The fruits should be treated with lemon juice when sliced to prevent oxidation.
A lemon is being squeezed over the fruit.
sentence one just says that the fruit should be treated with lemon juice but doesn't say that the lemon is being squeezed over the fruit.
exists e1 p1 x1.(n_fruit(x1) & exists e2 e3 p2 x2 x3.(when(e2,e3) & Recipient(e3,p2) & Topic(e3,x1) & v_slice(e3) & exists e4 x4.(Theme(e4,x4) & Actor(e4,x1) & v_prevent(e4) & n_oxidation(x4)) & with(e2,x2) & n_juice(x2) & of(x2,x3) & n_lemon(x3) & Theme(e2,x1) & v_treat(e2)) & Topic(e1,p1) & Actor(e1,x1) & v_should(e1))
exists e1 x1 x2.(n_fruit(x2) & over(e1,x2) & Theme(e1,x1) & v_squeeze(e1) & n_lemon(x1))