When making wholemeal bread is it advisable to maybe add a little sweetener for the yeast like black treacle/molasses or honey to aid the rising ?
All of those are added for taste, only. They should be added to the dough and not to the yeast proofing (if you do that) where you add a little water to dry yeast and wait for it to get bubbly to prove it is active. These days it is unnecessary to do that with Instant yeast unless it was stored in warm conditions or is very far past its expiration date.
If your wholemeal loafs are turning out dense there are other reasons for that.
Maybe at your house, those sugars are only added for the taste, but if they are there, the yeast will feed on them and the bread will have both a different taste and texture. The addition of a little sugar also causes the loaf to turn out softer in both crust and crumb. Not only that, but the crust will brown more quickly as well. At my house, the bread does rise more quickly when sugar is added to the dough.
I do agree that if the wholemeal loaf is turning out dense, there are other reasons, usually poor gluten development or under-hydration (wholemeal flours do need more water). But technically, adding a little sugar does make a difference as well. It's just that it may not be enough on its own.
sweetener of some kind to whole meal breads to counteract the bitterness imparted by the hard bits of the whole meal. .
Since wheat flour is deficient in the enzyme diastase, diastatic malt is often added to convert starch into maltose (malt sugar). The yeast and other microorganisms then feed upon the maltose. While bread flour and AP flour is almost always contains diastatic malt, whole wheat flour usually does not. In order to get a good rise out of whole wheat dough, either malt or sugar should be added to the dough. Yeast will feed upon most sugars, with the exception of lactose (milk sugar).
Thanks for the advice everyone