It is good to study the feasts
However leaven is sin and nobody wants to offer up praise mixed with leaven
1 Corinthians 5:8
Therefore let us keep the feast, not with old leaven, neither with the leaven of malice and wickedness; but with the unleavened bread of sincerity and truth.
Barley will not bond with leaven and the reason we see unleavened bread before Pentecost and leavened bread afterwards is because Christ who is without sin comes into sinful man as a light in the midst of a dark place. On the other hand wheat will bond with leaven that represents sin thus we have bread made with leaven representing Christians who have the Holy Spirit but are still dealing with a sin issue
A sin offering is without leaven the same as Jesus Christ is without sin who is our sin offering. Meat offerings were also without leaven and this is the fruit we want to offer up and not leavened bread.
Meat offerings were fleshless finely ground flour (fully prepared to do the Lord's work) without any leaven (sin) that is how we are to become
Consequently Paul said that we may be resurrected as some other grain because Jesus was sown into what is mortal so that we can put on immortality by being resurrected without sin the same as Jesus is........ Paul was saying you were sown in wheat for the hope of being resurrected as barley (the other grain that is without sin)
Jesus said to Peter that Satan wanted to sift him like wheat because that is what Satan does to the wheat (christians) that he was unable to do with the barley that represents Christ
However Jesus said to Peter that He would intercede for Peter "until he be converted (changed to barley) and be able to strengthen his brothers, Thus the death that Peter died that glorified God was his death to self that allowed him to be converted and resurrected sinless unto Christ.
Obviously churches that partake of leavened bread for the body of Christ during communion are doing so out of ignorance and are insulting God.
Blessings'
Doug