The Experts below are selected from a list of 240 Experts worldwide ranked by ideXlab platform
Dimas A. M. Zaia - One of the best experts on this subject based on the ideXlab platform.
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Determination of total proteins in cow milk powder samples: a comparative study between the Kjeldahl Method and spectrophotometric Methods.
Journal of Food Composition and Analysis, 2003Co-Authors: Neide Kiyoko Kondo Kamizake, Mauricio M Gonçalves, Cássia T. B. V. Zaia, Dimas A. M. ZaiaAbstract:Abstract In the present paper, a comparative study between the Kjeldahl Method and several spectrophotometric Methods was carried out for the determination of total proteins in a range of milk powder samples (skim milk powder, whole milk powder, whey protein powder, buttermilk powder). The most important finding of this paper was that the Bradford Method could be used for the determination of total proteins in skim milk powder and whole milk powder samples (without extraction of lipids) instead of the Kjeldahl Method. The Bradford Method showed the highest sensitivity of the spectrophotometric Methods. Using casein and BSA as standard proteins, the Lowry Method showed the lowest variation of specific absorbance indicating either casein or BSA could be used as a standard. The UV-220 nm Method with previous extraction of lipids showed the best results for the determination of total proteins in all the samples; all the results were not statistically different (P>0.05) from those obtained by the total protein nitrogen (TPN) without extraction of the lipids. The Bradford Method (without extraction of lipids) showed the best results for the determination of total proteins in all the samples whose results were not statistically different (P>0.05) from those obtained for total nitrogen by the Kjeldahl Method. However, when these results were compared to TPN they were statistically different from each other (P
Annibal Duarte Pereira Netto - One of the best experts on this subject based on the ideXlab platform.
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is it possible to screen for milk or whey protein adulteration with melamine urea and ammonium sulphate combining Kjeldahl and classical spectrophotometric Methods
Food Chemistry, 2013Co-Authors: Virginia De Lourdes Mendes Finete, Marcos Martins Gouvea, Flavia Ferreira De Carvalho Marques, Annibal Duarte Pereira NettoAbstract:The Kjeldahl Method and four classic spectrophotometric Methods (Biuret, Lowry, Bradford and Markwell) were applied to evaluate the protein content of samples of UHT whole milk deliberately adulterated with melamine, ammonium sulphate or urea, which can be used to defraud milk protein and whey contents. Compared with the Kjeldahl Method, the response of the spectrophotometric Methods was unaffected by the addition of the nitrogen compounds to milk or whey. The Methods of Bradford and Markwell were most robust and did not exhibit interference subject to composition. However, the simultaneous interpretation of results obtained using these Methods with those obtained using the Kjeldahl Method indicated the addition of nitrogen-rich compounds to milk and/or whey. Therefore, this work suggests a combination of results of Kjeldahl and spectrophotometric Methods should be used to screen for milk adulteration by these compounds.
Samar I. Salama - One of the best experts on this subject based on the ideXlab platform.
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NEW Method FOR DETERMINATION OF PROTEIN CONTENT OF GOAT'S MILK AND COMPARED WITH DIFFERENT MethodS
Journal of Food and Dairy Sciences, 2014Co-Authors: M. Sh. Gomaa, M. E. Abdel-aziz, E. H. Hafez, Samar I. SalamaAbstract:A total of 45 samples of goats milk were collected during the milk production season to estimate %protein by Kjeldahl Method and also as much as formol number. All samples were analyzed and correlation coefficient between the results was calculated to get a constant factor from which we can estimate protein content by formol titration Method directly. The calculated factor was 2.505 and the suggested concluded equation for protein determination was as follows: Protein content (%) = 2.505 x formol No – 0.114. However, the differences when applying such equation and Kjeldahl Method were statistically insignificant. Protein content (%) by Kjeldahl Method (A) differed significantly from that given by Milkoscan Method (B) as shown in the following equation: A = 1.2008 x B – 0.4428
A. E. Beet - One of the best experts on this subject based on the ideXlab platform.
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A modified universal semi‐micro Kjeldahl Method for the determination of nitrogen in coal and other carbonaceous materials
Journal of Applied Chemistry, 2007Co-Authors: A. E. BeetAbstract:A semi-micro Kjeldahl Method is described, in which for the first time an unmistakable colour indication is given of the completeness of conversion into ammonium sulphate. Instead of the usual catalysts, crystalline potassium permanganate is used as oxidant and digestion is complete in about 13 minutes; the distillation takes about 8 minutes. With only a single distillation unit, 36 determinations can easily be made in a working day. The Method has been thoroughly tested in our laboratories for about six months.
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a modified universal semi micro Kjeldahl Method for the determination of nitrogen in coal and other carbonaceous materials
Journal of Chemical Technology & Biotechnology, 2007Co-Authors: A. E. BeetAbstract:A semi-micro Kjeldahl Method is described, in which for the first time an unmistakable colour indication is given of the completeness of conversion into ammonium sulphate. Instead of the usual catalysts, crystalline potassium permanganate is used as oxidant and digestion is complete in about 13 minutes; the distillation takes about 8 minutes. With only a single distillation unit, 36 determinations can easily be made in a working day. The Method has been thoroughly tested in our laboratories for about six months.
Neide Kiyoko Kondo Kamizake - One of the best experts on this subject based on the ideXlab platform.
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Determination of total proteins in cow milk powder samples: a comparative study between the Kjeldahl Method and spectrophotometric Methods.
Journal of Food Composition and Analysis, 2003Co-Authors: Neide Kiyoko Kondo Kamizake, Mauricio M Gonçalves, Cássia T. B. V. Zaia, Dimas A. M. ZaiaAbstract:Abstract In the present paper, a comparative study between the Kjeldahl Method and several spectrophotometric Methods was carried out for the determination of total proteins in a range of milk powder samples (skim milk powder, whole milk powder, whey protein powder, buttermilk powder). The most important finding of this paper was that the Bradford Method could be used for the determination of total proteins in skim milk powder and whole milk powder samples (without extraction of lipids) instead of the Kjeldahl Method. The Bradford Method showed the highest sensitivity of the spectrophotometric Methods. Using casein and BSA as standard proteins, the Lowry Method showed the lowest variation of specific absorbance indicating either casein or BSA could be used as a standard. The UV-220 nm Method with previous extraction of lipids showed the best results for the determination of total proteins in all the samples; all the results were not statistically different (P>0.05) from those obtained by the total protein nitrogen (TPN) without extraction of the lipids. The Bradford Method (without extraction of lipids) showed the best results for the determination of total proteins in all the samples whose results were not statistically different (P>0.05) from those obtained for total nitrogen by the Kjeldahl Method. However, when these results were compared to TPN they were statistically different from each other (P
