insulin response in horses. In a cross-over design, six horses (ages 4,15 years, mean body weight ± SD: 450 ± 37 kg) were fed in random order: untreated oats, finely ground, steam-flaked and popped oats. The total oat intake varied between 1.05,1.5 kg/day, and the amount of diet was adjusted to a starch content of 630 g starch per day and horse (1.2,1.5 g starch/kg BW/day). During the stabilization period of 10 days, horses additionally received 6 kg grass hay. Following this adaptation period, plasma glucose and insulin responses to the respective dietary treatments were tested. Horses were fed their test diet (exclusively oats), and blood samples were collected at defined times to determine glycaemic and insulin response. Oat feeding resulted in a significant increase in mean plasma glucose and insulin concentration. However, glucose and insulin peaks as well as their respective areas under the curves were not clearly influenced by oat processing. The glycaemic index varied between 94.7 ± 11.2% (steam-flaked oats) and 102.6 ± 14.5% (finely ground oats, n.s.), the insulin index ranged between 93.8 ± 18.9% (popped oats) and 150.0 ± 77.6% (finely ground oats, n.s.). The insulin reaction to oat feeding showed a high variability between the horses. The results of this study indicate that the glucose and insulin responses are not clearly altered by the different types of oat processing. However, the glucose and insulin responses tended to be lower in thermally treated oats when compared with untreated or finely ground oats. [source]

EFFECTS OF CO-IMMOBILIZATION OF PECTINASE AND AMYLASE ON ULTRAFILTRATION OF APPLE JUICE SIMULATE

JOURNAL OF FOOD PROCESS ENGINEERING, Issue 6 2001
MARÍA E. CARRÍN
ABSTRACT In view of its possible application in apple juice clarification, the potential of co-immobilized pectinase/amylase by physical adsorption on a polysulfone ultrafiltration hollow fiber was examined. Solutions containing different concentrations of pectin and starch were used. The effect of various operational parameters on the production of reducing compounds, mainly galacturonic acid and maltose, was investigated. Results indicated that relative permeate flux, during ultrafiltration of starch-pectin solutions, was up to 35% higher when commercial pectinase and amylase were co-immobilized on a hollow fiber membrane. Although the concentration of reaction products increased up to 50% with the pectin concentration, the same was not verified when the starch content changed from 3.85 to 5.00 mg/mL. However, the reference permeate flux was improved when starch was added to substrate, independently of its concentration. Considering the size of an average starch granule, this increase in permeate flux was attributed to the removal of pectin gel by dragging. Permeate fluxes were comparable for both batch and permeate recycling operations. [source]

EFFECT OF PECTINOLYTIC AND AMYLOLYTIC ENZYMES ON APPLE JUICE TURBIDITY

JOURNAL OF FOOD PROCESSING AND PRESERVATION, Issue 2 2006
V. SORRIVAS
ABSTRACT The mechanisms governing the enzymatic clarification of apple juice were studied by electron microscopy techniques. Full ripe and unripe apple juice samples (Granny Smith) were treated with commercial pectinase (Solvay 5XLHA) and amylase (Röhalase HT) enzymes, respectively. Scanning electron microscopy studies revealed that commercial amylolytic enzymes quickly reduced starch content in unripe apple juice to undetectable values. It was also observed that after pasteurization of this juice (90C, 5 min) all starch granules gelatinized. Using transmission electron microscopy, it was possible to observe pectin bonded to ripe apple juice particles. This protective colloid is known to be responsible for cloudy juice stability. The effect of pectic enzyme to destroy the protective pectin colloid was also detected with this technique. As a result of the enzymatic treatment, average particle size initially increased from 1000 to 1500 nm and decreased thereafter to ,1100 nm, and Z-potential increased in absolute values from ,9.6 to ,11.4 mV. It was speculated that the destruction of the weak pectin net by the action of the specific enzyme caused particle aggregation, followed by the collapse of aggregates, increasing the number of particles <500 nm. [source]

ROLE OF TUBER DENSITY IN POTATO SLOUGHING

JOURNAL OF TEXTURE STUDIES, Issue 2 2006
Í BLAHOVEC
ABSTRACT A new CPEM method was developed and used to study the cooking curves of two potato varieties showing differences in texture and of one variety cultivated in four different regimes. The two main cooking curve stages (i.e., cooking and disintegration) can be described by simple linear equations, with density as an independent parameter. The parameters in the equation describing the cooking stage were reformulated to express directly the role of starch. The two new parameters obtained were weakly correlated and expressed separately cooking time sensitivity to starch content and the basic potato characteristic in relation to sloughing. Data obtained indicate only a minor role of starch content during the first part of cooking that is determined primarily by basic potato characteristics probably related to the cell wall properties. In the second stage of disintegration, starch content plays a more important role. [source]

Characterizing diversity in composition and pasting properties of tuber flour in yam germplasm (Dioscorea spp.) from Southern Ethiopia

Effect of processing and storage time on in vitro digestibility and resistant starch content of two bean (Phaseolus vulgaris L) varieties

JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 12 2003
Perla Osorio-Díaz
Abstract Seeds from two commercial bean varieties were cooked and stored for different times and analysed for chemical composition and in vitro starch digestibility. Parallel portions of cooked seeds were dried at 55 °C, milled and stored as flours. In general, protein and ash contents in both samples did not change with storage time, but statistical differences were shown between the two varieties (p < 0.05). Available starch (AS) contents in flours from the ,negro' variety did not change (p < 0.05) with storage time and, in general, were higher than in ,flor de mayo' samples, whose AS levels decreased during storage. The lower AS in ,flor de mayo' flour could be the consequence of formation of resistant starch due to retrogradation. Samples of whole ,negro' seeds did not show differences in AS content at 0, 24 and 48 h of storage compared with the corresponding flours, but at 72 and 96 h the AS increased in the whole samples. ,Flor de mayo' showed a similar pattern in flour and whole samples, with slightly higher values in the whole seeds. In general, total resistant starch (RS) content in the two varieties was higher in the flours than in ,whole' seeds, a fact that is not easy to explain at present. ,Negro' flour presented an RS content around 65.0 g kg,1, and approximately 55.0 g kg,1 was recorded in ,flor de mayo', with slight changes when storage time increased. Whole ,flor de mayo' showed significant levels of the retrograded portion of resistant starch (RRS), which did not change with storage time (p < 0.05). However, values were lower than in the flours. A pattern similar to that of the ,negro' variety was obtained for ,flor de mayo', since the flour exhibited higher amounts of RRS; however, in this variety, the RRS content in ,whole' samples decreased after prolonged storage. Flours presented higher amylolysis rates than whole samples, and the ease of digestion increased with storage time. Copyright © 2003 Society of Chemical Industry [source]

Effect of section of yam (Dioscorea cayenensis) tuber used in minisett on the biochemical properties of the resultant tuber

JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 13 2002
Andrew O Wheatley
Abstract The effect of the section of yam (Dioscorea cayenensis) tuber used as planting material in minisett on the biochemical properties of the resultant tuber was studied. The biochemical parameters invertase (EC 3.2.1.26), acid phosphatase (EC 3.1.3.2), peroxidase (EC1.11.1.7), polyphenol oxidase (EC 1.10.3.1), total sugars and starch were evaluated in tubers resulting from field-grown and tissue culture-derived setts of the cultivars Roundleaf and Blackwiss yellow yams. No significant differences were observed between tubers resulting from field-grown and tissue culture-derived setts relative to the parameters studied. Invertase activity was found to be highest in tubers from middle-derived setts, while tail-derived setts had the lowest activity for both cultivars. Middle-derived tubers were also found to have significantly higher levels of acid phosphatase activity and starch content. However, middle-derived tubers had the lowest level of total sugars. Polyphenol oxidase and peroxidase were also found to be significantly higher in tubers from middle-derived setts. These results suggest a higher rate of active starch formation in tubers from middle-derived setts. © 2002 Society of Chemical Industry [source]

Influence of heating conditions and starch on the storage modulus of Russet Burbank and Yukon Gold potatoes

JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 15 2001
Renan Bu-Contreras
Abstract The storage modulus of Russet Burbank (RB) and Yukon Gold (YG) potato discs (13.3,mm,× 4.5,mm) was measured continuously during heating in water at temperatures ranging from 40 to 80,°C for 120,min using a dynamic mechanical analyser with a heating stage. The starch content of YG potatoes was higher than that of RB potatoes, but the raw starch granule size distribution of both varieties was similar. RB samples had the highest storage modulus values (25% higher than raw tissue) when heated in 60,°C water for 35,min. Image analysis revealed that the perimeters of starch granules in the potato samples increased by about 50% during heating for 30,min at 60,°C. Heating temperature and time and starch content influenced the storage modulus. © 2001 Society of Chemical Industry [source]

Effects of CO2 and light on tree phytochemistry and insect performance

OIKOS, Issue 2 2000
Jep Agrell
Direct and interactive effects of CO2 and light on tree phytochemistry and insect fitness parameters were examined through experimental manipulations of plant growth conditions and performance of insect bioassays. Three species of deciduous trees (quaking aspen, Populus tremuloides; paper birch, Betula papyrifera; sugar maple, Acer saccharum) were grown under ambient (387±8 ,L/L) and elevated (696±2 ,L/L) levels of atmospheric CO2, with low and high light availability (375 and 855 ,mol×m,2×s,1 at solar noon). Effects on the population and individual performance of a generalist phytophagous insect, the white-marked tussock moth (Orgyia leucostigma) were evaluated. Caterpillars were reared on experimental trees for the duration of the larval stage, and complementary short-term (fourth instar) feeding trials were conducted with insects fed detached leaves. Phytochemical analyses demonstrated strong effects of both CO2 and light on all foliar nutritional variables (water, starch and nitrogen). For all species, enriched CO2 decreased water content and increased starch content, especially under high light conditions. High CO2 availability reduced levels of foliar nitrogen, but effects were species specific and most pronounced for high light aspen and birch. Analyses of secondary plant compounds revealed that levels of phenolic glycosides (salicortin and tremulacin) in aspen and condensed tannins in birch and maple were positively influenced by levels of both CO2 and light. In contrast, levels of condensed tannins in aspen were primarily affected by light, whereas levels of ellagitannins and gallotannins in maple responded to light and CO2, respectively. The long-term bioassays showed strong treatment effects on survival, development time, and pupal mass. In general, CO2 effects were pronounced in high light and decreased along the gradient aspen birch maple. For larvae reared on high light aspen, enriched CO2 resulted in 62% fewer survivors, with increased development time, and reduced pupal mass. For maple-fed insects, elevated CO2 levels had negative effects on survival and pupal mass in low light. For birch, the only negative CO2 effects were observed in high light, where female larvae showed prolonged development. Fourth instar feeding trials demonstrated that low food conversion efficiency reduced insect performance. Elevated levels of CO2 significantly reduced total consumption, especially by insects on high light aspen and low light maple. This research demonstrates that effects of CO2 on phytochemistry and insect performance can be strongly light-dependent, and that plant responses to these two environmental variables differ among species. Overall, increased CO2 availability appeared to increase the defensive capacity of early-successional species primarily under high light conditions, and of late-successional species under low light conditions. Due to the interactive effects of tree species, light, CO2, and herbivory, community composition of forests may change in the future. [source]

Genetic analysis and QTL mapping of stalk digestibility and kernel composition in a high-oil maize mutant (Zea mays L.)

PLANT BREEDING, Issue 3 2010
H.-W. Wang
With 1 figure and 5 tables Abstract A high-oil maize inbred line Ce03005 derived from ethylmethane-sulphonate mutagenesis was used to study the genetic basis of stalk digestibility and kernel chemical compositions, and evaluate the genetic relationship between traits. Quantitative trait loci (QTL) mapping employed 211 lines of F3 and F4 generations derived from Ce03005 × B73. Nuclear magnetic resonance and near-infrared reflectance spectrometry were used to analyse the following phenotypic traits: stalk digestibility and related traits including in vitro dry matter digestibility (IVDMD), in vitro cell wall digestibility (IVNDFD), neutral detergent fibre (NDF), acid detergent fibre (ADF), water soluble carbohydrate (WSC), and kernel composition including kernel oil content (KOC), kernel protein content (KPC) and kernel starch content (KSC). Correlation analysis indicated that IVDMD, IVNDFD and WSC were significantly (P = 0.01) positively correlated with KOC, while ADF and NDF were negatively correlated with KOC. Six QTL for IVDMD, five for IVNDFD, six for NDF, eight for ADF, three for WSC, eight for KOC, seven for KPC and 10 for KSC were detected in F3 and F4 generations. Five major QTL (R2 > 10) of qIVDMD6, qIVNDFD6, qNDF6, qADF6, qWSC6 andOlicm6 shared the same confidence interval on chromosome 6. The results suggested that KOC may be closely related or share the same QTL for stalk quality traits, and its change may have influences to the stalk components. [source]

Seasonal shifts in dormancy status, carbohydrate metabolism, and related gene expression in crown buds of leafy spurge

PLANT CELL & ENVIRONMENT, Issue 12 2005
JAMES V. ANDERSON
ABSTRACT Crown buds of field-grown leafy spurge (Euphorbia esula L.) were examined to determine relationships between carbohydrate metabolism and gene expression throughout para-, endo-, and eco-dormancy during the transition from summer, autumn, and winter, respectively. The data indicates that endo-dormancy plays a role in preventing new shoot growth during the transition from autumn to winter. Cold temperature was involved in breaking endo-dormancy, inducing flowering competence, and inhibiting shoot growth. An inverse relationship developed between starch and soluble sugar (mainly sucrose) content in buds during the shift from para- to endo-dormancy, which continued through eco-dormancy. Unlike starch content, soluble sugars were lowest in crown buds during para-dormancy but increased over two- to three-fold during the transition to endo-dormancy. Several genes (AGPase, HK, SPS, SuSy, and UGPase) coding for proteins involved in sugar metabolism were differentially regulated in conjunction with well-defined phases of dormancy in crown buds. Marker genes for S-phase progression, cell wall biochemistry, or responsive to auxin were also differentially regulated during transition from para-, endo-, and eco-dormancy. The results were used to develop a model showing potential signalling pathways involved in regulating seasonal dormancy status in leafy spurge crown buds. [source]

New evidence for a role of vessel-associated cells and phloem in the rapid xylem refilling of cavitated stems of Laurus nobilis L.

PLANT CELL & ENVIRONMENT, Issue 8 2004
S. SALLEO
ABSTRACT Xylem recovery from embolism was studied in Laurus nobilis L. stems that were induced to cavitate by combining negative xylem pressure potentials (PX = ,1.1 MPa) with positive air pressures (PC) applied using a pressure collar. Xylem refilling was measured by recording the percentage loss of hydraulic conductance (PLC) with respect to the maximum 2 min, 20 min and 15 h after pressure release. Sodium orthovanadate (an inhibitor of many ATP-ases) strongly inhibited xylem refilling while fusicoccin (a stimulator of the plasma membrane H+ -ATPase) promoted complete embolism reversal. So, the refilling process was interpreted to result from energy-dependent mechanisms. Stem girdling induced progressively larger inhibition to refilling the nearer to the embolized stem segment phloem was removed. The starch content of wood parenchyma was estimated as percentages of ray and vasicentric cells with high starch content with respect to the total, before and after stem embolism was induced. A closely linear positive relationship was found to exist between recovery from PLC and starch hydrolysis. This, was especially evident in vasicentric cells. A mechanism for xylem refilling based upon starch to sugar conversion and transport into embolized conduits, assisted by phloem pressure-driven radial mass flow is proposed. [source]

Altered metabolic fluxes result from shifts in metabolite levels in sucrose phosphorylase-expressing potato tubers

PLANT CELL & ENVIRONMENT, Issue 10 2002
A. R. Fernie
Abstract As reported in a previous paper (Plant, Cell and Environment 24, 357,365, 2001), introduction of sucrose phosphorylase into the cytosol of potato results in increased respiration, an inhibition of starch accumulation and decreased tuber yield. Herein a more detailed investigation into the effect of sucrose phosphorylase expression on tuber metabolism, in order to understand why storage and growth are impaired is described. (1) Although the activity of the introduced sucrose phosphorylase was low and accounted for less than 10% of that of sucrose synthase its expression led to a decrease in the activities of enzymes of starch synthesis relative to enzymes of glycolysis and relative to total amylolytic activity. (2) Incubation of tuber discs in [14C]glucose revealed that the transformants display a two-fold increase of the unidirectional rate of sucrose breakdown. However this was largely compensated by a large stimulation of sucrose re-synthesis and therefore the net rate of sucrose breakdown was not greatly affected. Despite this fact major shifts in tuber metabolism, including depletion of sucrose to very low levels, higher rates of glycolysis, and larger pools of amino acids were observed in these lines. (3) Expression of sucrose phosphorylase led to a decrease of the cellular ATP/ADP ratio and energy charge in intact growing tubers. It was estimated that at least 30% of the ATP formed during respiration is consumed as a result of the large acceleration of the cycle of sucrose breakdown and re-synthesis in the transformants. Although the absolute rate of starch synthesis in short-term labelling experiments with discs rose, starch synthesis fell relative to other fluxes including respiration, and the overall starch content of the tubers was lower than in wild-type tubers. (4) External supply of amino acids to replace sucrose as an osmoticum led to a feed-back inhibition of glycolysis, but did not restore allocation to starch. (5) However, an external supply of the non-metabolizable sucrose analogue palatinose , but not sucrose itself , stimulated flux to starch in the transformants. (6) The results indicate that the impaired performance of sucrose phosphorylase-expressing tubers is attributable to decreased levels of sucrose and increased energy consumption during sucrose futile cycling, and imply that sucrose degradation via sucrose synthase is important to maintain a relatively large sucrose pool and to minimize the ATP consumption required for normal metabolic function in the wild type. [source]

Structure-property relationship in polyurethane elastomers containing starch as a crosslinker

POLYMER ENGINEERING & SCIENCE, Issue 5 2000
Sonal Desai
Polyurethane elastomers were synthesized using polypropylene glycol (PPG 2000) as the polyol and starch as the multifunctional crosslinker in varying concentrations. Thermal and mechanical properties were measured by DSC, DMA and tensile tests. The morphology was examined by SEM. The swelling behavior of the polyurethanes in various solvents was investigated and the solubility parameter was determined. All these properties were compared with those of polyurethanes containing 1,1,1 -trimethylol propane (TMP) as the crosslinker. Starch-based polyurethanes exhibited better mechanical properties. The effect of varying the starch:TMP ratio on the mechanical strength was also studied. With increasing starch content, the tensile strength and elongation increased. The starch-based PUs exhibited two glass transitions, whereas TMP-based PUs exhibited one Tg. No significant difference in the Tgs of the two PUs was observed. The activation energy of St-PU calculated from DMA was 69 kcal/mol. Soil degradation tests indicated greater biodegradability in polyurethanes containing starch than in those containing TMP. [source]

Reduced amino acid content in transgenic potato tubers due to antisense inhibition of the leaf H+/amino acid symporter StAAP1

THE PLANT JOURNAL, Issue 2 2003
Wolfgang Koch
Summary Transport processes across the plasma membrane of leaf vascular tissue are essential for transport and distribution of assimilates. In potato, leaves are the predominant sites for nitrate reduction and amino acid biosynthesis. From there, assimilated amino acids are exported through the phloem to supply tubers with organic nitrogen. To study the role of amino acid transporters in long-distance transport and allocation of organic nitrogen in potato plants, a gene encoding a functional, leaf-expressed amino acid permease StAAP1 was isolated. Similar to the sucrose transporter SUT1, StAAP1 expression was induced during the sink-to-source transition, indicating a role in phloem loading. To test the role of StAAP1, expression was inhibited by an antisense approach. Transgenic plants with reduced StAAP1 expression were phenotypically indistinguishable from wild type, as were photosynthetic capacity and tuber yield. However, tubers from antisense StAAP1 plants showed up to 50% reduction in free amino acid contents. In comparison, starch content was not affected or tended to increase relative to wild type. The reduction in all amino acids except aspartate in the antisense plants is consistent with the properties of amino acid permeases (AAPs) found in heterologous systems. The results demonstrate an important role for StAAP1 in long-distance transport of amino acids and highlight the importance of plasma membrane transport for nutrient distribution in plants. [source]

The rate of transport through a phosphate translocator affects delayed luminescence induction: an experiment and a theoretical model

ANNALS OF APPLIED BIOLOGY, Issue 1 2001
S KHUZNETSOVA
Summary Delayed luminescence (DL) induction curves were studied in leaves from a mutant pea line containing mutations at both the r and rb loci, compared with leaves from wild type plants. Genes at the r and rb loci encode starch branching enzyme and ADP - glucose pyrophosphorylase, respectively. The presence of mutations at both loci, previously known to reduce the starch content in the dry mature seed by 75%, have been shown to lower the starch level in leaves by at least 20%. During induction, the half-time for the DL intensity decrease from maximum to steady state in the mutant was 1.5 ± 0.2 times longer than for the wild type. It is proposed that the prolongation of the induction period in leaves from the mutant plants is caused by a lack of inorganic phosphate (Pi) restricting the rate of ATP synthesis at the beginning of induction. The reduced Pi would be compensated by triose flow from the chloroplast, via the triose phosphate translocator, being exchanged for Pi from the cytosol. Analysis of our theoretical photosynthesis model confirmed that a decrease in the rate of Pi released from the Calvin cycle could lead to a prolongation of the induction period. [source]

Evaluation of the influence of different species and cultivars of lupin kernel meal on the extrusion process, pellet properties and viscosity parameters of salmonid feeds

AQUACULTURE NUTRITION, Issue 1 2010
B. GLENCROSS
Abstract This study examined the influence of different lupin species and cultivars and their inclusion levels on the physical properties of an extruded diet. Lupin kernel meals were included into a fish diet formulation at 0%, 10%, 20% and 30%. Soybean meal was also included in a series of diets on a similar basis as a reference. The diet mashes were extruded using a laboratory-scale APV19:45 twin-screw extruder. The pellets were examined for radial expansion, bulk density, vacuum oil uptakes, sink rate, shear and crush strengths. Inclusion of lupin kernel meal significantly increased bulk density, sink rate, shear and crush strength of the pellets. With the increase in lupin kernel meal inclusion level, a concomitant decline in vacuum oil uptake and radial expansion was also observed. An assessment of the diet mashes using a Rapid Visco Analyser showed that the inclusion of lupin kernel meals increased the rate and degree of gelatinization of the mash starch content compared with that with a similar inclusion level of soybean meal. The inclusion of lupin kernel meals in the diet mash also improved the water-holding capacity of the extrudate, which has important implications for the reduction in extruder wear. [source]

The reduction of starch accumulation in transgenic sugarcane cell suspension culture lines

BIOTECHNOLOGY JOURNAL, Issue 11 2008
Stephanus J. Ferreira
Abstract Starch only occurs in small amounts in sugarcane, but is, nevertheless an unwanted product because it reduces the amount of sucrose that can be crystallized from molasses. In an attempt to reduce the starch content of sugarcane, the activities of ADP-glucose pyrophosphorylase (AGPase) and ,-amylase were manipulated using transgenic approaches. Transformation vectors to reduce AGPase activity and to increase plastidial ,-amylase activity were constructed and used for the transformation of sugarcane calli. The results of the manipulations were analyzed in suspension cultures. AGPase activity was reduced down to between 14 and 54% of the wild-type control. This led to a reduction in starch concentration down to 38% of the levels of the wild-type control. ,-Amylase activity was increased in the transgenic lines by 1.5,2 times that of the wild-type control. This increase in activity led to a reduction in starch amounts by 90% compared to wild-type control cells. In both experiments, the changes in starch concentrations could be correlated with the change in enzyme activity. There were no significant effects on sucrose concentrations in either experiment, indicating that these approaches might be useful to engineer regenerated sugarcane for optimized sucrose production. [source]

Agronomic factors affecting the yield and quality of forage maize in Ireland: effect of sowing date and plastic film treatment

Physicochemical, mechanical and thermal properties of brown rice grain with various moisture contents

INTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 9 2004
Wei Cao
Summary The effects of moisture content on the mechanical and thermal properties of either a short-grain variety (Akitakomachi) or two long-grain varieties (Delta and L201) of brown rice were studied. Total starch contents of the three varieties were comparable, but the amylose content of L201 was significantly higher than that of the other two varieties. The maximum compressive strength of brown rice grain was much higher than the maximum tensile strength. L201 showed the highest maximum compressive and tensile strengths. The phase transition temperatures (glass transition temperature Tg and melting temperature Tm) were examined by differential scanning calorimetry. The Tg and Tm for L201 were higher than those for Delta and Akitakomachi. The maximum compressive strength, maximum tensile strength, Tg and Tm for the three varieties of brown rice grains decreased with increasing moisture content. The Tg of individual brown rice kernels decreased from 53 to 22 °C as moisture content increased from 12 to 25% wet basis. A statistical model was calculated by using linear regression to describe the change in Tg in terms of moisture content. [source]

Effects of Tuber Storage and Cultivar on the Quality of Vacuum Microwave-dried Potato Chips

JOURNAL OF FOOD SCIENCE, Issue 2 2003
J.F. Lefort
ABSTRACT: Influences of storage and cultivar on vacuum microwave-dried (VMD) potato chip quality were investigated. Tubers of several cultivars were stored at 12 °C for 0 to 4 mo, or at 4 °C for 5 to 10 mo, followed by reconditioning at 12 °C for 2 wk. Blanched potato slices (2.5 to 3.0 mm thick) were vacuum microwave-dried to produce fat-free potato chips. Chips were assessed by instrumental and sensory methods for texture and instrumentally for color. Tuber composition influenced chip texture but not color. Less breaking force was required for chips produced from cultivars with low specific gravity and starch contents. Tubers stored for up to 10 mo yielded chips of good quality. [source]

Chemical composition and in vitro starch digestibility of pigmented corn tortilla

JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 13 2007
Juan Pablo Hernández-Uribe
Abstract BACKGROUND: Tortillas were prepared from two (blue and regular white) maize varieties and compared with regard to chemical composition and in vitro starch digestibility, i.e., available starch (AS), total (RS) and retrograde (RRS) resistant starch contents, amylolysis rate and predicted glycemic index (pGI). The impact of cold storage (4 °C) on digestibility was also investigated. RESULTS: Despite its higher protein and lipid contents, pigmented tortilla exhibited lower AS content than the white product. AS in both types of tortilla decreased during the first 2 days of storage, and remained stable thereafter. Blue tortilla had lower RS content (21 g kg,1 dry matter basis) than the white tortilla (30 g kg,1 dry matter basis). RS values were slightly higher in 2 day-stored tortillas than in their fresh counterparts. Although the RRS content in recently made white tortillas was greater than in the colored preparation, stored blue tortillas exhibited double RRS values compared with freshly baked samples. ,-Amylolysis of blue tortilla was slower than in the white sample. Consequently, blue tortilla exhibited a lower pGI value. pGI for the white tortilla decreased upon cold storage, a change that was not be observed for the colored preparation. CONCLUSION: Starch digestibility characteristics of blue tortilla make it suitable for people with special nutritional or metabolic requirements. Copyright © 2007 Society of Chemical Industry [source]

Cell wall polysaccharides of bush butter (Dacryodes edulis (G Don) HJ Lam) fruit pulp and their evolution during ripening

JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 8 2001
Crépin Ella Missang
Abstract Cell wall material was isolated as alcohol-insoluble solids (AIS) from bush butter endocarp tissue at different stages of ripeness. AIS were then extracted with 0.05,M CDTA followed by increasing concentrations of KOH (0.05, 1 and 4,M respectively). The chemical extractions solubilised a total of 51.6,60.6% of AIS, the yields of CDTA extracts accounting for approximately 9.6,12.2% of AIS. The extracts as well as the residues were analysed for their sugar composition and protein and starch contents. CDTA extracted the bulk of uronic acid in AIS, but the uronic acid content (after dialysis) of these extracts showed a significant decrease as the fruits ripened (from 439 to 252,mg,g,1 between the first and the last degree of ripeness). Analysis of the CDTA extracts by anion exchange and size exclusion chromatography showed a gradual appearance of new pectic populations at low degrees of methylation and low molecular weights, indicating that CDTA-soluble pectins are demethylated and depolymerised during ripening. The dilute alkali (0.05,M KOH) extracts were essentially composed of proteins in addition to a minor quantity of pectin. The 1,M KOH and principally 4,M KOH treatments led to the extraction of hemicelluloses, mainly xyloglucan-like and mannan-like polymers. These extracts also contained substantial amounts of protein and starch. No variation related to the degree of ripeness was visible in the sugar composition of the alkali extracts. The molecular weight distribution of the hemicelluloses did not change with the degree of ripeness. The final residues accounted for 21.4,27.3% of AIS and were mostly composed of glucose (827,908,mg,g,1). All these results suggested that only CDTA-soluble pectins were involved in bush butter fruit softening. © 2001 Society of Chemical Industry [source]

Production and physicochemical characterization of resistant starch type III derived from pea starch

MOLECULAR NUTRITION & FOOD RESEARCH (FORMERLY NAHRUNG/FOOD), Issue 1 2003
Undine Lehmann
Abstract Smooth pea starch was used for the production of physiological important resistant starch type III. For reduction of the molecular weight of the starch, different strategies including enzymatic debranching and acid hydrolysis (lintnerization( were tested to obtain an optimal starting material for retrogradation. The resulting polymer chain lengths were analyzed by high-performance anion-exchange chromatography. Temperature regimes and starch concentrations in gel were optimized during the retrogradation with the aim to obtain a high yield of resistant starch. Optimal conditions led to resistant starch contents up to 74%. The products were thermostable and showed no loss of resistant structures after autoclaving. The peak temperatures of the thermal transition were at approximately 147°C. The resulting resistant starch products are suitable for the generation of functional foods. [source]

Relation among plant growth, carbohydrates and flowering time in the Arabidopsis Landsberg erecta × Kondara recombinant inbred line population

PLANT CELL & ENVIRONMENT, Issue 8 2010
MOHAMED E. EL-LITHY
ABSTRACT Arabidopsis thaliana natural variation was used to study plant performance viewed as the accumulation of photo-assimilates, their allocation and storage, in relation to other growth-related features and flowering-related traits. Quantitative trait locus (QTL) analysis using recombinant inbred lines derived from the cross between Landsberg erecta (originating from Poland) and Kondara (originating from Tajikistan) grown on hydroponics, revealed QTLs for the different aspects of plant growth-related traits, sugar and starch contents and flowering-related traits. Co-locations of QTLs for these different aspects were detected at different regions, mainly at the ER locus; the top of chromosomes 3, 4 and 5; and the bottom of chromosome 5. Increased plant growth was associated with early flowering and leaf transitory starch, and correlated negatively with the levels of soluble sugar at early phases of development. From the significant correlations and the co-locations of the QTLs for these aspects, we conclude that there is a complex relationship between plant growth-related traits, carbohydrate content and flowering-related traits. [source]