Physicochemical properties of water caltrop and starches from different varieties and development stages

Abstract

This study is undertaken to investigate the effect of variety and reproduction stage from two water caltrop genuses on the chemical composition and physicochemical properties of starch. The two water caltrop genuses are Trapa. Taiwanensis Nakai and Trapa. Quadrispinosa Roxb.. The physicochemical properties of starch include the appearance of starch granule using Scanning Electron Microscope (SEM), the distribution of starch granule diameter using Mastersizer, the crystalline strength and morphology using X-ray Diffraction Meter, the range of gelatinized temperature and enthalpy using Differential Scanning Calorimeter (DSC), the pasting property of gelatinized starch using Rapid Visco-Analyser (RVA). Hope to compare that water caltrop process and to establish the functional characteristics of the isolated starches from water caltrop at different growth times. The results showed dry matter content, total starch content, pectin substance, phosphorous, amylase activity and amylose content increased during growth of 7 to 42 days. In the morphological properties of starch, all water caltrop starch granules showed round to oval shape and some particles appeared the polyangular shape. The size of isolated starch granules was increased with the extent of growth time at period of 7-42 days in two water caltrop varieties. The range was between 15-32 μm. The particle values of D(V, 0.1), D(V, 0.5), D(V, 0.9), D(4, 3) and D(3, 2) increased during growth 7 to 42 days. The profiles of two cultivars of water caltrop starches showed typical A-type X-ray pattern, and the peak intensity of X-ray diffraction patterns increased slightly during maturity. The onset, peak, conclusive temperatures and enthalpy of gelatinization of starch gelatinization increased with the increase of growth time, but the range of gelatinization appear the decrease tendency during the growth time extension. The temperature range of gelatinization of water caltrop starches were about between 69OC to 78OC. The gel of water caltrop starches belonged to soft gel according to the analysis of gel consistency. As the increase of growth time, pasting temperature, peak viscosity, final viscosity and breakdown were increased, but viscosity after 95OC holding and setback no significantly tendency in two cultivars of water caltrop starches.

本實驗以二角菱角（Trapa. Taiwanensis Nakai）及四角菱角（Trapa. Quadrispinosa Roxb.）為材料，探討品種、生育期對其化學組成、生長物性因子、酵素活性及澱粉理化性質之影響，利用掃描式電子顯微鏡（sanning electron microscope, SEM）觀察澱粉顆粒外觀，雷射粒徑分析儀測定澱粉顆粒粒徑分布，X-射線繞射分析儀分析澱粉顆粒結晶強度，示差掃描熱分析儀（differential scanning calorimeter, DSC）測定糊化溫度及糊化熱焓值，快速黏度分析儀（rapid visco-analyser, RVA）測定澱粉成糊特性，以期作為菱角加工利用之參考。 實驗結果顯示，兩種品種菱角隨種植時間的延長（7-42天），菱角的乾物重、澱粉、果膠物質、磷與直鏈澱粉含量會有增加趨勢，而澱粉酶、澱粉液化酶與澱粉醣化酶活性會在第35天時達最高值。在生長物性因子方面，菱角果仁重量、體積及總體積密度（bulk density）都會隨生長天數的延長而呈現上升之趨勢，其總體積密度會由0.58 g/ml上升至1.16 g/ml。菱角澱粉的顆粒呈現圓形、卵圓形或多邊形，具光滑的表面。隨著生育期的增加，兩種品種菱角澱粉顆粒均呈現增加的趨勢，大小約介於15~32 µm 之間，由雷射粒徑分布儀所求得之D（V, 0.1）、D（V, 0.5）、D（V, 0.9）、D（4,3）、D（3,2）等粒徑數值都隨生育天數的增加而上升。菱角澱粉的結晶型態均為A-type結晶，且結晶強度會隨生長天數的增加而有逐漸增強之現象。兩種品種的菱角澱粉糊化初溫（onset temperature, TO）、糊化峰溫（peak temperature, TP）、糊化末溫（conclusive temperature, TC）及糊化熱（heat of gelatinization, ΔH）均會隨生長天數的延長，而呈現上升之趨勢，但糊化範圍（gelatinization range）則呈現逐漸下降的趨勢，菱角澱粉糊化範圍約在69℃~78℃之間。二角菱與四角菱澱粉成糊性質之糊化溫度（pasting temperature）、尖峰黏度（peak viscosity）、終點黏度（final viscosity）及黏度裂解值（breakdown）均會隨之增加，但95℃下維持黏度與黏度回升值（setback）則沒有明顯變化之趨勢。由統計分析結果顯示，生育天數之不同對澱粉理化性質影響較明顯，品種間的差異則不顯著。