938 resultados para Food industry and trade -- Quality control
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
Multivariate quality control studies applied to Ca(II) and Mg(II) determination by a portable method
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A portable or field test method for simultaneous spectrophotometric determination of calcium and magnesium in water using multivariate partial least squares (PLS) calibration methods is proposed. The method is based on the reaction between the analytes and methylthymol blue at pH 11. The spectral information was used as the X-block, and the Ca(II) and Mg(II) concentrations obtained by a reference technique (ICP-AES) were used as the Y-block. Two series of analyses were performed, with a month's difference between them. The first series was used as the calibration set and the second one as the validation set. Multivariate statistical process control (MSPC) techniques, based on statistics from principal component models, were used to study the features and evolution with time of the spectral signals. Signal standardization was used to correct the deviations between series. Method validation was performed by comparing the predictions of the PLS model with the reference Ca(II) and Mg(II) concentrations determined by ICP-AES using the joint interval test for the slope and intercept of the regression line with errors in both axes. (C) 1998 John Wiley & Sons, Ltd.
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Anthracnose causes severe damage to the mango skin. Therefore, there is need to do the post-harvest phytosanitary treatment of the fruits through soaking in fungicide solution, which associated with the hydrothermal treatment has resulted into improved benefits. The present work has aimed at studying anthracnose control and post-harvest quality of mangoes (Mangifera indica L.), cv. Van Dyke after hydrothermal treatment associated with chemical through the physical, physicochemical, chemical and phytopathologic analyses. The mangoes coming from the commercial orchard of the town of Jana ba-MG, of the 2000 crop, were harvested at the commercial maturation stage. After selection according to color uniformity, size and absence of mechanic and physiologic injuries, they were shipped in plastic boxes to the EPAMIG - CTNM - Nova Porteirinha - MG, fruit post-harvest laboratory, where the samples were submitted to the hydrothermal treatment in cold bath in solution containing the fungicides Thiabendazole (Tecto 400 mL/100L), Proclaraz (Sportak 10L/100L) and Imazalil (Magnate 200mL/100L). After air-drying, the fruits were packed in plastic trays and stored at room temperature (25 +/- 2 degrees C and RH 70%) for a 12-day period and evaluated as to the intrinsic quality characteristics every 4 days. The experiment was conducted a completely randomized with 8 treatments, 4 replicates and experimental unit consisting of 4 fruits. The variations of pH, total soluble solids, total titrable acidity and total soluble sugars have not endangered the organoleptic characteristics of mangoes cv. Van Dyke stored under room temperature (25 +/- 2 degrees C and RH 70%) till 8 days' storage. The association of the hydrothermal treatment with the chemical was efficient in fruit anthracnose control for till 12 days' storage. The fungicide Prochloraz (Sportak 110 mL/100L), associated with the hydrothermal treatment, completely inhibited the appearance of anthracnose symptoms.
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The evolution of the food sector has increased interest in the identification of new starches with distinct properties. Curcuma longa and Curcuma zedoaria rhizomes, which are already used in industry to obtain food coloring and pharmaceutical products, may become commercially interesting as starch raw materials. This work aimed to characterize the starch of two Curcuma species. The results revealed that the rhizomes of two species showed low dry matter and high starch contents. The amylose contents of the starches (22% C. longa and 21% C. zedoaria) were similar to potato starch. The results of microscopic analysis showed flat triangular shape and the size was 20-30 mum for two starches. The final viscosity of C longa was high (740 RVU) and the pasting temperature was 81 degreesC. In C. zedoaria the final viscosity was 427 RVU and the pasting temperature was 78 degreesC. These results differed from standard commercially used natural starches. (C) 2003 Elsevier Ltd. All rights reserved.
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Isotope screening is a simple and cheap test for determining the photosynthetic pathway used by plants. The scope of this work was to classify the photosynthetic type of Melissa officinalis L. and Cymbopogon citratus [DC.] Stapf, through studies of the carbon isotope composition (δ13 C), and we are proposing the use of carbon isotope composition results as a tool to control the quality of medicinal plants. For studies of δ 13C (13 C% = [R (sample)/R (standard) - 1] × 10 -3), dried, powdered leaves were analyzed in a mass spectrometer coupled with an elemental analyzer for determining the ratio R (R = 13CO2/12CO2). As results, M. officinalis presented a C3 photosynthetic type, and C. citratus presented a C4 photosynthetic type. The carbon isotope composition from this study can be used as quality control of M. officinalis adulterants.
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Includes bibliography
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Euphorbia tirucalli Lineu (Aveloz) belongs to the family Euphorbiaceae and is used in the treatment of cancer and warts. Some studies have reported that phorbol esters are the active principles responsible for the antitumor activity of Aveloz. The production of these molecules occurs in greater quantity in May, during the morning. This study aimed to evaluate whether the physico-chemical parameters of Aveloz homeopathic aqueous solutions such as pH, electrical conductivity and refractive index change due to storage time. Such parameters were measured regularly for 180 days. All solutions were prepared according to the method of grinding with lactose and subsequent dissolution in aqueous medium, as described in the Brazilian Homeopathic Pharmacopoeia, using as starting point the Aveloz latex collected in May. Homeopathic aqueous solutions containing only lactose were also prepared and evaluated as a control group. The potencies that were analyzed for electrical conductivity, pH and refractive index were: 4cH, 7cH, 9cH, 12cH, 14cH, 15cH, 29cH, 30cH. As a result, we found out that there was only statistical difference (p=0.035) in electrical conductivity between the homeopathic solutions containing Aveloz and the homeopathic solutions without Aveloz, when 15cH potency was compared. We also observed that the electrical conductivity increased with the aging of the solutions but is not directly related to the pH or the refractive index of the solutions, indicating that the aging process may alter the electrical conductivity of the homeopathic medicines. The presence of gas inside the glass that stores these solutions may affect the electrical conductivity measurements. Finally, no statistically significant difference was observed (p> 0.05) in the pH and refractive index.
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Incluye Bibliografía
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Incluye Bibliografía
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Includes bibliography
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The development of an electroanalytical method for simultaneous determination of copper and lead ions in sugar cane spirit (cachaça) using carbon paste electrode modified with ascorbic acid and carbon nanotubes (CPE-AaCNT) is described. Squarewave voltammetry (SWV) with anodic stripping was employed, and this technique was optimized with respect to the following parameters: frequency (50 Hz), amplitude (100 mV) and scan increment (9 mV). The analytical curves were linear in the range from 0.0900 to 7.00 mg L - 1 for lead and copper. The limits of detection were 48.5 and 23.9 µg L - 1 for lead and copper, respectively. The developed method was applied to the simultaneous determination of copper and lead in five commercial samples of sugar cane spirit. The results were in good agreement with those obtained by F AAS/GF AAS (flame atomic absorption spectrometry/graphite furnace atomic absorption spectrometry) and showed that CPE-AaCNT can be successfully employed in the simultaneous determination of these metals in real sugar cane spirit samples.