Jamieson, Fausset and Brown on Genesis 27:4

4. make ... savory meat--perhaps to revive and strengthen him for the duty; or rather, "as eating and drinking" were used on all religious occasions, he could not convey the right, till he had eaten of the meat provided for the purpose by him who was to receive the blessing [Adam Clarke] (compare Ge 18:7).

that my soul may bless thee--It is difficult to imagine him ignorant of the divine purpose (compare Ge 25:23). But natural affection, prevailing through age and infirmity, prompted him to entail the honors and powers of the birthright on his elder son; and perhaps he was not aware of what Esau had done (Ge 25:34).