Antimicrobial activity of chitosan coating against food pathogens | |
| Author | Huynh Nguyen Bao Loan |
| Call Number | AIT Thesis no. BP-02-10 |
| Subject(s) | Chitosan Anti-infective agents |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science, School of Environment, Resources and Development |
| Publisher | Asian Institute of Technology |
| Series Statement | Thesis ; no. BP-02-10 |
| Abstract | Effect of chitosan on antimicrobial activity has been studied with four types of chitosans at 0.1 % (w/v) concentration. Chitosan HD (96% DD; 745,357 Dalton), LD (65% DD; 760,366 Dalton), HM (95% DD; 850,000 Dalton) and LM (96%; 250,000 Dalton) were chosen for the analysis. Inhibition and inactivation of three common pathogenic bacteria (Escherichia coli, Staphylococcus aureus and Salmonella weltevreden), which contaminated fish ball, were studied with chitosan treament. The in vitro study showed that the inhibition effect of chitosan was significant for the growth of pathogenic bacteria, especially for S. aureus. On the infected fish balls, the bacterial growth curves of control samples were significantly different as compared with other chitosan treated samples. The dependence of DD and MW on the antimicrobial activity varied with the strains of bacteria. E. coli was more sensitive with the change of DD, Salmonella weltevreden with MW and S. aureus with either DD or MW. Dipping in chitosan solutions can reduce microbial spoilage to extend the shelf life . Moreover, the sensory quality of the products also enhanced. During prolong storage (of unsterilized samples), when comparing the coating and mixing methods, the chitosan mixed fish ball significantly effect on growth inhibition of organism. It showed lower value of cell count number. With sterilized samples, coating fish balls with HD or LM chitosan was chosen on the basis of low number of organisms and sensory evaluation. The effect of chitosan as preservative coating on postharvest storage of tomato has been investigated in the second part of study. Two fungi that cause the sour rot and soft rot diseases on fresh tomato were selected for analysis. The in vitro experiment described Geotrichum candidum was more resistant to chitosan than Rhizopus stolonifer. However, when chitosan was applied as a coating for tomato, the opposite result was observed. Coating of tomato with chitosan delayed the ripening process as performed in reduction of weight loss and color change. In addition, chitosan coated tomatoes were firmer the control samples after prolonged storage. Chitosan was found to reduce infection on tomato by these fungi. The influence of different MW chitosans was clear as compared with that of DD on fungal radial growth, color development, and the firmness. Low MW and high DD chitosans were more effective than high MW and low DD for control the infection of Rhizopus stolon(fer and Geotrichum candidum on keeping quality of tomato. |
| Year | 2002 |
| Corresponding Series Added Entry | Asian Institute of Technology. Thesis ; no. BP-02-10 |
| Type | Thesis |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Department of Food, Agriculture and Natural Resources (Former title: Department of Food Agriculture, and BioResources (DFAB)) |
| Academic Program/FoS | Bioprocess Technology (BP) |
| Chairperson(s) | Rakshit, Sudip K.; |
| Examination Committee(s) | Jindal, V. K., Athapol Noomhorm; |
| Scholarship Donor(s) | The Royal Netherlands Government; |
| Degree | Thesis (M. Sc.) - Asian Institute of Technology, 2002 |