Search results for "STAR"
showing 10 items of 4285 documents
Characterizing physicochemical, nutritional and quality attributes of wholegrain Oryza sativa L. subjected to high intensity ultrasound-stimulated pr…
2020
Abstract When ultrasonic stimulation is applied to plant seeds it may promote the development of new adaptive characteristics during germination, thus providing an alternative to regulate nutritional and physicochemical attributes of germinated seeds. However, there is rather limited information concerning high-intensity ultrasound (HIU) effects on the germination process of crop seeds as foodstuff. This investigation aimed at examining the effects of a novel processing pattern, which coupled HIU stimulation (28 kHz, 17.83 W cm−2) to a pre-germination stage, on the physicochemical, nutritional and quality changes of wholegrain brown rice (WBR; Oryza sativa L.). Results suggested that HIU st…
Scaling theory of star polymers and general polymer networks in bulk and semi-infinite good solvents
1988
Theorie d'echelle utilisant l'equivalence entre la fonction generatrice du nombre total de configuration et la fonction de correlation a plusieurs spins du modele de Heisenberg classique a n composantes dans la limite n→0
Third virial coefficient for 4-arm and 6-arm star polymers
2008
We discuss the computation of the third virial coefficient in polymer systems, focusing on an additional contribution absent in the case of monoatomic fluids. We determine the interpenetration ratio and several quantities that involve the third virial coefficient for star polymers with 4 and 6 arms in the good-solvent regime, in the limit of a large degree of polymerization.
Quercetin as natural stabilizing agent for bio-polymer
2014
The introduction of antioxidants in polymers is the main way to prevent or delay the degradation process. In particular natural antioxidants receive attention in the food industry also because of their presumed safety. In this work bio-polymers, i.e. a commercial starch-based polymer (Mater-Bi®) and a bio-polyester (PLA), and a bio-polyether (PEO) were additivated with quercetin, a natural flavonoid antioxidants, in order to formulate bio-based films for ecosustainable packaging and outdoor applications. The photo-oxidation behavior of unstabilized and quercetin stabilized films was analyzed and compared with the behavior of films additivated with a commercial synthetic light stabilizer. Th…
Differential function of the phosphoglucomutase isozymes PGM1 and PGM2
1979
A total of 13 metabolites thought to be possibly inhibitory were tested for their influence on PGM isozyme activities, each at several different concentrations. The analysis of statistical significance was based on enzyme activities obtained by densitometric measurements of starch gels. Five of the substances were found to inhibit PGM activity, three of which definitely and a further one probably led to a significantly stronger inhibition of the isozymes of the PGM2 locus than of PGM1 isozymes. They are (1) fructose-1,6-diphosphate, (2) adenosine triphosphate, (3) citrate, and (4) possibly 2,3-diphosphoglycerate. Thus, PGM1 isozymes proved to function better in hard or perhaps marginal meta…
Relaxations Below Glass Transition Temperature in Bread and Its Components
1999
ABSTRACT Dry glassy bread, cooked gluten, and gelatinized wheat starch-sucrose mixtures were prepared. Dielectric properties were studied as a function of temperature at different frequencies ranging from 100 to 1,000 kHz. Both bread and starch samples exhibited a tan δ peak at -53°C at 10 kHz, which is associated with a secondary relaxation characterized by an activation energy of 50 kJ/mol. The gluten sample did not show any relaxation in the temperature range studied. The magnitude of the relaxation peak was sensitive to the sucrose concentration of the starch sample. The higher the sucrose content, the greater the amplitude of the peak. Such an effect is attributed to a greater β-relaxa…
Processing and Mechanical Properties of Natural Fiber Reinforced Thermoplastic Starch Biocomposites
2007
Natural fiber reinforced starch polymers are processed by compression molding. Potato, sweet potato, and corn starch are used as matrices. Three types of natural fibers, namely sisal, jute, and cabuya, are used in concentrations varying from 2.5 to 12.5% w/w in the composites. Different plasticizers are used for the starch polymers, such as water and glycerol. Mechanical properties are assessed by tensile and impact tests. In both cases, improved mechanical properties are obtained at increasing fiber contents. Tensile strength appears to be markedly improved with the addition of 10% by weight of sisal fibers, while the best results for impact strength are obtained for cabuya fibers.
Influence of xanthan gum and locust bean gum upon flow and thixotropic behaviour of food emulsions containing modified starch
2007
Abstract Low oil content mayonnaises are food emulsions which exhibit shear thinning and thixotropic behaviour. They include generally modified starch in their formulation. In this work we study the effect of substituting part of this starch with other natural gums, such as xanthan gum or locust bean gum, upon the consistency and stability of the emulsions in relation to stirring. The gels prior to final emulsification have also been analyzed. Steady flow curves of all systems are well described by the Carreau model. The emulsions containing the greatest percentage of gums presented significantly higher viscosity than the reference emulsion and the emulsions containing the synergistic mixtu…
Revisiting delta-6 desaturase regulation by C18 unsaturated fatty acids, depending on the nutritional status.
2009
Dietary polyunsaturated fatty acids (PUFA) play a key role in regulating delta-6 desaturase (D6D), the key enzyme for long-chain PUFA biosynthesis. Nevertheless, the extent of their effects on this enzyme remains controversial and difficult to assess. It has been generally admitted that C18 unsaturated fatty acids (UFAs) regulate negatively delta-6 desaturase (D6D). This inhibition has been evidenced in regard to a high glucose/fat free (HG/FF) diet used in reference. However, several nutritional investigations did not evidence any inhibition of desaturases when feeding fatty acids. Because the choice of the basal diet appeared to be of primary importance in such experiments, our goal was t…
Effect of Ti(IY) on some indicators of physiological activity inCapsicum annuum, L.
1994
SummaryPaprika pepper (Capsicum annuum, L., cv. Negral) plants grown in a greenhouse were supplied Ti(IV) ascorbate through the roots or through leaves. Biomass production, peroxidase (donor: H2O, oxidoreductase; EC 1.11.1.7) activity, and malic acid, starch and chlorophyll concentrations were determined in different plant organs. It was observed that Ti increased the concentration of some of the metabolites studied and promoted both peroxidase activity and biomass production. The profitable effect of the Ti treatments could occur because they enhance the availability of other nutrients. This effect could be due to the low redox potential of the Ti+3/Ti+4 system that catalyzes the activity …