| Summary: | 碩士 === 國立屏東科技大學 === 食品科學系所 === 100 === In Taiwan, 160,000 tons of waste oyster shells are deposited on the beach every year and cause environment problem. Studies have shown that ashed oyster powder with high pH has inhibition effect that can extend shelf-life of food products. This research purpose has two parts: At first, we discuss oyster micro-powder ashed at different temperatures (600℃-1000℃) was added at different concentrations (0.79mg/mL-200 mg/mL) into media to study the inhibitory effect on growth of food pathogens such as Escherichia coli BCRC10675, Staphylococcus aureus BCRC12947, Salmonella typhimurium BCRC10780, Bacillus cereus BCRC10603, Vibrio parahaemolyticus BCRC12959, Kloeckera apiculata BCRC20539, and Aspergillus niger BCRC30204. The results show that the shell powder by high temperature treatment (ashed at 900℃ for 5 hours) at a concentration of 1.25% was strongly inhibitory to growth of food pathogens, and the diameter of growth inhibition was more than 10.0 mm. Inhibition of A. niger growth showed that 800℃ shell powder ashed 5 hours with a concentration of 1% reduced A. niger mycelium weight. Second, we study the extension of the shelf- life of food products (Soy products, baked product, rice, noodles). Results show that total bacterial counts after adding 0.5% shell
powder (ashed at 900℃ for 5 hours) to tofu and frozen tofu, reduce 4.19×106 CFU/mL and 4.16×105 CFU/mL, respectively, compared with the commercial tofu. Texture profile analysis of tofu to add 0.1% ash shell powder higher hardness than the not to add shell powder in tofu. The results of tofu sensory evaluation, add 0.1% ash shell powder has the best overall acceptability, and add 0.1% ash shell powder tofu tissue hardness is the highest. Homemade baked product add 1% shell powder is extended by 10 days of shelf life than not added shell powder. Add 0.5% of the shell powder and cooked rice texture profile analysis chewiness higher than not added shell powder. Results show that total bacterial counts after adding 0.5% ash shell powder (ashed at 37℃ for 24H) to cooked rice, reduce 3.2 Log (CFU / mL). Results show that total bacterial counts after adding 0.1% ash shell powder (ashed at 5℃ for 24H) to cooked rice, reduce 3.6 Log (CFU/mL). Results show that total bacterial counts after adding 0.5% ash shell powder (ashed at 25℃ for 15days) to homemade noodle, reduce 1Log (CFU/mL). Ash shell powder in the application of food to extend shelf-life.
Keywords : oyster shells, calcium oxide, ashing, shelf-life
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