碩士 / 國立中興大學 / 食品暨應用生物科技學系 / 96 / Lactobacillus acidophilus is a popular strain of lactic acid bacteria and often added in consumer foods. L. acidophilus processes lots of important physiological functions beneficial to human health and numerous foods which containing it are now popular for use as dietary adjuncts for human. Freeze-drying is a popular method used in the culture preservation of microorganisms. The processes of freeze-drying might cost a lot of energy consumption and its freezing operation might cause damage of microorganisms. Controlled low-temperature vacuum drying (CLTVD) is a method to dry products as cold as possible without freezing. The sample dried by this method could therefore avoid the damage of freezing. Far-infrared radiation (FIR) possesses many advantages, such as low cost and low temperature, etc., and is frequently used in dehydration operation. On the other hand, cell immobilization is one of methods to protect the microorganisms and could effectively provide protection to microbial cells in order to increase their tolerance to unfavorable ambient conditions, such as freezing and drying. In this study, κ-carrageenan was applied to immobilize L. acidophilus to make the microcapsules, and the immobilized cells were processed by freezing and drying operations. Far-infrared radiation heating was applied in the freeze-drying and controlled low-temperature vacuum drying of immobilized cells in order to improve the survival of L. acidophilus. Conditions with the combination of various pre-freezing temperatures and different far-infrared radiation intermittences were used in the studies. Results indicated that free cells were liable to be killed in high intermittent heating, and no significant difference in viabilities of the immobilized cells among different intermittences was found in controlled low-temperature vacuum drying. In freeze-drying, there was a significant difference in viabilities between free cells and immobilized cells. It showed that the survivals were close in different pre-freezing temperatures and different intermittences. In conclusion, immobilization by κ-carrageenan could effectively protect L. acidophilus against the damage of drying and freezing.
| Identifer | oai:union.ndltd.org:TW/096NCHU5255014 |
| Date | January 2008 |
| Creators | Huan-Chieh Chen, 陳煥傑 |
| 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 | 102 |
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