doing的问题.the iron content of tomato sauce cooked in an iron

doing的问题.
the iron content of tomato sauce cooked in an iron pot for three hours showed a striking increase,the level going up nearly 30 times.
going up ,是什么用法,为什么要ing呢,我知道该句子谓语是showed,实在不明白going是什么用法
还有，coffee can interfere with iron being absorbed into the body.
这个being 又当如何理解呢。