Why Christ offer his blood and flesh, when in fact was offering food?

It was symbolic

Jesus breaking bread: "Take eat, this is my body which is given unto you" 

Jesus pouring wine: "Take, drink, this is my blood which is shed for you" 

Jesus opening a jar of mayonnaise: "Take, swallow, this is..." 

Judas: "Okay stop there!" 

Why DID Christ offer his blood and flesh [no comma] when in fact HE was offering food?

Read it again.  You missed a few things.

When instituting the Memorial, Jesus did not miraculously change the bread and the wine into his literal flesh and blood. Instead, he said of the bread: “This means my body.” Regarding the wine, he stated: “This means my ‘blood of the covenant,’ which is to be poured out in behalf of many.” (Mark 14:22-24) Clearly, then, the bread and the wine were to be viewed as symbols, or emblems.

On that highly important occasion in 33 C.E., Jesus used unleavened bread left over from the Passover meal. (Ex. 12:8) In the Scriptures, leaven at times denotes corruption or sin. (Matt. 16:6, 11, 12; Luke 12:1) Thus, Jesus’ use of unleavened bread was significant because it fittingly represented his sinless body. (Heb. 7:26) 

The wine that Jesus used on Nisan 14, 33 C.E., represented Jesus’ blood, as does the Memorial cup of wine today. At Golgotha, a place outside Jerusalem, his blood was poured out “for forgiveness of sins.” (Matt. 26:28; 27:33)

At the Last Supper, Jesus revealed himself to be the true Passover Lamb (of God) who takes away the sins of the world. Then, he gave the leaders of his Church a supernatural (but very practical) way to celebrate that singular event, while continuing to consume the same, soul saving, sacrificial Lamb of God, until the end of time. By the Word of God, through the power of the Holy Spirit, under the auspices of Catholic Ministerial Priesthood and through the authentic Church, ordinary bread and wine becomes the body, blood, soul and divinity of Jesus Christ, who is salvation; fulfilling the promise of the Passover, while edifying and sanctifying the People of God.

Jesus satisfied the legal requirement, blood for blood, soul for soul, necessary to pay "the ransom" in exchange for the perfect life Adam lost, by supplying his literal flesh and blood. - Deut. 19:21; Psalm 49:7-8; Matthew 20:28.

Just as, on Atonement Day, the High Priest took animal blood into the Most Holy of the tabernacle or temple and presented it there before God, similarly did Jesus, by presenting the value, or merit, of his lifeblood before God in heaven. (Le 16:2-19; Heb 9:11-14, 24, 28; 10:11-14)  See NWT study note on Ephesians 1:7 https://wol.jw.org/en/wol/b/r1/lp-e/nwtsty/49/1#s=7&study=discover&v=49:1:7

"But this man offered one sacrifice for sins for all time." By exercising faith in that sacrifice, one is FIGURATIVELY feeding on his flesh and blood. Only by doing that, one rides the road to everlasting life. - Hebrews 10:12, 38; John 6:53-59.

His Blood and Flesh is His Spirit and Word.

Actually Christ didn't offer, it was ordained by their god, you know the "one" he sold.

Look up the word "memorial" on google.  Luke 22:19

Only the 'savior' of the christ-based faiths will ever be 
pompous enough to make his flock believe that they cannot 
enter Heaven, or be in the presence of their very own Creator, 
unless he is there too. This is how we know that Christ has 
never 'offered' anything at all. 

The only place that he seems to be able to appear is in print, 
and in your question. Otherwise, Christ is just a no-show.