| 摘要: | 本實驗是探討儲存條件對大豆分離蛋白的物化特性變化與對製作百頁豆腐的影響。儲存條件分別為常溫組（儲存溫度25℃、樣品水活性0.25）、高溫組（儲存溫度45℃、樣品水活性0.25）、低溫組（儲存溫度5℃、樣品水活性0.25）、高濕組（儲存溫度25℃、樣品水活性0.75）、光照組（每天12小時光源照射、儲存溫度25℃、樣品水活性0.25）、抽氣組（儲存袋使用真空包裝、儲存溫度25℃、樣品水活性0.25）及高溫高濕組（儲存溫度45℃、樣品水活性0.75）等七組。
每28天採樣一次，共8次(實驗時間為224天)。分批測定樣品的顏色、氮溶指數、蛋白質疏水性、酸鹼值、蛋白質功能性（膠質性、乳化性、起泡性、黏稠性、保水性），並以電泳觀察蛋白質的變化。然後，將大豆分離蛋白做成百頁豆腐，測定原料漿黏度與成品顏色、密度及質地。
結果發現：(1)大豆分離蛋白在高溫組與高溫高濕組的顏色偏為紅黃色，而高濕組則偏為黃綠色。(2)儲存時間越長，氮溶數值越降低，高溫組、高濕組與高溫高濕組的變化很顯著。(3)高溫高濕組的蛋白質疏水性展開度最高。(4)所有樣品在儲存後都偏向酸性。(5)高濕組與高溫高濕組的蛋白質功能性顯著變差。(6)若以電泳展開高溫高濕組的蛋白質，發現蛋白質減少且有電荷位移現象。(7)高濕組與高溫高濕組的原料漿黏度降低、百頁豆腐質地變差。(8)以百頁豆腐內切面的顏色來看，高溫高濕組明顯偏為黯淡的紅黃色。(9)隨著儲存時間越長，各實驗組的百頁豆腐密度越大。
總結，溫度與濕度是影響大豆分離蛋白儲存的重要因素；換句話說，低溫與抽氣包裝對大豆分離蛋白是最好的儲存方式。
This study is going to investigate the effect of different storage condition of soy protein isolate (SPI) and the quality of paiyen tofu. SPI was stored in 7 different conditions which were the room temperature treatment (25℃, Aw 0.25), the high temperature treatment (45℃, Aw 0.25), the low temperature treatment (5℃, Aw 0.25), the high humidity treatment (25℃, Aw 0.75), the light treatment (12hours daylight exposure, 25℃, Aw 0.25), the vacuum treatment (vacuum packaging, 25℃, Aw 0.25) and the high temperature-high humidity treatment (45℃, Aw0.75).
The experiment was 224 days totally, every 28 days sampling once and totally 8 sampling times. SPI sample was examined the following items：color, nitrogen solubility, hydrophobicity, pH, functional properties (including gelation, emulsification, foaming ability, viscosity, water holding capacity) and electrophoresis. Then paiyen tofu was made and determined its color, density and texture and the viscosity of half product.
The result found：(1) The color of the SPI has changed to reddish yellow in the high temperature - high humidity treatment sample and to yellowish green in the high humidity treatment sample. (2) The longer the storage time, the lower the nitrogen solubility. The phenomenon is especially obvious in the high temperature treatment and the high temperature - high humidity treatment samples. (3) The highest degree of hydrophobicity is found in the high temperature - high humidity treatment sample. (4) All the samples become more acid after being stored. (5) The functional properties of SPI sample are decreased significantly in the high humidity treatment and the high temperature - high humidity treatment samples. (6) Electrophoresis result found after storage, the protein molecule weight of SPI significantly decreased and the charge of the protein molecule has migrated. (7) The viscosity of half product of paiyen tofu and the texture of paiyen tofu declined significantly in the high humidity treatment and the high temperature - high humidity treatment samples. (8) The inside color of paiyen tofu become dark reddish yellow in the high temperature - high humidity treatment sample. (9) The longer the storage time, the greater the density of paiyen tofu.
In conclusion, the temperature and the humidity are most two important factors affecting SPI quality during storage. On the other hand, low temperature and vacuum packaging are the best way to preserve SPI. |
