Quality control is an important part of each step in the raisin making process. While the grapes are growing, they are checked for ripeness by squeezing the juice from a grape and using a refractometer. This allows the growers to determine how much sugar is in the grape. They are also tasted and their weight per volume is measured to give a measure of the quality of the fruit. During picking, workers are careful not to place bunches with insects or mold on the trays. They also try not to break berries as the liquid will attract insects. Knives are used to cut down the grape bunches to prevent damage. At the factory, the raisins are thoroughly inspected. They are also subjected to a variety of laboratory analyses to ensure the production of a consistent, high quality product.