The offerings made of flour and grain were to always include salt. The references to salt in Matthew and Luke highlight the qualities of salt. It preserves, it heals, and it creates thirst. All of these relate to the offerings being made. They were intended to preserve the covenant between the Israelites and God, to heal the Israelites of their iniquity, and to cause them to thirst for deeper relationship with God.
Salt is also an element essential to life. Remember the old Star Trek episode with the creature that killed people by sucking the salt from their bodies? And as important as it is to us today, it was even more critical to a life without chemical preservatives or refrigeration. Israelites obtained salt either from the mountain ridge of pure rock salt on the southwest end of the Dead Sea, or from salt deposited on the shore through evaporation. They used salt to preserve their food, to add to animal feed, as well as in the concoction of incense and to sprinkle on offerings of meat or grain.
Leviticus also refers to a covenant of salt between God and the Israelites. In the Middle East, there are many references to salt in terms of building relationships, establishing a loyal friendship, pledging allegiance or loyalty to a king, or forming a bond through breaking bread together with salt. The chemical nature of salt, its stability and strong ionic bonds, exemplify the eternal nature of God's relationship with us.
Every element of the offerings was significant. Everything God does in our lives is significant. No detail is haphazard or meaningless.