- 學位論文
順丁烯二酸對澱粉的結構與流變行為在升降溫過程中的影響
Effects of Maleic Acid Addition on Structural Variation and Rheogolical Behavior of Tapiaca Starch during the Simulated Cooking (Heating/Cooking) Process
摘要
木薯澱粉隨著不同順丁烯二酸的含量，於升降溫過程中的結構變化，已使用小、廣角度X光散射實驗、流變儀實驗以及微分掃描式熱差卡計所測量。由廣角度X光散射實驗結果得知該木薯澱粉包含了A與B-type的結晶，其重量比例為四比一。由小角度X光散射實驗得知澱粉的半結晶層是由blocklet結構所組成的，而blocklet則是由結晶層與非結晶層交替形成，其結晶層厚度tc與非結晶層厚度ta分別為7.5與1.1奈米，總區間長度為8.6奈米，並有著百分之二十的亂度。從流變儀與小角度X光散射實驗的結果得知，直鏈澱粉會與支鏈澱粉共同存在於結晶層裡，當結晶開始有明顯的融解時，也就是在六十度C之後直鏈澱粉會離開結晶區域，並釋放到水溶液中進而增加黏度。在糊化溫度後，也就是在六十六度C，澱粉粒瓦解，並且有大量的直鏈澱粉溶解至水中。在降溫過程中，澱粉水溶液則會在七十度C左右產生膠聯，並且他的碎形維度會從二增加至二點三，而黏度則是持續增加。數據分析的結果指出，直鏈澱粉與支鏈澱粉形成的奈米尺度的聚集結構，在降溫過程會持續聚集，形成一個碎形結構。由微分掃描式熱差實驗以及流變儀的結果顯示，順丁烯二酸不會影響澱粉的融化行為。而在六十度C之後，澱粉結晶開始融解，此時從小角度以及廣角度X光散射實驗也得到一致的結果。在降溫的過程中，碎形結構所貢獻的Q不變量強度，會隨著降溫過程而增加，且越多的順丁烯二酸含量的澱粉，增加的強度則會更加明顯。從這結果我們可以推測順丁烯二酸會幫助膠聯的反應進而形成碎形結構。由上述結果指出，直鏈澱粉在升溫過程會被釋放出來，並增加黏度；在升溫過程時，順丁烯二酸則會稍微幫助膠聯，並在降溫時有明顯的增強現象，尤其是在四十六度C左右開始會增強支鏈澱粉的回凝現象，使膠聯現象更加明顯。
並列摘要
The morphological variations of starch with maleic acid during heating and cooling processes are observed by differential scanning calorimetry, small/wide angle x-ray scattering (SAXS /WAXS) and rheometer. The WAXS fitting profile shows the mixed of A- and B-type crystal in the tapioca starch with a ratio of A and B is about 1:4, and the SAXS fitting results suggest that the semicrystalline layers are composed of blocklets. Blocklets are lamellar-structure particles, which are alternately composed of polydisperse crystalline layers and amorphous layers, and their thickness are tc ≈ 7.5 nm and ta ≈ 1.1 nm with a lamellar long period L ≈ 8.6 nm of 20 % polydispesity. The results from viscosity profile and SAXS fitting profile in heating process indicate that amylose chains are co-crystallized with amylopectin in crystalline region. When the crystal size decreases significantly, corresponding to the melting of crystalline region after 60 °C, which amylose would be unleashed from the crystalline layer and increases its viscosity. After the gelatinization temperature at about 66 °C, starch granules collapsed and large amount of amylose chains released into water solution. During the cooling process from 85 to 30 °C, it gels at about 70 °C and the fractal dimension increased from about 2 to 2.3. Viscosity is also continuously increasing during cooling. It shows some amylopectin and amylose nanocluster aggregate as a fractal structure in the system. Differential scanning calorimetry and viscosity profiles indicate that maleic acid does not affect much its transition temperatures during melting, which are consistent with the variation of lamellar Q invariant from SAXS and relative crystallinity from WAXS; crystalline region start to melt after 60 °C and gelatinize after 66 °C. Maleic acid may enhance the effect of releasing amylose chains and increase its viscosity in higher maleic acid content case after gelatinization. In cooling process, Q invariant of ellipsoidal fractal structure from SAXS would increase, which can describe the behavior of free particles aggregate into fractal structure. Higher maleic acid content will increase its Q invariant of fractal structure. This result suggests that maleic acid would enhance the cross-link reaction and the formation of fractal structure. According to the results above, it demonstrate that amylose chains would be unleashed out of the crystalline region increase the viscosity of solution after melting; moreover, maleic acid would enhance the cross-link reaction slightly in heating and significantly in the cooling process below a retrogradation temperature ca. 46 °C.