Ruth 2:14-

"At mealtime Boaz said to her, 'Come over here. Have some bread and dip it in the wine vinegar (KJV leaves out wine).' When she sat down with the harvesters, he offered her some roasted grain (parched corn, KJV). She ate all she wanted and had some left over."

Vinegar (Hebrew chomets) was a beverage. It generally consisted of wine or strong drink turned sour. It was probably made by mixing water with new grape juice and left to ferment.

The Nazarites were forbidden to drink it (Numbers 6:3).

It may have been excessively sour (Proverbs 10:26).

It was similar to the posea of the Romans, which was a thin, sour wine, unintoxicating, and used only by the poor. This is what is referred to under the name vinegar in the KJV (wine, wine vinegar in the NIV) in the narrative of the Lord's crucifixion (Matt. 27:34,48; Luke 23:36; John 19:29,30)

The parched (roasted, NIV) corn is prepared from kernels of wheat that are not fully ripe. These are either roasted in a pan or on an iron plate. Sometimes the stalks of wheat are tied in small bundles and the heads of grain held over the fire until roasted.

In Leviticus 23:14, the roasted grain is classed with bread and new grain (green ears, KJV). Jesse sent and ephah of it with ten loaves of bread to his sons in the army by the hand of David (1 Sam.17:18). Abigail took five measures of it as part of her present to David (1 Sam.25:18). David also received it with other provisions from his friends when he had fled from his son Absalom (2 Sam.17:28).

In Leviticus 2:14 it is called, "green ears of corn dried by the fire" (KJV), but more accurately in the NIV: "new grain roasted in the fire." Corn wasn't known in either Europe or the Middle East until it was brought from the Americas into Europe by Columbus and other explorers.

Grain, especially rice, is the most common food element in the world.