Wheat flour dough Alveograph characteristics predicted by Mixolab regression models

BACKGROUND: In Romania, the Alveograph is the most used device to evaluate the rheological properties of wheat flour dough, but lately the Mixolab device has begun to play an important role in the breadmaking industry. These two instruments are based on different principles but there are some correlations that can be found between the parameters determined by the Mixolab and the rheological properties of wheat dough measured with the Alveograph. RESULTS: Statistical analysis on 80 wheat flour samples using the backward stepwise multiple regression method showed that Mixolab values using the ‘Chopin S’ protocol (40 samples) and ‘Chopin + ’ protocol (40 samples) can be used to elaborate predictive models for estimating the value of the rheological properties of wheat dough: baking strength (W), dough tenacity (P) and extensibility (L). The correlation analysis confirmed significant findings (P < 0.05 and P < 0.01) between the parameters of wheat dough studied by the Mixolab and its rheological properties measured with the Alveograph. CONCLUSION: A number of six predictive linear equations were obtained. Linear regression models gave multiple regression coefficients with $R_{\rm {adjusted}}^{2} > 0.70$ for P, $R_{\rm {adjusted}}^{2} > 0.70$ for W and $R_{\rm {adjusted}}^{2} > 0.38$ for L, at a 95% confidence interval. Copyright © 2011 Society of Chemical Industry     

Preliminary studies on the influence of boron on the foliar biomass and quality of tobacco leaves subjected to $\hbox{NO}_3^-$ fertilisation

The aim of the present work was to determine the influence of different B dosages on foliar biomass and quality in tobacco plants (Nicotiana tabacum L var Tennesse 86). Tobacco plants were grown under controlled conditions and submitted to regular fertilisation with macro‐ and micronutrients. The B was applied to the nutrient solution in the form of H₃BO₃ at 5 µM (B1), 10 µM (B2) and 20 µM (B3). The results indicated that under the experimental conditions of this work the increased application of B favoured the growth and development of the leaves, this leading to improved biomass production in tobacco leaves. The increase in foliar biomass in treatment B3 is due largely to the stimulation of assimilation. However, this situation has negative consequences for tobacco quality, given that the B3 treatment augmented the concentration as well as the foliar concentration of nicotine, both effects being harmful for human consumption. Finally, a close and directly proportional relationship was found in our experiment between the parameters foliar biomass production, total N concentration, chlorophyll concentration and decline in quality. © 2001 Society of Chemical Industry     

Magnetic resonance imaging of connective tissue: a non‐destructive method for characterising muscle structure

A magnetic resonance imaging technique based on susceptibility‐induced contrast was used to visualise the spatial distribution of connective tissue in meat. Magnetic resonance imaging of bovine meat samples was carried out with a high‐field 4.7 T imager. Magnetic resonance images obtained with spin‐echo and gradient‐echo sequences were compared to elucidate the role of connective tissue in the additional signal losses observed in the gradient‐echo images. maps were reconstructed from the multiple gradient‐echo images, which provide quantitative information. Comparison with histological pictures indicates that these maps exhibit the overall organisation of the primary perimysium at the scale of the whole muscle. The distinct perimysial organisation shown between the Gluteo biceps and Pectoralis profundis muscles illustrates the potential of magnetic resonance imaging for characterising the muscle connective tissue structure. © 2000 Society of Chemical Industry     

The relative merits of the presence of hull on the nutritional qualities of the African yam bean flour

The flour from three colour cultivars of hulled and dehulled seeds of the African yam bean (AYB) (Sphenostylis stenocarpa) was analysed for anatomical fractions; proximate, mineral, fatty and amino acids composition. The seed hull varied between 8.25% and 9.14%. Na, K. Ca, Mn, Fe, Zn are preferably found in the hulled samples. Essential fatty acids as well as essential amino acids are more enriched in the hulled samples than in the endosperm. Correlation coefficient results showed that proximate composition (r, r, r), mineral composition (r, r, r), fatty acids (r, r, r), fatty acids saturation (r, r, r) and amino acids (r, r, r) were significant at α = 0.05 in the samples shown in parentheses with values having high positive correlation coefficients ranging from 0.82 to 1.00. These results showed that dehulling of African yam bean seeds will lead to reduction in the nutritional qualities of the AYB.     

The extraction of radiolabelled inorganic sulphate from blood plasma

A study was conducted into factors governing the efficiency of the ion exchange method for extracting ³⁵S-labelled inorganic sulphate (SO) from blood plasma, using Dowex′1-X8 ion exchange resin. The study compared effects of trichloroacetic acid (TCA) strength as protein precipitant, different HCl strengths as resin eluent, sodium citrate/HCl (SC/HCl) versus HCl as eluents, and evaluated ultrafiltrated (UF) plasma upon the adsorption and recovery of added ³⁵SO. Both adsorption and release of ³⁵SO from the resin were inhibited by the presence of TCA, and HCl was not as effective as 1 M SC/2 M HCl in releasing ³⁵SO adsorbed to resin. The rates of ³⁵SO adsorbed onto resin and recovered were markedly increased by using UF plasma and 1 M SC/2 M HCl as eluent, with the values being 96.3 ± 0.11% and 91.1 ± 0.39%, respectively, where 1 g resin was used. Therefore, the use of UF for deproteinising and 1 M SC/2M HCl as eluent are recommended for extracting ³⁵SO from blood plasma when Dowex′1-X8 resin is used as the ion exchanger.     

A model of temperature effects on microbial populations from growth to lethality

The propagation/destruction rate constant of microbial populations over the entire temperature range from growth (k(T) > 0) to lethality (k(T) < 0) can be described by a single mathematical model in the from: where b is a dimensionless constant related to the height of the growth peak, T_m and T_c temperatures characteristic of the growth and lethal regimes and a₁ and a₂ constants (temperature units) indicating the span of the growth region and the steepness of k(T) in the lethal temperature region respectively. The fit of the model is demonstrated with published data on the effect of heat on two bacteria. Since bacterial spores, unless germinated, do not multiply, a reduced version of the model is sufficient to describe their destruction rate at moderate (almost no effect) and high (lethal) temperatures ie . The fit of this equation is demonstrated with published data on the heat destruction kinetics of two bacilli spores. If the relationship between the model's constants and environmental conditions such as pH, a_w, salts concentration, etc can be expressed algebraically the model can be used to describe the combined effect of the various factors within the frame work of a single mathematical equation. Although the model's applicability is only demonstrated with a limited number of microorganisms the concept that a single model can describe both the propagation and lethal regimes can be useful in other types of biological populations, eg insects.     

An SEC−MALLS Study of Molecular Features of Water‐soluble Amylopectin and Amylose of Tef [Eragrostis tef (Zucc.) Trotter] Starches

The molecular features of five tef starches along with those of commercial normal maize starch were investigated by size‐exclusion chromatography with multi‐angle laser light scattering‐differential refractive index detection (SEC/MALLS‐DRI) after solubilization in water by cooking in a household pressure cooker. The weight‐average molar mass ( ) and weight‐average root‐mean square radius of gyration (<R_g>_w) of the amylopectin (AP) of tef starches ranged from 10.1×10⁷ g/mol (156 nm) to 16.5×10⁷ g/mol (205 nm) with a mean of 13.9×10⁷ g/mol (186 nm). The AP of the tef starches was considerably smaller than that of maize starch ( = 19.6×10⁷ g/mol, <R_g>_w = 207 nm). These considerably smaller AP molecules in tef starches were most probably responsible for the low paste viscosity of tef starches as compared to maize starch. In most tef starches, the polydispersity index (PI) of the AP was broader than that of the AP of maize starch. The intermediate fraction (IN) 1.0−1.6, mean = 1.1) of most tef starches were similar to those of the IN of maize starch. The amylose (AM) (range 1.5×10⁶−3.0×10⁶ g/mol, mean = 2.2×10⁶ g/mol) and size (range 176−214 nm, mean = 191 nm) of most tef starches was also apparently similar to that of the maize starch ( = 2.3×10⁶ g/mol, <R_g>_w = 193 nm), but the polymer distribution was narrower. The AM−iodine complex of the tef starches had a λ_max range of 611−679 nm and the absorption shifted toward longer wavelengths by 8−14 nm as compared to the maize starch AM−iodine complex. The blue value (absorption at λ_max) for 1 mg/mL of tef AM had a range of 2.3−2.8 (mean = 2.5), whereas for the maize starch, the mean was 2.2. The branched nature of tef starches was also investigated by debranching with isoamylase and determination of chain lengths (DP_n) of the branches by size exclusion chromatography with refractive index detector (SEC‐RI). The AP in tef starches had a polymodal distribution with a periodicity similar to that of cereal starches. The branches had DP_n values of A = 11, B1 = 16, B2 = 46 (range 46−47), B3 = 70 (range 69−72) and B4 = 118 (range 113−123). The outer (A + B1) chains were shorter than those of maize starch AP with abundance (74%, w/w) only slightly less than that of the maize starch (75%, w/w). The slow rate of retrogradation, the slightly lower percent crystallinity, the lower gelatinization temperatures and the lower gelatinization enthalpy observed for tef starches (as compared to maize starch) are probably related to the shorter outer (A + B1) chain lengths of their amylopectin molecules, and may be the foundation of the comparably good keeping quality of tef injera, the main staple in the Ethiopian diet.     

Effect of root zone pH and form and concentration of nitrogen on accumulation of quality‐related components in green tea

Green tea quality is greatly influenced by concentrations of free amino acids, polyphenols (mainly catechins) and caffeine. The present study investigated the principal relationship between selected nutritional factors (form and concentration of N supply, root zone pH) and accumulation of these quality‐related components of tea (Camellia sinensis (L.)) plants. Tea plants were hydroponically cultured with NH , NO and NH NO at pH 4.0, 5.0 and 6.0 in one experiment and supplied with varying N concentrations (0.75, 2.0 and 4.5 mmol L^?1, NH /NO^?₃ = 3:1) in another experiment. Concentrations of free amino acids were considerably higher in NH ‐ than in NO ‐fed plants. This was attributed to the much greater absorption of NH compared with NO . Furthermore, the relative allocation of absorbed N to free amino acids, particularly theanine and glutamine, was substantially increased by NH nutrition, suggesting that NH was more readily assimilated than NO into theanine. The concentration of caffeine was increased in NH ‐ and (NH NO )‐supplied plants, whereas concentrations of catechins were reduced in (NH NO )‐fed plants. Root zone pH did not influence concentrations of most free amino acids in young shoots, with the exception of theanine, which increased at low pH (4.0) irrespective of N form; this likely stemmed from an accumulation effect, as growth decreased more strongly than N absorption. Raising the N supply increased plant N allocation to free amino acids. The increase was most striking for arginine, while theanine was only marginally affected. This may have adverse consequences for green tea quality, as less favourable taste characteristics have been attributed to arginine. Copyright © 2007 Society of Chemical Industry     

Molecular Structure of Starch from Pueraria lobata (Willd.) Ohwi Relative to Kuzu Starch

The molecular structures of starches from Pueraria lobata (Willd.) Ohwi were examined and compared with those of other tuberous and root starches. The fresh tubers were collected from three Chinese main Pueraria lobata (Willd.) Ohwi growing regions. The chain distributions of the amylopectins as determined by gel permeation chromatography were similar to those of the amylopectins of other starches. Among the three amylopectins studied, the respective β‐amylolysis limits were 55%, 56% and 58% which were similar to that of kuzu amylopectin. The number average degree of polymerization ( ) values of the amylopectins were 8.7‐9.7×10³, lower than those of sweet potato and potato amylopectins (9.9×10³ and 11.2×10³, respectively). The number of branch chains per amylose molecule was 5.0. The average chain length ( ) of the Pueraria lobata (Willd.) Ohwi amyloses was similar to those of kuzu (310), sweet potato (310) and tapioca amyloses (340), but lower than those of lily (475) and potato (670).     

Quantity/intensity relations in soils and the potassium nutrition of the strawberry plant (Fragaria SP)

In glasshouse pot experiments over two years, the strawberry plant used potassium primarily from sources which were in instantaneous equilibrium with the soil solution. Leaf potassium concentration at flowering and fruiting was highly correlated with the initial equilibrium potassium activity ratio (AR) of the soil, and a linear relationship existed between 1/Leaf-K and 1/AR Yield of fruit was less well correlated with AR than with the quantity of labile potassium in the soil. the gradient of the straight line part of the quantity/intensity (Q/I) graph was increased for 2 of the 5 soils after the period of intensive cropping; this could be related to an increase in the amount of exchangeable calcium+magnesium in the soil.     

A rapid in vitro enzymic and chromatographic predictive model for the in vivo rat-based protein efficiency ratio of mixed food proteins

A nutritional quality index in the nature of an enzymatic protein efficiency ratio (E-PER) was computed from the amino acid data of 18 different food products by means of multiple regression equations. The regression was performed by setting amino acid values derived from enzymic hydrolysis of the food proteins as the independent variables with the rat-based PER values as the dependent variables. The multiple regression gave the following equation. The multiple correlation coefficient for this regression was 0.942 and the coefficient of variation was 88.7%. The prediction equation was tested on amino acid-PER data of 22 different foodstuffs and it successfully predicted (± 0.22) the PER of 17 and an effectiveness of 77.3%.     

Effects of Suspension Crosslinking Reacting Conditions on the Sizes of Starch Microspheres

Using the method of suspension crosslinking polymerization and epichlorohydrin as the crosslinking agent, starch microspheres have been synthesized. And the effects of reacting parameters, including the surfactant concentration, stirring speed, two phases viscosities and densities on the microspheres mean size (18–36μm) are also discussed. One equation is deduced to demonstrate these effects:      

Determination of dry matter and crude protein contents of undried forages by near‐infrared reflectance spectroscopy

Near‐infrared reflectance spectroscopy (NIRS) was used to predict the dry matter (DM) and crude protein (CP) contents of untreated forage samples. Four hundred forage samples were analysed in reflectance mode. Two mathematical treatments based on the order of derivative of log(1/R), the gap in data points and the numbers of data points used in the first and second smoothings were applied. Predictive equations were developed using modified partial least squares (MPLS) with internal cross‐validation. The coefficient of determination of calibration and the standard error of cross‐validation (SECV, in parentheses) for DM were 0.92 (12.4), 0.92 (12.6) and 0.93 (11.7) for the two treatments and log(1/R) respectively on a g kg^?1 fresh weight basis. For CP the NIRS calibration statistics yielded and SECV (in parentheses) values of 0.85 (19.8), 0.85 (19.5) and 0.87 (18.1) for the two treatments and log(1/R) respectively on a g kg^?1 fresh weight basis. It was concluded that NIRS is a suitable method to predict the dry matter and crude protein contents of fresh forage without sample preparation. © 2002 Society of Chemical Industry     

Ion chromatographic determination of inorganic anions in vinegar samples

An ion chromatographic procedure (IC) with chemical suppression is described for the simultaneous determination of the anions Cl^?, NO, HPO and SO at ppm levels in vinegar samples. The moderately strong eluent composed of NaHCO₃/Na₂CO₃ was chosen and sample pretreatment was required to reduce the influence of acetate on the chloride peak. The results obtained by IC were compared to those from standard methods.     

Determination of plant iron,manganese and zinc by wet ashing procedures

The efficacy of HNOHClO₄ and HNOHClO₄-HF digestion mixtures for wet ashing of selected plant samples of field and greenhouse origin for Fe, Mn and Zn analyses was studied. The ternary digestion mixture was required for the determination of Fe, but not of Mn and Zn, in six unwashed field-grown samples, including four botanical Standard Reference Materials from the US National Bureau of Standards. The ternary digestion mixture was also required for the analysis of Fe in both washed and unwashed tops of field-grown flax (Linum usitatissimum L.). However, washing appreciably reduced plant Fe and Mn, presumably by removing soil contamination. In addition, the superiority of the ternary digestion mixture for Fe analysis was much less for the washed samples. The contents of Fe, Mn and Zn in washed tops of greenhouse-raised flax and soya beans (Glycine max L. Merr.) were similar with both digestion mixtures. It is recommended that in plant nutrition studies involving Fe, the efficacy of HNOHClO₄ digestion procedures be routinely checked by completely dissolving any siliceous residue with HF.     

Dissolution of various sources of gypsum in aqueous solutions and in soil

The dissolution of six sources of gypsum in water and 0.01 M CaCl₂ was examined in the presence and absence of soil. The gypsum samples included: analytical grade (AR), three sources of flue-gas desulphurisation (FGD) gypsum, phosphogypsum (PG), and mined gypsum (MG). Dissolution in aqueous solutions was monitored by measuring the concentration of calcium (Ca²⁺) and sulphate (SO) ions. In soils which adsorb small amounts of SO^?2₄, dissolution was estimated from the increase in the concentration of Ca²⁺ and SO in gypsum-treated soil over the control soil. However, in soils which adsorb significant amounts of SO, measurement of solution SO concentration underestimates the extent of dissolution. Gypsum dissolution was larger in water (15.20 mmol litre^?1) than in 0.01 M CaCl₂ (11.12 mmol litre^?1), and this was attributed to the Ca²⁺ common-ion effect. The rate of dissolution decreased in the order: AR > FGD > PG > MG. Dissolution was 2 to 10 times faster for powdered (< 500 .m) gypsum than for the discs obtained by pelletising. The differences in the rate of dissolution between the gypsum sources and between powder and disc samples were related to both surface area and the presence of CaCO₃, impurity. The rate of dissolution was 3 to 8 times faster in the presence than in the absence of soil. Whereas the dissolution of gypsum in the presence of soil followed first order reaction kinetics, it followed second order kinetics in the absence of soil. This difference in reaction kinetics resulted from the continuous removal of Ca2+ and SO by the soil.     

Acceptability of diets containing olive oil fried sardines (Sardina pilchardus) in the prevention of dietary hypercholesterolaemia in rats

Garlic (Allium sativum L) bulb explants produced undifferentiated white globular callus when grown on MS medium having 2,4-dichlorophenoxy-acetic acid (2,4-D) and Kinetin (Kn). Such callus when grown on medium having indole-3-yl-acetic acid (IAA) and/or Kn developed into the differentiating callus which had comparatively more allicin than that of undifferentiated callus. The effect of sucrose, NH/NO ratios and hormone concentrations on growth and allicin development in the callus was investigated. There was a significant increase in allicin development in callus when grown for up to 4 weeks on medium (a) having sucrose at 3% and 5% levels; (b) having NH and NO ratios at 2:1 and 1;1; and (c) with Kn alone at a concentration of 0.5 mg litre^?1, which produced a tenfold increase in allicin content.     

A COMPARISON OF THE FARINOGRAPH AND A MODIFIED SHEAR-PRESS FOR MEASURING THE RHEOLOGICAL PROPERTIES OF DOUGH AND ITS FINISHED PRODUCTS1

The development of a single texture testing instrument for determining the complicated properties of dough and the textural characteristics of the final product of dough will eliminate the need for a series of specialized instruments. The farinograph and a modified shear-press were used to determine the rheological properties of doughs made from 15 mixtures of all purpose wheat flour, hard wheat flour and 6% soy fortified wheat flour adjusted with 54.7, 58.0, 61.1, 64.6 and 67.9% water absorptions. The shear-press was also used to determine the textural characteristics of the finished products. The shear-press was found to be equal to the farinograph in providing information on certain rheological properties of dough, and high correlations were obtained between these ‘texturegrams’ and farinogram parameters. For instance, the correlation between “viscoelasticity” per texturegram and “maximum consistency” per farinogram was 0.982; between “viscoelasticity” per texturegram and “elasticity” per farinogram was 0.969; and the correlation between “stability of viscoelasticity” per texturegram and “twenty minute drop” per farinogram was 0.941. The adhesive and cohesive properties of dough obtained from shear-press texturegrams explained 88.4% of the variance of the hardness of the end-products. The consistency and elasticity of dough obtained from farinograms explained 90.6% of the variance of the hardness of the end-products. If the method of water absorption and mixing of flour could be standardized, the shear-press could be utilized both for predicting rheological properties of bakery products from determinations on doughs as well as direct evaluations of the finished products.     

Transport of organic acid anions and guanosine into vacuoles of Saccharomyces pastorianus

Isolated vacuoles of the yeast Saccharomyces pastorianus accumulate citrate, α-ketoglutarate, malate and guanosine. This accumulation is Mg ATP-dependent and inhibited by protonophores. The ionophores monensin and A23187 (electroneutral Meⁿ⁺/nH⁺-exchange) inhibit guanosine accumulation but fail to block citrate uptake. Mg²⁺ ions (2 mM ) increase the values of both Δ$ \tilde \mu $H⁺ components and stimulate the uptake of all the above compounds. Ca²⁺ ions (1 mM ), hyperpolarizing the yeast vacuolar membrane and dissipating the pH gradient, inhibit guanosine uptake and stimulate that of citrate. It is concluded that guanosine is transported into yeast vacuoles by an H⁺/guanosine antiporter while citrate, malate and α-ketoglutarate are translocated by a uniporter(s) at the expense of the membrane potential (positive inside).     

Nutritive evaluation of herbage from permanent meadows by near‐infrared reflectance spectroscopy: 1. Prediction of chemical composition and in vitro digestibility

This study was implemented to evaluate the potential of near‐infrared reflectance spectroscopy (NIRS) technology to estimate the chemical composition and in vitro digestibility of botanically complex herbage mixtures characterised, moreover, by a noteworthy variation among samples in the maturity of the forage plants. A total of 107 herbage samples harvested from permanent meadows located in the uplands of León (northwestern Spain) were analysed to determine their chemical composition. In addition, the in vitro digestibility of each herbage sample was measured by two different in vitro procedures using buffered rumen fluid. A Bran + Luebbe InfraAlyzer 500 spectrophotometer was used to obtain the near‐infrared spectra corresponding to each herbage sample. Prediction equations developed for the estimation of the chemical components showed that NIRS technology could predict these parameters accurately, especially the crude protein and neutral detergent fibre contents ( in both cases). In vitro digestibility parameters could also be predicted with an acceptable degree of accuracy using NIRS technology, particularly the in vitro Tilley and Terry organic matter digestibility ( , standard error of prediction (SEP) = 2.165% organic matter) and the in vitro dry matter true digestibility measured according to the Goering and Van Soest procedure ( , SEP = 2.208% dry matter). Copyright © 2005 Society of Chemical Industry