Nutritional and physicochemical evaluations of tahina (sesame butter) prepared from heat‐treated sesame seeds

Dehulled sesame seeds were roasted using different heat treatments. The effects of roasting treatments on the nutritive value, physicochemical properties and sensory properties of produced tahina were studied. Resultant tahina contained 586–594 g kg⁻¹ crude oil, 219–226 g kg⁻¹ crude protein and <30 g kg⁻¹ crude fibre and ash. Crude protein, crude fibre, ash and N‐free extract in tahina samples were not affected by roasting treatments. However, crude oil was decreased by steam roasting and hot plate roasting. Hot plate roasting was more effective in reducing raffinose content than other roasting treatments, whereas vacuum roasting was less effective in reducing raffinose content than other roasting treatments. Tahinas were good sources of essential amino acids, especially sulphur‐containing amino acids, aromatic amino acids and tryptophan. Hot air roasted tahina followed by vacuum roasted tahina had higher total essential amino acid contents than steam roasted and hot plate roasted tahinas. Lysine was the first limiting amino acid in tahinas. Tahinas had a relatively high in vitro protein digestibility (over 83%). Tahina is a good source of niacin. Hot air roasted tahina had the highest content of B group vitamins compared with other tahina samples. Resultant tahinas had relatively high amounts of Na, Mg, K, Cu, Zn and Fe and a low amount of Ca. Roasting treatments did not affect the mineral contents. All roasted samples had a typical protein spectrum with a maximum absorption at 280 nm and minimum at 260 nm. However, the spectrum of hot air roasted tahina proteins was sharper than the spectra of other tahina proteins. Size exclusion HPLC fractionated tahina proteins into two fractions for hot roasted and vacuum roasted tahinas and three fractions for steam roasted and hot plate roasted tahinas. The gel filtration pattern of tahina proteins contained four peaks with identical elution volumes but different proportions. Hot air roasted and vacuum roasted tahinas had higher panel scores than steam roasted and hot plate roasted tahinas for all tested sensory properties. © 2000 Society of Chemical Industry     

Binding of aflatoxin B1 by probiotic bacteria

The ability of six probiotic bacteria to bind a common food carcinogen, aflatoxin B₁, was assessed. The studied strains included Lactobacillus strains and one Bifidobacterium strain. The strains were incubated in vitro with alfatoxin B₁ and the toxin residue in the supernatant was measured using high‐performance liquid chromatography. The aflatoxin‐binding capacity of the strains was found to range from 5.8 to 31.3%. The results further support the observation that a number of probiotic bacteria are able to bind specific dietary contaminants. Although the extent of binding varies depending on the bacterial strain used, the data may explain some of the antimutagenic and anticarcinogenic effects of probiotic micro‐organisms. © 2000 Society of Chemical Industry     

Effect of stabilising heat treatment on characteristics of electrolytic alumina coating on ferritic stainless steel

The effect of stabilising thermal treatment on the characteristics of conversion coatings modified by electrolytic alumina deposits have been studied using SIMS analysis and X‐ray diffraction in grazing incidence. Before heating, alumina deposit obtained is in form of amorphous boehmite gel. Heat treatment at 800°C in air leads to a very uniform coating morphology and induces diffusion phenomena. After heating (24 h), the coating is constituted of two layers: an alumina (δ‐Al₂O₃) outer layer and a chromium oxide (α‐Cr₂O₃) inner layer. At the coating/steel interface mixed oxide (iron, chromite) are present. The electrolytic alumina deposit blocks the chromium oxide in the deep zone.     

Physico‐chemical and technological studies on sugar beet roots

The morphological and chemical characteristics of ten varieties of sugar beet roots were evaluated during the season of 1996–1997. The best morphological characteristics were found in Top, Ito and Pamela varieties. The highest expected technological yield of sugar was found in Pamela and Top. The chemical constituents of different varieties of sugar‐beet roots showed significant differences. The suitability of sugar beet juice for preparing beet syrup as a new product was also evaluated and compared with sugar cane syrup. Purified beet‐syrups concentrated under vacuum or under atmospheric pressure showed more stability during storage than sugar cane syrup. The effect of storage conditions (at cold storage and at room temperature) and packaging materials (glass and polyethylene high‐density bottles) on properties of beet‐syrup and sugar cane syrup were also studied.     

Physicochemical Properties of Different Types of Starch Phosphate Monoesters

Different types of starch were phosphorylated to different degrees of substitution using monosodium and disodium hydrogen orthophosphate at 160 °C under vacuum. Generally, phosphation enhanced the physicochemical properties of the modified starches compared to their native counterparts. Solubility and swelling power greatly increase when phosphorylation was carried out to a low degree of substitution, while the solubility and swelling power decreased gradually by increasing the degree of substitution. However, the values of the monoesters were still higher than those of the corresponding native polysaccharides. Viscosities of different starch types except corn amylose showed the highest values at the lowest degree of substitution, when the degree of phosphation increased the viscosity values decreased. Native potato starch formed a clear paste (96% transmittance) due to the presence of phosphate groups while the paste clarity of potato starch decreased gradually by increasing the degree of phosphation. Generally, phosphorylation increased the light transmittance of the other starches investigated at the lowest degree of substitution but the clarity decreased by increasing the degree of substitution.     

The economic utilisation of sulphonation process residues in the petroleum industry

Sulphonation process residues in the petroleum industry are not exploited in line with their scientific or economic potential. The traditional routes for disposal of these residues can contribute to pollution, whereas various chemical techniques can be used to produce valuable products with domestic and industrial applications. The present work deals with the utilisation of sulphonation process residues. It is found that economic utilisation of sulphonation process residues from the petroleum industry involves the following:

• 1 A comparative evaluation of the performance of the products obtained with other available products demonstrated their efficiency and value.
• 2 Production of highly paraffinic oils with low aromatic content, with potential for use as spray oils, and the utilisation of their residues in the preparation of oil‐soluble neutral and overbased calcium sulphonates, to be used as detergentdispersant additives for crankcase lubricating oils.
• 3 Regeneration of used lubricating oils and use of their residues in the preparation of water‐soluble sodium sulphonates for use as surfactants.
• 4 Reducing the aromatic and sulphur content of kerosene for eventual employment as a carrier solvent for household in secticide.

     

Improved LMI conditions for gain scheduling and related control problems

The gain scheduling problem considered in this paper concerns a linear system whose state-space equations depend rationally on real, time-varying parameters, which are measured in real time. A stabilizing, parameter-dependent controller is sought, such that a given ℒ︁₂-gain bound for the closed-loop system is ensured. Sufficient linear matrix inequality (LMI) conditions are known, that guarantee the existence of such ‘gain-scheduled’ controllers. This paper improves these results in two directions. First, we show how to exploit the realness of the parameters using a ‘skew-symmetric scaling’ technique. Moreover, we show how to apply this technique in a time-varying and/or nonlinear setting. We first devise a general result pertaining to control synthesis of interconnection of dissipative operators, and apply it to the gain-scheduling problem. Owing to its generality, this result can be applied to other problems such as anti-windup control, nonlinear control and model reduction. © 1998 John Wiley & Sons, Ltd.     

Electroplating of cobalt from aqueous citrate baths

Electroplating of cobalt onto steel substrates from citrate baths has been investigated under different conditions of bath composition, current density, pH and temperature. A detailed study has been made of the influence of these variables on the potentiodynamic cathodic polarization curves, cathodic current efficiency and the throwing power as well as the throwing index of these baths. The optimum bath composition has been established and it contains: CoSO₄.7H₂O (0·36 mol dm⁻³) trisodium citrate (0·19 mol dm⁻³) and citric acid (0·1 mol dm⁻³) at pH 5·0. The microhardness of cobalt electrodeposited from citrate baths is high and it may be, under certain conditions, two or three times higher than that reported for cobalt electrodeposited from other different baths. The surface morphology of the as-plated cobalt was investigated by using scanning electron microscopy (SEM) while the structure was studied by using X-ray diffraction analysis and anodic stripping voltammetry (ASV) techniques. © 1998 Society of Chemical Industry     

Theoretical Prediction and Experimental Study of Benzimidazole Derivate as a Novel Corrosion Inhibitor for Carbon Steel in 1.0 M HCl

Protection of Metals and Physical Chemistry of Surfaces - The inhibiting effect of benzimidazole derivate (DBI) on corrosion of carbon steel (CS) at temperature range of 303–333 K was...