Which is a greater sin - to eat meat on Good Friday or to spoil it I'd cooked 4 meals on Wednesday and left two for today, failing to take into account the fast. I'm not sure whether the meals will be safe to eat tomorrow. Which would be a greater sin - to eat them, or to let them become spoiled?
Regarding whether the Church can impose fasting as a matter of precept, St. Thomas Aquinas writes (Summa Theologica II-II q. 147 a. 3 ad 2):


  It will be a mortal sin to disobey a commandment through contempt of the lawgiver's authority, or to disobey it in such a way as to frustrate the end intended by him: but it is not a mortal sin if one fails to keep a commandment, when there is a reasonable motive, and especially if the lawgiver would not insist on its observance if he were present. Hence it is that not all, who do not keep the fasts of the Church, sin mortally.


If there is no way (which is very unlikely) to preserve the food (e.g., by refrigerating, canning, fermenting, salting, etc.) or feed it to animals—and since letting food go to waste would be a sin of wastefulness, which is against justice—it may be a "reasonable motive" to consume it immediately.