| Cocoa beans are the raw material of chocolate, and also the important flavoring in varieties of food. Alkalization should be used in the cocoa product processes to meet the different desire of customer, which can modify the color and flavor of cocoa powder. The main study of this paper is aiming at finding the trend of cocoa color change and the alkalized conditions, and collects hundreds of statistics to establish the model of the alkalization for cocoa manufacture and analyzing the color and the flavor of the alkalized cocoa powder.Firstly, we find the relationship between the color of cocoa powder with darker after alkalized in different conditions (pressure, lye, time). The result showed that alkalizing the cocoa nibs under pressure was easy to get the darker color, and the△E value increased from 2.83 at 100℃to 6.64 at 0.06Mpa. On this bases, we establied the model with more than 100 samples could predict relatively well. This model can predicted well between the relationship of alkalized conditions and the alkalized cocoa powder.Then, we analyzed the compounds influenced cocoa color: anthocyanin and total polyphenols. The results showed that the content of anthocyanin decreased with the stronger degree of alkalization, because this compound become other red and brown polymers though complexion, and after heavy alkalization the of cocoa powder F3/ F1incresed from 3.29 to 6.66. Also the content of catechins, tannins and total polyphenols decreased after alkalization though the complexion and polymerization with protein, polysaccharide.Also, using GC-MS,GC-Oand HPLC, we analyzed the volatile flavor compounds , the aroma compounds and non-volatile flavor compounds. The results showed that the flavor of the light degree alkalized cocoa powder increased a lot, however, the heavy alkalized cocoa powder showed much off-flavor. Methylxanthin, the most important bitterness compounds in cocoa powder also changed with different alkalized conditions, and it increasd after alkalization. However, the caffein decreased after alkalization. Adding sugar to the alkalized process, the cocoa powder changed a lot compared to the normal alkalized cocoa powder in color and flavor. The value of F2/ F1 is 2.18, and incresed one more times. At the same time, the F2/F3and a/b increased to 0.39 and 1.33,respectively, which showed the unique brown-red. And also the flavor of this powder blessed with the cream and fruit aroma. |
