Flour Matrix Research Articles

Effect of mercerization of flax fibers on wheat flour/flax fiber biocomposite with respect to thermal and tensile properties

New composites materials, 100% ecofriendly based on modified wheat flour as matrix and flax fiber as fillers have been obtained by means of an extrusion process. The wheat flour matrix contains non-toxic plasticizers and is mixed well with natural fibers. One sample series without specific fiber surface treatment and a second series with a mercerization surface treatment have been prepared. The content of fillers varies from 0% w/w to 20% w/w. In this work the performances of these new composites in term of thermal stability, mechanical behaviours are compared and discussed in regard to the fiber treatment efficiency and composition. We observe an interesting behaviour: the efficiency is found the best for a fiber composition close to 10% w/w.

Dynamic chelation ion chromatography of transition and heavy metal ions using a mobile phase containing 4-chlorodipicolinic acid

The chromatographic behaviour of selected transition and heavy metal ions, the lanthanides, uranium and aluminium, on a neutral polystyrene–divinylbenzene (PS–DVB) stationary phase (7 μm Hamilton PRP-1) dynamically modified with 4-chlorodipicolinic acid, was investigated to evaluate retention characteristics. Complicated retention factor against pH plots were found for these metals demonstrating changes in retention order. It was concluded that complexation between the metal ions and the ligand adsorbed on the resin was strongly influenced by the decrease in dynamic loading with increase in pH, coinciding with changes in the metal-to-ligand ratio in the mobile phase. Possible reversed-phase interactions between metal–chlorodipicolinic acid complexes and the hydrophobic PS–DVB stationary phase also could not be ruled out. An eluent of 0.25 m M chlorodipicolinic acid, 1 M potassium nitrate at pH 2.2 was suitable for the separation of seven transition and heavy metal ions in under 20 min on a 250×4.6 mm column (with 50-mm guard column), determined in a certified water sample with good accuracy ( R 2≥0.994) and reproducibility (RSD 1–4.2%). Pb(II), Cd(II) and Cu(II) were additionally analysed in <10 min in a more complicated certified rice flour matrix, using the same eluent but adjusted to pH 1.5, again with good accuracy ( R 2≥0.998) and reproducibility (RSD 0.48–1.38%).

Durability of Wood Flour-Thermoplastic Composites under Extreme Environmental Conditions and Fungal Exposure

The main purpose of this research work was to investigate the response of wood flour reinforced polyethylene composites to 2 hours water boiling, five complete boiling and freezing cycles and fungal (Gloeophyllumm Traebum/Brown-rot fungus) exposure. Five composite formulations were manufactured and analyzed (0, 50, 60, 70 and copper carbonate treated 60% wood flour/polyethylene composites). The results showed that wood flour loading decreased the resistance of the composites to moisture and fungal environment. The exposure of the composites to 2 hours water boiling and five complete boiling and freezing cycles caused serious damage to the interfacial adhesion between wood flour and polyethylene matrix due to contraction and swelling stresses developed during cyclic exposure. The addition of 1 percent copper carbonate salt during compounding of wood flour and polyethylene prevented the colonization and proliferation of fungus on the surface of the composites, but had a negative effect on the water uptake and flexural properties of the composites.

Factors affecting sample preparation in the gas chromatographic determination of plant sterols in whole wheat flour

A fractional factorial experimental design was applied to study factors affecting sample preparation prior to a gas chromatographic determination of total plant sterols in cereal samples. Whole wheat flour was chosen for the representative matrix. Altogether six factors were studied at two levels. The most affecting factors were a type of hydrolysis (combined acid hydrolysis and alkaline hydrolysis over alkaline hydrolysis alone), extraction solvent after saponification (chloroform over hexane–ether), and sample amount (1.0 g over 2.0 g). Also, it was shown that there is no need to perform total lipid extraction prior to hydrolysis. The use of acid hydrolysis prior to alkaline saponification was found to be essential in a plant sterol analysis of flour matrix. In a further method development, that procedure is to be optimized with various foods of plant origin in order to establish a general method to determine plant sterols. Toivo et al., Factors in the determination of plant sterols

Laboratory and Field Comparisons of Strains of Bacillus thuringiensis for Activity Against Noctuid Larvae Using Granular Formulations (Lepidoptera)

The toxicity of 6 strains of Bacillus thuringiensis representing 4 serovars, aizawai, galleriae, kurstaki, and kumamotoensis, were evaluated in laboratory and field studies for activity against 3 lepidopteran crop pests, Heliothis virescens (F.), Spodoptera exigua (Hübner), and Trichoplusia ni (Hübner). Results of laboratory tests showed that some B. thuringiensis strains isolated from Mexico (GM-7 and GM-I0), were sufficiently toxic to warrant further investigation as potential bioinsecticides for lepidopteran control. Nixtamalized corn flour was used to create a B. thuringiensis granule formulation that remained toxic for at least 2 yr. Field tests were conducted in 1994 and 1995 on corn plots in a semiarid region in central Mexico. Granular formulations were made with 2% (wt:wt) or 4% (wt:wt) of a spore-crystal B. thuringiensis concentrate and tested with carbaryl and Dipel 2X. In 1994, the corn yields obtained from plots treated with 2 strains from the Howard Dulmage collection (HD-187 and HD-193-kurstaki and galleriae, respectively) and 1 Mexican strain (GM-lO, aizawai) at 2% were significantly higher than from plots treated with Dipel 2X or the untreated control. Formulations of 4% containing strains GM-7, GM-I0, HD-187, HD-193, and HD-263 provided better insect control than formulations made with C-4. These tests indicated that B. thuringiensis survived in the nixtamalized flour matrix complex and was effective in causing pest reduction. In the 1995 field test, the 3 most toxic strains were evaluated individually or by mixing 2 in the same granular formulation at a total dose of 3%.The highest yields of com were obtained from plots treated with strain HD-263 (kurstaki, which had originally shown the highest efficacy in laboratory bioassays, and with strain GM-I0 (aizawai), formulated 2 yr earlier. These data suggest that the product can be produced and retain shelf life suitable for commercialization.

The value of sweet potato flour in bread-making

The aim of this research was to evaluate the effect of microwave or steam pre-treatment of raw sweet potato on physicochemical and microstructural properties, and the bioaccessibility of β-carotene in sweet potato flour. This is the first report on using the in vitro digestion model suitable for food, as proposed in a consensus paper, to assess the bioaccessibility of β-carotene in sweet potato flour. The pre-treatments produced a rearrangement of the flour matrix (starch, protein and non-starch polysaccharides), which was greater by using microwaves (M6) conducting to a greater increase in the phase transition temperatures up to 4.14 °C, while the enthalpy presented the higher reduction (4.49 J/g), both parameters in respect to the control. The resistant starch fraction was not modified, with about 3% in all samples. Microwave (M6) and all the steam pre-treatments showed the higher bioaccessibility of β-carotene. This flour can be used in the development of new products with high β-carotene content.