| Summary: | 碩士 === 國立屏東科技大學 === 食品科學系所 === 97 === In order to maintain softness of bread, bakers would add additives, such as softener. However, in addition to raising the cost of products, these additives are even harmful to human body. Therefore, this study aimed to probe into the optimum conditions for producing α-amylase from liquid and solid strain of Aspergillus terreus, and then add α-amylase to the dough for milk bread, to discuss the influence of α-amylase on baking quality of milk bread. The results showed that when the liquid culture method is employed to discuss the optimum culture conditions for producing active α-amylase from the strain Aspergillus terreus, the activity of α-amylase in the culture medium could reach 765.832 U/mL, if stirred speeds was 170rpm, inoculum size was 7% (v/v), the culture medium was composed of 7% (w/v) comerical fructose, 0.2% soybean protein (w/v), 0.15% NaCl (w/v), 0.05% MgSO4 (w/v) and 0.05% KH2PO4 (w/v), the initial pH value of the culture medium was 7.0 ± 0.2, and it was cultured under vibration for 24 hours at the temperature of 37℃. When the solid fermentation method was adopted to discuss the optimum conditions for producing α-amylase from the strain of Aspergillus terreus, the results showed that the activity of α-amylase could reach 1376.75 Unit/g, if rice was used as solid fermentation substrate with 5% (v/w) inoculum size, and cultured for 72 hours at the temperature of 30℃. Following this, α-amylase was dried for 48h with cold air, and stored at 4℃ after being ground to powder. The coarse ferment powder was applied to the production of milk bread. The results revealed that compared with the control group, a better effect (3.48 ± 0.07) could be achieved by adding 1% (w/w) koji rice powder to milk bread made from the dough, with the specific volume of 5.11 cm3/g. Measuring and analysis results of other textures analysis are as follows: hardness 1.13 kgf, springiness 13.36 mm, cohesiveness 0.96, water activity 0.97, rapid visco analysis 133 cp and surface color analysis 39.75; and analysis results of fundamental components are as follows: calories 373 Kcal/100 g, crude protein 11.6 g/100 g, crude fat 3.0 g/100 g, carbohydrate 49.9 g/100 g, sodium 295 mg/100 g, moisture 34.1g/100g and ash 1.4 g/100 g. Storage test results of milk bread indicated that the specific volume of milk bread made from the dough stored for 96 hours by adding 1% (w/w) koji rice powder remained unchanged, and measuring and analysis results of other textures are as follows: hardness 2.18 kgf, springiness 7.58 mm, cohesiveness 0.73, water activity 0.95, rapid visco analysis 248 cp and surface color analysis 39.75.
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