Feather protein

Owing to the economic importance of wool most investigators have used this material as a convenient source of a-keratin. When parallel studies have been made on hairs from other animals and on nails, claws, hoofs, and quills it has been found that conclusions reached by studying wool proteins apply, with only minor qualifications, to other keratinized tissues. Feathers are only of slight economic value and correspondingly less attention has been devoted to their chemistry, despite the fact that feather proteins are more readily solubilized and purified and that feather rachis yields X-ray diffraction patterns of excellent quality. 

Fig. 16. Electron micrographs (upper) of a cross section of feather rachis (Filshie and Rogers, 1962) (lower) of fibrils obtained by reconstituting extracted feather proteins (Filshie et al., 1964).

Future progress will most likely depend on further correlation between evidence from electron microscopy. X-ray diffraction, sequence analysis, and solution studies. A promising line of investigation is the study of the fibrous material regenerated from solutions of feather proteins (Woodin, 1956 Fraser and MacRae, 1959, 1963 Filshie et al., 1964). An example of fibrils obtained in this way is shown in Fig. 16. 

Table 2.2. Proportions of essential amino acids in the tissue, egg and feather proteins of the domestic fowl...

Using synchrotron-based FTIR microspectroscopy to reveal chemical features of feather protein secondary structure comparison with other feed protein sources. /. Agric. Food Chem.,... 

Taskin M, Esim N, Ortucu S (2012) Efficient production of L-LA from chicken feather protein hydrolysate and sugar beet molasses by the newly isolated Rhizopus oryzae TS-61. Food Bioprod Process 90 773-779. doi 10.1016/j.fbp.2012.05.003 Tay A, Yang ST (2002) Production of L(+)-LA from glucose and starch by immobilised cell of Rhizopus oryzae in a rotating fibrous bed bioreactor. Biotechnol Bioeng 80 1-12. doi 10.1002/ bit. 10340... 

Lin H, Sritham E, Lim S, Cui Y, Gunasekaran S (2010). nthesis and characterization of pH-and salt-sensitive hydrogel based on chemically modified poultry feather protein isolate. / Appi Poiym Sci, 116,602-609. 

In the United States, more than 16.3 x 10 kg of human-inedible raw materials are available each year, and the rendering industry is a valuable asset in diverting these into valuable ingredients for use primarily in animal foods (4). The three largest meat packers are responsible for nearly four-fifths of aU red meat production (5) and enormous amounts of rendered meat meal and animal fat. Three broiler producers account for about 40% of the total broiler production. American Proteins, Inc. (RosweU, Georgia), the world s largest processor of poultry by-products, produces more than 450,000 t of poultry meal, feather meal, and poultry fat each year. It also produces more than 100,000 t of fish meal, fish oil, and fish products each year. Pish meal production worldwide in 1986 was estimated at 6.23 x 10 t, which with the 125 x 10 t of meat and bone meal plus 6.67 x 10 t of feather meal and poultry by-product meal (6) is the primary source of animal proteins used by the pet food industry. 

Eeather meal, first hydroly2ed and then oxidi2ed, produces cysteic acid [13100-82-8] an excellent precursor for taurine in cats (20). Hydroly2ed feather meal may supplement the taurine provided by other dietary animal proteins and help replace part or all of the synthetic taurine in cat food formulations with considerable cost savings. 

Production by Isolation. Natural cysteine and cystine have been manufactured by hydrolysis and isolation from keratin protein, eg, hair and feathers. Today the principal manufacturing of cysteine depends on enzymatic production that was developed in the 1970s (213). 

Wool belongs to a family of proteins, the keratins, that also includes hair and other types of animal protective tissues such as horn, nails, feathers, and the outer skin layers. The relative importance of wool as a textile fiber has declined over the decades as synthetic fibers have increa singly been used in textile consumption. Wool is still an important fiber in the middle and upper price ranges of the textile market. It is also an extremely important export for several nations, notably AustraUa, New Zealand, South Africa, and Argentina and commands a price premium over most other fibers because of its outstanding natural properties of soft handle (the feel of the fabric), moisture absorption abiUties (and hence comfort), and superior drape (the way the fabric hangs) (see Fibers Textiles). Table 2 shows wool production and sheep numbers in the world s principal wool-producing countries. 

Wool, as a keratin, is a highly cross-linked, insoluble proteinaceous fiber, and few animals have developed the specialized digestive systems that aUow them to derive nutrition from the potential protein resource. In nature, these few keratin-digesting animals, principally the larvae of clothes moths and carpet beetles, perform a useful function in scavenging the keratinous parts of dead animals and animal debris (fur, skin, beak, claw, feathers) that ate inaccessible to other animals. It is only when these keratin-digesting animals attack processed wool goods that they are classified as pests. Very often they enter domestic or industrial huildings from natural habitats such as birds nests. 

Alpha helices are sufficiently versatile to produce many very different classes of structures. In membrane-bound proteins, the regions inside the membranes are frequently a helices whose surfaces are covered by hydrophobic side chains suitable for the hydrophobic environment inside the membranes. Membrane-bound proteins are described in Chapter 12. Alpha helices are also frequently used to produce structural and motile proteins with various different properties and functions. These can be typical fibrous proteins such as keratin, which is present in skin, hair, and feathers, or parts of the cellular machinery such as fibrinogen or the muscle proteins myosin and dystrophin. These a-helical proteins will be discussed in Chapter 14. 

Proteins, Nitrated. Proteinaceous or albuminoid materials (glue, bones, hides, leather, hair, feathers, etc) can be nitrated in a two-stage process to yield expl yel oils. Thus, glue is treated first with 3.6 pts by wt of 66°Be sulfuric acid and 2.7 pts of 36°Be nitric acid. The resultant oil is sepd from the heavier spent acid and nitrated further with 3 pts of oleum and 2.6 pts of 36°BS nitric acid. Both nitrations are conducted at 15—20°, and never above 40°. The resulting oily expl can be used alone or mixed with other materials... 

Carotenoids are essential to plants for photosynthesis, acting in light harvesting and especially in protection against destructive photooxidation. Without carotenoids, photosynthesis in an oxygenic atmosphere would be impossible. Some animals use carotenoids for coloration, especially birds (yellow and red feathers), fish and a wide variety of invertebrate animals, where complexation with protein may modify then-colors to blue, green or purple. ... 

Dust from animal houses consists mainly of organic matter (23). The preferred technique for investigating both the material composition of the dust and feed stuff is the WEENDER Analysis Technique (24). Table II shows the composition of dust from pig and hen houses compared to the feed fed. The differences in the protein content between dust and feed support the opinion that an important part of the dust originates from feathers, hairs, and skin cells of the animals. 

Slight SH, Prabhakaram M, Shin DB, Feather MS and Ortwerth BJ (1992) The extent of N-(carboxymethyl)lysine formation in lens proteins and polylysine by the autoxidation products of ascorbic acid. Biochim Biophys Acta 1117, 199-206. 

Feathering Test. Modified soy proteins were investigated as a substitute for sodium caseinate in coffee whitener. A 15 mg/mL protein solution was heated at 70 C for one hour with intermittent stirring. To 10 mL of the solution, 1.5 g of Louana vegetable oil was added. The... 

Cysteine can be obtained by hydrolysis from cysteine-rich proteins in hair or feathers or from petrochemical sources. Cysteine is an important raw material in Maillard reactions for the preparation of process flavours, but it can also serve as a source of ammonia and hydrogen sulfide for the preparation of flavour chemicals, such as the terpene sulfur compounds mentioned in Sect. 13.2.4 and furfuryl mercaptan mentioned in Sect. 13.4.2.4. 

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