CHAPTER
9
Pasta, Noodle, and Breakfast Cereal Products Durum wheat is used almost exclusively to make pasta products. These products are extremely popular all over the world and come in a variety of forms (Figs. 9.1 and 9.2). Spaghetti, lasagna, linguine, and vermicelli are examples of pasta products known as “long goods.” Macaroni, rigatoni, ziti, and penne are examples of “short goods.” All these products are extruded and identical in formulation, although they have many shape and sizes. The formulas used to produce traditional pasta are simple, usually consisting of only semolina, water, and possibly enrichment. As with all wheat-based products, the number of pasta products has undergone a very significant proliferation in recent years. Products with a focus on health, such as whole-wheat pasta, are now commonly available in the market. Noodles are related products but are often made with soft wheat flour instead of semolina. Common ingredients found in noodles, in addition to semolina or flour and water, are salt and eggs. These products are similar to pasta in formulation, processing, and the issues associated with them. Many breakfast cereals are also made from wheat. The products in this category are very diverse, and the formulations and processes
Fig. 9.1. Pasta long goods (from left to right: lasagna, fettuccine, whole-wheat spaghetti, linguine, and vermicelli).
131
In This Chapter Ingredients and Formulation
Pasta Noodles Breakfast Cereals
Processing
Pasta Noodles Breakfast Cereals
Product and Processing Issues Pasta Noodles Breakfast Cereals
Troubleshooting
Fig. 9.2. Pasta short goods (from left to right, top: large rings, rigatoni, rotini, spirals; bottom: cavatappi, bowties, penne, and campanelle).
132
/
CHAPTER NINE
vary considerably as well. Many types of breakfast cereals have been considered healthy for many years; others have undergone transformation to healthier versions in recent years.
Ingredients and Formulation PASTA Semolina from durum wheat is preferred for the production of pasta products. Pasta made from semolina is a desirable yellow color in the dry form and is durable enough for packaging and shipping without a high degree of breakage. When cooked, the pasta is cohesive, and it does not break apart or spilt while being boiled in water. The cooking water is free of starch, and the product resists overcooking. These characteristics in the pasta product are provided by semolina, because of its hardness, the characteristic of its gluten protein matrix, and the dispersion of the pigments throughout the endosperm. Other ingredients often included in pasta are spinach and tomatoes. According to the U.S. Code of Federal Regulations (21 CFR 139), the only other ingredient required to make pasta is water. In recent years, due to economic considerations, more durum flour is being used in the production of pasta. Durum flour contains much higher percentages of damaged starch than semolina. Since damaged starch is very hygroscopic, this necessitates the addition of high levels of water in the pasta to reach the consistency required for extrusion. Subsequently, more water must also be removed in the drying process. This requirement has resulted in new dryer designs and temperature/humidity/time profiles that provide more efficiency in this costly process. Whole-wheat pasta is also becoming more popular. Due to the presence of bran and germ, it is very difficult, if not impossible, to produce pasta with the traditional translucent yellow color of pasta made with semolina or refined durum flour. Most pasta made with whole-wheat flour is brown and contains visible specks. The high levels of water required for whole-wheat flour pasta also cause the same issue of water removal noted above for products containing durum flour. Fragility is also a major issue since the bran particles create points of weakness in the structure. Many consumers are willing to disregard these differences from traditional pasta. This may be at least partially because many pasta products are consumed with sauces that obscure the appearance of the pasta.
NOODLES Noodles are made with semolina and all types of flour, but soft white wheat flour is often preferred. If strong, high-protein flour is used, the noodles are too elastic and chewy when cooked. Weak low- protein flour, however, is also not desirable because the noodles become very sticky or disintegrate when cooked. Since appearance is
Pasta, Noodle, and Breakfast Cereal Products
important, the flour used in noodle production should also be free of bran, especially if red wheat is used. Consequently, low-extraction flours are often used. It is also important to ensure that enzyme activity in the flour is low. For example, if sprout-damaged flour is used, the α-amylase contained in it causes a rapid breakdown in the integrity of the noodle. Polyphenol oxidase, which fosters the production of the dark pigments, is also detrimental to quality. Noodles for Asian markets are made from flour with very strict quality requirements. Japanese noodles require a low- ash (0.36–0.40%), low-protein (8–10%) wheat flour that has a creamy white appearance. The noodle produced from Australian standard white (ASW) wheat is preferred because of its good surface appearance, favorable texture, and minimal cooking loss. Amylograph curves of ASW wheat flour are similar to those of native Japanese wheats, and it is possible that this characteristic is important to the final quality of the noodle. Chinese noodles are made from hard wheat flours with very low ash (i.e., 0.33–0.38%) and protein amounts ranging from 10.5 to 12%. Color and texture are very important quality attributes, and consequently, the flour must deliver these characteristics. Noodles, like pasta, are made from very simple formulas. Noodles made in the United States include eggs, but in other parts of the world, egg is not a required ingredient. Salt is used in noodle formulations everywhere. In addition to flavor, salt affects the texture of the noodle, generally making it more cohesive and elastic. Some noodles are fried, and therefore oil, absorbed during frying, is a component of these noodles.
BREAKFAST CEREALS Most wheat-based breakfast cereals are made from the whole grain. Exceptions are farina, which is simply the middlings isolated from a standard milling process, and some extruded cereals made from wheat flour. All types of wheat are used. Wheat flakes are usually made from soft wheat. The preferred wheat type for puffed wheat is durum, although hard wheats are used as well. In products such as shredded wheat, where appearance is an important factor, white wheat is preferred over red wheat. Other ingredients commonly used in the production of breakfast cereals are sugar, malt syrup, salt, and enrichment.
Processing PASTA Pasta production consists of three basic operations: mixing, forming, and drying (Fig 9.3). Pasta dough is usually formulated at about 31% moisture. This is a low moisture level compared with those of bread doughs, which generally are about 45%. When mixed, pasta dough generally has the appearance of wet sand, with dough balls of
\
133
134
/
CHAPTER NINE
Fig. 9.3. Production line schematic for long-Âand short-Âgoods pasta. (Reprinted from [1])
about 2.5 cm (1 in.) in diameter. Initially, water is added to the semolina and or durum flour in a premixer. It is then transferred to a main vacuum mixer for further mixing (Fig 9.4). Air is excluded during mixing by the creation of a partial vacuum to ensure that the final product does not contain microscopic air bubbles. Air diffuses light; hence, air bubbles cause the pasta to appear opaque and detract from the translucent appearance desirable in pasta products. Additionally, air bubbles in dried pasta are points of weakness that foster breakage. The oxygen in air is also required in the bleaching reaction that affects durum pigments and is catalyzed by the enzyme lipoxygenase. Hence, minimizing air in the pasta also inhibits oxidation of the desirable yellow pigments. After mixing, the dough is fed into the barrel of a cold forming extruder, where it is subjected to high pressure as it transverses the length of the barrel form the infeed to the die. The considerable friction involved in extrusion generates heat, which can be detrimental. Therefore, pasta extruders are usually jacketed with cold water to avoid excessive temperatures. Dies are available in many shapes and sizes representative of the variety of pasta products made (Figs. 9.5 and 9.6). The surface of the die can affect the cooking quality of the pasta because it molds the surface of the extruding pasta dough. If the pasta surface is irregular, there is more surface area, which causes the product to cook faster. If the surface has major flaws, part of the pasta may break off during cooking. A surface that is too smooth hydrates and cooks more slowly
Pasta, Noodle, and Breakfast Cereal Products
Fig. 9.4. Premixer (top); main vacuum mixer (bottom). (Reprinted from [2])
\
Fig. 9.5. Short-goods die and pasta product. (Reprinted from [2])
and often yields a sticky or mushy exterior. Bronze dies produce the best product, but because such dies lack durability, stainless steel and Teflon-coated dies are often used. After extrusion, the product is cut to the desired length. Long goods are draped over rods for transport through the drying process. Short goods are shaken to avoid clumping and are transported through the dryers on conveyor belts. The dough exiting the die contains about 31% moisture, and the finished pasta contains about 12%. The drying operation must be engineered to accomplish this slowly. Rapid drying leads to checking (i.e., fissures
Fig. 9.6. Extrusion die for long-goods pasta.
135
136
/
CHAPTER NINE
in the product), which is a major cause of breakage. If the product is dried too slowly, however, it can become moldy, or in the case of long goods, it can stretch and become misshapen. Drying is generally accomplished in three phases. The first is a rapid drying phase that dehydrates the surface. Although this is only about 10% of the drying time, it removes about one-third of the moisture. It is followed by a “sweating” period of 2–4 h, which allows the water in the product to slowly equilibrate at 90% relative humidity. The final phase is a long, slow drying to 12% moisture that usually takes 10–16 h. Modifications of this process may include several alternate periods of drying and sweating.
NOODLES
Fig. 9.7. Various types of oriental noodles. Top, dried noodles. Bottom left, wet noodles; center two, ramen noodles; right two, packaged wet noodles. (Courtesy P. A. Seib)
Fig. 9.8. Processing of various types of oriental noodles. (Reprinted from [4])
Noodle processing generally involves sheeting rather than extrusion. Doughs are mixed at about 35% moisture. Because this is not enough water to develop the gluten to the extent that it is developed in bread products, the primary purpose of the mixing is to hydrate the flour and other ingredients. After mixing, the dough is allowed a rest period to fully hydrate the flour particles. The dry, noncohesive dough is then fed through a series of sheeting rolls and sheeted to a final thickness of about 2 mm. Sheeting is unidirectional, and the gluten fibrils are therefore aligned to give the product the most strength in the lengthwise direction. The thin sheet is then cut in the long direction, followed by another cut to the desired length. If the noodle is to be dried, the drying process is usually similar to the process described above for pasta. In many parts of the world, noodles can also be fried or sold fresh. In the case of Oriental noodles, the many different types (Fig. 9.7) result from a variety of related but unique processing schemes (Fig. 9.8).
Pasta, Noodle, and Breakfast Cereal Products
\
137
BREAKFAST CEREALS Breakfast cereals (Fig. 9.9) are commonly made with corn, rice, oats, and wheat. The different types of wheat- based breakfast cereals can be categorized by process. They include hot cereal products (e.g., farina) and ready-to-eat products such as wheat flakes, puffed wheat, shredded wheat, and baked wheat (5). Perhaps the simplest wheat-based cereal is farina, which is composed of chunks of wheat endosperm and defined by standards of identity in the Code of Federal Regulations (6). Farina is the first middling stream in a hard wheat mill. It is isolated, enriched, packaged. and sold as a hot breakfast cereal. Another wheat-based cereal requiring cooking is rolled wheat, which is similar to rolled oats. It is made by a simple process including steaming and rolling whole-wheat kernels. Cracked wheat is made by coarsely grinding Fig. 9.9. Wheat-based breakfast cereals (clockwise from top: puffed wheat, baked wheat, wheat flakes, and shredded wheat). wheat kernels. These wheat-based hot cereals are not as popular as their oat- based counterparts. The starting material for wheat flakes is whole soft, red or white winter wheat kernels, which are lightly steamed and run through rollers with gaps set slightly less than the width of the grain. The kernels are not crushed but are “bumped” by this process. The bumped wheat is loaded into a cooker with sugar, malt syrup, salt, and water and steamed. The cooker is rotated before steaming to mix the ingredients. After steaming, the result is an agglomerated mass of the cooked ingredients. The lumps are broken in machines called lump breakers into smaller pieces called grits, which are particles about 0.375 in. (1 cm) in diameter. The grits are then dried, cooled, run through flaking rolls, and toasted. Gun- puffing wheat requires the whole grain to be thoroughly cooked before a sudden pressure drop occurs in the environment surrounding the grain. The wheat kernels are first soaked in a brine solution to toughen the bran and make it adhere better to the kernel during the puffing operation. An alternative to soaking in brine is to partially remove the bran in a pearling operation (i.e., abrading the outer layers of the kernel). The wheat kernels are then loaded into a puffing gun. In general, a puffing gun is a steel vessel capable of withstanding high pressure and equipped with burners to heat the vessel to 400–500°F (200–260°C). About one part water is added for every 25