金银花贮藏过程中的美拉德反应

Research on Maillard Reaction during Storage of Lonicerae japonicae Flos

为了探索金银花贮藏过程中的变色机理,为合理贮藏提供理论依据,在45、55、65、75℃条件下进行加速货架测试试验,用色差仪测定金银花贮藏过程中的颜色参数,紫外可见分光光度计测定游离氨基酸、还原糖等成分含量,HPLC法测定5-羟甲基糠醛(5-HMF)含量,并对所得数据进行统计分析。结果表明,随贮藏时间延长和温度升高,金银花暗度值和色差值增加,褐变指数增大,提示金银花在贮藏过程中发生褐变生成了有色物质;金银花提取液A420nm值稳定上升,说明褐变生成的有色物质为类黑素;氨基酸和还原糖含量随贮藏时间延长逐渐降低,且水提液p H值在贮藏过程中显著下降,说明氨基酸和还原糖可能为褐变的初始反应物;5-HMF不断积累,且温度每升高10℃,褐变反应加快3~5倍,说明5-HMF可能为褐变反应的中间产物,5-HMF生成量和褐变速度密切相关。金银花贮藏过程中颜色参数、氨基酸、还原糖、p H值、A420nm值及5-HMF的动态变化,说明发生了美拉德反应,这是发生褐变的机理之一。

To explore the color-changing mechanism of Lonicerae japonicae Flos during storage and provide theoretical bases for its reasonable storage,the mechanism of maillard reaction was studied with colorimeter measuring the color changes,UV-Vis detecting the contents of amino acid and reducing sugar,high performance liquid chromatography（ HPLC） determining the content of 5-HMF during storage under the condition of 45,55,65,75℃ by accelerated shelf life testing（ ASLT） method,and the obtained data were analyzed. The results showed that the dark degree value,color difference value and the browning index of Lonicerea japonicae Flos increased with the storage time prolonging and the temperature rising,which showed that browning reaction occurred in the process of storage and non-ferrous material was produced. The A420 nmvalue of Lonicerea japonicae Flos extracts rose stably,which showed that the non-ferrous material was class melanin. With the storage time extension,the contents of amino acid and reducing sugar reduced,and the p H value of aqueous solution decreased significantly,which showed that amino acid and reducing sugar might be the initial reactants of Lonicerea japonicae Flos during browning reaction. The content of 5-HMF was gradually accumulated,and the browning reaction sped up 3 - 5 times with every increase of 10℃. It showed that 5-HMF might be the intermediate product of browning reaction,and the generation of 5-HMF and browningrate was closely related. We could confirm that maillard reaction happened in the process of storage of Lonicerea japonicae Flos through dynamic changes of the color parameters,the contents of amino acid and reducing sugar,p H value,A420 nmand 5-HMF,which was the mechanism of browning reaction.