Baking Science and Technology

BAKING SCIENCE AND TECHNOLOGY

Function of Ingredients in Bread Production

Learning Objectives • Describe the functions of the major and minor ingredients in white pan breads: water, yeast, salt, sugar, fats and oils, mold inhibitors, and dough conditioners • Describe dough and bread attributes when specific ingredients are over and under dosed • Compare different forms of ingredients: dry yeast vs. compressed yeast vs. cream yeast; granulated sugar vs. HFCS, liquid milk vs. dry milk solids, etc. • Describe proper handling of specific ingredients

Baking bread begins with combining the appropriate ingredients as outlined in a formula. Bakers combine various ingredients to make a wide variety of breads. Selecting the right ingredients makes the difference between producing excellent breads and poor quality breads. Any signiﬁ cant change in ingredients will affect the ﬁ nal product quality and customer satisfaction. A strong understanding of how individual ingredients function and how they interact in a dough system is critical.

The most basic and ancient bread formulas consist of ﬂ our, water, salt, and yeast. From that basic formula, thousands of varieties have been created. Breads may include ingredients such as milk, eggs, various fats, fruits, nuts, sweeteners, etc.

Wheat and Flour Wheat fl our dough has the unique ability to retain the gas produced during yeast fermentation or by chemical leavening. The fl our is responsible for the characteristic structure of bakery foods. Wheat fl our is made from one or blends of six classes of wheat: durum, hard red spring, hard red winter, hard white, soft red winter, and soft white. Wheat Class Avg Wheat Typical Uses Protein % Durum 14-16% Pastas, spaghetti, macaroni Hard Red Spring (HRS) 13-14% Pan breads, rolls, buns Hard Red Winter (HRW) 11-12% Pan breads, artisan breads and rolls, pizza crusts Hard White (HW) 11-12% Noodles, flat breads, breads Soft Red Winter (SRW) 10% Cakes, pastries, biscuits, crackers Soft White (SW) 10% Asian noodles, flat breads, cakes, pastries, crackers

Winter wheats are planted in the fall, germinate and begin to grow, and then become dormant during the cold winter months. They resume growth in the spring and are harvested during the early summer. For winter wheat to produce seed, it must undergo temperatures near freezing for several days. If the wheat does not encounter the cold, the plants become a grass and do not form kernels. This type of wheat grows in regions where the winters are moderate and relatively dry.

Spring wheats are planted in the spring and harvested in late summer. Spring wheats are grown in regions where winters are severe, and also in regions where winters are mild. Spring wheats generally have higher protein contents than do winter wheats (for hard spring and hard winter). There is an inverse relationship between grain yield and protein content of the grain; hard spring wheats have a lower yield of grain per acre than hard winter wheats.

The terms “red” and “white” indicate the color of the wheat kernel, not the fl our milled from the wheat. The color comes from a single layer of cells in the pericarp. Red wheat is pigmented, and white is not. The color component contributes a bitter or astringent fl avor to the bran and to any fl our that contains high concentrations of bran, such as red whole wheat fl our.

Hardness relates to the mechanical force required to crush a kernel. In hard wheats, the ﬁ rst point of fracture is at the cell wall, rather than through the cell contents. In soft wheats, the fracture occurs primarily through the cell contents.

Hard wheat varieties are generally higher in protein and are used principally in the production of yeast-leavened products. The soft wheats yield ﬂ ours that are suitable for the production of chemically-leavened products such as cakes, pastries, cookies, crackers, doughnuts, pie crusts, etc.

Durum wheat is used in the manufacture of macaroni, spaghetti, and similar pasta products. In the US, durum is grown in the same regions as hard red spring wheats. Durum is genetically different from the other wheats. It has 28 pairs of chromosomes: common wheat has 42. Durum wheat is also much harder in texture than common wheat. Durum is made into durum ﬂ our and semolina.

The wheat kernel consists of three major, distinct parts: germ, endosperm, and bran (pericarp). The structure and location of these parts are shown on page 4.

A Kernel of Wheat

The largest part of the wheat kernel is the starchy ENDOSPERM (about 80% of the total kernel). The white flour produced during milling comes from the endosperm.

The BRAN is the outer coat of the seed (pericarp). It is made up of several layers that protect the germ and endosperm and makes up 12-16% of the kernel.

The GERM, or embryo, is the living part of the seed and makes up 2-3% of the kernel weight. The fact that the seed is living makes it easier to store. One of the great advantages of cereal grains is that they can be stored for long periods of time (several years under ideal conditions). The germ is also where growth of the new plant is initiated after the seed is planted.

The ALUERONE layer surrounds the endosperm and is usually found in bran. It is one cell layer thick and is high in minerals, vitamins, phytonutrients, and protein. This protein is non-gluten forming.

The aleurone is the outer layer of the endosperm, and is often included as a portion of the bran. The pericarp is the outer protective layer of the kernel, and creates the majority of the bran portion. Chemically, the bran contains relatively large percentages of ash (inorganic minerals), ﬁ ber (cellulose and arabinoxylans), and proteins. Some of these materials lower the quality of white ﬂ our and most are removed in the milling process. The outer bran layers are tough because of their high cellulose content. This makes it easier to separate the bran from the endosperm during milling.

The germ, or embryo, is the living portion of the wheat kernel. Under proper conditions, the germ grows into a new wheat plant. The germ is relatively high in protein (primarily enzymes), lipids (fat), and ash. If the germ is left in the ﬂ our during the milling process, it quickly becomes rancid. Part of the germ can be recovered during milling; it is stabilized and sold as a specialized food ingredient. The remainder of the germ is sold as animal feed.

The largest part of the wheat kernel is the endosperm. It supplies energy to the new plant as it grows from an embryo. The endosperm is made up of starch granules in a protein matrix. The protein matrix is made up of gluten-forming proteins. The endosperm also contains a small amount of lipids and non-starch polysaccharides. The non-starch polysaccharides are primarily arabinoxylans and are the major constituents of the endosperm cell walls. The endosperm’s aleurone layer is free of both starch and gluten, and is made up of protein bodies instead of a protein matrix which also contain, lipids, a high concentration of minerals (ash), and many phytonutrients.

Bread flour Milled from hard wheat usually containing more than 10.5% protein. These flours contain proteins that produce a strong gluten when mixed into a dough, which, along with high absorption and good tolerance, makes the flours suitable for making yeast-leavened products.

High gluten flour Milled from hard wheat, usually spring wheat. Generally used in the manufacture of hearth breads. Usually 12.5-14% protein.

Pastry flour Low protein (less than 10%) flour milled from soft wheat, with ash less than 0.50% and little mixing tolerance. Pastry flour is used to produce many products, including low-ratio cakes, piecrusts, and cookies.

Cake flour A highly refined (low ash) flour milled from soft wheat, having fine particle size. Treated with chlorine for bleaching (lowers pH), in the US. Used in high-ratio batter cakes.

All-purpose flour Also known as hotel and restaurant flour. Usually made from low protein hard red winter wheat or a blend of hard winter and soft winter wheats. Is designed to serve general household use for all bakery foods, therefore, it is not the ideal flour for any specific bakery food.

Wheat ﬂ our’s gluten-forming protein matrix makes it ideal for the production of many baked goods. When wheat ﬂ our is mixed with water, the gluten matrix is developed, and a structure-forming network is created. Once this network is heated in an oven, the structure is set.

Vital Wheat gluten Wheat gluten can be extracted from fl our and sold as a separate ingredient, “vital wheat gluten”. Vital wheat gluten is sold in a dry fl our form and is added to formulas to help strengthen weak fl ours or to create extra loaf volume. A 1% addition of vital wheat gluten will increase the fl our protein content by 0.6% and absorption by 1.5%. The addition of vital wheat gluten to a formula may extend mixing times and improve tolerances. Normal levels range from 1-5% for most variety pan and hearth-style breads and buns.

Vital wheat gluten is not typically added to white pan breads, but is often used in variety breads and whole grain breads. “Whole grain” means that all of the essential parts and naturally occurring nutrients of the entire grain seed in their original proportions remain when the grain is processed. In other words, 100% of the original kernel must be present—all of the bran, germ and endosperm—in order to meet the whole grain deﬁ nition. When whole wheat ﬂ our is used, the effectiveness of the gluten network is diluted with the other wheat components. Vital wheat gluten is used to fortify or strengthen the dough system.

Water The main function of water is hydration. Ingredients must have water in order to function as expected. For example, ﬂ our must be hydrated in order to form gluten and for the starch to gelatinize. Water also serves as a dispersing agent and a medium for fermentation. There is a direct relationship between the amount of water present in a dough system and the rate of fermentation. The total amount of water in dough is referred to as absorption. As the absorption increases, so does the fermentation rate. Water is also used to control dough temperature, and can be used in the form of ice. A typical absorption for white pan bread is 57-62%.

In production, there are several ways to determine if absorption levels are optimized. Since water is usually the least expensive ingredient used in a dough system, it is critical to add as much as possible into the dough without affecting manufacturing or ﬁ nished product quality. As the dough is mixing, it will form a mass with nothing left sticking to the sides of the mixing bowl. This is referred to as clean-up. It is the initial point of it becoming one, cohesive mass. Identifying a target clean-up time will help control absorption. A dough that cleans up too early is likely under absorbed. A dough that cleans up too late is over-absorbed. Clean- up time should be monitored for each individual dough.

If a dough is kicked out of the mixer with too little water, there may be problems during production. Depending on the type of dough divider being used, inconsistent dough weights may occur and it may be difﬁ cult to sheet the dough properly. Proof times may have to be extended in order to meet target proof heights, and overall loaf volume may still be low due to reduced oven kick. In the ﬁ nished products, staling will occur more rapidly. The consumer will notice a harsher mouth feel and the texture will be more brittle.

On the other hand, a dough with too much water will also have problems. A sticky dough will be kicked out of the mixer, and that stickiness will cause problems throughout production. The dough may hang up in the divider, rounder, overhead proofer, and moulder. It will proof quickly and will have greater oven kick. The fi nished product may be too big to fi t in the packaging, increasing waste product. The fi nished product may have weak sidewalls with a very open cell structure. Water is an excellent crumb softener. It is important to have the right amount in the dough, but not too much.

Yeast Yeast is a living organism which can be affected by storage practices, dough temperatures, pH, availability of water, and food supply. Of these control points, the most important is temperature. Yeasts are microorganisms that convert sugar into alcohol and carbon dioxide.

Yeast’s primary function in a bread dough is to provide leavening. It contributes to ﬂ avor and aroma through fermentation. Several forms of yeast are used: active dry yeast, instant dry yeast, compressed yeast, or cream yeast. The type of yeast used depends on the volume of product.

Home bakers or small retail bakers may use a form of dry yeast since refrigeration is not necessary, and the shelf-life is fairly long. Active dry yeast needs no refrigeration and has 2-12 months storage life, depending on packaging. Active dry yeast must be rehydrated with water at 105-110°F (40-43°C) for about 10-15 minutes before use. Active dry yeast comes in 1 and 2-lb packages hermetically sealed with inert gases or vacuum-sealed for extension of shelf-life as well as larger sized packages.

For instant dry yeast, no refrigeration is required and storage life is one year or more due to packaging in inert gases or under vacuum. Once the package is opened, it is recommended that it be used within three days. Instant dry yeast is extremely convenient since it does not have to be hydrated prior to use unlike the active dry yeast does. It may be added directly with the other dry ingredients and blended, or delayed until no loose water is visible in the dough.

Compressed yeast is commonly used in retail bake shops as well as in large wholesale bakery production. It can be purchased in many sizes, from 1-pound cakes to 50-pound bags. The general water content of compressed yeast is 70% and is highly perishable outside of refrigerated storage conditions of 36-45°F (2-7°C). Bakers should keep only one operating hour’s worth of yeast on the shop ﬂ oor. For unused portions, remove the air from the bag and close it tightly to prevent the fresh yeast from being exposed to higher temperature, moisture, and oxygen, which will cause autolysis. Typical use level in breads is 2-5%.

Autolysis is the process by which the yeast destroys itself through its own enzymes, breaking down the cellular structure of the yeast. This allows the release of glutathione from the yeast cell. Glutathione acts as a reducing agent on gluten proteins and weakens the dough structure. This creates a dough which mixes faster than normal and which is stickier and slacker, requiring more dusting fl our for proper machining. It may also cause longer proofi ng times and greater pan fl ow, along with weaker sidewalls.

Cream yeast is commonly used in wholesale production. Cream yeast is approximately 80% water. It is delivered in a refrigerated tanker truck and pumped into a tank on site. The storage life of this yeast is between 10-14 days. During production, the cream yeast circulates between the holding tanks and the mixer in well-insulated pipes. This prevents the yeast from settling out, and provides for faster scaling and very consistent temperature control. The advantage of cream yeast is that there is no packaging or handling needed. The main disadvantage is the need for specialized handling equipment at the bakery. Generally, this consists of two jacketed stainless-steel storage tanks maintaining storage temperatures in the range of 35-39°F (1-4°C). A bakery will need to process large quantities of yeast to offset the initial equipment costs and possible higher ingredient costs.

Both compressed and cream yeasts must be refrigerated. When converting from one type of yeast to another, water must be adjusted for consistency in doughs.

Yeast performs other functions in addition to leavening. During fermentation, yeast converts fermentable sugars such as maltose, glucose, fructose, and sucrose into carbon dioxide and alcohol, which generates heat. A baker can judge fermentation by monitoring the increase in temperature. Flavors are generated by the acids that are created during fermentation. Acids also mellow the gluten which can reduce the energy requirements to fully develop a dough.

Since yeast’s effectiveness is altered by storage and handling practices, it is critical that the suppliers’ recommendations be followed. Compressed yeast that is allowed to warm on the production ﬂ oor will have less gassing power than fresh yeast brought directly from the cooler and mixed into a dough. Poor yeast handling practices can generate doughs with inconsistent proof times and varying ﬁ nished product volumes. As yeast ages in storage, it’s gassing power reduces. This may be most noticeable in cream yeast. When a yeast supply has aged, proof times may need to be extended slightly in order to achieve the ideal proof height.

Table 1 Handling Conditions of Fresh Baker’s Yeast

Fresh

Cream Yeast Compressed Yeast Storage temperatures 36-45°F 36-45°F (2-7°C) (2-7°C) Shelf-life 10 days 2-3 weeks % water 80% 70% Converting from 1.5-1.8 times compressed

Table 2 Handling Conditions of Dry Baker’s Yeast

Dry

Active Dry Yeast Instant Dry Yeast Storage temperatures Ambient Ambient (unopened) (unopened) Shelf-life 2 years (vacuum) 2 years (vacuum) Percent water 6-8% 4-6% Using the yeast Must be Does not need to prehydrated in be prehydrated 105-110°F (41-43°C) water Converting from 40-50% 33-40% compressed

Salt Salt brings out the fl avor in baked goods. Salt is typically used at levels of 1.50-2.25%. Bread made with less salt will taste blander, and bread made with more than 2.25% salt will taste salty. In addition to adding fl avor, salt also inhibits fermentation due to the osmotic pressure effect, which is the partial dehydration of the yeast cell. Salt also toughens the gluten. Weak fl ours can be strengthened by adding salt. Salt lengthens mixing time, so it is common to delay the addition of the salt until the end of the mixing process. When the addition of salt is delayed, the toughening effect is also delayed, and mixing time can be reduced by 10-20%. The advantages of reduced mixing time include increased mixer capacity in terms of pounds per hour, lower fi nished dough temperatures, and less energy use. Faster fl our hydration also occurs with delayed salt.

Some bakers do not delay the addition of salt due to the increased chances of mistakes: forgetting to add the salt or adding double, and reduced tolerance, resulting in over mixing. When salt is omitted or doubled, the error will be noticeable in processing as well as in the ﬁ nished product. A dough in which the salt addition was forgotten will most likely be over mixed, sticky, and problematic throughout

processing. Simply tasting the dough will be the quickest and easiest way to verify the error. The ﬂ avor of an unsalted bread is extremely bland and unappealing. With no salt present, the dough will proof very quickly.

Sugar The main functions of sugar are to provide food for the yeast and give a sweet ﬂ avor to the ﬁ nished product. In normal bread production, 3-3.5% fermentable solids are required for yeast activity. This food supply can come from added sugar, conversion of starches to sugars, or a combination of both. Sugar is not an essential ingredient. Secondary functions of sugar are all related to non-fermented (residual) sugar. When residual sugar levels are higher, crust color is darker, taste is sweeter, and moisture retention is improved due to the hygroscopic properties of sugar.

There are many kinds of sugars, or fermentable carbohydrates, used in baking. The most common is 42 high fructose corn syrup (HFCS). This syrup has the same sweetness on a solid basis as sucrose (table sugar), it is easier to handle for large bakeries since the syrup can be pumped, and costs less than traditional granulated sugar. The 42 means that 42% of the solids in the syrup are fructose. Higher numbers mean the syrup will be sweeter.

When storing syrups, it is important to keep the temperature slightly warm, around 85 degrees. If the syrup gets cold, it will crystallize during storage. If the syrup gets too hot, it will darken or caramelize. Some companies are reverting back to granulated sugar due to the consumers’ perception that it is healthier than HFCS. Other sweeteners such as honey, brown sugar, and molasses have grown in popularity as consumers purchase more all natural, whole grain, and multigrain bread varieties. Artiﬁ cial sweeteners such as sucralose are used in products when a lower calorie or carbohydrate count is needed.

Use levels for sugars range from 0-15%. When sugar use is higher than 15%, the product becomes a sweet dough. If a scaling error occurs and the sweetener level is too high or too low, production issues and ﬁ nished product attributes will be affected. For example, a dough with too little HFCS being used will perform as if it is under absorbed. The HFCS delivers not only the sweetener,

but a portion of water as well. The dough will be tight and may result in uneven scaling. It may take longer to proof since the food source for the yeast will be limited. The level of residual sugar will be lower, so the crust color of the ﬁ nished product will be very pale. A dough with double the HFCS will behave much like an over absorbed dough. The extra syrup will not only contribute higher levels of sugar, but also additional water. The dough will be very sticky. If it can be processed, it will ferment and proof rapidly. The ﬁ nished crust color will be dark, if not burnt, due to the much higher levels of residual sugars.

Fats and Oils Fats and oils are used in bread production to provide overall lubrication and to aid with slicing. A minimum of 0.7-1% is recommended for good slicing, although some bakers use less than this in low-calorie breads, and higher levels of 2-5% in richer bread products. Besides lubricating the baked crumb, fats and oils also lubricate the dough, easing dough expansion and helping with the handling of the dough throughout the makeup processes. They also tenderize the crumb and improve shelf life by delaying staling. White pan bread usage is between 1.5-3%.

The most commonly used fat or oil is soybean oil. Oil is easier to handle than solid shortening since it can be pumped into the mixer, and, if used in combination with emulsifi ers, the baker can make very good bread using vegetable oil. In an effort to reduce cholesterol, some bakers remove all animal fats such as lard and butter from formulations. Bakers have switched to vegetable oils that have been hydrogenated to become solid fats, and contain high levels of trans fat. Other fat sources are used to reduce the trans fats in fi nished products, and palm has become a low-to-no trans source for those products. When a certain fl avor is desired, that may dictate the fat or oil that is used. Butter is a good example of a specifi c fat imparting a specifi c fl avor.

Milk Milk solids are used in bread formulas for many reasons, and they offer a wide range of functionality. Milk is high in lysine and calcium, and the overall nutritional quality of the milk protein is excellent. Milk solids also impart a rich fl avor to a fi nished product. They also create a deeper crust color which can contribute to an improved fl avor profi le. In addition to fi nished product benefi ts, milk solids provide function and benefi t to dough processing.

Milk is an excellent buffer, so milk solids can slow or regulate fermentation. They also strengthen the gluten matrix, which improves overall process tolerance. Use levels of milk or milk replacers is between 0-4%.

Liquid milk is rarely in the baking industry for two main reasons: it is very perishable, and the serum protein in milk has a weakening effect upon the gluten protein in wheat fl our. By using high- heat treated nonfat dry milk (NFDM), the baker is able to get the benefi ts of milk without the disadvantages. Two disadvantages to NFDM are the cost of NFDM, the introduction of a top 8 allergen. As a result, bakers may use milk replacers because they are less expensive than NFDM and do not contain milk allergens. The replacers are usually blends of soy fl our and whey. The whey provides lactose sugar and some protein. However, the whey only has about 1/3 the amount of protein of the non-fat dry milk, so soy fl our is added to make up for the lack of protein. Whey and soy are also a top 8 allergens, so the pros and cons must be weighed when working these ingredients into formulas.

Mineral Yeast Food Mineral yeast foods are compound ingredients that have three main functions, all of which help maintain consistency. When minor ﬂ uctuations in pH occur in the water supply, mineral yeast food reduces the impact on process and product. When large baking companies want to use standard formulas at different plants in different regions, mineral yeast foods ensure a consistent product.

1. Water conditioner: calcium (carbonate or sulfate) and magnesium (phosphate or chloride) to control water hardness, monocalcium phosphate to control pH 2. Yeast conditioner: ammonium salts supply nitrogen for yeast 3. Dough conditioner: oxidizing agents strengthen protein

Use level of mineral yeast foods ranges from 0-0.75%.

Mold Inhibitors Mold inhibitors are additives that delay mold and bacteria growth. Mold inhibitors will also inhibit yeast growth. To produce a mold- free product, it is most important to have a sanitary production facility where equipment and plant air are kept clean, and employees follow good manufacturing practices. Good sanitation habits will limit the amount of unseen mold that makes contact with the product.

Bread is an ideal medium for mold growth, because mold likes fairly warm temperatures, slightly acidic conditions, oxygen, and moisture. If we do not use a mold inhibitor in the formulation, we can expect mold to appear in 3-5 days on a product stored at room temperature. Freezing or refrigerating product will lengthen the time it takes to make mold appear. However, refrigeration may cause bread to become ﬁ rm more rapidly.

Whether or not mold inhibitors are an essential ingredient depends on the required amount of shelf-life to satisfy the customer. Mold inhibitors are classiﬁ ed as artiﬁ cial or natural. The most commonly used mold inhibitor in bread is calcium propionate, because it is effective and relatively inexpensive. Potassium sorbate and sorbic acid should not be used in dough since they both damage the yeast. Potassium sorbate is often used in 10% solution with water and sprayed on the surface of products after baking. Sorbic acid is oil soluble and can be mixed with the oil used to lubricate slicer blades.

Natural mold inhibitors include vinegar, raisin juice concentrate, and fermented products such as ﬂ our, starch or whey. Vinegar lowers the pH, but it is not a good mold inhibitor by itself. If using raisin juice as a natural mold inhibitor, the sugar in the juice must be factored into the overall formula. Fermented or cultured products are label-friendly. Made by culturing or fermenting lactic acid bacteria, they are generally grain or dairy based (ﬂ our, starch, or whey). During fermentation the lactic acid bacteria produces organic acids and other compounds that work to slow mold.

Enzymes Enzymes are biological catalysts that accelerate chemical reactions. They start the reaction going, but are not changed by it. Most Dough conditioners enzymes are protein materials, but not gluten-forming protein. include: Because enzymes are proteins, they are sensitive to heat, and • Enzymes all enzymes have an optimum temperature range for activity. • Oxidizing agents Within that range, activity increases with temperature until • Reducing agents the denaturation point is reached, and then the enzyme stops • Emulsifiers functioning. Besides temperature, enzymes are also dependent on pH, amount of time allowed for the reaction, availability of water, amount of enzyme used, and the availability of substrate. A substrate is what the enzyme converts in reaction. Each enzyme has a speciﬁ c substrate.

Enzymes are added to bread dough to increase the shelf-life, improve processing of dough, or provide sugars for yeast. There are several enzyme groups that are commonly added to doughs: amylases, proteases, hemicellulases, lipases, and oxidases. Often bakers add enzymes that have been blended together. The baker can add enzymes in powder or tablet form. The amount necessary depends on the strength of the ingredient used and the desired effect.

As an example of what enzymes do in bread, amylases converts starch into sugar and other dextrins by breaking the large starch molecules into smaller ones. The sugars produced provide food for yeast. The right amylase will also make a product softer. Protease enzymes are used to weaken the protein in the dough to decrease mixing time, improve machinability, and/or increase the pan ﬂ ow of the dough. These effects are accomplished by breaking the long protein chains into smaller units

The effects of enzymes depend on time, temperature, and the level of enzyme used. For example, if an equipment breakdown interrupts production, protease enzymes in the dough have more time to work, which creates a greater weakening effect on the protein than was expected. The enzymes will not stop their reactions until they are denatured by the high temperatures of the oven. The amount necessary depends on the strength of the ingredient used and the desired effect.

Oxidizing Agents Oxidizing agents improve dough strength by creating bonds between the protein chains. They improve dough handling for better machining and contribute to improved gas retention giving better volume and tighter grain to the ﬁ nished product. Some oxidants are fast acting, working in the mixer and early make-up stage, while others are late acting, working in the proofer and early oven stage. The amount of use is calculated in parts per million (ppm). Oxidants are available in tablet or powder form. Doughs are generally sensitive to oxidants and optimizing usage levels is as important as proper mix times. Calcium peroxide is considered an oxidant, but is typically used for its dough drying capabilities. It tends to take away the stickiness without stiffening the dough. It is commonly used in bun production. Use levels are about 20-40 ppm, and it is available in a powdered form. It should be added with the other dry ingredients because it reacts immediately on contact with water. Table 3 Action Typical Usage US Limit (PPM) (PPM) Potassium bromate Late 10-30 75 Calcium bromate Potassium Iodate Fast 3-20 75 Calcium iodate Calcium peroxide Fast 40-70 75 Azodicarbonamide Fast 5-45 45 Ascorbic acid Medium 30-100 NONE

Reducing Agents Reducing agents are used to weaken the protein, reducing the mixing times and improving dough machinability. Reducing agents break bonds between the proteins during mixing, the opposite effect of oxidizing agents. L-cysteine is a most common reducing agent used in the US. A 20-40 ppm usage level will give a 25-40% reduction in mix time. The weakening effect can continue out of the mixer, therefore reducing process tolerance, so L-cysteine should only be used when all other methods of mix reduction have been tried. Other reducing agents are inactive dry yeast and sorbic acid.

Emulsifiers Emulsifi ers are added to bread doughs for strengthening the dough and making the product softer. Dough strengtheners are emulsifi ers that function in a dough by bonding with the protein, improving the gluten strength. This results in improved machinability and gas retention. The fi nished loaf should have better volume, symmetry, texture, and grain. A number of the dough strengtheners also function to various degrees as crumb softeners.

Crumb softeners are emulsiﬁ ers which function in a dough by bonding with the starches. They will slow down the crumb ﬁ rming of a product, extending its shelf-life. Mono- and di-glycerides are the most commonly used crumb softeners.

Table 4 FDA Approved Strengtheners And Softeners

US limits Strengthening Softening Sodium Stearoyl -2 Lactylate (SSL) 0.5%* Excellent Very Good Calcium Stearoyl-2Lactylate (CSL) 0.5%* Excellent Good Diacetyl Tartatic Acid Esters of Fat Forming Acids (DATEM) None Excellent Fair Ethoxylated Mono and Diglycerides (EOM) 0.5%* Very Good Poor Sucrose Esters None Excellent Fair Polysorbate 60 0.5%* Fair Very Good Succinylated Monoglyerides (SMG) 0.5%* Good Good Mono and Diglycerides (Mono and Di) None None Excellent

* 21 CFR 136.110: The total alone or in combination cannot exceed 0.5%