探討不同催化劑對於玉米澱粉乙醯酯化反應之影響

Effects of various catalysts on acetylation reaction of corn starch

紀帆益(Fan-Yi Chi)

指導教授 ： 呂廷璋

國立臺灣大學/生物資源暨農學院/食品科技研究所/碩士(2012年)

https://doi.org/10.6342/NTU.2012.00657

摘要

乙醯酯化澱粉依其取代度高低，分別廣泛應用在食品工業以及非食品工業上。本研究之目的是找到反應效能(reaction efficiency)良好的催化劑並期望藉由催化劑的輔助提升反應速率，在冰醋酸環境下，快速生產乙醯酯化澱粉。本實驗以玉米澱粉為反應基質、醋酸酐為反應劑，利用不同物質為催化劑(硫酸、磷酸、硝酸、鹽酸、碘)，浸潤於冰醋酸中，於95℃熱水浴加熱並攪拌。結果顯示有添加催化劑之組別其乙醯酯化反應效能優於無添加催化劑之組別，各催化劑之輔助效能大小，依序為硫酸>硝酸>磷酸>碘，而鹽酸處理組水解情況嚴重。除了磷酸處理組外，其他各組之反應效能隨醋酸酐莫耳數的減少有上升的趨勢，並利用傅立葉轉換紅外線光譜(FTIR)分析，隨著取代度的增加，在1754、1435、1375、1240cm−1之訊號也隨之增強。在光學性質方面，可觀察到澱粉經過乙醯酯化反應後，偏光十字現象減弱，在相同取代度上以硝酸為催化劑之處理組，減弱最大。結晶繞射圖譜結果顯示，乙醯酯化澱粉相較於天然澱粉之結晶指標較小，且在取代度0.4中，以硝酸之結晶指標最小，相較天然澱粉降低了56%；在取代度0.5中，則為無添加催化劑之組別結晶指標最小，相較天然澱粉降低了77%。膨潤力方面，經過乙醯酯化反應之澱粉，在低取代度部分(小於1)其膨潤力相較天然玉米澱粉都有上升趨勢，水溶性指標又以硫酸處理組上升最多。在澱粉成糊性質中，發現經過乙醯酯化修飾之澱粉，其成糊溫度和達最大尖峰黏度之溫度均有下降趨勢，且setback相較天然玉米澱粉也較低。

關鍵字

玉米澱粉 ； 冰醋酸 ； 催化劑 ； 乙醯酯化澱粉 ； 取代度

並列摘要

Acetylated starch is widely used in the food industry as well as in the non-food industry according to its different levels of degree in substitution. The goal of this research is to find a catalyst with good reaction efficiency that helps accelerate the reaction rate in glacial acetic acid environment to produce acetylated starch rapidly. Corn starch is used as a reaction matrix, acetic anhydride as the reagent, and different materials as catalysts (sulfuric acid, phosphoric acid, nitric acid, hydrochloric acid, iodine), infiltrated in glacial acetic acid at 95 °C hot water bath, heated and stirred. The results shows that the experiment groups added with the catalyst is better than the control group without catalyst in the performance of reaction, while the auxiliary performance of each catalyst, sulfuric acid > nitric acid > phosphoric acid > iodine, and hydrochloric acid treatment group hydrolysis is very serious. Except for phosphoric acid treated group, the reaction rate of other groups decline as the mole number of acetic anhydride rises, and at the same time, according to the Fourier Transform Infrared Spectroscopy (FTIR) analysis, with the increase of degree of substitution, the signals at 1754, 1435, 1375, 1240cm-1 also increase. As for the optical properties, it can be clearly and easily observed that after the acetylation of starch, the phenomenon of birefringence is weakened, with the nitric acid treated group decreases most seriously. The Crystalline indicates that compared to the native corn starch collected from normal corns, the index of acetylated starch is smaller. Under the degree of substitution 0.4, the crystalline index of nitric acid treated group is the smallest, and it decreases 56% compared to the native corn starch. While under the degree of substitution 0.5, the crystalline index of non-catalyst treated group is the smallest, which decrease 77% compared to the native corn starch. As for the swelling power of the acetylated starch, in the part of low substitution degree (said to be less than 1), shows an increasing inclination compared to the native corn starch. Especially the sulfuric acid treated group is the highest in the part of water solubility index. Lastly, the starch pasting profile indicates that acetylated starch shows a decreasing inclination in pasting temperature and peak temperature, and its setback is lower compared to the native corn starch.

並列關鍵字

corn starch ； glacial acetic acid ； catalyst ； acetylated starch ； degree of substitution

參考文獻

李宜真. 於醋酸溶液中以微波輔助修飾之玉米澱粉理化特性. 國立臺灣大學, 2010.

鄭雅方. 以微波-醋酸處理生產顆粒狀冷水可膨潤玉米澱粉. 國立臺灣大學, 2011.

Adedokun, M. O.; Itiola, O. A., Material properties and compaction characteristics of natural and pregelatinized forms of four starches. Carbohydr. Polym. 2010, 79, 818-824.

Agboola, S. O.; Akingbala, J. O.; Oguntimein, G. B., Production of Low Substituted Cassava Starch Acetates and Citrates. Starch - Starke 1991, 43, 13-15.

Baek, M. H.; Yoo, B.; Lim, S. T., Effects of sugars and sugar alcohols on thermal transition and cold stability of corn starch gel. Food Hydrocolloids 2004, 18, 133-142.