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Similar Chemical Compositions (similar + chemical_composition)
Selected AbstractsThe optimization of the extrusion process when using maize flour with a modified amino acid profile for making tortillasINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 7 2006Jorge Milán-Carrillo Summary Maize with a modified amino acid profile, i.e. greater amounts of lysine and tryptophan than normal, is known as ,quality protein maize' (QPM). The objective of this work was to find the best combination of extrusion process variables to produce QPM flour for making tortillas. QPM grits were mixed with lime and water and had a moisture content of 28%. The single screw extruder operation conditions were selected from factorial combination of three process variables: extrusion temperature (ET, 70,100 °C), lime concentration (LC, 0.1,0.3% of the maize weight) and screw velocity (SV, 80,250 rpm). Response surface methodology was used as an optimization technique. In vitro protein digestibility (PD); total colour difference (,E) of the flours, and tortilla puffing (TP) were chosen as response variables. A graphical method was used to obtain maximum PD, TP and minimum ,E. The optimum combination of process variables was: ET = 85 °C/LC = 0.21%(w/w)/SV = 240 rpm. Tortillas from QPM flour had similar chemical composition, physicochemical and sensory properties to tortillas from commercial nixtamalized maize flour; however, the former had the highest (P , 0.05) available lysine content and were therefore better nutritionally. [source] THE COMPOSITION OF TWO SPANISH PEPPER VARIETIES (FRESNO DE LA VEGA AND BENAVENTE-LOS VALLES) IN DIFFERENT RIPENING STAGESJOURNAL OF FOOD QUALITY, Issue 6 2008ANA BERNARDO ABSTRACT The chemical composition of two traditional varieties of Spanish peppers, "Fresno de la Vega" and "Benavente-Los Valles" harvested in the provinces of León and Zamora, respectively, at different ripening stages (green mature, breaker and red) were evaluated. Herein we report the global composition, mineral and trace element contents, and the most relevant physicochemical parameters of each variety of pepper collected in 2 consecutive years. Both pepper varieties showed a similar chemical composition, except in vitamin C content, which resulted to be about 70% higher in Fresno de la Vega peppers. Red ripe fruits were high in total carbohydrates, fructose, glucose, sucrose, fat (64.5, 29.14, 25.57, 2.94, 1.79/100 g dry weight, respectively) and total soluble solids (6.83°Brix). Ascorbic acid content also increased progressively during ripening, reaching a mean value of 1.81 mg/100 g dry weight for Fresno de la Vega peppers. Potassium was the most abundant of the analyzed elements in the all samples, followed by phosphorus, magnesium, calcium and sodium. The order of the levels of the trace elements was iron > manganese > zinc > copper. PRACTICAL APPLICATIONS This report underscores the potential value of two traditional varieties of Spanish peppers and provides information on their composition during ripening to decide the proper harvesting time, which can be useful in the food industry. [source] Microstructure and physical properties of open-cell polyolefin foamsJOURNAL OF APPLIED POLYMER SCIENCE, Issue 2 2009M. A. Rodriguez-Perez Abstract The cellular structure, physical properties, and structure,property relationships of novel open-cell polyolefin foams produced by compression molding and based on blends of an ethylene/vinyl acetate copolymer and a low-density polyethylene have been studied and compared with those of closed-cell polyolefin foams of similar chemical compositions and densities and with those of open-cell polyurethane foams. Properties such as the elastic modulus, collapse stress, energy absorbed in mechanical tests, thermal expansion, dynamic mechanical response, and acoustic absorption have been measured. The experimental results show that the cellular structure of the analyzed materials has interconnected cells due to the presence of large and small holes in the cell walls, and this structure is clearly different from the typical structure of open-cell polyurethane foams. The open-cell polyolefin foams under study, in comparison with closed-cell foams of similar densities and chemical compositions, are good acoustic absorbers; they have a significant loss factor and lower compressive strength and thermal stability. The physical reasons for this macroscopic behavior are analyzed. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 [source] Relevance of Osteoinductive Biomaterials in Critical-Sized Orthotopic DefectJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 5 2006Pamela Habibovic Abstract Several publications have shown the phenomenon of osteoinduction by biomaterials to be real. However, whether the ability of a biomaterial to initiate bone formation in ectopic implantation sites improves the performance of such osteoinductive biomaterial in clinically relevant orthotopic sites remains unclear. No studies have been published in which osteoinductive potential of a biomaterial is directly related to its performance orthotopically. In this study, we compared osteoinductive and nonosteoinductive biphasic calcium,phosphate (BCP) ceramics ectopically and in a clinically relevant critical-sized orthotopic defect in goats. The two materials, BCP1150 and BCP1300, had similar chemical compositions, crystallinities, and macrostructures, but their microstructures differed significantly. BCP1150, sintered at a lower temperature, had a large amount of micropores, small average crystal size, and hence a high specific surface area. In contrast, BCP1300, with few micropores, had a significantly lower specific surface area as compared to BCP1150. Twelve-week intramuscular implantation in goats (n,=,10) showed that bone was induced in all BCP1150 implants, while no signs of bone formation were found in any of the BCP1300 implants. After 12 weeks of implantation in a bilateral critical-sized iliac wing defect in the same goats, BCP1150 showed significantly more bone than BCP1300. In addition, the analysis of fluorochrome markers, which were administered to the animals 4, 6, and 8 weeks after implantation to follow the bone growth dynamics, showed an earlier start of bone formation in BCP1150 as compared to BCP1300. Significantly better performance of an osteoinductive ceramic in a critical-sized orthotopic defect in a large animal model in comparison to a nonosteoinductive ceramic suggests osteoinduction to be clinically relevant. Further improvement of material osteoinductive properties is thus a significant step forward in the search for alternatives for autologous bone graft. © 2006 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res [source] Mycenaean pottery from the Argolid and Achaia,a mineralogical approach where chemistry leaves unanswered questionsARCHAEOMETRY, Issue 2 2002A. Hein The chemical classification of Mycenaean pottery from the Northern Peloponnese by neutron activation analysis (NAA) resulted in two groups with very similar chemical compositions assigned to production centres in the Argolid and in Achaia, respectively. The statistical separation of these two groups on the basis only of their chemical composition was difficult, and not clear-cut for all of the examined samples. A complementary mineralogical examination by X-ray diffraction (XRD) of some selected samples indicated differences in the mineralogical composition, which confirmed the determined chemical differences. Furthermore, a clay sample was examined, which showed a composition similar to that of the pottery. [source] | ||||||||||