The physico-chemical properties of duck’s salted egg white and its application

• Main Authors: Huang, Jan-Jeng, 黃健政
• Other Authors: Tsai, Jenn-Shou
• Format: Others
• Language: zh-TW
• Published: 1999
• Online Access: http://ndltd.ncl.edu.tw/handle/21373821634466137303

博士 === 國立海洋大學 === 食品科學系 === 87 === This study was to investigate the physico-chemical and functional properties of salted duck egg white (SDEW) which was treated by electrodialysis desalination or powderization processing. And, the effect of SDEW powder on textural characteristics of tilapia surimi product has been studied. The protein content of duck egg white (DEW) and chicken egg white (CEW) were 13.1 and 10.6 %; the ovalbumin and conalbumin were 75.6, 2.6% and 59.4, 14.5%; the surface hydrophobic intensity were 168 and 205 (So/100mg protein); the surface sulfhydryl group were 1.76 and 4.13 (mM/g), respectively. Both of surface hydrophobic intensity and surface sulfhydryl group were increased with increasing heating temperature from 10 to 80℃. When heating temperature up to 90℃, the surface hydrophobic intensity and surface sulfhydryl group of CEW were 1.4 and 2.5 times higher than DEW. The conalbumin of CEW had a higher aggregation than DEW during heating, but the gel strength of DEW was 208 g.cm, being 1.5 times higher than CEW. As the duck egg was pickled for 8 weeks, the egg white''s pH was decreased from 9.3 to 7.1; the NaCl content increased from 0.49 to 7.32%; the surface hydrophobic intensity increased from 177 to 372 (So/100mg protein); the Zeta potential was decreased from -48.3 to -26.4 (mV); but the soluble protein content was not significantly changed. The SDEW was desalinized by electrodialysis. When the NaCl was removed by 95%, the pH of SDEW was slightly increased and surface hydrophobic intensity decreased by 30％, the soluble protein was remained at 95 %, and the similar distribution of protein molecules'' pattern was observed by SDS-PAGE. In the emulsion stability, except that fresh duck egg white showed a higher value, the various SDEW''s samples had no significant differences even by electrodialysis desalination treatment. Both foamability and foam stability of SDEW decreased with increasing pickling time, but the values increased after electrodialysis desalination treatment. The breaking force of SDEW''s gel decreased with pickling time, but the breaking point increased. After electrodialysis desalination treatment, both the breaking force and point of SDEW''s gel significantly decreased. There were no significant changes in proximate composition of salted duck egg white powder (SDEWP) with different drying methods, which contained 36 % of NaCl and 62% of crude protein. The protein solubility of SDEWP with freeze drying and drum drying were 99.8 and 7.5 %, respectively. The surface hydrophobic intensity of SDEWP with spray drying was 347.9 (So/100mg protein), being 4 times higher than drum dried sample. Except the drum dried sample, all the SDEWP showed one transition temperature at 94℃, which 10℃higher than DEW was analyzed by Differential Scanning Calorimeter. Also, the SDS-PAGE pattern showed the similar distribution of protein molecules of SDEWP with different drying methods, except the drum dried sample. The foaming properties of SDEWP were decreased 4-8 times after drying treatment. There were no significant differences in emulsifying activity and gel strength among the different sample, except the drum dried sample had a lowest emulsifying ability and could not form a gel. Extraction of tilapia salt-soluble protein (TSSP) with drum dried sample showed the highest relative extraction ratio. And, there are no significant differences in the relative extraction ratio of TSSP among with other samples and control (mix of fresh duck egg white powder and NaCl). When the heating temperature up to 70℃, the turbidity of the TSSP solution mixed with SDEWP (except the drum-dried sample) were sharply increased than TSSP solution or SDEWP solution alone. As the extracts were analyzed by SDS-PAGE, a higher quantity of myosin heavy chain was obtained with the mix of fresh duck egg white powder and NaCl. And, there are no significant differences among each kind of protein molecules and ratio in the TSSP''s extracts when different SDEWP were applied. The tilapia surimi added with drum dried SDEWP to obtain a highest gel strength being 657 g.cm, but the lowest in rigidity and hardness than other samples was found. When each mixtures of TSSP/CEW, TSSP/DEW and TSSP/SDEW solution were heated at 90℃, the surface hydrophobic intensity was decreased to 13.2, 73.5 and 62.3%; the surface sulfhydryl group was decreased to 4.9, 88.7 and 86.0%; the protein solubility was decreased to 29.6, 85.8 and 82.4 %, respectively. These values decreased sharply than each individual of TSSP, CED, DEW and SDEW solution. As an insoluble aggregates was produced from TSSP/SDEW mixture solution after heating at 90℃, it was suggested that the hydrophobic interaction between the two kinds of protein molecules was primary, then the disulfide bonding was secondary.