探討馬鈴薯、一般玉米與糯性玉米澱粉的混合系統之糊化與凝膠性質變化

Changes of pasting and gelling properties of potato, normal corn and waxy corn starch blends

李昱宗(Yu-Tsung Lee)

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(2014年)

https://doi.org/10.6342/NTU201704486

摘要

自然的澱粉以顆粒型態存在，需要於溶液中提高溫度使其顆粒糊化膨潤後產生黏度與膠體，澱粉的成糊與凝膠性質除受澱粉來源與組成影響外，也受糊化與凝膠的條件的影響。於真實的食品系統中常以混合澱粉的方式進行加工，為瞭解澱粉混合後的成糊與凝膠性質。本研究以直鏈澱粉含量與成糊性質不同的三種澱粉進行混合，探討混合澱粉系統之成糊與凝膠性質之變化。實驗設計利用高膨潤力之馬鈴薯澱粉(Potato starch, PS)與高溶解度之稀沸馬鈴薯澱粉(Thin-boiling potato starch, TBP)做為基底，混合一般玉米澱粉(Normal corn starch, NCS)與糯玉米澱粉(Waxy corn starch, WCS)及其稀沸澱粉，分別為稀沸一般玉米澱粉(Thin-boiling normal corn starch, TBC)與稀沸糯玉米澱粉(Thin-boiling waxy corn starch, TBW)，以不同比例(100/0, 75/25, 50/50, 25/75與0/100)進行混合，而天然馬鈴薯混合稀沸馬鈴薯澱粉做為對照組。
結果顯示，於成糊性質觀察，PS/TBP組隨PS比例下降，其相關的黏度指標值均呈簡單的線性趨勢下降，然而混合天然/稀沸NCS與WCS皆偏離此線性趨勢。輔以掃描式熱分析之糊化熱性質數據可知混合澱粉系統中已糊化之澱粉會延緩未糊化澱粉顆粒之糊化溫度。而冷卻過程之最終黏度(Final viscosity, FV)和回升黏度(Setback, SB)偏離PS/TBP組之結果最為顯著，表示混合澱粉冷卻過程其交互作用最為明顯。而於TBP組混合玉米澱粉組(TBP/WCS, TBP/NCS, TBP/TBC與TBP/TBW)其相關指標亦成線性，表示混合系統中，高膨潤力澱粉影響其成糊之黏度。此外於PS/WCS與PS/TBW於50/50下出現雙峰，然高溫之尖峰黏度(Peak viscosity, PV)證實為來自天然馬鈴薯澱粉，而非糯玉米澱粉之尖峰黏度。
使用低剪力之動態流變分析觀察混合澱粉之顆粒膨潤性質，PS/TBP組別其相對指標未與混合比例並非線性關係，表示於低剪切力環境下，易造成澱粉顆粒不易破裂導致此現象。於膠體堅實度於PS/TBC=50/50達最高，表示澱粉溶出物與澱粉顆粒於此比例下達到平衡。綜合上述，混合澱粉系統中，相較於溶解度與直鏈澱粉含量，膨潤力對於成糊性質之黏度指標的影響較為明顯，而直鏈澱粉溶出率與顆粒殘留影響了膠體堅實度。

關鍵字

混合澱粉 ； 糊化 ； 凝膠 ； 膨潤力 ； 溶解度指標

並列摘要

Native starch exists in granule form, which needs to be heated in solution to make it swell and gelatinize, and form gel. There are many factors that would affect the properties of pasting and gelling of starch, including its source, composition, thermal property, concentration and so on. Blended starch is commonly used in food industry to impart desired properties. This study aims to understand of pasting and gelling properties of blended starch. This study used three pure starches with different amylose contents and pasting properties Native potato starch (PS) and thin-boiling potato starch (TBP) were blended with normal corn (NCS), waxy corn starch (WCS) and their thin-boiling modified starch, thin-boiling normal corn (TBC) and thin-boiling waxy corn (TBW) at different ratios (100/0, 75/25, 50/50, 25/75 and 0/100.). Native/ thin-boiling potato starch blends were used as control.
The results showed that PS/TBP decreased linearly with decreased PS ratio, while PS/WCS, PS/NCS, PS/TBC and PS/TBW did otherwise Using differential thermal analysis (DSC), it was found that starch with lower gelatinization temperature delayed the gelatinization temperature of starch with higher gelatinization temperature in blended starch. Pasting properties- final viscosity (FV) and setback have significant differences compared with PS/TBP group, which indicated that there was obvious interaction of blended starch during cooling procedure. The correlated factors of TBP blended group (TBP/WCS, TBP/NCS, TBP/TBC, and TBP/TBW) also show linearity, which mean that starch high swelling power will affect the pasting viscosity in the blended system. In addition, PS/WCS and PS/TBW show double peaks under 50/50 blended ratio. Yet the peak viscosity at the high temperature is proved to be native potato starch instead of waxy corn starch.

Low shear dynamic rheometer was used to observe swelling property of the blended starch. There was no observed linear relationship between dynamic modulus and blend ratio in PS/TBP group. The reason for this might be because starch granules are not easily broken in a low shear environment. Maximum gel firmness was observed for PS/TBC=50/50, which might indicate that leached out amylose and intact starch granule are most stable at this ratio. In summary, considering amylose content, solubility index and swelling power, swelling power has the greatest impact on pasting properties of the blended starch. On the other hand, leached-out amylose and intact starch granules had the greatest impact on gel firmness.

並列關鍵字

Blended starch ； Viscoamylograph ； Gelatinization ； Pasting property ； Swelling power ； Solubility index

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