Protein content applications

Characterizing the resultant complex for the amount of protein per liposome is somewhat more difficult than in other protein conjugation applications. The protein-liposome composition is highly dependent on the size of each liposomal particle, the amount of protein charged to the reaction, and the mole quantity of reactive lipid present in the bilayer construction. An approach to solving this problem is presented by Hutchinson et al. (1989). In analyzing at least 17 different protein-liposome preparations, the ratio of proteindipid content (pg protein/pg lipid) in most of the complexes ranged from a low of about 4 to as much as 675. In some instances, however, up to 6,000 molecules of a particular protein could be incorporated into each liposome. 

The original applications of NIR were in the food and agricultural industries where the routine determination of the moisture content of foodstuffs, the protein content of grain and the fat content of edible oils and meats at the 1% level and above are typical examples. The range of industries now using the technique is much wider and includes pharmaceutical, polymer, adhesives and textile companies. The first in particular are employing NIR spectrometry for the quality control of raw materials and intermediates and to check on actives and excipients in formulated products. Figure 9.26(b) demonstrates that even subtle differences between the NIR spectra of enantiomers can be detected. 

Soy Protein Concentrates. Both non-functional (low or no solubility) and functional (good solubility, emulsification capacity, and dispersibility) soy protein concentrates (70% protein, dry basis) are commercially available for use in meat products (2-4, 6, j), 15) Normally, a highly functional product with no harsh or bitter flavors is desirable. When used to replace lean meat, non-hydrated concentrate can be used at levels up to 6-7% in finished nonspecific emulsion meats Higher replacement levels or formulas with specific cost/nutrition requirements may use soy protein concentrate with a judicious amount of textured soy protein (6). Excellent yields, cost savings, texture, flavor and nutrient profiles are possible. However, most soy protein concentrates lack sufficient solubility or sufficiently low viscosities to be used in brines for absorption or injection into whole muscle tissue. When legal standards for protein content exist (13), more concentrate must be used to achieve legal minimums. Brine viscosities increase and uniform distribution of brine components throughout the specific whole muscle piece is restricted. Finished product appearance and flavor are easily compromised. Thus, use of soy protein concentrates in whole muscle applications is limited. 

For the application of indirect calibration methods, one should have several samples available with known constitution. These samples should be of exactly the same type as the unknown sample. For example for the determination of the fat, water and protein content in wheat by near infrared reflectance spectrometry, one should have available a number of wheat flour samples of which the amount of fat, water and protein is known, or determined by a conventional method. 

Emulsification properties. Caseins and caseinates are commonly selected for food product applications that require surfactant properties, e.g., emulsification and foam stabilization, since they contain high protein contents of > 90 %, are highly soluble, and are resistant to heat-induced denaturatlon in products to be subjected to high temperature processing conditions (15). 

Protein solubility Protein in specific buffer is centrifuged at 20,000 x g for 30 min. Protein content of sample and supernatant is determined. Protein solubility (%) = (protein cone, in supernalanl/protein cone, in sample) x 100 Advantages Applicable for various proteins. Assay was found to be repeatable in Collaborative study. Disadvantages Requires strict control of buffer, pH, and centrifugation conditions for repeatable results. Morret al. (1985)... 

The protein fraction is filtered and dried to become high (60%) protein content com gluten meal. The starch slurry can be dewatered and dried to produce regular com starch. Dry starch can be sold as is or heat treated in the presence of acid catalysts to produce dextrins. Or, it is chemically modified before dewatering and drying to produce modified starches used in food and industrial applications. Lastly, it can be hydrolyzed to produce com sweeteners. 

Activation with 14 MeV neutrons has been used to determine the oxygen content of various metals such as beryllium 20>, Cl, F, O, Na, Si, and various rare earths in complex molten salt electrolytes 45>, the protein content of food products by means of the nitrogen content 46>, i60/180 and 14N/15N isotopic ratios in stable isotope tracer experiments 47,48), and in a wide variety of other applications. One application we... 

Wood, D. E., P. L. Jessen, and R. E. Wood Industrial Application of Fast Neutron Activation Analysis for Protein Content of Food Products. Paper presented at the 52nd Annual Meeting of the American Association of Cereal Chemists, Los Angeles, California, April, 1967. 

Polymers may be induced to encapsulate other molecules by a variety of means (Risch and Reineccius, 1995) as diverse as dipping, spray-drying, extrusion, evaporation, and coacervation each technique has its special applications, strengths, and weaknesses. Advantages in common are the protection and slow release of the encapsulate. In any of the mechanisms, a coagulable polymer precipitates around a core of labile material. Polysaccharides are regular encapsulating polymers (Risch and Reineccius, 1995) acacia gum is particularly efficacious because of its protein content. 

Among the items that have been measured are vitality, intracellular pH, DNA and RNA content, and specific plasmids [77,408]. Besides nucleic acids [204], other intracellular components can also be analyzed, e.g. storage materials [2, 82,294], enzymes and protein content [6,338], or the cell size [60,61]. The physiological state can also be rapidly assessed [331]. Furthermore, this technique allows the separation of certain cells using a cell sorter, e.g. for strain improvement [28]. The flow cytometry technique has also been used in connection with molecular probes for identification and viability determination of microbial communities [98]. This application of viability estimation is becoming increasingly important [63, 136, 188, 454]. Unfortunately, the equipment is expensive and most of the measurements are tricky and laborious and not well designed for on-line application. 

There are many ways in which hormone-receptor interactions may be studied, the classic method being the Scatchard technique, named in honor of George Scatchard. This technique is applicable to any protein-small molecule interaction, and it provides a means of determining the heterogeneity of binding sites, dissociation constants, and the number of binding sites per receptor unit. The last may be a protein molecule, a cell, a cell membrane fragment, or a unit volume of cytosol with a known protein content. 

---