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INTRO
Pasta is a popular food in many households throughout North America. Many pasta products are developed from the mixing, extrusion and drying of durum wheat semolina with water. Pasta is a popular food with an excellent nutritional profile. Pasta contributes a large portion of carbohydrates to the diet as well as has protein and is low in fat [1]. Pasta also has a moderate source of some vitamins such as B vitamins and folic acid. This nutritional profile allows pasta to be included as part of a healthy diet. The convenience of a dried pasta product is also very desirable to consumers. In the industrialized world of today, there is a trend toward buying easy to prepare and ready to serve convenience foods. Dried pasta can be prepared easily by boiling in water and is ready to eat. Pasta has a very long shelf life and could last years if it is packaged and handled appropriately [1]. This has desirable implications for consumers because there is very little money lost from spoiling and it can be very easily stored. Pasta also has a good consumer value because there is virtually no change in sales when in bad versus good economic times [1].
Among the various pasta shapes and sizes there is spaghetti. Spaghetti is one of the pasta products that is a popular choice among consumers. The processing of dried spaghetti is reviewed in this paper. There are many different brands of spaghetti on the market and the quality is important to ensure the product sells to consumers. The processes of mixing, extrusion, drying and packaging are all important in the development of a shelf stable, quality product. The objectives of the process are to consistently produce a quality product by using processes that ensure homogenous mixing, protect the gluten network to ensure cooking quality, and to ensure the product dries in such a way to produce a uniform, strong product. The end product will reflect to process by being a quality product that will store well, rehydrate uniformly, maintain its shape and produce a tasty cooked product that is desirable to the consumer [1].
References [1]
MARCHYLO, B.A. and DEXTER J.E. (2001) Pasta production, chapter 6: Cereal Processing Technology.
I can modify this as soon as I see the rest of the paper to make it flow better and intro the processes and their objectives.
First Paragraph: Inputs Pasta is basically a mixture of flour, egg, water and salt. It is quite nutritious as it offers starchy carbohydrate, protein, B vitamins, Iron and Folic Acid. In itself, pasta is not a fattening food - it is the accompanying sauces that contributes the additional calories. Typically a 2 oz portion of dry pasta will contain 210 Calories consisting of 75% carbohydrate, 13% protein and 1.5% fat. Pasta is a mixture of water and semolina made from grinding the endosperm of high quality, hard durum wheat.Durum wheat helps pasta retain its structure and shape when cooked. Other grains, such as corn, rice, quinoa, spelt, and kamut can also be used as they give the softer and sticky texture to pasta. The whole grain wheat makes the pasta darker and more nutritious, or wheat with other flours, including non-grain flours such as soy-bean flour. Eggs are used not only for coloring the pasta, but also make the dough elastic, soft and resistant. A blend of semolina and durum wheat farina or flour can also be used in the production of pasta; however, it has a less desirable color and appearance than 100% durum wheat semolina. Pasta can also be coloured and flavoured with the addition of a variety of ingredients at the manufacturing stage i.e. eggs, spinach, tomato puree, red pepper puree, chilli, shellfish stock, mushrooms, truffles and squid ink. These speciality pastas are best served with a complementary sauce or a very simple drizzle of oil or butter as their flavour can be quite strong. The spaghetti process being reviewed in this paper only has two input materials, water and semolina, typically combined in a ratio of 25-30 kg of water for every 100kg of dry semolina. If eggs are included in the ingredients these are added and the water content would be adjusted. The resulting mixture of water and semolina is a stiff dough. There are several considerations in the selection of semolina for pasta processing. Homogenous hydration of the semolina particles during mixing is important in the quality of the final product. Small particles of semolina hydrate more rapidly than coarse particles in the mixing process. In order to prevent uneven hydration and the appearance of white specks or streaks of unhydrated semolina, the input particle size distribution is as narrow as possible with emphasis on uniform, fine semolina particles, especially with high speed mixing processes. Another consideration in semolina quality for processing is the protein content. High protein content of the semolina results in a cooked pasta texture that is more firm and less sticky, both desirable characteristics by consumers. Semolina is a favoured grain product for pasta making due to its high protein content of 13-14% dry matter basis. Protein content of semolina is due to gluten, a wheat protein. Strong gluten is important for processing, as a strong protein network will result in less sticky dough, with better extrusion properties, and more desirable texture of the final product.

Changes anticipated? Color changes: Carotenoid pigment, xanthophyll - pasta processing conditions as well as the raw material quality (pigment level) influence yellowness of the final product. Bright yellow color makes it desirable characteristic of the durum semolina. - The colour from xanthopyll may only be significant if we use egg as an ingredient as egg yolk is the source of carotenoids. I think semolina has mininmal beta carotene but I'll look more into it :) - Pasta yellow – quality of semoline – natural carotenoid pigments, protein, lipoxygenase (LOX) activity, and processing conditions - Processing – pigment losses (16.3% loss of beta carotene) - -pH of dough activates LOX 2 and LOX 3 enzymes –pigment loss - - LOX activity is main factor in colour loss - Want semolina with low LOX activity (more important than beta carotene content) Red references (Cereal processing technology)- Ang written in red – will add ref later
this part has not been finished... how would you like to word this?

Mixing There are 3 processed involved in the mixing of pasta. Mixing, kneading and extruding are the 3 essential parts of the mixing of the pasta. During the mixing stage, water must be added to the semolina flour so that the moisture content reached approximately 30%. The flows of the inputs into the mixer are regulated by one of two types of dosers (volumetric or gravimetric),which have precise and constant outputs that are measured by the dosers. The semolina flour absorbs the water until it forms a homogenous mixture. If yellow pasta is desired, then whole egg can also be added to the dough mixture (3).The importance of the homogeneity of the mixture is so that there are no imperfections in the final, dried product like white spots. To ensure that the semolina flour particles absorbs the water equally, the flour is sifted, often by a 0180mm mesh sleeve, so that a maximum of 25% of the particles pass through the mesh sleeve. The temperature of the water used is dependant on the type of the pasta and its shape, so 40-65 degree Celsius water is generally used. For spaghetti, which is a long pasta, the dough which has homogenously absorbed the water will be mixed in a twin shaft mixing chamber for 16-18 minutes. To ensure that the dough does not ball up, each of the shafts will turn in opposite directions. This type of movement is non-centric which will ensure that the dough does not form a ball. Many modern pasta mixture plants have moved from using the traditional dual shaft mixers to using a new type of continuous pasta-press technology. The Bühler Brothers, in Switzerland, engineered the press in 1934 (2). Using a press reduces the mixing time from 16-18 minutes to about 2-3 minutes, which reflects the other durations of the pre-drying and drying pasta production cycles. The continuous pasta press is capable of producing 3500kg/h of spaghetti and up to 8000 kg/h of macaroni (5). While the pasta is in the mixing process there are several things to consider. One of the most important aspects to consider while mixing is determining an adequate speed to ensure that the mixture has achieved particle suspension (6 – P205). Njs = Sv0.1 dp0.2 (g∆p/pL)0.45 D-0.85 X0.13 (6 – P205). Where “s” is for shape factor which is a dimensionless value that accounts for shape of mixer, type of paddle, distance from paddle to outside of mixer and paddle to tank ratio. “dp” refers to particle diameter, “D” is a value for the paddle diameter. “pL” refers to liquid density, “g” is the constant for gravitational acceleration, “∆p” is the solid-liquid density difference . “X” is the solid concentration by weight (X100) and “v” refers to the liquid kinematic viscosity (6 – P205). Another important aspect to consider is the energy balance around the mixer. All energy from the energy inputs to determining the final temperature of the pasta dough can be determined and adjusted by using the energy balance equation (7). ∑Mi ⋅Δhi =Mflour ⋅Δhw +M⋅Em −Qj where ∆hw=15.1kj/kg(7 #12.1,12.2) Where “Mi” is the mass of the ingredients and “∆hi” is the change in enthalpy of the ingredients. “Mflour” is the mass of the flour, ∆hw is the heat of flour wetting, “M” is the mass of the dough, “Em” is the energy input per unit mass and “Oj” is the heat transferred through the mixers exterior (7). The semolina and water is mixed in the pre-mixer until the dough is adequately hydrated, this mixture is then passed onto the mixer which is used with a vacuum to remove air bubbles from the dough, during the initial mixing process (5). The adequate hydration of the dough makes it so the gluten/protein matrix can develop within the pasta once it is at the extrusion stage of production as it does not occur during the mixing stage (5). Once in the mixer warm water is added to the dough to bring the moisture content of the dough to 28-32% (5). For this type of mixer, it is necessary to use finely granulated semolina flour. The press technology makes use of vacuum equipment to remove any small air bubbles within the pasta dough, because air bubbles can result in a pale and unattractive pasta and can weaken the dried product. While the conventional dual shaft mixer uses the length of time and magnitude of mixing to remove the air bubbles from the dough. After the mixing stage the pasta is fed to the extruder after, in some cases, being given time to rest on a “stabilization belt” which feeds the pasts to the extruder (4). View PDF for pictures and citations -- Extrusion The kneading and shaping stages in pasta production are done in a machine called an extruder. There are several zones in the extruder which are involved in conveying, compacting, kneading, relaxing, and extruding the pasta dough. Upon entering the extruder, the hydrated semolina mixture first contacts the extrusion screw. The screw is exposed so that the semolina mixture may be dropped directly from the mixer onto the screw as it turns. The hydrated semolina is conveyed from the screw into the extrusion barrel where it is compacted. There is an increase in pressure from approximately 0 to 2 MPa which helps to transform the hydrated semolina, which is granular in composition, into a compacted dough. During compaction there is also an increase in temperature due to friction between the dough, the screw, and walls of the barrel. The friction is necessary in order to compress the dough as well as move it down the channel. The excess heat is removed by a warm water jacket that engulfs the extrusion barrel, which keeps the temperature of the dough and barrel at approximately 45°C. The ideal temperature for pasta extrusion is between 45 and 50°C, as anything above 50°C will denature the proteins, impeding gluten production and therefore resulting in a soft sticky product. Using a cold water jacket will cool the dough and barrel too much, resulting in undesirable dough viscosity. The frictional heat can be calculated which, in turn, helps determine how much the system needs to be cooled so the pasta exits the extruder at the desired temperature of 45°C. For example, if the dough enters the extrusion screw at 35°C, and frictional heating causes an additional 33°C rise in dough temperature, the dough will leave the extruder at (35+ 33°C) = 68°C, which means that approximately two thirds of the heat would need to be removed by the water jacket. One variable involved in determining the frictional heat is the specific mechanical energy (SME). The SME is the amount of energy transferred to the pasta product during the extrusion process and is calculated as the mechanical energy (kJ/s) to extrude pasta divided by the pasta production flow rate (kg/s). Elevated dough moisture or temperature can result in decreased dough viscosity and therefore decreased SME. Under normal operating conditions for pasta extrusion the SME is typically 70 KJ/Kg. To determine the frictional heating of the dough: first calculate the heat capacity of the dough using the following equation: Cp (kJ/kg°C) = 1.44 + 2.74Xw Where Cp is heat capacity and Xw is moisture content For example, if the moisture content is 30%: Cp = 1.44 + 2.74 (0.30) = 2.26 KJ/Kg°C The next step is to divide the SME (specific mechanical energy, KJ/Kg) by the Cp value to get the temperature. If the estimated SME = 75 KJ/Kg: Frictional heat = (75 KJ/Kg)/ (2.26 KJ/Kg°C) = 33°C After the dough has been compacted it continues to move along the extrusion screw, where it is kneaded by forward flow and back pressure forces. The gluten molecules in the dough are stretched and aligned with the directional movement of the screw. However, the flow rate of the dough is not uniform as it moves down the extrusion screw, which results in irregular dough development. To increase homogeneity of the dough, a kneading plate is attached to the end of the screw. A kneading plate is stainless steal with small holes and works by splitting the dough into many small strands of dough that remix on the other side of the plate. It aligns the protein matrix and starch granules of the pasta. After the kneading plate comes the extension tube which is used only when extruding long pasta, such as spaghetti . In the extension tube the dough is allowed a brief rest before entering the die. By the time the dough has reached the end of the extension tube it is considered fully developed as it has become translucent and cohesive. The die is composed of a rectangular support and multiple inserts. The production output is determined by the number of inserts in the die, therefore it must be balanced with the pasta press. Too many could cause the die to weaken and bend under the 10 MPa of pressure, which could decrease the density of the pasta product or cause strands to overlap during extrusion. Too few can cause excessive back pressure which could damage the die and/or the extruder and subsequently reduce production output. The shape of the opening in the insert determines the shape of the pasta - for spaghetti it is circular. The inserts are also coated with Teflon which helps decrease the coefficient of friction and increase the rate of extrusion. The Teflon also helps yield a pasta product with a smooth surface which decreases its exposed surface area, preventing it from absorbing water to quickly and from soaking up too much pasta sauce when cooked. Extruder output is described by the following equation: Extruder output = drag flow - pressure flow - leakage flow. Drag flow is the forward movement of the dough due to the relative motion between the screw and the barrel. Pressure flow is the backward flow of dough in the screw channel due to a pressure gradient across the screw length. Leakage flow is the backward flow between the flights and the extruder barrel due to a pressure gradient. Further information regarding the details to this equation is beyond the scope of this course. The long spaghetti stands are deposited on a spreader, which spreads the long strands on sticks and cuts them into a uniform length as the product comes out of the die. There is some trim that results from the uneven flow out of the die. The trim is simply collected and brought back into the mixer through the trim return system. The pasta attached to the sticks is transferred to the dryer. See PDF for extra --
Pasta drying (Jessica)
The next step of pasta processing is drying. The goal of drying process is to remove the moisture content in the dough, so that the final product has an extended shelf-life and can be stored for quite a long time. Besides that, removal of water can also secure the food safety because as we know, microbes grow in the food where water activity is high, this is why we have to remove the water and make a smaller percentage of moisture content [1]. This drying process is also one of the important steps in the pasta processing because this step has a really big effect in the final product. Due to the use of high temperature in this step, we have to be very careful, so that the final product is still marketable and being desired by consumers. Therefore, we have to have a good appearance and quality of the product, as well as preventing the loss of nutrients during the process [3]. See PDF for more...
How Processing can affect nutritional and sensory quality of pasta Spaghetti is an ideal grain product for diabetics because the carbohydrates are slowly digested, maintaining steady blood glucose levels leading to levelled insulin release. Also, pasta has a slower rate of gastric emptying, to prolong satiety. These benefits are attributed to the processing of the pasta noodles. The extrusion process forms a dense, firm texture that takes longer to digest. The dense noodle has a tight protein structure, limiting porosity and therefore reducing surface area for alpha-amylase interaction. The density of the spaghetti is also related to the protein content and gluten strength of the durum wheat. Mixing can improve the associative forces of gluten structures by altering thiol and disulphide groups. Particle size is also an important aspect of digestibility. Having a large particle size is another method to decrease alpha-amylase interaction and gastric emptying. Grinding is not a step in production because it would decrease the particle size and increase the glycemic index of the product. During cooking, the swelling of the noodles is restricted by the protein matrix and oligosaccharides content by trapping some of the gelatinized starch granules, reducing susceptibility to the alpha-amylase enzyme (Fardet, A., Hoebler, C., Baldwint, P.M., Bouchet, B., Gallant, D.J., Barry, J.L. (1998). Involvement of the protein network in the in vitro degradation of starch from spaghetti and lasagne: a microscopic and enzymic study. Journal of Cereal Science 27 p.133-145. American Academic Press Limited). The yellow colour of spaghetti made without eggs can be attributed to the quality of the semolina, determined by the amount of carotenoid pigments, levels of protein and ash, and lipoxygenase (LOX) activity (Borrelli, G.M., Troccoli, A., Di Fonzo, N., Fares, C. (1999). Durum wheat lipoxygenase activity and other quality parameters that affect pasta colour. Cereal Chemistry. 76(3):335-340. American Association of Cereal Chemists Inc). More commonly known as a precursor of vitamin A, carotenoids are essential in the human diet because we are unable to synthesize them. They exhibit antioxidant properties important for the prevention of many diseases, immune function, and eye function. Isomers of carotenoids have different melting points, solubility and stability. However, they are all sensitive to oxidation by light and oxygen. In plants, carotenoids become bioavailable when the food matrix is disturbed, such as during processing (Venugopal, V. (2009). Carotenoids. In Venugopal, V. Marine Products for healthcare: Functional and Bioactive Nutraceuticals Taylor and Francis Group Boca Raton, FL). Borrelli et al (1999) explain how processing combined with LOX-2, LOX-3 enzyme activity plays a vital role in pasta colour and nutritional value by reducing carotenoid content by 16.3%. A dough pH of 4.8 is preferred over pH 6.6 to maintain carotenoid by reducing enzyme activity. High temperatures for drying the dough may can also inactivating the LOX-2 and LOX-3 enzymes. However, Marchylo and Dexter (2001) note the temperature should not exceed 50°C to prevent damage to the gluten network. Furthermore, high temperature and ultra high temperature processing can result in loss of lysine, vitamins and form furosine. Mixing and extrusion under vacuum can decrease carotenoid oxidation. It should be noted many other quality parameters of the semolina may also have an effect pasta colour (Marchylo, B.A., Dexter, J.E. (2001) Ch.6 Pasta Production In Ed. Gavin Owens Cereals Processing Technology. Woodhead Publishing Canadian Grain Production, Winnipeg). Mineral content is minimally affected by processing. However, water used for dough production can slightly increase calcium and copper, and the equipment used can release low levels of iron and copper into the product (Cubadda, F., Aureli, F., Raggi, A., Carcea, M. (2008). Effect of milling, pasta making and cooking on minerals in durum wheat. Journal of Cereal Science 49 p. 92-97). (http://www.greatfood.ie/item_display.asp?cde=3&id=1113) (http://www.food-info.net/uk/qa/qa-fp145.htm)(http://www.greatfood.ie/item_display.asp?cde=3&id=1113) (http://www.food-info.net/uk/qa/qa-fp145.htm)



( Editing_on_word.pdf this is how Mandy will be editing. To add to the instructions, check mark means you agree with the changes made, "x" means you don't. If you agree with the changes, just highlight the section and click the check mark. Changes that you make are indicated by word, so don't worry about who edit what. - I hope that makes sense...
The edited part will be attached as a hyperlink so you can open it in word to read and/or adjust accordingly. I will be posting this link below: )


Check out the document. the Changes are done, except for drying but look at the blue text for clarification. All the editing is done on my part.

ANG: sorry I deleted the above comment somehow, but added a paraphrase.... I need to make a few changes but how do I reload the changes I made to the document? Do I save on my computer and repost the link????? I am currently working on the conclusion: post a note for me if you have ideas for input.

MANDY: when you save the document, considering that you've "tracked changes," the changes you have made will also appear when other open the document. So, basically just save it and name it "pasta processing (ang)" or something will be fine. Replacing the document all together will be ok too, being that word will recognize difference users editing it.



ANG: here is the final version with the conclusion.... take a look and make any comments. I will be checking on or before Sunday evening. The conclusion is long but remember it is worth as much as the body. I hope it is ok, if you think more needs to be written let me know please. Thanks.