Determination of Nitrogen and Protein Content of Meat and Meat Products

Benedict, Robert C.

doi:10.1093/jaoac/70.1.69a

Cited by 29 publications

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“…Protein concentration was determined by the modified Biuret method of Umemoto () and the Dumas combustion method using the LECO TruSpec nitrogen analyzer (LECO Corporation, St. Joseph, MI) and a conversion factor of 5.4 for protein determination (Benedict and Ellis ).…”

Section: Methodsmentioning

confidence: 99%

Thermal Stability of Chicken Keel Bone Collagen

Losso

Ogawa

2013

Journal of Food Biochemistry

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Acid‐soluble and pepsin‐solubilized collagen were isolated from chicken keel bone and analyzed by electrophoresis and circular dichroism. The denaturation temperature of chicken keel bone was determined by circular dichroism and compared to denaturation temperature of black drum or alligator bone. Our results show that collagen from chicken keel bone is a mixture of type II and type I, has predominantly the amino acids glycine, proline and hydroxyproline, and its secondary structure is predominantly triple‐helix. The onset of the denaturation temperature is 37C; at 44C, 50% of the collagen is denatured and the denaturation is complete at 48.8C making it the highest of vertebrate collagen denaturation temperatures reported in the literature. The high heat stability of chicken keel bone collagen may be in part ascribed to its imino acid content. Because of the high heat stability and low methionine content, chicken keel bone collagen is a high value‐added product with several biochemical and biomedical applications. Practical Applications The denaturation temperature of chicken keel bone collagen is above body temperature and allows applications in cosmetics where other types of collagen may be denatured because of their low denaturation temperature. Chicken type II collagen is well tolerated by patients with rheumatoid arthritis and is effective in the treatment of rheumatoid arthritis. Methionine‐restricted diet inhibits the growth of solid tumor such as gastric cancer, glioblastoma, medulloblastoma and neuroblastoma. Chicken type collagen may be a medical food for patients with solid tumors mentioned above.

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Section: Methodsmentioning

confidence: 99%

Thermal Stability of Chicken Keel Bone Collagen

Losso

Ogawa

2013

Journal of Food Biochemistry

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“…For example, the nitrogen content of collagen is 18%. Consequently, the nitrogen-to-protein ratio in meat products will vary as a function of the collagen level (Benedict 1987).…”

Section: Introduction -625 the Flawed Viewpointmentioning

confidence: 99%

Converting Nitrogen into Protein—Beyond 6.25 and Jones' Factors

Mariotti

Tomé

Mirand³

2008

Critical Reviews in Food Science and Nutrition

994

572

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The protein content in foodstuffs is estimated by multiplying the determined nitrogen content by a nitrogen-to-protein conversion factor. Jones' factors for a series of foodstuffs, including 6.25 as the standard, default conversion factor, have now been used for 75 years. This review provides a brief history of these factors and their underlying paradigm, with an insight into what is meant by "protein." We also review other compelling data on specific conversion factors which may have been overlooked. On the one hand, when 6.25 is used irrespective of the foodstuff, "protein" is simply nitrogen expressed using a different unit and says little about protein (s.s.). On the other hand, conversion factors specific to foodstuffs, such as those provided by Jones, are scientifically flawed. However, the nitrogen:protein ratio does vary according to the foodstuff considered. Therefore, from a scientific point of view, it would be reasonable not to apply current specific factors any longer, but they have continued to be used because scientists fear opening the Pandora's box. But because conversion factors are critical to enabling the simple conversion of determined nitrogen values into protein values and thus accurately evaluating the quantity and the quality of protein in foodstuffs, we propose a set of specific conversion factors for different foodstuffs, together with a default conversion factor (5.6). This would be far more accurate and scientifically sound, and preferable when specifically expressing nitrogen as protein. These factors are of particular importance when "protein" basically means "amino acids," this being the principal nutritional viewpoint.

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“…Fruiting bodies of mushrooms contain notable nonprotein nitrogen compounds, such as nucleic acids and chitin. The former, responsible for the umami taste of mushrooms, contain = 15 16% nitrogen (Benedict, 1987). Chitin, a polymer of N-acetylglucosamine, exists in the cell wall of mushrooms.…”

Section: Introductionmentioning

confidence: 99%

Nitrogen‐to‐Protein Conversion Factors for Some Common Edible Mushrooms

Fujihara¹,

Kasuga²,

Aoyagi³

et al. 1995

Journal of Food Science

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Mushrooms (13) common to Japan were analyzed for total nitrogen (TN), amino acid nitrogen (AAN), amide-N and nonprotein nitrogen. The distribution of protein nitrogen averaged 67% to TN. Averaged nitrogen-to-protein conversion (N:P) factor was 5.99. Application of the factor for estimation of protein content resulted in a considerable difference from amino acid residue (AAres) levels, due to the high level of nonprotein nitrogen. A net N:P factor, defined as the proportion of AAN to TN, was proposed. The averaged value of 3.99 was derived from analytical TN and AAN data of mushrooms. Calculated protein values using this factor were in good agreement with AAres.

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Determination of Nitrogen and Protein Content of Meat and Meat Products

Cited by 29 publications

References 0 publications

Thermal Stability of Chicken Keel Bone Collagen

Thermal Stability of Chicken Keel Bone Collagen

Converting Nitrogen into Protein—Beyond 6.25 and Jones' Factors

Nitrogen‐to‐Protein Conversion Factors for Some Common Edible Mushrooms

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