碩士 / 國立海洋大學 / 食品科學系 / 91 / Abstract
The aims of the study are to explore the effects of the molecular weight of chitosan, the concentration of sodium alginate solution and the pH of chitosan solution on the physical-chemical properties of the chitosan-sodium alginate polyelectrolyte complex (CS-AL PEC) and to establish the application conditions of the CS-AL PEC casing. The physical-chemical properties studied including the rehydration property, tensile stress, tensile strain and thermal property and the analyzation of the composite ratio of chitosan and sodium alginate in the PEC. Chitin was extracted from red shrimp (Solemocera prominenitis) processed waste, then the high degree of deacetylated chitosan was prepared by hot alkali deacetylation. The HCl degradation on chitosan prepared were used to get the same degree of deacetylation but different molecular weight chitosans. Response surface methodology (RSM) was used to set the experimental design. The same degree of deacetylation but different molecular weight chitosans and sodium alginate were used to prepare the PEC. SAS statistics analysis package was used to regressing the data of the experiments and the results obtained were as following:
During hydrolysis of high degree of deacetylated chitosan (DD = 93%) by HCl (8N) at 55℃, changed in the degree of deacetylation was not significant. However the molecular weight decreased significantly over time. At the time, the molecular weight decreased to 1/10 of the original molecular weight, the rate of degradation became level off. It is because the activity energy of glucosidic bond of N-acetyl-glucosamine was lower.
The results of differential scanning calorimeter (DSC) and RSM studies show that the properties of the CS-AL PEC affected by the molecular weight of chitosans, the concentration of sodium alginate solution and the pH of chitosan solution. The results show that (1) higher chitosan solution pHs used in the system, the interaction of chitosan and sodium alginate was mainly due to entanglement between chitosan and alginate molecules. On the other hand, lower chitosan solution pH, the interaction of chitosan and sodium alginate mainly via the ionic bond. (2) higher sodium alginate concentration used in the system, the interaction of chitosan and sodium alginate mainly via the ionic bond. On the other hand, lower sodium alginate solution, the interaction of chitosan and sodium alginate tended to be the entanglement of molecular chains. (3) lower molecular weight of chitosan in the system, the interaction of chitosan and sodium alginate tended to be the ionic bond. However, higher molecular weight of chitosans, the interaction of chitosan and sodium alginate tended to be the entanglement of molecular chains. It may be due to that the longer chain molecule facilitate the entanglement. However, the longer the molecular chain of chitosan, the higher the numbers of amino group have. The interaction of chitosan and sodium alginate will tend to be the ionic bond. Therefore, the interaction of the high molecular weight chitosan will be affected by the pH of chitosan solution and the concentration of sodium alginate solution in the system. The results show that the optimal molecular weight of chitosan is 150 ~ 160 kDa and the pH of chitosan solution and the concentration of sodium alginate solution depended on the conditions used.
The CS-AL PEC casing was more endured to be ruptured in deep frying treatment than gelatin casing. It maybe due to the junction zone was resistant to be destroyed in the frying treatment. During boiling, the gelation casing could sustain the original shape, but the CS-AL casing could not. It maybe due to the destruction of the junction zone and ionic bond by the permeation of water molecule and hydrolysis process. Therefore, the CS-AL casing was more suitable to be used in the frying treatment.
| Identifer | oai:union.ndltd.org:TW/091NTOU0253014 |
| Date | January 2003 |
| Creators | Kou-Min Chang, 鐘國銘 |
| Contributors | R. H. Chen, 陳榮輝 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 101 |
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