Nutritional composition samples

An overview of the application of atomic spectrometric techniques to the elemental analysis of milk samples has been given. Elemental composition of milk, its nutritional role, sample preparation methods for analysis and measurement techniques have been described in detail. It appears that ICP-MS and ICP-AES are the most reliable techniques for the multielemental analysis of major, minor, and trace elements in milk samples. 

The preferred method for the analysis of boron is inductively coupled plasma atomic emission spectroscopy (ICP-AES). Inductively coupled plasma mass spectroscopy (ICP-MS) is the most widely used nonspectrophotometric method for analysis of boron, as it uses small volumes of sample, is fast, and applies to a wide range of materials. When ICP equipment is unavailable, colorimet-ric/spectrophotometric methods can be utilized. However, many of these methods are subject to interference and should be used with caution (WHO, 1998). Part of the discrepancy in the nutritional composition of boron may be related to differences in methods of analysis. 

As with studies of many other herbs and nutritional supplements, interpretation of clinical trials of valerian is hampered by small sample sizes, suboptimal study design, lack of specified inclusion and exclusion criteria, and unknown composition of valerian extract (Plushner, 2000). Furthermore, none of the trials have included children or teenagers. Nevertheless, several studies have showed a mild hypnotic action in persons with insomnia and in normal sleepers, as well as a mild sedative effect (Leathwood and Chauffard, 1983, 1985 Balderer and Borbely, 1985). One report has described an anxiolytic effect (Kohnen and Oswald, 1988). There are suggestions that valerian may have beneficial effects on sleep latency, frequency of waking, nighttime motor activity, and overall sleep quality. 

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. 

In general it has to be stated that molecular species analysis of phospholipids is not frequently applied in food analysis most of the studies involving molecular species are instead found in the fields of biochemistry and nutrition. Thus, in the recent reviews by Bell and by Olsson and Salem, special emphasis has been given to the characterization of biological tissue samples (83,84). However, the molecular species composition has been shown to affect the accuracy of the quantification of phospholipid classes and hence is important in food analysis too (47,52). In the vast majority of published methods, isocratic elution has been used. In our opinion, this should be ascribed mainly to the fact that the traditional UV detector remains. Keeping account of the inherent problems associated with UV detection of underivatized phospholipids, it is astonishing that ELSD has hardly been exploited in this subdomain. As far as the stationary phase is concerned, nearly all methods prefer octadecyl-coated stationary phases. 

From a nutritional viewpoint, it is necessary to stress the current importance of carrying out the multielemental analysis of milk samples (either human, cow s, or formula milk) in order to establish the reference values of essential elements and quantify the levels of potentially toxic elements. This fact is more relevant to formula milk production for premature babies as some essential elements are not stored by the fetus during its development in the uterus. Attention has been already paid to the qualitative and quantitative composition (analysis) of proteins, lipids, carbohydrates, and, of course, essential elements. However, in the case of human nutrition, knowledge on the particular species (compounds) in which a given element is present (chemical speciation) is now urgently needed, because the absorption and bioavailability of the essential element will strongly depend on that particular chemical form. Thus, although only the total element daily requirements have been considered here, it is important to stress that more attention must be paid to the chemical form in which essential and potentially toxic elements are present in milk. Such aspects are dealt with in detail in Chapter 13 by B. Michalke et al. 

Two samples of homogenized food waste were used to match hydrolysis and SSF fermentation profiles to the kinetic models. The first sample was a mixture of processed ready-to-eat packaged food (PRE). LC analysis matched the composition of simple sugars and glycerol found on the PRE packages. Additional nutritional data on packages was used to determine starch (by difference), protein, ash, and lipids content. Theoretical ethanol yield for the PRE sample at a concentration of 100 g/1 was 32.0 g/1. 

The applications of plasma emission spectrometry are very broad. The technique is used for clinical chemistry, biochemistry, environmental chemistry, geology, specialty and bulk chemical production, materials characterization of metal alloys, glasses, ceramics, polymers and composite materials, atmospheric science, forensic science, conservation and restoration of artworks by museums, agricultural science, food and nutrition science, industrial hygiene, and many other areas. The versatility of plasma emission spectrometry comes from its ability to determine a large number of elements rapidly in a wide variety of sample matrices. 

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