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RESEARCH BACKGROUND: Animal collagen has been widely utilized in foods, cosmetics and biomedical fields. The non-edible portion, such as fish skin and bones, are obtained during cooking. Most of them are currently discarded as wastes, although the nutritional value of the skin and bones is high. The non-edible portion needs to be reused in order to reduce environmental impact, as it is one of the sources of environmental pollution. EXPERIMENTAL APPROACH: Collagen was prepared by cold acetone treatment from Sakhalin taimen skin as a waste produced during cooking. Next, the colour, SDS-polyacrylamide gel electrophoresis, ultraviolet absorption, subunit composition, amino acid composition, denaturation temperature and attenuated total reflectance-Fourier transform infrared spectroscopy analyses were conducted to explore the properties of the collagen. Lastly, we attempted to improve the functional properties of the collagen for future applications using chemical modification technique (succinylation). RESULTS AND CONCLUSIONS: Cold acetone treatment easily removed the fats and pigments from the skin. The odourless and pure white collagen was obtained with high yield. The α3 chain did not exist in the collagen. Sakhalin taimen skin collagen had rich α-helix and low ß-sheet structures. Succinylation caused the secondary structural changes of the collagen molecule. Moreover, it made it possible not only to increase the viscosity of the collagen solution but also to improve the solubility of the collagen under the physiological conditions around pH=6. NOVELTY AND SCIENTIFIC CONTRIBUTION: This finding is the first report on the absence of the α3 chain from salmonid fish skin collagens. The succinylated collagen from Sakhalin taimen skins as useful biomass has potential to utilize in foods, cosmetics and related industries.
RESUMO
Collagen from emu skins as a by-product was prepared. The skins were hardly solubilized in acetic acid, however were successfully solubilized on digestion with 10 % pepsin (w/w) for 4 days. The yield of pepsin-solubilized collagen (PSC) was about 27.3 %, on a raw weight basis. By SDS-PAGE and CM-Toyopearl 650 M column chromatography, the presence of a fourth subunit that was previously designated α4 was confirmed. The denaturation temperature of the PSC was 31.5 °C, about 6-7 °C lower than that from the porcine skins. ATR-FTIR analysis indicated that the helical arrangements of the PSC from emu skins existed and its structures of PSC were changed slightly due to the loss of N- and C-terminus domains in similar to that from the porcine skins. That is, the PSC from emu skins did not possess telopeptide chains as major portion of antigenic sites in collagen. The present study indicates that a large quantity of emu skins as by-products have potential as a good alternative source of high-quality collagen for industrial purposes in the foods, cosmetics, and pharmaceutical and biomedical fields.
RESUMO
Yam tsukuneimo tuber mucilage tororo hydrolysates were prepared by autolysis and three different peptic enzymes. Except for pepsin hydrolysate, tororo was perfectly digested. Each hydrolysate for 100 mg/ml significantly prolonged the induction period of auto-oxidation of linoleic acid, which was similar to 5 mM ascorbic acid. These hydrolysates also possessed high scavenging activities such as superoxide anion radicals, hydroxyl radicals, and DPPH radicals. Moreover, high antihypertensive activities were detected in these hydrolysates except for autolysate, which were similar to various fermented foods such as miso, natto, sake, cheese, and so on. Present findings suggest that yam tsukuneimo tuber mucilage tororo may be useful for preventing diseases associated with reactive oxygen species and blood pressure in the body system and it can fully absorb the useful components from it to digest using the gastrointestinal enzymes.