sauce incorporates a small amount of tomato concentrate and a green sauce called pesto originates from Genoa. In Central Italy, there are sauces such as tomato sauce, , and the egg-based carbonara. Tomato sauces are also present in Southern Italian cuisine, where they originated. In Southern Italy more complex variations include pasta paired with fresh vegetables, olives, capers or seafood. Varieties include , (tomatoes, eggplant and fresh or baked cheese), (fresh sardines, pine nuts, fennel and olive oil), (literally with garlic, [olive] oil and hot chili peppers), (crispy peppers and breadcrumbs). Pasta can be served also in broth (, or stuffed pasta like tortellini, and ) or in vegetable soup, typically minestrone or bean soup (). Processing Fresh Ingredients to make pasta dough include semolina flour, egg, salt and water. Flour is first mounded on a flat surface and then a well in the pile of flour is created. Egg is then poured into the well and a fork is used to mix the egg and flour. There are a variety of ways to shape the sheets of pasta depending on the type required. The most popular types include penne, spaghetti, and macaroni. Kitchen pasta machines, also called pasta makers, are popular with cooks who make large amounts of fresh pasta. The cook feeds sheets of pasta dough into the machine by hand and, by turning a hand crank, rolls the pasta to thin it incrementally. On the final pass through the pasta machine, the pasta may be directed through a machine 'comb' to shape of the pasta as it emerges. Matrix and extrusion Semolina flour consists of a protein matrix with entrapped starch granules. Upon the addition of water, during mixing, intermolecular forces allow the protein to form a more ordered structure in preparation for cooking. Durum wheat is ground into semolina flour which is sorted by optical scanners and cleaned. Pipes allow the flour to move to a mixing machine where it is mixed with warm water by rotating blades. When the mixture is of a lumpy consistency, the mixture is pressed into sheets or extruded. Varieties of pasta such as spaghetti and linguine are cut by rotating blades while pasta such as penne and rotini are extruded. The size and shape of the dies in the extruder through which the pasta is pushed determine the shape that results. The pasta is then dried at a high temperature.