Metabolism compositional analysis

A number of procedures used to determine protein quality involve bioassays. Bioassays require feeding live animals protein ingredients for a specified period of time, and then estimating the nutritive value of the protein. Two such assays are the rat-based protein efficiency ratio (PER) bioassay and the human nitrogen balance assay (Dimes et al., 1994). Animal feeding experiments require chemical analyses of both the dietary inputs and then the metabolic output of the animal (e.g., body composition analysis, fecal sample analysis, collection, and assay for urine) from which the efficiency of protein metabolism can be predicted as well as how the protein supports animal growth and cell maintenance. 

Contents I. Introduction 168 II. Sampling Techniques 168 III. Compositional Analysis 169 A. Moisture and total solids 169 B. Fat 171 C. Protein 171 D. Ash 172 E. Salt and chloride content 172 F. Acidity and pH 172 G. Calcium and phosphorus 173 IV. Monitoring Cheese Ripening 173 A. Assessment of lactose, lactate, and citrate metabolism 174 B. Assessment of lipolysis 178 C. Assessment of proteolysis 180 D. Assessment of smaller breakdown products 194 V. Novel and Rapid Instrumental Methods 196 VI. Concluding Remarks 200 References 201... 

Macromolecular biomass composition is of obvious interest when the biomass itself is the product, such as algal biomass in [18], or for production of singlecell protein, for e.g. animal feedstock. Moreover, for a precise metabolic flux analysis, changes in biomass composition should be taken in account. For example, Henriksen et al. [19] observed with E. coli under different growth rates, that the levels of DNA and lipids were relatively constant, whereas the proteins and stable RNA levels increased with the specific growth rate and the total amount of carbohydrates decreased. 

Metabonomic analysis involves the quantitation of the dynamic multivariate metabolic response of an organism to a pathological event or genetic modification [1]. The concept of metabonomics has evolved over two decades of H NMR spectroscopic analysis of the multicomponent metabolic composition of biofluids, cells, and tissues under different physiological and... 

Wittmann C, Heinzle E (2001) Modeling and experimental design for metabolic flux analysis of lysine-producing Corynebacteria by mass spectrometry. Metab Eng 3 173-191 Wong MS, Causey TB, Mantzaris N, Bennett GN, San KY (2007) Engineering poly(3-hydroxy-butyrate-co-3-hydroxyvalerate) copolymer composition in E. coli. Biotechnol Bioeng 99 919-928... 

LC—MS is a powerful tool for the analysis of Chinese herbal medicines including identification of active ingredients, compositional analysis, and metabolic profiling. However, structural verification with the complementary information from other spectrometric methods or hyphenated techniques is needed along with comparison with reference compounds. 

There have been a number of criticisms of body composition analysis studies. Firstly, intrauterine accretion estimates have assumed that stillborn fetuses were of normal size for gestational age and, therefore, that the accretion of each specific nutrient was normal for that gestational age. Based on the argument that infants who die in utero are probably not of normal size for gestational age, the estimated fetal content of each nutrient is likely an underestimate of true fetal composition. Secondly, when estimating oral requirements for the pre-term infant, the values used for absorption and excretion of nutrients were based on metabolic studies on full-term infants (Fomon and May, 1958). These values have been extra-... 

Campbell, R.G. and A.C. Dunkin, 1983. The effects of energy intake and dietary protein on nitrogen retention, growth performance, body composition and some aspects of energy metabolism of baby pigs. Br. J. Nutr. 49, 221-230. Kovner, I.,Taicher and A. Mitchell, 2009. Calibration and validation of EchoMRI whole body composition analysis based on chemical analysis of piglets. Int. J. Body Comp. Res. (in press). 

Amino acid analysis has long been of importance for nutritional purposes. Recently, there has been an increasing interest in assessing the exact amino acid composition of new protein sources, infant formulas, nutraceutical-type products, or supplements targeted at people with unusual metabolic needs. There is also a regulatory necessity to have rapid methods available for amino acid determination to verify product consistency with that declared on the label [196]. 

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