基于体外全仿生消化模型分析海带和紫菜中微量元素的生物可给性

Bioaccessibility of Trace Metals in Laminaria japonica and Porphyra yezoensis Using in Vitro Digestion Model

探究海带和紫菜中6种必需元素(Cu、Fe、Mn、Zn、Co和V)与5种有害元素(As、Cd、Pb、Al和Sr)的生物可给性及胃、肠消化过程中As、Cd等有害元素的形态转化,分析加工过程对样品中元素含量、形态及生物可给性的影响,结果表明:紫菜对除Sr外10种元素的富集能力均显著高于海带,经加工,海带和紫菜中6种人体必需微量元素含量均下降;紫菜中必需元素的生物可给性高于海带,加工后海带中不同元素的生物可给性变化不同,海带和紫菜中Zn的生物可给性最低。紫菜中As、Cd、Pb、Al的含量显著高于海带,且加工后均显著下降。海带和紫菜中Pb的生物可给性最低,分别为6.7%和21.4%。Cd、As、Al、Sr的生物可给性较高,为57.3%~90.6%,且加工前、后变化较小。在胃、肠消化液的作用下,海带和紫菜样品中As的形态发生显著变化,部分形态的有机砷在消化过程中可能转化成无机砷。煮熟加工不会改变样品及其仿生消化液中As的形态,总As含量的降低主要表现在大分子有机砷的糖含量降低。煮熟能显著降低紫菜样品及其仿生消化液中无机离子态Cd2+的浓度。本研究结果对于科学评估海带和紫菜中必需微量元素的营养价值和有害元素的食用风险提供重要依据。

In vitro digestion model was used to detect the bioaccessibility of 6 essential trace metals(including Cu,Fe,Mn,Zn,Co and V)and 5 harmful trace metals(including As,Cd,Pb,Al and Sr)in fresh and cooked seaweed(Porphyra yezoensis and Laminaria japonica),with microwave digestion and inductively coupled plasma-mass spectrometry(ICP-MS)for measurement of total content of trace metals in the samples and residue,and the high-performance liquid chromatography coupled to inductively coupled plasma-mass spectrometry(HPLC-ICP-MS)for measurement of As and Cd species in the samples and chime.Results showed that 6 essential trace metals in two kinds of seaweed decreased after cooking,and their bioaccessibility in P.yezoensis were higher than in L.japonica.In addition,different trace metals exhibited different changes in the bioaccessibility for cooked L.japonica,with the highest bioaccessibility of Sr and the lowest bioaccessibility of Fe and Zn.The total content of As,Cd,Pb and Al in P.yezoensis was higher than that in L.japonica,and all of them decreased after the seaweed were cooked.Pb bioaccessibility in both cooked L.japonica and P.yezoensis were lowest(6.7%and 21.4%respectively),while the bioaccessibility of Cd,As and Al was 77.4%,82.1%and 57.8%respectively for L.japonica and was 74.6%,71.7%and 67.5%respectively for P.yezoensis.A significant difference in the arsenic species in seaweed occurred during the gastrointestinal digestion,and some organic arsenic species may be transformed to be inorganic arsenic.Cooking would not change the As species in the seaweeds and the gastrointestinal juices,and the decreasing of total arsenic for the cooked seaweed may mainly include the dissolved organic arsenic.Content free inorganic cadmium Cd2+in the fresh P.yezoensis and gastrointestinal juices could be significantly decreased after cooking.No matter for the fresh or cooked samples and gastrointestinal juices,no Cd2+could be found in L.japonica.Present results may provide important information on the evaluation of nutritional value of essential trace metals and risk assessment of toxic trace metals in seaweed.