What are the criteria of foods that God commands us to judge prior to eating? 

 

Verses 172-173 of Chapter 2
O ye who believe! Eat of the good things that We have provided for you, and be grateful to Allah, if it is Him ye worship. He hath only forbidden you dead meat, and blood, and the flesh of swine, and that on which any other name hath been invoked besides that of Allah. But if one is forced by necessity, without wilful disobedience, nor transgressing due limits,- then is he guiltless. For Allah is Oft-forgiving Most Merciful.

Verses 3-4 of Chapter 5

You are forbidden carrion and blood, the flesh of swine and of that animal which has been slaughtered in any other name than that of Allah, and of the strangled animal, and of that beaten to death or killed by a fall or gored to death or mangled by a beast of prey -save of that you duly slaughtered while it was still alive and of that which is slaughtered at (un-godly) shrines. It is also unlawful for you to try to find your fortune by means of divining devices, for all these things are sinful acts, Today the disbelievers have despaired of (vanquishing) your religion; therefore do not fear them but fear Me. Today I have perfected your religion for you and completed My blessing on you and approved Islam as the way of life for you, (Therefore observe the limits prescribed by the Law); if, however, one, dying of hunger, eats of any of these forbidden things, provided that he is not inclined towards sin, he will find Allah Forgiving and Compassionate. They ask you what has been made lawful for them. Say, "All the good and pure things have been made lawful for you. You may also eat of what the hunting animals, which you have trained to hunt in accordance with the knowledge Allah has given you, catch and hold for you, you should, however, mention Allah's name over it, and fear to violate the Law of Allah. for Allah is swift at reckoning."