Stady on pigemnt stabilities and degradation kinetics of adzuki bean

Abstract

Adzuki bean is bright red, smooth surfaced and unique flavored, which is popular with consumers. It's often the used to make desserts, baking ingredients, cold food…etc. Many factors affect quality the processes of adzuki food products, where color is one of the factors to influence the quality factor. In the study, the No.6 adzuki bean of Pin-tong is used as the raw materials, investigating the changes in color cooking of adzuki bean. The various solvents were employed to extract anthocyanin, to idenlify the isolation and purification of adzuki bean peel anthocyanin, conferring to the stability of the adzuki beans during different processes. Adzuki beans were heated at various temperatures to determine the kinetic parameter. Different concentration of sucrose, vitamin C and amino acid in model system were to investigate their influences on the color quality and anthocyanin patterns of adzuki beans, hoping to establish related information, to provide related research and product deullopment, to be made as references for improving the quality. The results were as follows. During the cooking process of whole adzuki beans, seed coat and cotyledon, the heating temperature and time showed influences on the pigment reveals the influence. The pigment mainly come from adzuki bean seed coat, pigment loss in adzuki bean peel steadily increases with the increases of heating temperature and time, which to influence quality of products. During heating, the pigment production Millard reaction its bright red color. The various solvent extracted adzuki bean anthocyanin and methanol containing 0.1% HCl showed the highest extract. Effect of pH values on absorbance in adzuki bean anthocyanin, which pH 1.0 was the most absorbance. The Fe2+ reacted with anthocyanin to produce with hyperchromic effects, which favored the stability of pigment. Heating temperature increase, there is a loss of solids in the product anthocyanin, causing the anthocyanin to degrade. The activation energies (Ea) were 33.44 kJ mol_1 at 60~90℃, and 56.12 kJ mol_1 at 100~121℃. Heating the pH 3.0 model system at 100℃ concentrations of 10% sucrose hyperchromic effects, favoring the heat stability of pigment, while vitamin C did not show hypercheromic effect, which was not biracial to the heat stability of pigment. Monomeric ACN increased before heating and polymeric increased after heating, due to the presence of sucrose or vitamin C. Monomeric ACN was found to the highest with the addition of 10% sucrose. Heating the pH 3.0 model system at 100℃, the DI is the highest, after adding lysine and sucrose, and Monomeric ACN increased before heating and polymeric increased after heating.

紅豆（adzuki bean）其表面呈現亮麗紅色、平滑特性及特殊豆香味，深受東亞國家消費者喜愛，經常被製成甜點、糕點、餡料及冰品等，色澤常是成品品質判定因子之一。本研究利用紅豆（屏東6號）為材料，探討烹煮過程中色澤變化，再利用不同溶劑萃取紅豆色素萃取並進行花青素分離及純化，另探討不同加工處理對紅豆花青素之安定性。紅豆花青素熱降解動力學及探討模擬系統中探討添加不同濃度蔗糖、維生素C和胺基酸對紅豆花青素顏色品質及聚合型態之影響，期待能建立相關資訊，提供相關研究及產品研發，品質改進之參考。結果顯示如下： 以整粒紅豆、種皮及子葉進行烹煮實驗時，烹煮溫度及時間對紅豆色素有顯著影響，紅豆色素主要來自種皮，種皮之色素隨著加熱溫度及時間增加而溶出愈多；子葉則呈現破損、組織崩裂；另在加熱過程中湯汁會因梅納反應而呈現褐紅色，而影響製品品質及外觀。以不同溶劑萃取紅豆花青素，實驗中以酸性甲醇萃取率為最佳，其次酸性乙醇，以去離子水之萃取率最差。在花青素安定性方面，隨著pH值提高吸光值有下降趨勢；以pH 3.0裂解指數（DI）最低呈現較佳之穩定性；添加鐵離子會與花青素產生向紅效應（hyperchromic effect）具有促進花青素顏色保存。在熱裂解動力學方面，花青素會因高溫影響致使產品產生濃縮效應，其固形物溶出，造成花青素降解，在60~90℃部分活化能為33.44 KJmol-1，在100~ 121℃部分活化能為56.12 KJmol-1。在紅豆色素安定性模擬系統方面，發現添加10%蔗糖濃度具有濃色效應（bathochromic effect），可減少熱裂解之作用亦有減緩色素降解效果；而添加維生素C保色效果並不明顯，且隨著添加濃度愈高而有熱降解的作用，兩者在加熱前花青素單體（monomeric ACN）較多，加熱後花青素聚合體（polymeric ACN）會增加，其中花青素單體（monomeric ACN）以添加10%蔗糖為最高。添加不同胺基酸方面，離胺酸（lysine）與糖於紅豆花青素模擬系統中花青素降解指數（DI）值較高，褐變較高，兩者在加熱前花青素單體（monomeric ACN）較多，加熱後花青素聚合體（polymeric ACN）會增加。