仙草葉膠、羧甲基纖維素鈉與關華豆膠應用於粉圓模式系統之評估

Abstract

本研究旨在探討多醣膠，包括仙草葉膠（HG）、羧甲基纖維素鈉（CMC）以及關華豆膠（GG）之混合比例(仙草葉膠搭配其他多醣膠= 0/4、1/3、2/2、3/1、4/0)以及多醣膠的濃度(0.5%)，對粉圓模式系統糊化特性及凝膠現象、所成凝膠於冷藏期間之黏彈性質、以及對珍珠奶茶模式系統品質之影響。在快速黏度分析實驗中，混合系統的黏度隨著CMC與GG的比例增加而升高；當HG/CMC的比例為0/4、1/3及2/2，HG/GG的比例為0/4及1/3時，混合膠的黏度比單獨澱粉系統高。示差掃描熱分析的結果發現，混合系統的凝膠尖峰溫度較單獨澱粉系統高，而熱焓值則明顯低於單獨澱粉系統。在動態流變測定中，單獨添加CMC和GG的混合系統，其儲存模量與耗損模量皆隨著頻率增加而顯著增加，顯示所成混合系統之行為屬於弱膠結構。在HG/CMC混合系統中，儲存模量隨著仙草葉膠的比例增加而增加；然而在HG/GG混合系統中，當比例為0/4、 1/3及2/2時，儲存模量依序下降，直到3/1及4/0時該模量才又上升。 在粉圓模式樣品冷藏期間之動態黏彈性方面，隨著儲藏天數增加，混合系統的儲存模量亦增加。與市售粉圓相較，粉圓模式樣品的回凝係數皆較低，然以HG/CMC＝0/4、2/2以及HG/GG＝0/4、1/3、2/2之回凝較輕微。將粉圓模式樣品浸泡於水中時，其儲存模量皆有明顯下降趨勢，浸泡於奶茶者則較無明顯變化。在官能品評分析方面，不論是香氣、硬度、彈性及整體喜好性，除HG/CMC＝0/4者之官評分數低於市售粉圓者外，其餘粉圓模式樣品均優於市售粉圓，顯示適量HG搭配CMC或GG或可應用於改善粉圓因冷藏回凝而使質地變硬之現象。

The objective of this research was to systematically examine the pasting/gelling and rheological properties of starch pearl model system as a function of mixed gum type (hsian-tsao leaf gum / carboxymethylcellulose or hsian-tsao leaf gum / guar gum) and ratio (0/4, 1/3, 2/2, 3/1,4/0). Rapid visco-analysis results indicated that the viscosity of the polysaccharide/starch mixed systems increased with increasing the ratio of CMC or GG in mixed gum. While HG/CMC=0/4, 1/3, 2/2 and HG/GG=0/4, 1/3, the viscosity of the mixed system was higher than that of starch alone system. Such results suggested an increase in the effective concentration of starch, leading to synergistic interactions with the mixed gum. In thermal analysis, except for HG/GG=0/4, the peak temperature (Tp) of the mixed system was higher and the enthalpy was significantly lower than those of starch alone system. This may be attributed to lower ratios of free water available for starch due to immobilization of water molecules by gums, the lower heat transfer and mass transfer of water, which could make starch gelatinization more difficult in the presence of gum. Dynamic rheological properties test indicated that the storage and loss modulus of the mixed systems increased with frequencies, and tan δ was lower than 1, indicated the composite systems could be classified as weak gels rheologically. Storage modulus of the mixed system increased with increasing refrigerated storage. It is possible that for a gelatinized starch paste, the swollen gelatinized starch granules, consisted mainly of amylopectin, are embedded in the continuous matrix, consisted mainly of amylose. Reordering of amylopectin during storage reinforces the interpenetrating amylose gel matrix due to increase in the rigidity of the granules, which results in an increase in storage modulus.