True protein

Crude protein = %nitrogen X 6.25. Does not accurately reflect true protein content. Algal cells may contain nonprotein nitrogen substances, eg, 4—6% nucleic acids, dry wt basis. 

Haulm (stem) The possibility of using winged bean haulm as a potential raw material for single cell protein production in the tropics has been investigated by Zomer et al. (78). Semi-sol id fermentation of haulm, using various fungi, yielded a product containing 20% true protein, a 30% increase over the native material. The fermentation also increased the sulfur amino acid content by 1.5 to 6 fold. 

Although gelatin behaves as a model protein in many respects, it has little or no tertiary structure and is not denatured by heating at temperatures in excess of 100°C. Albumin, on the other hand, is a true protein and is denatured at temperatures of... 

Milk composition expressed in terms of the contents of water (or total solids = 100 - water), fat, protein, lactose, and ash is called gross composition. Protein is often calculated as crude protein by multiplying total N by 6.38, but sometimes it is corrected to true protein 6.38 (TN -NPN) in a few studies, casein and whey protein have been calculated separately. Lactose should be expressed on an anyhydrous basis, but as pointed out previously, this has not always been done. For bovine milk the sum of fat, true protein, anhydrous lactose, and ash would be expected to fall about 0.2-0.3 percentage units short of the total solids contents because of the materials (citrate, NPN, and mis-... 

The level of substitution of the antibody after reaction with SPDP is determined spectrophotometrically. A sample of the derivatized antibody is treated with DTT at a final concentration of 5 mM, and the optical density measured at 280 nm and 343 nm. The pyndine-2-thione released by reduction has a molar extinction coefficient at 343 nm of 8.08 x 103Mcm (12) This product also absorbs at 280 nm with a molar extinction coefficient of 5.1 x 103M/cm. The true protein absorbance is determined from the formula ... 

Food yeast, molasses-grown, is dried to about 5% moisture and has the same chemical composition as bakers yeast. In terms of micrograms per gram of yeast, the vitamin content is 165 thiamine 100 riboflavin 590 niacin 20 pyridoxine 13 folacin 100 pantothenic acid 0.6 biotin 160 para-ainiiiobeuzoie acid 2710 choline and 3000 inositol. YeasL crude protein contains 80% amino acids 12% nucleic acids and 8% ammonia. The latter components lower the true protein content to 40% of the dry cell weight. 

Alternate Protocol 2 In Vivo or True Protein Digestibility to Determine... 

IN VIVO OR TRUE PROTEIN DIGESTIBILITY TO DETERMINE PROTEIN QUALITY... 

Calculate the true protein digestibility using the following equation True protein digestibility = [PI - (FP - MFP)]/PI x 100 where PI equals protein intake (g) FP is fecal protein (g) and MFP is the metabolic fecal protein (g). The MFP is calculated from the amount of protein in the feces of rats fed a protein-free diet (Sarwar, 1996). 

PDCAAS (%) is calculated as the product of the true protein digestibility and the amino acid score (or lowest amino acid ratio) relative to reference protein. Amino acid composition of protein is determined by hydrolyzing the protein into its component amino acids and then separating the amino acids chromatographically as described below. True protein digestibility is determined according to Alternate Protocol 2. 

Correct the amino acid score for protein digestibility by multiplying the lowest amino acid ratio with true protein digestibility (see Alternate Protocol 2). An example ... 

Crude protein. This is determined as N content x 6.25. It is a measure of protein present, based on the assumption that the average N content is 16 g of N/lOOg of protein. Some of the N in most feeds is present as non-protein N (NPN) therefore, the value calculated by multiplying N x 6.25 is referred to as crude rather than true protein. True protein is made up of AAs which can be measured using specialized techniques. 

Badr and Georgiev (1990) determined the crude protein, true protein, non-protein... 

The terms proteose and peptone refer to protein breakdown products of large polypeptides these differ from true proteins in that they are not coagulated by heat. A wide variety of peptides are formed when proteins are hydrolyzed in the digestive tract or in the laboratory. 

The average conversion factor for estimation of true protein, based on the ratios of total amino acid residues to amino acid N, determined for 23 various food products is 5.68 and for different classes of foods, 5.14-6.61 (Table 1.2). The N P factor of 4.39, based on analysis of 20 different vegetables, has been proposed by Fujihara etal. (2001) for estimating the true protein content in vegetables. A common N P factor of 5.70 for blended foods or diets has been recommended by Sosulski and Imahdon (1990). 

The previously discussed models fall under the category of linkage models in that the protein species are all identified and linked together with the energies for their formation controlling their relative prevalence. These models work well as approximations but fall short for descriptions of true protein thermodynamics where multiple conformations of unknown identity can coexist. Linkage model approximations can be used to define the... 

It was SoEENSEN (1909) who pointed out that proteins and their decomposition products are capable in many instances of disturbing the colorimetric pH determination. The influence of proteins lies in their amphoteric character which enables them to bind (adsorb) both acid and basic dyes. Although the effect of proteins on different indicators can not be predicted specifically, the disturbing influence generally seems to be strongest on the ac d side of the isoelectric point. The effect of decomposition products is much less marked than that of the true proteins themselves. 

The parameter, D, calculated is probably strongly related to a true protein diffusivity, but an exact boundary layer theory for protein solutions is needed to accurately establish that relationship. However, irrespective of a theoretical explanation, the observed Independence of graphs of J versus P from axial velocity and fiber length is a new region of Xhe protein ultrafiltration process that should be investigated further. 

Modgil, R. and Mehta, U. 1994. Effects of different levels of Collosobruchus chinensis L. infestation on proximate principles, true protein, methionine and uric acid contents of greengram and redgram. 

PDCAAS is calculated as true protein digestibility (TD) x Amino Acid Score (AAS) (WHO/FAO/UNU Expert Consultation, 2007). 

AOAC International (2000). AOAC Official method 991.29 True protein digestibility of foods and food ingredients Rat bioassay first action 1991. In "Official Methods of AOAC International", (W. Horwitz, Ed.), 17th edn, Vol. II, pp. 66-67. AOAC International, Gaithersburg, MD (Chapter 45). 

Nature of Ricin — This appears to be a true protein for a preparation of ricin has been obtained, which is a typical albumin, and which is so active that 0.0005 mg. is fatal to a kilogram of rabbit i.e., 1 part of the ricin is fatal to 2,000,000 parts of rabbit the fatal dose for man would therefore be about 0.035 mg., or 1 /2,000 grain (Osborne, Mendel and Harris, 1905 Osborne, 1909). The agglutinating action is also very powerful. 

The chemical nature of crude protein in feedstuffs is the primary factor determining how rapidly it is degraded to ammonia or escapes microbial degradation. To compare feedstuffs, feed nitrogen can be divided into NPN, true protein, and unavailable fractions, which Pichard and van Soest (1977) labeled as the A, B, and C fractions, respectively (Fig. 18.3). The A fraction is rapidly attacked by rumen bacteria and converted to ammonia. Approximately 20% of the crude protein in SBM is in the A fraction and is degraded in the rumen at a rate of 300%/h (NRC, 1996). In contrast, a more undegradable protein source like distillers grains has 6% of the crude protein in the A fraction. 

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