How Does the Preparation of Rye Porridge Affect Molecular Weight Distribution of Extractable Dietary Fibers?

Extractable dietary fiber (DF) plays an important role in nutrition. This study on porridge making with whole grain rye investigated the effect of rest time of flour slurries at room temperature before cooking and amount of flour and salt in the recipe on the content of DF components and molecular weight distribution of extractable fructan, mixed linkage (1→3)(1→4)-β-d-glucan (β-glucan) and arabinoxylan (AX) in the porridge. The content of total DF was increased (from about 20% to 23% of dry matter) during porridge making due to formation of insoluble resistant starch. A small but significant increase in the extractability of β-glucan (P = 0.016) and AX (P = 0.002) due to rest time was also noted. The molecular weight of extractable fructan and AX remained stable during porridge making. However, incubation of the rye flour slurries at increased temperature resulted in a significant decrease in extractable AX molecular weight. The molecular weight of extractable β-glucan decreased greatly during a rest time before cooking, most likely by the action of endogenous enzymes. The amount of salt and flour used in the recipe had small but significant effects on the molecular weight of β-glucan. These results show that whole grain rye porridge made without a rest time before cooking contains extractable DF components maintaining high molecular weights. High molecular weight is most likely of nutritional importance.     

Identification of New QTLs for Dietary Fiber Content in Aegilops biuncialis

Grain dietary fiber content is an important health-promoting trait of bread wheat. A dominant dietary fiber component of wheat is the cell wall polysaccharide arabinoxylan and the goatgrass Aegilops biuncialis has high β-glucan content, which makes it an attractive gene source to develop wheat lines with modified fiber composition. In order to support introgression breeding, this work examined genetic variability in grain β-glucan, pentosan, and protein content in a collection of Ae. biuncialis. A large variation in grain protein and edible fiber content was revealed, reflecting the origin of Ae. biuncialis accessions from different eco-geographical habitats. Association analysis using DArTseq-derived SNPs identified 34 QTLs associated with β-glucan, pentosan, water-extractable pentosan, and protein content. Mapping the markers to draft chromosome assemblies of diploid progenitors of Ae. biuncialis underlined the role of genes on chromosomes 1M^b, 4M^b, and 5M^b in the formation of grain β-glucan content, while other QTLs on chromosome groups 3, 6, and 1 identified genes responsible for total- and water-extractable pentosan content. Functional annotation of the associated marker sequences identified fourteen genes, nine of which were identified in other monocots. The QTLs and genes identified in the present work are attractive targets for chromosome-mediated gene transfer to improve the health-promoting properties of wheat-derived foods.     

Soy flour in European-type bread

Effect of soy flour, soy protein concentrate, and isolate on dough and loaf properties of breads produced from flour, yeast, salt, and water with no shortening or added improvers was investigated. Wheat flour, rye flour, and mixtures of the two were included in the studies. Three wheat flours, varying in baking quality and extraction, ash content 0.65 and 0.80%, were used; 1.5, 3, and 5% soy products, flour basis, were added. Water absorption increased 3.8–4.7% at the 3% soy level and 6.1–7.3% at the 5% level of soy product addition. Dough development time and stability were increased and dough softening reduced. Dough gassing power increased ca. 7–25%. By using a shorter proofing time, more intensive mixing, and the sponge dough process, loaves only slightly smaller in volume than the control were obtained at the 3% soy level. Panel evaluations scored bread highest with 1.5 or 3% soy flour and that with 3 or 5% soy protein concentrate as lowest, but acceptable. Use of 2% lard as shortening, or 2% lard plus emulsifier, produced soy breads of excellent quality and ca. 25% higher loaf volume than controls.     

Molecular weight dependence of growth and morphology of it-poly(butene-1) spherulites

Molecular weight dependence of growth and morphology of spherulites of isotactic poly(butene-1), iPB-1, and those of the mixtures with atactic poly(butene-1), aPB-1, were examined by atomic force microscopy (AFM) and polarizing optical microscopy (POM) in order to examine the mechanism of the structural evolution by the branching and re-orientation of lamellar crystals at the growth front. The width of lamellar crystals and the characteristic size of the inner structure of spherulites decreased with increasing molecular weight. The result suggests that the mobility of the melt determines the sizes in spherulites and supports the growth front instability induced by a gradient triggering the branching. The sizes in the mixtures also decreased with increasing weight-averaged molecular weight, M_w. The size dependence in low M_w region, however, was too strong and that in high M_w was too weak in comparison with the predicted dependence for the prepared M_w. It has been concluded that the peculiar behaviors should be discussed with effective M_w influenced by the occurrence of separation and exclusion of non-crystallizing aPB-1 at the growth front.     

Compatibilization of recycled poly(ethylene terephthalate) and polypropylene blends: Effect of polypropylene molecular weight on homogeneity and compatibility

The effectiveness of compatibilizers in enhancing the dispersion of polypropylene (PP) at various molecular weights in recycled polyethylene terephthalate (RPET) was elucidated. The idea of incorporating PP of different molecular weights evolved from the intention of simultaneously recycling the PET bottles together with the PP‐based bottle caps, which are often of low molecular weight (M_w). Three grades of PP with known molecular weights were blended with RPET at various loadings of compatibilizers. Morphological analyses suggest that the dispersion of the PP particles was more homogeneous, and the average particle size was smaller when low M_w PP was incorporated. This indicates that the interaction between the compatibilizer and PP particles was more intense with the presence of a large number but shorter PP molecular chains. Moreover, specimens containing low M_w PP were found to remain homogeneous regardless of compatibilizer and PP content in the RPET/PP blends. The homogeneity of the blends significantly affected their mechanical performance as well. Higher stiffness, yield strength, deformability, and toughness were observed when low M_w PP was incorporated, regardless of PP and compatibilizer loadings. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Relations between Wallace plasticity and Mw for natural rubber

Wallace plasticity and the weight‐average molar mass (M_w) were measured on natural rubber samples of different origins. A sigmoidal model describes the relations between Wallace plasticity and M_w (0.872 > r² > 0.992) for given families of samples. The families of samples analyzed differed through their clonal origin, collection method (cup lumps or latex), and type of processing (CV or non‐CV). This study showed that two samples of natural rubber can be identical in terms of plasticity, but very different in terms of the average polyisoprene chain length or M_w. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 3078–3087, 1999     

Synthesis and biological activity of medium range molecular weight polymers containing exo‐3,6‐epoxy‐1,2,3,6‐tetrahydrophthalimidocaproic acid

A new monomer, exo‐3,6‐epoxy‐1,2,3,6‐tetrahydrophthalimidocaproic acid (ETCA), was prepared by reaction of maleimidocaproic acid and furan. The homopolymer of ETCA and its copolymers with acrylic acid (AA) or with vinyl acetate (VAc) were obtained by photopolymerizations using 2,2‐dimethoxy‐2‐phenylacetophenone as an initiator at 25 °C. The synthesized ETCA and its polymers were identified by FTIR, ¹H NMR and ¹³C NMR spectroscopies. The apparent average molecular weights and polydispersity indices determined by gel permeation chromatography (GPC) were as follows: M_n = 9600 g mol^?1, M_w = 9800 g mol^?1, M_w/M_n = 1.1 for poly(ETCA); M_n = 14 300 g mol^?1, M_w = 16 200 g mol^?1, M_w/M_n = 1.2 for poly(ETCA‐co‐AA); M_n = 17 900 g mol^?1, M_w = 18 300 g mol^?1, M_w/M_n = 1.1 for poly(ETCA‐co‐VAc). The in vitro cytotoxicity of the synthesized compounds against mouse mammary carcinoma and human histiocytic lymphoma cancer cell lines decreased in the following order: 5‐fluorouracil (5‐FU) ≥ ETCA > polymers. The in vivo antitumour activity of the polymers against Balb/C mice bearing sarcoma 180 tumour cells was greater than that of 5‐FU at all doses tested. © 2001 Society of Chemical Industry     

Polystyrene-equivalent molecular weight versus true molecular weight in size-exclusion chromatography

The evaluation of the size-exclusion chromatography (SEC) concentration elution curves by means of a calibration dependence obtained in a given SEC set for a polymer different from the polymer to be analyzed results in an error in the determination of both molecular weight and molecular-weight distribution (MWD). The problem is analyzed assuming the validity of the universal-calibration concept. The differences between the true and apparent values of molecular weight, MWD and M_w/M_n depend on and are expressed in terms of the parameters of the Mark-Houwink-Kuhn-Sakurada equation, describing the molecular-weight dependence of intrinsic viscosity, for the polymer to be analyzed and the polymer used for calibration. The differences in molecular weight and the M_w/M_n ratio are typically tens of percent and, in extreme cases, can amount up to a factor of three for molecular weight and a factor of two for the M_w/M_n ratio.     

Effects of molecular weight and molecular weight distribution on creep properties of polypropylene homopolymer

The molecular weights of the industrial-grade isotactic polypropylene (i-PP) homopolymers samples were determined by the melt-state rheological method and effects of molecular weight and molecular weight distribution on solid and melt state creep properties were investigated in detail. The melt-state creep test results showed that the creep resistance of the samples increased by M_w due to the increased chain entanglements, while variations in the polydispersity index (PDI) values did not cause a considerable change in the creep strain values. Moreover, the solid-state creep test results showed that creep strain values increased by M_w and PDI due to the decreasing amount of crystalline structure in the polymer. The results also showed that the amount of crystalline segment was more effective than chain entanglements that were caused by long polymer chains on the creep resistance of the polymers. Modeling the solid-state viscoelastic structure of the samples by the Burger model revealed that the weight of the viscous strain in the total creep strain increased with M_w and PDI, which meant that the differences in the creep strain values of the samples would be more pronounced at extended periods of time.     

Molecular weight development in emulsion copolymerization of n‐butyl acrylate and styrene

The seeded emulsion copolymerization of n‐butyl acrylate and styrene in a weight ratio of 50/50 was investigated. The effect of the type of process (batch vs. semicontinuous) and the amounts of initiator and emulsifier charged into the reactor on the time evolution of the fractional conversion, number of polymer particles, and weight‐average molecular weight (M_w) was analyzed. It was found that the M_w depends to a slight extent on the type of process and the emulsifier concentration and to a larger extent on the initiator concentration. The molecular weight distributions (MWDs) and the gel content of the final latexes were also analyzed. In the absence of chain transfer agents (CTAs), the fraction of gel was higher in the semicontinuous processes. It was also found that the gel content increased with increasing initiator concentration in the recipe. The addition of 1 wt % CTA avoided gel formation and led to an important reduction of the M_w. Nevertheless, the MWDs presented a shoulder or even a second peak at high molecular weights that was due to reactions of chain transfer to the polymer. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1918–1926, 2003     

Förster Resonance Energy Transfer (FRET) Correlates of Altered Subunit Stoichiometry in Cys-Loop Receptors, Exemplified by Nicotinic α4β2

We provide a theory for employing Förster resonance energy transfer (FRET) measurements to determine altered heteropentameric ion channel stoichiometries in intracellular compartments of living cells. We simulate FRET within nicotinic receptors (nAChRs) whose α4 and β2 subunits contain acceptor and donor fluorescent protein moieties, respectively, within the cytoplasmic loops. We predict FRET and normalized FRET (NFRET) for the two predominant stoichiometries, (α4)₃(β2)₂ vs. (α4)₂(β2)₃. Studying the ratio between FRET or NFRET for the two stoichiometries, minimizes distortions due to various photophysical uncertainties. Within a range of assumptions concerning the distance between fluorophores, deviations from plane pentameric geometry, and other asymmetries, the predicted FRET and NFRET for (α4)₃(β2)₂ exceeds that of (α4)₂(β2)₃. The simulations account for published data on transfected Neuro2a cells in which α4β2 stoichiometries were manipulated by varying fluorescent subunit cDNA ratios: NFRET decreased monotonically from (α4)₃(β2)₂ stoichiometry to mostly (α4)₂(β2)₃. The simulations also account for previous macroscopic and single-channel observations that pharmacological chaperoning by nicotine and cytisine increase the (α4)₂(β2)₃ and (α4)₃(β2)₂ populations, respectively. We also analyze sources of variability. NFRET-based monitoring of changes in subunit stoichiometry can contribute usefully to studies on Cys-loop receptors.     

An amphoteric water‐soluble copolymer. II. Effect of its molecular weight on the dispersion of barium titanate in water

An amphoteric water‐soluble copolymer, that is, polyacrylamide/(α‐N,N‐dimethyl‐N‐acryloyloxyethyl)ammonium ethanate (PAAM/DAAE) was synthesized and it showed the ability to disperse BaTiO₃ (BT) particles in aqueous solutions. In this work, the effect of molecular weight of this polymer on the dispersing properties was further examined. The results indicate that the effectiveness of three polymer samples with different molecular weights in the dispersion of BT particles is P2 (M_w = 1.1 × 10⁵) > P1 (M_w = 1.2 × 10⁴) > P3 (M_w = 3.0 × 10⁵). Apparently, P2 is most effective in dispersing the particles, reducing the viscosity of the suspensions, and obtaining highest green and sintered densities. This is attributed to the highest adsorption of this polymer onto BT powder, and causes strongest electrostatic and steric repulsions. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 886–891, 2006     

Polybenzimidazole (PBI) molecular weight and Mark‐Houwink equation

The molecular weight, and intrinsic viscosity of polybenzimidazole (PBI) and its phosphonylated derivatives are reported. The relationship between intrinsic viscosity [η] and weight average molecular weight (M_w) for PBI has been established in H₂SO₄ and DMF‐LiCl. The Mark Houwink constants K_w of 5.2 × 10^?3 mL/g, α of 0.92 for H₂SO₄ solvent systems and, K_w of 3.2 × 10^?2 mL/g, α of 0.754 for DMF‐LiCl solvent system have been determined at M_w < 65,000. The intrinsic viscosity of PBI determined by the Huggins–Kraemer method was compared with a single point method, and found that both methods fit well for PBI in relatively low concentration solvent system, giving ～ 99% accuracy. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

A Cross between Bread Wheat and a 2D(2R) Disomic Substitution Triticale Line Leads to the Formation of a Novel Disomic Addition Line and Provides Information of the Role of Rye Secalins on Breadmaking Characteristics

A bread wheat line (N11) and a disomic 2D(2R) substitution triticale line were crossed and backrossed four times. At each step electrophoretic selection for the seeds that possessed, simultaneously, the complete set of high molecular weight glutenin subunits of N11 and the two high molecular weight secalins of rye, present in the 2D(2R) line, was carried out. Molecular cytogenetic analyses of the BC₄F₈ generation revealed that the selection carried out produced a disomic addition line (2n = 44). The pair of additional chromosomes consisted of the long arm of chromosome 1R (1RL) from rye fused with the satellite body of the wheat chromosome 6B. Rheological analyses revealed that the dough obtained by the new addition line had higher quality characteristics when compared with the two parents. The role of the two additional high molecular weight secalins, present in the disomic addition line, in influencing improved dough characteristics is discussed.     

Molecular weight and chain conformation of amylopectin from rice starch

By using laser light scattering (LS) and size exclusion chromatography combined LS, we have investigated the molecular weight and chain conformation of amylopectin from rice of India (II‐b), japonica (IJ‐b), and glutinous (IG‐b) in dimethyl sulfoxide (DMSO) solution. The weight‐average molecular weight (M_w) and radius of gyration (〈S²〉^½) of amylopectin were determined to be 4.06 × 10⁷ and 128.5 nm for India rice, 7.41 × 10⁷ and 169.6 nm for japonica rice, 2.72 × 10⁸ and 252.3 nm for glutinous rice, respectively. The 〈S²〉^½ values were much lower than that of normal polymers, indicating a small molecular volume of amylopectin, as a result of highly branched structure. Ignoring the difference of degree of branching, approximated dependences of 〈S²〉^½ and intrinsic viscosity ([η]) on M_w for amylopectin in DMSO at 25°C were estimated to be 〈S²〉^½ = 0.30M_w^0.35 (nm) and [η] = 0.331M_w^0.41 (mL g^?1) in the M_w range studied. Moreover, from the 〈S²〉^½ values of numberless fractions obtained from many experimental points in the SEC chromatogram detected with LS, the dependence of 〈S²〉^½ on M_w for the II‐b sample was estimated also to be 〈S²〉^½ = 0.34 M_w^0.347, coinciding with the above results. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Identification of Novel Chromosomal Aberrations Induced by 60Co-γ-Irradiation in Wheat-Dasypyrum villosum Lines

Mutations induced by radiation are widely used for developing new varieties of plants. To better understand the frequency and pattern of irradiation-induced chromosomal rearrangements, we irradiated the dry seeds of Chinese Spring (CS)-Dasypyrum villosum nullisomic-tetrasomic (6A/6D) addition (6V) line (2n = 44), WD14, with ⁶⁰Co-γ-rays at dosages of 100, 200, and 300 Gy. The M₀ and M₁ generations were analyzed using Feulgen staining and non-denaturing fluorescence in situ hybridization (ND-FISH) by using oligonucleotide probes. Abnormal mitotic behavior and chromosomes with structural changes were observed in the M₀ plants. In all, 39 M₁ plants had structurally changed chromosomes, with the B genome showing the highest frequency of aberrations and tendency to recombine with chromosomes of the D genome. In addition, 19 M₁ plants showed a variation in chromosome number. The frequency of chromosome loss was considerably higher for 6D than for the alien chromosome 6V, indicating that 6D is less stable after irradiation. Our findings suggested that the newly obtained γ-induced genetic materials might be beneficial for future wheat breeding programs and functional gene analyses.     

Effect of molecular weight on crystallization of semirigid poly(phenylene sulfide) under shear flow

Isothermal crystallization of poly(phenylene sulfide) with three molecular weights (M_w = 22k, 48k, and 52k, respectively) under shear condition has been investigated. It appears that shear can induce all these three PPS samples to form a thread‐like crystal structure which consists of the numerous stable nuclei that align tightly in the direction of shear. Crystallization kinetics of PPS has been greatly influenced by shear flow. Higher shear rate and long shear time can lead to decrease of spherulite growth rate of PPS. Also, the spherulite growth rate of PPS is affected by supercoolings and molecular weight. For the lower molecular weight (M_w = 22k), the spherulite growth rate is independent on the shear rate and shear time; while for the higher ones (M_w = 48k and 52k), with the increasing of shear rate, the spherulite growth rate of PPS increases to reach maximum at first, and then decreases. The lower the crystallization temperature is, the more the spherulite growth rate changes, showing that higher orientation of molecular chains can be obtained more easily with increased supercooling. A model has been proposed to explain the mechanism of thread‐like crystal formation under shear flow. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Calculation method of molecular weight averages in polymerization with chain-length-dependent termination

A systematic method for calculating the molecular weight distribution moments in free radical polymerization where termination rate depends on the size of the participating radicals, is presented. The central part of the method is the evaluation of the distribution of termination rates in the balance equations. From an adopted functional form of the termination rate constant, the moment equations are derived. For evaluating the moments of the termination rate distribution an approximate reconstruction of the radical chain length distribution using Laguerre polynomials is proposed. The calculation method can handle termination by disproportionation and combination simultaneously and allows easily to take into account diffusioncontrolled initiation, propagation and chain transfer reactions. The usefulness of the method is illustrated by simulating the bulk polymerization of methyl methacrylate and styrene. The calculated results of conversion, molecular weight averages (M _n,M _w,M _z and M _z+1) and polydispersity are in good agreement with the reported experimental data.     

Physical–chemical and structural stability of PHBV/wheat straw fibers based biocomposites under food contact conditions

This aricle aims at investigating for the first time the ability of using poly(3-hydroxylbutyrate-co-3-hydroxyvalerate) (PHBV)/wheat straw fibers (WSF) biocomposites as food contact materials for packaging applications. For that purpose, the impact of the filler size and content on overall migration and mechanical properties was assessed under standardized testing conditions using the food simulant liquids (FSL). Very high overall migration values were noticed in the case of hydrophilic FSL, that is, water, acetic acid 3% (wt/vol), ethanol 20% (vol/vol), and ethanol 95% (vol/vol), related to the leaching of water extractable components of WSF. Low migration values were obtained in contact with isooctane and olive oil, demonstrating the possibility of using biocomposites in contact with fatty products. To answer the lack of methodologies to simulate different types of food for which PHBV-based composites could be more specifically dedicated, including food products of low or intermediate water activity such as fruits and vegetable, bread, and cheese, a new range of new solid food models based on agar-agar gels have been developed. Results showed that the water activity (a_w) was the main parameter governing the overall migration of PHBV/WSF materials, suggesting that such composite materials could only be used as food contact materials in the case of food products with an a_w equal or lower than 0.90.