Unit 3 wheat flour products


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Unit 3 wheat flour products

  1. 1. Unit 3 Wheat flour productsWheat bread Bread is one of the most common, convenient and inexpensivefoods, with leavened forms now the most popular in many countries although flat breads remain very common in India and the Middle East the main ingredients are wheat flour, sugar, salt,yeast and water. The major production methods used today in wholesale bread production are the sponge and dough process, the straight dough method and the no-time dough method 1
  2. 2. sponge and dough process Bread preparation according to this process is described by the process production line shown in Figure 1. In the first stage, a portion of flour is mixed with water and yeast and fermented for a certain period of time to produce a sponge. Subsequently, the balance of water and flour is added along with other formula ingredients to the fermented sponge, mixed to a fully developed dough, which is divided into pieces to yield bread loaves of desired weights after baking. 2
  3. 3.  The dough pieces are then rounded, given a relaxation period by passing them on a belt, sheeted and shaped into elongated dough pieces placed into baking pans transferred for proofing where they are proofed to desired heights baked cooled sliced wrapped 3
  4. 4.  The packaged breads are distributed through retail outlets and stores. Their expected shelf life is about 4 days after baking in stores and an additional 5 days in the home. Although the bread is still edible and safe even after that storage time, it becomes stale and thus loses its customer acceptance due to organoleptic and physicochemical crumb changes. 4
  5. 5. Fig 1 Flow chart of bread production by the sponge and dough process. 5
  6. 6. B. Straight Dough Method Breads made using this method are generally produced in retail operations. The doughs for breads and various small bakery products are prepared in a single step by incorporating all formula ingredients at the mixer. The dough is mixed to a full gluten development and then fermented to maturity without or with degassing by punching during the fermentation step. Then the fully fermented dough is divided and machined in the same manner as in the sponge and dough process. 6
  7. 7. C. No-Time Dough Process This method is essentially a straight dough method where the dough mixing is effected mainly mechanically by the action of high-energy input of special mixers. The mixing step can be further enhanced by addition of reducing agents (L-cysteine, inactive dry yeast preparations containing glutathione) or various proteolytic enzymes. The reaction of reducing agents has to be controlled by the addition of suitable leaves of oxidants. 7
  8. 8.  The fully mixed doughs are given short or no fermentation, then are divided, rounded, molded, proofed, and baked. This method is especially suited for frozen dough manufacturing and retail bakeries. 8
  9. 9. Bread Production Equipment The commercial production line detailing the equipment used in the sponge and dough process is shown in Figure 1. The mixer is generally a high-speed horizontal, which is applied for both sponge and dough mixing. The proofing room is a chamber with temperature and humidity controls. The divider is a device that divides the fermented dough into dough pieces of desired weight. 9
  10. 10.  The divided dough pieces are then rounded in a rounder. The rounded dough is briefly relaxed in a overhead proofer, then sheeted and molded by means of a molder into elongated dough pieces, which are deposited into pans and transferred into a proof box. The fully expanded (proofed) doughs are baked in a tunnel oven depanned cooled Sliced packaged.. 10
  11. 11. Types of Breads and Typical Formulas A .White Pan Bread The major type of bread manufactured in the United States is white pan bread. This type of bread is a standardized product and is federally regulated in respect to its moisture content (38% maximum) and enrichment. 11
  12. 12.  White hearth breads are produced with or without lactic acid fermentation, called sour by the trade. The main difference between pan and hearth bread is in the baking step: hearth breads are baked on an open hearth but pan in baking pans. The type of heat transfer during hearth-baking leads to formation of a solid, crisp, flavorful crust and other attributes associated with this type of bread. 12
  13. 13. Functions of Bread Ingredients Flour-Structure.2. Protein (gliadin and glutenin) and water form viscoelastic material, called gluten. Gluten retains gas formed by sugar fermentation and contributes to structure of dough and bread.2. Starch + water + heat forms a viscous paste that sets to a gel after baking. During bread storage the starch crystallizes (retrogrades and contributes to firming (major part of staling) of breads. 3. Protein content for bread flour: 11.13%, 14% moisture basis. 13
  14. 14. Water-Hydration1. Combines (hydrates) protein to form gluten.2. Hydrates flour gums (pentosans) and mill-damaged starch granules.3. Solvent, dispersing agent, and medium for chemical and biochemical reactions4. Aids dough mobility. 14
  15. 15. Yeast-Leavening1. Produces carbon dioxide, ethanol by fermentation of fermentable sugars.2. Conditions dough biochemically.3. Forms flavor precursors (by-products of alcoholic fermentation).4. Rate of fermentation is controlled by temperature, nutrient supply, water level, pH, sugar concentration, salt, and level and type of yeast. 15
  16. 16. Salt-Flavor Enhancer1. Helps control fermentation.2. Toughens dough by interaction with gluten. Sugar-Energy Source for Yeast4. Fermentable carbohydrates (fermentation).5. Flavorresidual sugars (sweeteners), fermentation by- products, Maillard-type compounds during baking. 16
  17. 17. 3. Crust colorresults of caramelization (sugars and heat) and nonenzymatic browning (reducing sugar plus amino group of proteins, amino acids, etc.).4. Extends shelf life by increasing hygroscopicity due to presence of residual sugars and tenderizing the crumb. 17
  18. 18. Shortening-Lubrication1. Ease of gas cell expansion in doughs.2. Lubricates slicing blades during bread slicing.3. Extends shelf life.4. Tenderizes crust. 18
  19. 19. Dairy products-Nutrition and Crust Color Enhancement• Protein (high in lysine) and calcium.• Flavor enhancement.• Crust color (browning reaction and caramelization).• Buffering effect in doughs and liquid ferments 19
  20. 20. Enrichment-Nutrition1. Standards of Identity require the following levels per 454 gram of bread: Fe = 12.5 mg Niacin = 15.0 mg Ca (optional ingredient) = 600 mg Riboflavin - 1.1 mg Thiamine = 1.8 mg 20
  21. 21. Wheat gluten- Enhancement of Flour Strength1. Increases dough strength (1% gluten increases protein content by 0.6%).2. Increases water absorption [1% added gluten (flour basis) enhances absorption by 1.5% (flour basis)].3. Improves dough mixing of fermentation tolerance.4. Increases bread loaf volume.5. Especially used in formulation of specialty breads. 21
  22. 22. Stability of Bakery Foods A. StalingBakery foods are perishablethey undergo physicochemical, sensory, and microbial changes as indicated in Table 30. The generic term for this is staling." It is advisable to follow the staling process with sensory tests, since flavor changes unrelated to firming often occur during storage. In a simplified manner, starch gelatinizes during baking and amylose is leached out. Upon cooling the amylose component crystalizes and determines the fresh firmness of bread; amylopectin retrogradation proceeds slowly and causes firming during storage. 22
  23. 23.  The process is heat-reversible because retrograded amylopectin can be reverted to its amorphous state, which reduces firmness. 23
  24. 24. Cookies Cookies have great commercial appeal because they are characterized by a formula high in sugar and shortening and low in water. In general, cookies are produced using soft wheat flour that has a relatively weak gluten strength. The weak gluten and the relatively high quantities of fat and sugar in the dough allow plasticity and cohesiveness without the formation of a strong gluten network. 24
  25. 25.  Minimal gluten development is also controlled by carrying out the mixing process in two or even three stages. The mixing step is critical to obtaining a dough of correct consistency at the end of mixing. Depending of the formulation, cookie dough tends to become larger and wider as it bakes rather than shrinking like cracker dough. Control of this increase in size, known as spread, is a continuous problem in process control. A common way to classify cookies is by the way the dough is placed on the baking band. 25
  26. 26. Pasta Pasta is a generic term used in reference to the whole range of products commonly known as spaghetti, macaroni, and noodles. Raw Materials for Pasta Products The pasta products macaroni, spaghetti, vermicelli, and noodles are manufactured primarily from semolina, durum granulars, and flour produced from the milling of durum wheat. These are the preferred raw materials for the production of superior quality pasta products. 26
  27. 27.  To a lesser extent, farina and flour from common wheats are also used. In addition, pasta can be processed from blends of various nondurum materials with durum semolina or flour. However, blended products usually suffer a deficiency with respect to some quality attributes such as color or cooking quality. The degree to which blending is practiced is usually dependent on wheat availability and price, competitive pricing, and consumer acceptance in a given market. 27
  28. 28. Semolina Semolina is derived from the Italian word semola and the French equivalent semoule. Pasta products are manufactured principally from the three main milled products of durum wheat, namely semolina, durum granulars, and durum flour. Farina and flour from common wheat are also used, but to a lesser extent in the United States than elsewhere. For the production of good-quality pasta, the particle size of the semolina should not be too coarse nor too fine. Semolina milling is unique in that the objective of the process is to prepare granular middlings with a minimum of flour production. 28
  29. 29. Water Water used in pasta products should be pure, have no off-flavors, and be suitable for drinking. Since pasta can be processed below pasteurization temperatures, the bacterial count of the water is directly related to the bacterial count of the finished product. Consequently, only pure water of low total plate count should be used under these circumstances. 29
  30. 30.  The recent advent of high-temperature and ultra-high- temperature drying and microwave drying of pasta has resulted in lower levels of microbial counts in pasta products than previously experienced with conventional temperature drying. 30
  31. 31. Pasta ProductionA. Extrusion Process of shaping items by forcing them through a die In the continuous press, water is added to semolina to give a dough moisture content of approximately 31%. Uniform water/semolina mixing is carried out in a counter rotating mixing chamber with vacuum applied prior to extrusion. 31
  32. 32.  Counter rotating mixing shafts limit balling of the dough, and the applied vacuum reduces formation of small air bubbles in the dough and limits oxidation of the xanthophyll/lutein pigments. The presence of air bubbles in pasta gives it a chalky appearance and reduces its mechanical strength. Pigment oxidation reduces the attractive yellow appearance of the pasta and its subsequent consumer appeal. 32
  33. 33.  The heart of the continuous press is the extrusion auger, which kneads the dough into a homogeneous mass prior to extrusion through a die. Auger speed and temperature control of the dough contributes to the quality of pasta products. Most modern presses are equipped with sharp-edged augers having a uniform pitch over this entire length. The auger fits within a grooved extrusion barrel, which helps the dough move forward and reduces friction between the auger and the inside of the barrel during the extrusion process. Extruder barrels are normally equipped with water- cooled jackets to hold the pasta temperature near 40°C during the extrusion process. 33
  34. 34. Figure 2 pasta production line. 34
  35. 35. B. Drying Another critical step in pasta processing is drying. Moist pasta from the extruder needs to be dried from 31% to approximately 12% moisture so that the product will be hard, retain its shape, and store without spoiling. Regardless of dryer design and temperature-humidity- airflow control, problems can arise if the pasta is not dried carefully . If pasta is dried too rapidly, moisture gradients will occur, which can cause the product to crack or check. 35
  36. 36.  Checking can occur either during the drying cycle or as long as several weeks after the product has been packaged. If large stresses are present due to improper drying, any change in relative humidity can result in a checked product. It is essential that a pasta product be dried using a drying cycle tailored to meet that products requirements. 36
  37. 37.  Prior to 1974, conventional or low-temperature drying (LTD) of pasta utilized drying times of approximately 16 hours for long goods and 8 hours for short goods. High-temperature drying (HTD) was introduced into commercial drying lines in 1974. HTD raised drying temperatures from 55 to 75°C, which resulted in shorter drying times (10 hours for long goods, 4.5 hours for short goods), lower bacterial counts, and improved end-product quality 37
  38. 38.  More recently the evolution of pasta-drying technology has increased drying temperatures from 75 to 100°C and above. These drying cycles are referred to as very-high- temperature drying (VHTD) or ultra-high-temperature drying (UHTD). The advantages of VHTD include significantly reduced drying times (5.5 hours for long goods, 2.5 hours for short goods), improved end-product quality (Table 10), and reduced investment and operating costs. A typical VHTD profile is shown in Figure 3. 38
  39. 39. Fig.3 long cut pasta moisture curve. M-moisture and t-drying time 39
  40. 40. C. Packaging There are thousands of different sizes, shapes, and types of packages in which pasta products may be sold . However, they all perform the same basic functions, such as keeping the product free from contamination, protecting it from damage during shipment and storage, and displaying the product favorably and with consumer appeal. 40
  41. 41. Factors Influencing Pasta QualityA. Pasta Processed from Semolina/Farina Although durum wheat semolina is the raw material of choice for the production of pasta products, almost any type of wheat may be used for producing pasta products Studies have shown that the mill streams of durum were more yellow than those obtained from bread wheats and that they gave lower absorptions, which is an advantage in pasta processing since less water has to be removed in drying. 41
  42. 42.  It was also shown that pasta processed from durum wheat granular mill streams (GMS) with other bread wheat GMS produces a better pasta product in appearance and cooked properties than pasta processed from the GMS of bread wheats alone. Wyland and DAppolonia studied the influence of drying temperature and farina blending on pasta quality. 42
  43. 43.  Blends were prepared that contained the durum semolina and 0.5, 10, 20, 40, 60, and 100% of each class of hard red spring (HRS) and hard red winter (HRW) wheat farina. Temperatures of 40, 60, 70, and 80°C were used in drying the spaghetti after extrusion. Results showed that increasing drying temperature improved spaghetti color, increased cooked firmness, and decreased cooking loss and cooked weight values. 43
  44. 44.  Increasing the proportion of HRS and HRW wheat farina in the farina-semolina blends brought about a decrease in cooking loss, cooked weight, and spaghetti color. Drying at the higher temperatures improved cooked firmness. Wyland and DAppolonia concluded that a good quality pasta product can be obtained by incorporating a certain percentage of farina with semolina and that the quality of these products can be improved with high- 44 temperature drying.
  45. 45.  Some countries such as Italy, France, and Greece place restrictions on the addition of common wheat to durum wheat pasta. To monitor compliance with these restrictions, methods have been developed to detect the presence of common wheats in durum wheat products. Sarwar and McDonald reported that sterol palmitate content can be used to detect pasta adulteration, while Barnwell et al. utilized reversed-phase high-performance liquid chromatography for this purpose. 45
  46. 46. B. Pasta Processed from Sprout-Damaged Grain Germination (sprouting) of grain before harvesting can be a problem when rain and cool weather prevent or slow down normal harvesting operations. Pasta manufacturers are particularly sensitive to using semolina milled from sprouted durum wheat in their pasta-processing operations since it can affect end- product quality. 46
  47. 47.  Several studies have been conducted of the problems of sprouting in terms of pasta quality. Some general conclusions from those studies indicate that test weight, kernel distribution, protein content, milling performance, pasta color, and cooking quality were not adversely affected by increasing sprout damage (decreasing Falling Numbers). The only major adverse effect appeared to be higher semolina speck counts and spaghetti shelf stability. 47
  48. 48.  It was also noted that sprout damage levels of 4.0% or higher (Falling Numbers of 120 or less) resulted in pasta products having high potential for checking and cracking in storage. Commercial manufacturers of spaghetti are concerned not only with the problems mentioned above but also with the tendency of spaghetti processed from sprout- damage grain to stretch and fall off the rods during drying. 48
  49. 49.  Because of such concerns a number of U.S. Research results indicate that pasta can be processed utilizing semolina with Falling Numbers of 250 without any apparent problems, so commercial manufacturers use of semolina with values of 350 and higher provides a large margin of safety. 49
  50. 50. C. Protein Quantity Versus Quality and Impact on Pasta Cooking Quality The cooking characteristics of pasta products are the ultimate tests in determining its quality. In general, cooked pasta should be neither mushy" nor "rubbery.“ It should retain its shape during cooking and be firm to the bite (al dente). Cooking time is important in terms of relative speed of cooking and tolerance to overcooking. 50
  51. 51.  Three major components of cooking quality assessment include cooked weight, cooking loss, and cooked firmness (texture). Cooked weight (expansion volume) is a measure of the water-absorbing capacity of the pasta during cooking and should be three times the weight of the dry material. Cooking loss is the percent solids lost to the cooking water. 51
  52. 52.  Cooked firmness determines the chewing characteristics of pasta. Cooked weight and cooking loss are relatively easy to measure, but objective measurements of firmness and stickiness has been the subject of study over many years. Objective firmness tests are now used routinely for cooked spaghetti, since it was shown they have a high positive correlation (r = 0.812) with taste panel scores. 52
  53. 53.  Research has also shown there is a significant positive correlation between cooking quality and protein quantity and quality. In general, results show that higher protein and stronger gluten protein in semolina produces pasta with better overall cooking quality and tolerance to extended cooking than do lower-protein, weaker-gluten products. Feillet et al. recently cited a number of publications dealing with the relationship between protein composition and cooking quality. 53
  54. 54.  Because of the positive correlation between stronger gluten and improved pasta cooking quality, considerable research has been directed towards the development and interpretation of prediction tests related to gluten quality. Dick reviewed some of the tests used to predict durum wheat and pasta quality. 54
  55. 55.  In his review, Dick discusses such prediction tests as the mixograph, farinograph, wet gluten, sodium dodecyl sulfate (SDS) sedimentation, electrophoresis, and chromatography and their relevance to pasta quality. DEgidio et al. analyzed 50 samples of 10 Italian durum varieties by various technological and chemical tests, obtaining 26 variables; a study of their value in predicting pasta cooking quality suggested manual evaluation and alveograph W value were the most efficient. 55
  56. 56.  Pasta Quality Evaluation No standard procedure exists for the determination of pasta quality in terms of appearance, color, and cooking quality. Pasta quality is such a subjective matter that what is acceptable in one country is not necessarily acceptable in another. Objective/subjective evaluation of pasta in laboratories around the world evolved with the perceived needs of the indigenous consumer. 56
  57. 57. Two examples reflect these differences. In Italy the evaluation of pasta cooked stickiness, firmness, and bulkiness is widely accepted and applied. The test is performed on spaghetti of 1.60-1.65 mm or 1.70-1.75 mm diameter cooked under standard conditions for 10-11 minutes according to the diameter. 57
  58. 58.  At least three expert tasters assess the cooked product for: 1. Stickiness, which is the state of surface disintegration of the cooked product, estimated by visual inspection, with or without the aid of a standard reference pasta. 2. Firmness, which is the resistance of the cooked pasta when chewed or flattened between the fingers or sheared between the teeth. 3. Bulkiness, which is the degree of adhesion of pasta strands after cooking and is evaluated visually and manually. 58
  59. 59.  By contrast, an evaluation procedure used in the United States involves objective procedures that not only assess the cooking quality of pasta but also that of the raw materials used in the processing of the pasta. Computer and statistical analysis of quality evaluation data provides for overall quality rating within major and minor fault parameters. 59
  60. 60.  Major emphasis is placed on such quality traits as wheat protein, semolina and spaghetti color, and spaghetti cooked firmness. Faults in any of these traits change the acceptability of the sample quickly. An advantage of this type of computer scoring system is its flexibility for adjustment to meet changing quality demands. 60
  61. 61. Conclusion This topic provides an overview of factors that can influence the processing and quality attributes of pasta products. Processing of pasta has evolved over many years from an art to a highly sophisticated system of continuous raw materials blending, mixing, extrusion, drying, and packaging technology as we know it today. 61
  62. 62.  In order to produce superior quality pasta, attention has to be paid to the source and quality of raw materials used; the quality of water mixed with the raw materials to form the dough prior to extrusion; the quality of other ingredients used in the dough mix; extrusion condition; and drying conditions. 62
  63. 63.  Taken in total, producing high-quality pasta is much more complicated than it might first appear. The roles played by the plant breeder, cereal chemist, producer, miller, and grain market can have significant influence on what the pasta manufacturers will use and process in their plants. This in turn will ultimately affect the consumers perception of the product as a desirable food. 63
  64. 64.  Pasta companies have become interested in the marketability of flavored pasta. Ostrove pointed out that pasta products have become more than simply a vehicle for sauces, but are available in nearly every conceivable flavor and color as a complement to any meat, fowl, or fish. Dehydrated powders of vegetable flavors are generally preferred because overall quality of the products tends to be better. 64
  65. 65.  Powders such as spinach, carrot, tomato, corn, broccoli, and others as well as spices like saffron and flavors like vanilla, mushroom, cayenne, and curry are becoming more and more popular. 65