yolk       
noun [ C or U ] uk/jəʊk/ us/joʊk/
 蛋黄
the yellow, middle part of an egg
  I like eggs lightly cooked so that the yolk is still runny. 我喜欢煮得嫩些的鸡蛋,这样蛋黄还是溏心的。 
 Separate the yolks from the whites. 将蛋黄从蛋清中分离出来。 
 See also: egg yolk
Compare: egg white