The Gemoro discusses a case (36a, 9 lines up till 3 lines up) of food Hekdesh Bein Hashemoshos, and differentiates between prior Kedusha that remains and new Kedusha starting to apply.
Why does the Gemoro not mention that point that we require the food to be edible before Shabbos (Seuda HaReuya mib'od yom), which is not the case if it is already Hekdesh. [In fact this is the point discussed in the case before this and in the case afterwards!]
Meir Eliezer Bergman
Bear in mind that Rava, who asked the two She'eilos, does not require 'Se'udah ha'Re'uyah mi'be'Od Yom', as is clear from the next case (which you yourself quoted), where Rava says 'I Techilas ha'Yom Koneh Eiruv ... '?, and Rav Papa refutes his proof with 'Se'udah ha'Re'uyah mi'be'Od Yom'. We only need to add that Rav Nachman, his Rebbe, does not require it either, since he does not cite it as the reason for saying 'Ein Eiruvo Eiruv' in the second case.
Unless we say that Rav Nachman could have answered that, but he preferred to answer Rava according to his (Rava's) reasoning, to explain his ruling even if one does not hold of 'Se'udah ha'Re'uyah mi'be'Od Yom'.
be'Virchas Kol Tuv