Zinc in the food chain - its biological importance. Part Two: Zinc in vegetable foodstuffs

摘要

On average, starch- and sugar-rich foodstuffs are poor in zinc (1 mg Zn/kg DM in maize starch, 3 mg Zn/kg DM in honey). Flour and other farinaceous products, cake, rolls and bread supply 6 to 18 mg Zn/kg DM; pearl barley, oat flakes and pulses contain 20 to 40 mg Zn/kg DM. Cereals, flour and pastry made from ecologically farmed grain contain more zinc than those made from conventionally farmed grain. Cereals not milled to a high extraction rate contain higher shares of bran, which contributes higher zinc contents. Ecologically produced brown cane sugar supplies more zinc than conventional beet sugar. Spices and herbs are rich in zinc, but without importance for the zinc supply. Ecologically grown herbs, fruits and vegetables contain a quarter less zinc than their conventionally grown counterparts. The phosphate fertilisation applied in conventional farming adds zinc to the soil, whereas long-time ecological farming depletes the zinc. Generally, vegetables are rich in zinc. Potatoes, cabbage, carrots, kale, kohlrabi and onions deliver 18 to 30 mg Zn/kg DM, pulses and radish 30 to 50, and lettuce, cauliflower, cucumber, spinach and especially asparagus 50 to 100 mg Zn/kg DM.