碩士 / 國立中興大學 / 食品暨應用生物科技學系 / 96 / Lactobacillus acidophilus possesses lots of important physiological functions beneficial to human health and numerous dried products which containing it are now popular for use as dietary adjuncts for humans and animals. However, low numbers of active L. acidophilus cells were found in the dried products. The freeze-drying method traditionally used for cells dehydration is slow and needs high cost. Therefore, competitiveness could be enhanced by means of the improvement of the drying operation, such as reduction in drying time, and enhancement of the viability and stability after drying, etc. Controlled low-temperature vacuum dehydration is a method to dehydrate products as cold as possible without freezing. Freezing damage could be avoided and high quality products as those produced by freeze-drying might be manufactured. Far-infrared radiation possesses many advantages, such as high thermal transmission, simple design, easy operation, and low cost, etc., and is frequently used in dehydration operation. Besides, intermittent heating is also often used in far-infrared heating in order to reduce drying time and improve product quality. On the other hand, cell immobilization technique and cryoprotectants could provide protection to microbial cells and increase their tolerance to freezing and drying operation. In this study, L. acidophilus and different cryoprotectants were immobilized in Ca-alginate, and immobilized cells were processed by freeze-drying and controlled low-temperature vacuum dehydration. Far-infrared radiation at different intermittences was applied in two drying operations. The viability, degree of injury and acidification of dried cells were compared.
Results indicated that immobilizing L. acidophilus with non-fat dry milk solids and trehalose in Ca-alginate beads could increase the viability and decrease the injury of cells after freeze-drying or controlled low-temperature vacuum dehydration. However, immobilization could not enhance the acidification of dried cells in AP test. In a comparison between freeze-drying and controlled low-temperature vacuum dehydration, cells processed by controlled low-temperature vacuum dehydration have higher viability, lower damage and better acidification ability.
| Identifer | oai:union.ndltd.org:TW/096NCHU5255022 |
| Date | January 2008 |
| Creators | Chih-Chieh Chen, 陳至潔 |
| Contributors | 金安兒 |
| 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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