Wheat proteins techniques

Since the introduction of HPLC in the field of protein analysis, this technique has become very popular because of its versatility. The development of improved or new packing materials has often resulted in a decrease in the analysis time. However, with regard to the analysis of food proteins, the application of HPLC has remained limited mainly to wheat proteins and milk proteins. A quick survey of recent literature confirms this observation, and most publications about the... 

Marchal, R., Lallement, A., Jeandet, R, Establet, G. (2003). Qarification of Muscat musts using wheat proteins and the flotation technique. J. Agric. Food Chem., 51, 2040-2048. 

PC loadings and their absolute values in the data reduction techniques has been proposed. This procedure has been successfully used for the smdy of the effect of carboxymethyl-P-cyclodextrin on the hydrophobicity parameters of steroidal drugs measured by TLC, and for the assessment of the binding characteristics of environmental pollutants to the wheat protein, gliadin, investigated by HPLC. 

Continued improvements in FFF instrumentation, refinements in technique and hyphenation with detectors such as MALLS have broadened the application of this method and effectively elevated it from the status of possibly useful technique to a reliable applied research tool for assessing the size and shape of wheat proteins. For additional reading concerning FFF theory, principles, and applications, the reader is referred to other sections of this encyclopedia as well as to Field-Flow Fractionation Handbook edited by Schimpf et al. A review of the application of FFF to wheat protein analysis can also be found in Preston and Stevenson. 

Commercial proteins (84) include zein—a water-insoluble protein from com (maize). Zein is thermoplastic and can be processed with extrasion and injectionmolding techniques. It forms strong, grease-resistant, and dyeable fibers. Starch has been blended with zein to increase water resistance natural fibers were added for increased modulus (85). Other commercial proteins include wheat protein, soy protein, and casein. 

NIR is a mature technique for the rapid quality testing of whole wheat, ground wheat, and fiour. Wheat protein, moisture, and hardness can be measured on ground grain... 

Malabsorption Syndrome, with Special Reference to the Effects of Wheat Gluten (Frazer), 5, 69 Mellituria, Nonglucose (Sidbury), 4, 29 Microbiological Assay Methods for Vitamins (Baker and Sobotka), 5, 173 Organic Acids in Blood and Urine (Nordmann and Nordmann), 4, 53 Paper Electrophoresis Principles and Techniques (Peeters), 2, 1 Paper Electrophoresis of Proteins and Protein-Bound Substances in Clinical Investigations (Owen), I, 238 Parathyroid Function and Hyperparathyroidism, Biochemical Aspects of (Nordin), 4, 275... 

In agricultural applications, the most commonly analyzed constituents are water, protein, starch, sugars, and fiber [16-20]. Such physical or chemical functions such as hardness of wheat, minerals, and food values have no actual relation to chemicals seen in the NIR. These are usually done by inferential spectroscopy. That is, the effect of minerals or the relationship of the spectra to in vitro reactions is used in lieu of chemical analyses to NIR active constituents. Considering that all shipments of grain from the US since the 1980s have been cleared by NIR, it can be argued that this is a critical application of the technique. 

For measuring water absorption by the excess water method, the techniques developed by Janicki and Walczak (described by Hamm, 21) for meats and by Sosulski (22) for wheat flour are modified. Lin et al. (17) modified the Sosulski technique for use with sunflower and soy meal products. This modified procedure has been employed for much of the research on water absorption of plant protein additives. Water absorption capacities of a soy flour, two soy concentrates, and two soy isolates were compared by Lin et al. (17) to those of a sunflower flour, three sunflower concentrates, and one sunflower isolate. The percent water absorption of the soy products increased as the total protein content of the samples increased from flour to isolate. The soy flour absorbed 130% water, the soy concentrates absorbed an average of 212% water, and the soy isolates absorbed an average of 432% water. No calculations were made, however, that related the percent water absorbed to protein content of the samples. The sunflower products, though similar in protein content, did not respond in the same magnitude or direction as the soy products. 

Identification of oat (Avena) cultivars by HPLC was first reported by Lookhart and coworkers (153-155) in combined electrophoresis/HPLC experiments. The HPLC technique used was a modification of the procedure described by Bietz (137) for wheat. Generally, the prolamin fraction, i.e., the alcohol-soluble fraction, of oat species generates complex polyacrylamide gel-electrophoresis (PAGE) and RP-HPLC patterns, with increasing complexity as ploidy of the selections increased. Readily (visible) identification of the cultivars was possible only when PAGE and RP-HPLC results were combined. An HPLC procedure for the characterization of the major oat protein fractions was developed by Lapvetelainen et al. (156). Salt-soluble, alcohol-soluble, and alkali-soluble protein fractions were extracted with 0.1 M NaCl, 52% ethanol, and 1% SDS in 0.05 M borate (pH 10), respectively. For the five cultivars examined, RP-HPLC separations of salt- and alkali-soluble proteins were very similar, whereas the prolamin fraction enabled culti-var differentiation, except for very closely related cultivars. 

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