氮稳定同位素的印迹规律与有机食品鉴别

SIGNATURES OF NITROGEN STABLE ISOTOPE AND DETERMINATION OFORGANIC FOOD AUTHENTICATION

有机生产中禁止使用化肥,肥料是有机食品认证中监管的农业投入品之一。不同来源的氮肥中稳定同位素1δ5N的丰度不同,由此农产品中δ15N的丰度也存在差异;有机肥种植的农产品中1δ5N丰度最高,不施肥种植的次之,而化学氮肥种植的则最低。施肥方式、作物类别、生长阶段和部位对农产品中1δ5N丰度的影响不一样,一般对于生长期较短的蔬菜适合用δ15N丰度标记其氮肥来源,对于生长期较长或具有固氮作用的作物则不适合。采用氮稳定同位素1δ5N丰度检测来标记作物的氮肥来源,对有机食品的真伪鉴别,质量监督体系的完善和消费者的权益保护具有积极的法规理论探讨价值和实际应用价值。

Chemical fertilizers were not permitted to be applied in organic agricultural production, so fertilizer as one of agricultural inputs is an important regulatory aspect in the organic food accreditation. Natural stable isotope abundances δ^15N from different nitrogenous fertilizers are different, the same as in the agricultural products. Natural abundances δ^15N in the agricultural products using organic fertilizer is higher than those in the products without using any fertilizer, while it is the lowest in the products using chemical nitrogenous fertilizer. Natural abundances δ^15N are also affected by the ways of fertilizer treatment, the types of the crops and the growth stages as well as the different parts of crops. Generally, natural abundances of δ^15N are preferred to trace nitrogenous fertilizer for the vegetables with shorter growing period, but not for the crops with longer growing period or nitrogen fixation. The techniques to trace the nitrogen abundances of δ^15N in the crops play a positive role, which is useful for the determination of organic food authentication, perfecting the system of quality and supervision and protecting public health, therefore it has a theoretical and applied value.