stews and to make gruel. Most frequently, grains were ground into flour to prepare bread. Bread making Bread was the main source of nourishment in biblical times, and making bread was a daily activity: Bread-making began with the milling of the grain. It was a difficult and time-consuming task performed by women. Each household stored its own grain, and it is estimated that it required at least three hours of daily effort to produce enough flour to make sufficient bread for a family of five. The earliest milling was performed with a pestle and mortar, or a stone quern consisting of a large lower stone that held the grain and a smooth upper stone that was moved back and forth over the grains (). This often left small pieces of grit in the flour. The use of the millstone became more widespread during the Iron Age, resulting in greater speed and increased production of flour. Smaller versions for household use, the rotary or beehive quern, appeared during the early Persian period. After the grain was milled into flour, it was mixed with water and kneaded in a large trough. For dough made with wheat flour, starter, called seor, was added. The starter was prepared by reserving a small portion of dough from a previous batch to absorb the yeasts in the air and thus help leaven the new dough. Seor thus gave the bread a sourdough flavor. Once prepared, the dough could be baked in various ways: Originally, the dough was placed directly on the heated stones of a cooking fire or in a griddle or pan made of clay or iron (). In the time of the First Temple, two types of oven were used for baking bread: the jar-oven, and the pit-oven. The jar-oven was a large pottery container, narrowing into an opening toward the top; fuel was burned on the inside to heat it and the dough was pressed against the outside to bake. The pit-oven was a clay-lined excavation in the ground in which the fuel was burned and then pushed aside before the loaves were baked on the heated surface. People also began placing a convex dome, initially earthenware and later metal, over the pit-oven and cooking the flatbreads on the dome instead of on the ash-covered surface; this type of oven is probably what was meant by the biblical machabat, often translated as "griddle".