碩士 / 國立海洋大學 / 食品科學系 / 88 / The aim of this research is to investigate the effects of shrimp chitosan on the gel strength, color changes, and bacterial counts of mackerel surimi. After reaction with 50% NaOH at 60℃-140℃ for 1-10 h, 7 chitosan products with deacetylation degrees of 40-96% were obtained. Among these 7 products tested, the chitosan products with 70% deacetylation (DD70) and 95% deacetylation (DD95), which were obtained by chitin reaction with 50% NaOH at 100℃, 1 h and 140℃, 10 h, respectively, increased most the gel strength of mackerel surimi. The gel strength of mackerel surimi incresed with the increasing concentration (1-4%) of DD70 and DD95 added； while the color of mackerel surimi did not significantly change after addition of these two chitosans. During storage at 4℃, chitosan (DD70, DD95) could delay the growth of bacteria in mackerel surimi and caused 2-3 log reduction of total aerobic plate count (TAPC). The gel strength of surimi with chitosan addition was higher than control group and the gel strength increased by 1.8 times for the surimi with DD95 added and stored at 4℃ for 41 days. Similar effects were also observed. When the chitosan-added surimi was stored at 20℃, the TAPC was decresed by 1-5 log cycle after 4 day storage at 20℃, and the gel strength was increased by 1.7 times after 8 day storage, compared to control group. The gel strength was increased by 2.7 times after 36 h storage at 37℃ for surimi added with DD70 chitosan. However, the TPAC was similar between the control and experimental groups during 37℃ storage. The antibacterial activity of chitosan added in powder form to fish homogenate was much lower than those added in solution form. In addition, the fish component significantly decreased the bacteriocidal activity of chitosan. The minimal lethal concentration (MLC) of DD95 and DD70 in nutrient broth were 200 and 500 ppm, respectively, and 500 and 1000 ppm, respectively for their MLC in fish juice. The inhibition percentages were 50% and 23%, respectively, for 1000 ppm of DD95 and DD70 in fish homogenate.
| Identifer | oai:union.ndltd.org:TW/088NTOU0253018 |
| Date | January 2000 |
| Creators | Li Yen Wen, 李晏雯 |
| Contributors | Tsai Guo Jane, 蔡國珍 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 80 |
Page generated in 0.002 seconds