The powder resulting from grinding wheat grains, graded by extraction rate and protein content for different uses: strong flours with high protein for bread, weak flours for cakes and biscuits, and durum semolina for pasta. Wholemeal flours are obtained by grinding whole grains, while white flour is produced by separating the germ and bran from the endosperm. Millers blend wheats to hit specifications for protein, ash, and water absorption, and flour is the most functionally complex ingredient in baking. Because raw flour can carry pathogens such as Salmonella and E. coli from the field, it is treated as a raw ingredient requiring a kill step in baking, and its storage must guard against moisture, pests, and off-odours.