Romera G F, Zuleta A, Sarchi M I, Sambucetti M E
Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Buenos Aires, Argentina.
Arch Latinoam Nutr. 2000 Sep;50(3):265-9.
Cereals are rich in fiber but also in phytate which is considered the principal inhibitor of mineral availability. On this basis, iron availability of fortified rice, and the inhibitory effect of bran phytate was studied in: white rice fortified with electrolytic iron (ABF) from commercial origin; and mixtures of ABF plus 4.76% and 9.09% of rice bran (ABF2 and ABF3 respectively) to simulate brown rice. Samples were analysed before and after phytic acid hydrolysis with phytase: Dietary fiber and phytic acid were assessed according AOAC; iron availability, expressed as dialisable iron by the in vitro method of Kapsokefalou and Miller modified by Valencia et al.; iron content was assessed by AAS. Results showed that added bran depressed iron availability, 9.65%; 4.04% and 1.82% as expected (ABF, ABF2 and ABF3 respectively). After phytic acid hydrolysis iron availability reached 28.20%; 27.95% and 25.30% for the same samples. These values were not different. After phytic acid hydrolysis, fiber content of ABF2 and ABF3 were lower than before. However multiple regression analysis of the data showed that fiber had not influence on iron availability and that phytic acid would be the principal responsible of it. These results indicate that brown rice should have a higher level of iron fortification than in white rice or be combined with other foods that improve iron availability as meats, vegetables or fruits.
谷物富含纤维，但也含有植酸盐，而植酸盐被认为是矿物质可利用性的主要抑制剂。在此基础上，对强化米的铁可利用性以及米糠植酸盐的抑制作用进行了研究：从商业来源获得的用电解铁强化的白米（ABF）；以及ABF分别与4.76%和9.09%的米糠混合（分别为ABF2和ABF3）以模拟糙米。在用植酸酶进行植酸水解前后对样品进行分析：膳食纤维和植酸根据美国官方分析化学师协会（AOAC）的方法进行评估；铁的可利用性通过由巴伦西亚等人修改的卡普索凯法洛和米勒的体外方法表示为可透析铁；铁含量通过原子吸收光谱法（AAS）进行评估。结果表明，添加米糠会降低铁的可利用性，如预期的那样分别为9.65%、4.04%和1.82%（分别为ABF、ABF2和ABF3）。植酸水解后，相同样品的铁可利用性分别达到28.20%、27.95%和25.30%。这些值没有差异。植酸水解后，ABF2和ABF3的纤维含量低于水解前。然而，对数据的多元回归分析表明，纤维对铁的可利用性没有影响，而植酸是其主要原因。这些结果表明，糙米的铁强化水平应高于白米，或者应与其他能提高铁可利用性的食物如肉类、蔬菜或水果搭配食用。
