富硒大蒜和洋葱中功能性硒化合物的稳定性研究

Studies on the stabilities of bioactive selenocompounds in selenium-enriched garlic and onion

本研究设计了几个实验 ,研究富硒大蒜和洋葱中水溶性含硒化合物的稳定性。结果发现 :冷冻干燥加工能保持富硒大蒜中含硒化合物化学性质 ,富硒大蒜室温水提液中Se 甲基 硒半胱氨酸不稳定 ,蒜氨酸酶专一抑制剂盐酸羟胺能有效抑制该含硒化合物丢失 ,提示Se 甲基 硒代半胱氨酸的分解反应可能主要受蒜氨酸酶催化。富硒洋葱中同样含有蒜氨酸酶 ,但其室温水提液中Se 甲基 硒半胱氨酸却能稳定存在。Se 甲基 硒半胱氨酸是富硒大蒜一种主要功能硒组分 ,加工储存过程中应避免它损失 ,以保障富硒大蒜医学功能的发挥。富硒大蒜和洋葱含硒化合物的稳定性差异、分解机理以及分解产物活性等均有待于进一步的研究。

It is reported that selenium (Se) incorporation into garlic increases the bioactivities of garlic. Hence, the chemical changes of selenocompounds during processing and storage will influence the bioactive effectiveness of Se-enriched garlic. The principal selenocompounds in Se-enriched garlic are water-soluble,and several comparative experiments are thus conducted to examine the stabilities of the selenocompounds in water extracts of Se-enriched garlic and Se-enriched onion. The results show that preparing the garlic powder by freeze-drying technique can maintain the chemical properties of the selenium compounds in Se-enriched garlic. Se-methyl-selenocysteine is unstable in water extract of Se-enriched garlic when the extract is prepared and stored at room temperature. Specific alliinase inhibitor hydroxylamine (NHOH·HCl) effectively prevents the loss of Se-methyl-selenocysteine, which suggests that the decomposition of Se-methyl-selenocysteine may be catalyzed by alliinase. Se-methyl-selenocysteine is one of the main bioactive selenocompounds in Se-enriched garlic. The procedures of processing and storage should be carefully chosen to prevent the loss of selenocompounds and the decrease of the bioactivity of Se-enriched garlic. Se-enriched onion also contains alliinase and Se-methyl-selenocysteine, but its Se-methyl-selenocysteine is proved to be stable in the same water extract as that of Se-enriched garlic. The stability differences of Se-methyl-selenocysteine in Se-enriched garlic and onion, the mechanism of selenocompound decomposition and the bioactivities of decomposed compounds in Se-enriched garlic need to be further studied.