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Preparation of Hydrolysates from Tuber of Yam (Dioscorea alata L.)
|摘要:||The tuber of yam contains sufficient of amino acid, proteins, mucin, allantoin, choline, fiber, vitamin A, B1, B2, C, and Ca, P, Fe, I, and etc. It is a good nutrient source for human being. Protein hydrolysates is a product from chemical or enzymatic hydrolytic reaction as macro protein molecular are hydrolyzed to an increasing degree, they form aggregates with lower average molecular weights, including proteoses, peptones, peptide, amino acid mixtures, and free amino acid mixture. From a nutritional point of view, the demand for protein or more amino acid can be fulfilled equally well either by intake of free amino acid, protein hydrolysates, or by intact protein assuming the bioavailability is the same. The objective of this investigation was to study the production and composition of hydrolysates from tuber of yam (Dioscorea alata L.) using hydrochloric acid. The characteristics of the yam hydrolysates were examined including, total nitrogen (TN%), formol nitrogen (FN%), degree of hydrolysis (DH%), dextrose equivalent (DE%), analysis of amino acid compositions, the amount of soluble solid, reducing sugar, total sugar, and salt content. Besides, the color and sensory evaluation analysis were investigated.
Results showed that as the acid concentration and hydrolysis time were increased, FN% and DH% of the hydrolysates were increased, and color became darker. Amino acid compositions of the yam hydrolysates were mainly glutamic acid (Glu) and aspartic acid (Asp) which contribute to its flavor attribute. When acid concentration was increased, the soluble solid and salt content were also increased, but the hydrolysis time and acid concentration were not significantly affected by TN%. When acid concentration and hydrolysis time increased, reducing sugar, total sugar, and DE% of the hydrolysates were decreased, which explain that in the presence of sugar and protein in yam tuber, Maillard reaction and caramelization reaction did occur. Sugar in the hydrolysate was also affected by acid and heat. Because the sugar was used for Maillard reaction, the DE% value cannot mean the true status. When acid concentration, hydrolysis time, and pH of the hydralysate were increased, the hydrolysates color was even darker. Results of the sensory experiment showed that the hydrolysates of the yam tuber is a promising ingredient for addition in sport drinks.
In conclusion, the higher acid concentration and longer hydrolysis time demonstrated efficient hydrolysis to obtain small molecular yam tuber hydrolysates. In the future, the yam hydrolysates will be used as a functional food, additive for designing new formulation in soft drink products. In the mean that, sure this product can be commercialized and its overall acceptability could be even higher.|
山藥塊莖含多種必需胺基酸、蛋白質及澱粉，另具有黏液質(mucin)、尿囊素(allantoin)、膽鹼(choline)、纖維素、維生素A、B1、B2、C、及鈣、磷、鐵、碘等礦物質，可提供人體多種必需的營養。蛋白質水解物，是蛋白質經化學或酵素之水解作用所製得之產品。巨大的蛋白質分子，經不同程度之水解作用會形成不同長度之分子。完整之蛋白質分子不似小分子的三或雙容易有效及快速地為人體所吸收，因此蛋白質需經水解成後才能提高其利用率。本實驗即利用化學方式水解山藥(Dioscorea alata L.)，並探討在不同水解條件下，所得山藥水解液之總氮含量、甲醛態氮含量、蛋白質水解率、胺基酸成分分析、可溶性固形物含量、還原醣含量、總醣含量、葡萄糖當量、氯化鈉含量及顏色之變化，並取適當之水解液進行官能品評。 結果顯示，山藥水解液隨著添加鹽酸濃度越高及加熱水解時間越長，所得之甲醛態氮含量及蛋白質水解率明顯隨之增加，且水解液之顏色也越深。水解液中胺基酸含量以以麩胺酸(Glu)及天門冬胺酸(Asp)最多，表示山藥水解液之呈味具有明顯之鮮味。可溶性固形物含量及氯化鈉含量隨著添加鹽酸濃度越高，其值明顯增加，但其不會隨著加熱水解時間增長而出現明顯變化。而添加鹽酸濃度及加熱水解時間對水解液之總氮含量，並無顯著的影響。由於山藥中同時存在醣類與蛋白質，所以會產生梅納反應，使水解液中醣類之變化受到影響。在強酸(4.8N)反應下，山藥漿中經酸分解所產生之還原醣會與胺基酸及蛋白質作用進行梅納反應，使得系統中之還原醣大量消耗，故所測得之DE%明顯下降。另外，水解液中因高溫及pH值變化會產生焦糖化反應。山藥汁去除山藥澱粉進行水解時，會使水解液中總氮含量、還原醣、總醣量、葡萄糖當量、可溶性固形物、鹽度及顏色之值明顯低於含山藥澱粉進行水解者。根據官能品評之結果，山藥水解液為新開發之產品，在顏色、風味、鮮味、甜味及苦味方面等，尚無法找到適當之比較品，但可經進一步改良而使其具有發展性。 由實驗結果可知，山藥汁經高鹽酸濃度及較長時間加熱水解後，所得之水解液中小分子物質(胺基酸、醣類等)含量較多，表示水解能力越佳。若要將水解液開發成具有市場性之產品，需依商品訴求目的不同而添加或降低其他物質進一步調味，以符合市場需求。
|Appears in Collections:||食品暨應用生物科技學系|
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