The study on development of chicken leg bone protein asfunctional food with antioxidative and antihypertensiveeffects

Autor: Fu-Yuan Cheng, 鄭富元
Rok vydání: 2007
Druh dokumentu: 學位論文 ; thesis
Popis: 96
Taiwan had become a member of WTO (World Trade Organizations). Since that, the type of chicken meat processing has changed large because of importing chicken legs. Products such as fresh deboned chicken meat and processing foods are being sold in increasing quantities. As a result, more and more byproducts like chicken leg bones are generated during processing. Most of these can not be utilized and are regarded as industrial waste, although some parts are used as feed stuff. However, they contain high amounts of protein in the form of meat, cartilage and bone morrow, and high value about 23.5% of crude protein was observed in them, which represented high potentials for developing nutraceuticals. Thus, the aims of current study try to utilize the chicken leg bones and develop functional food with antioxidation, antihypertension or both of them. Different temperature (80℃、90℃、100℃) and time (5、10、15) were carried out to investigate properties of heat extraction of chicken leg bone by analyzing the soluble protein, peptide content, electrophoresis, antioxidative activities and ACE inhibitory activities. The results showed that the higher temperature and longer heating time resulted in decreasing soluble proteins and peptide contents in heat extraction. In electrophoresis, the fragments of 55 kDa and 40-45 kDa disappeared after heating by 90℃ or 100℃ for 10 or 15 minters individually. Moreover, the significantly higher activities of reducing ability, Fe2+ chelating ability and inhibition of linoleic acid peroxidation were discovered in extraction that was heated by 90℃ or 100℃ for 15 minters. In addition, all treatments exhibited ACE inhibitory activities, while the highest one only showed 21%. Chicken leg bone proteins were hydrolyzed by Alcalase, pepsin or trypsin (enzyme and substrate ratio was 1%) for 12 hrs. The hydrolysates were gathered in every 2 hrs and lyophilized to investigate the change of pH value, soluble protein, peptide content, ACE inhibitory activity and antioxidative activity. Chicken leg bone protein hydrolyzed by Alcalase resulted in strong antioxidative and ACE inhibitory activities. The highest antioxidative activity was found in the fourth hour hydrolysate (66.0%), while it showed the poor ACE inhibitory activity (40.7%). This indicated that it is difficult to generate hydrolysate with both strong antioxidative and ACE inhibitory activity at the same hydrolysis condition in this study. However, for development of functional food, to select both the strongest antioxidative and ACE inhibitory activity is not necessary, but to select the hydrolysis condition that could result in those of better activities. Therefore, the eighth hydrolysate with both strong antioxidative (58.25 %) and ACE inhibitory activity (61.38 %) meantime, shows high potential to be utilized. Hydrolysates from Alcalase-treated still presented the highest peptide content and ACE inhibitory activity when enzyme and substrate ratio was raised to 2%. The fourth hour hydrolysate (A4H) showed the strongest ACE inhibitory activity (84.33%), IC50 value (0.545 mg/mL) and belonged to mixed noncompetitive ACE inhibitor. After oral administration (50 mg/kg bw) in spontaneously hypertensive rats (SHRs), a maximal reducing activity about 27 mmHg was discovered. Moreover, it was found that long-term (8 weeks) A4H treatment could attenuate the development of hypertension and cardiac hypertrophy in SHRs. Furthermore, ten ACE inhibitory peptides consisted of 5 to 10 amino acid residues were separated from hydrolysate (A4H) by gel filtration chromatography. These results suggested that chicken leg bone had a high potential to be utilized for developing ACE inhibitor as a potential ingredient of functional food intended to alleviate hypertension.
Databáze: Networked Digital Library of Theses & Dissertations
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