Thermal Behavior of Fowl Feather Keratin

Abstract

Differential scanning calorimetry (DSC) was applied to elucidate the thermal behavior of fowl feather keratins (barbs, rachis, and calamus) with different morphological features. The DSC curves exhibited a clear and relatively large endothermic peak at about 110-160 degrees C in the wet condition. A considerable decrease in transition temperature with urea and its helical structure content estimated by Fourier transform infrared spectroscopy (FT-IR), and the disappearance of one of the diffraction peaks with heating at 160 degrees C for 30 min, indicated that DSC could be used to evaluate the thermal behavior of keratin. Barbs showed a lower denaturation temperature than rachis and calamus. The pulverized samples showed a slightly higher denaturation temperature than the native samples. In the dry condition, thermal transition occurred in a markedly higher temperature region close to 170-200 degrees C. It is hence concluded that fowl feather keratins have very high thermal stability, and that the elimination of water brings about even greater thermal stability.

Effect of Sorbed Water on the Thermal Stability of Soybean Protein

“…They showed that the denaturation temperatures of -conglycinin and glycinin almost linearly increased from about 72 C to 102 C and from about 89 C to 129 C, respectively, as peak values evaluated by differential scanning calorimetry with a decreasing level of moisture. However, the other studies [5][6][7][8][9] did not show a linear increase in denaturation temperature with decreasing water content, and may have indicated a much higher denaturation temperature than the results reported by Sheard et al…”

“…DSC for the SPI, -conglycinin, and glycinin preparations was carried out to determine the thermal denaturation from 25 C to 230 C at a heating rate of 5 K/min by using an SSC-5020 DSC-6100 instrument (SII Nanotechnologies; Tokyo, Japan) as described by Takahashi et al 13) A silver sample capsule (70 ml) was pretreated at 250 C for 20 min to prevent any exothermal effect from the capsule at around 170 C. 9) In the case of measurement with a wet sample, about 55 mg of a 10% dispersion in a 0.03 M Tris-HCl buffer at pH 8.0 was put into the capsule, while about 10 mg of the sorbed waterconditioned sample was put into the capsule for measuring the denaturation behavior of a dry sample. Three measurements were performed.…”

“…4) Since the thermal denaturation of such other proteins as myoglobin, 5) lysozyme, 6) collagen, bovine serum albumin, 7) ovalbumin, 8) and keratin 9) is greatly affected by the water content, the water content is considered to be one of the most fundamental factors controlling denaturation. In respect of soybean protein, Sheard et al 3) were first to report the denaturation temperatures of soybean isolates (7S and 11S proteins, i.e., -conglycinin and glycinin) containing from 5% to 94% moisture (about 5.3% to 1,600% on a dry basis).…”

Interfacial Behavior of Fatty-Acylated Sericin Prepared by Lipase-Catalyzed Solid-Phase Synthesis

“…Smoothing was accomplished with the 11-point Savisky-Golay function, and the secondary structural contents were estimated from the peak area of the second-derivative spectrum according to the method previously described. 20) The peaks in the wavelength range of 1,600-1,700 cm À1 were generally assigned according to the results of Dong et al 21) and Beer et al, 22) , unordered. However, the major peak at 1,653 cm À1 was assigned in this experiment to an unordered structure, because sericin had a random coil structure.…”

Production of Microbial Bio-Pesticides from Waste Disposal of Chicken Feathers

“…Keratins are made up two main subunits such as alpha and beta keratins which composed various amino acids [5]. The feathers are mainly composed of beta-keratin [6,7]. The investigation spotlights on degradation of the keratin containing chicken feathers by the bacterial strains of B. thuringiensis serovar israelensis (Bti) and Bacillus sphaericus (Bs) which are helpful in the production of endotoxins to destroy the mosquito larvae.…”