Dough, Fermentation and Gluten An Inferiority Complex Carbohydrate Flour Hard or Soft Wheat Milled Ground Starch – primarily wheat but Hard wheat has high protein content – with other seeds can be used (e.g. rice, potato, gluten and is used in breads and quick bread corn…) Varieties: Soft wheat is low protein – used in cakes • Soft wheat – breads and batters pastries and cookies • Hard wheat – bread dough using eggs and yeast • Durum wheat – hardest with most gluten and used for pasta Wheat Anatomy White Flour Kernel – Endosperm, used White Flour is made mostly of the kernel • All-Purpose – used for many recipes and as a to make white flour. thickener(10-12% protein) Germ – Embryo – where • Southern Brands – for biscuits and frying – (8% protein) the sprout emerges, • Unbleached – Preferred for yeast requiring breads (bleach inhibits growth of microbes) Filled with oil and • Bread Flour – Higher protein content (12-14% high gluten nutrients. content) Bran – Protective outer • Cake Flour – High protein 6-8%, low gluten content • Seminola/Durum – high gluten from endosperm shell of the kernel. Fiber Whole Wheat Flour – Ground bran and germ plus the kernel. supplement More dense and will not rise as well (poor gluten formation). 1 Wheat Flour Gluten Starches – complex carbohydrates (70%) Gluten – a combination of two proteins which Fats – low amounts (germ) can stretch to form long elastic strands and ’ Proteins – several proteins including glutenin gives dough plastic (ability to rebound it s and gliadin (make up gluten) shape and keep a shape under pressure). • Helps to keep bubbles of gas in breads and other dough (slice-o-scope) • Called the muscle of flour Gluten – two proteins Gluten formation Glutenin – Long and very large proteins which Stretching of dough pulls the glutenin into long have lots of sulfur atoms. Coiled proteins strands which pulls back when relaxed. which can streatch and recoil. Sulfers help Kneading unfolds and aligns the proteins into hold these together strands Gliadins – Smaller proteins which act like lubricants or ball bearings – allowing parts of glutenins to move past each other Dough Strength = Gluten Formation Gluten Formation Glialdin Oxidizing agents – alter sulfur links and Glutenin increases strengths of gluten • Oxygen in air “ages” by allowing sulfur links to Stretched and kneaded dough Raw un-worked dough Elastic and strong structure = gluten form – giving more cross-links Loose structure – no gluten Coils and sulfur cross-links (black lines) of glutenin give the • Chlorine gas and brominates (can do same elastic ability to dough thing) but no longer approved • High protein (and gluten) flour give strong gas pockets good for breads • Ascorbic acid (vitamin C) is now used • Low gluten flours are weaker tender baked goods – cakes and cookies (that is why you don’t over mix pancake mix) • Also causes the flour to whiten (bleaching) • High water dough (called batter) dilutes gluten so they don’t mix/ bind - Click here to explore Gluten 2 Gluten Formation Shortening Stirring and kneading – release the sulfur ends of To shorten a dough is to weaken the structure glutenin and organize the protein into long strands – more elastic/strong of the protein so the bubbles are not trapped Salt – increases the gluten network by decreasing the and the network collapses charged repulsions between proteins • Fat (shortening) gives thin layers of gluten and Sugar – added sugars limit gluten development Fats and Oils – weaken bonds between glutenin fat are used to make pie crusts and puff pastry strands • Strong rich bread (lots of gluten) panettone – mix Acidity – create more of the same charge (negative) flour + water then kneads to get gluten, then add amino acids on glutenin and repulse each other – fats. weaker breads like sourdough (made sour by lactic acid producing bacteria) Gas Bubbles Yeast and Leavening Gas bubbles, trapped by the gluten and Where do the gas bubbles to make the dough starches create the empty space in breads, rise come from? smaller bubbles are found in pastries Fermentation (yeast ) and CO2 (leavening • Kneading and knocking down bread works to agents) create smaller bubbles and work large gas pockets into more smaller spaces Yeast Growing Yeast Baker’s Yeast – Saccharomyces Louis Pasteur (1859) discovered how yeast cerevisiae works: • Single cell fungus – over 160 species of yeast • Yeast feeds on starches (sugars) in flour • Yeast use sugar to metabolize that food for energy: (metabolism/fermentation) to produce carbon Glucose is converted to alcohol and carbon dioxide dioxide • • Baking expands the CO2 gas and burns off the The CO2 expands pushing the gluten proteins alcohol around in the flour • Bubbles are trapped by gluten and the proteins become fixed as the bread is baked 3 Foods for yeast Forms of Yeast Simple sugars (sucrose, fructose, glucose and Cake or compressed yeast – live pressed maltose) are found in smaller amounts in blocks of yeast. unsweetened flour • Must be kept moist and cold • Since yeast need sugar to grow and produce • Only lasts a few weeks gasses, this flour will give low rising breads • Used by professional bakers and gives best • Added sugar increases yeast activity results • YET – large amounts can decrease the yeast – sweet breads. So does salt! Forms of Yeast Forms of Yeast Active dry yeast – dormant, dried yeast. Instant dry yeast – dormant, dried yeast. • Granules of yeast with a coating from yeast • Improved version of active dry yeast, less debris culture and healthier yeast • Long shelf life (several months) • Long shelf life (several months) • To hydrate, must be soaked in 105-110oC water • No need to hydrate – can add as dry mix Leavening Agents Quick Breads – chemical reactions Dough with low gluten, runny batter and Early breads used potash (extract of wood minimal mixing (biscuits, pancakes) do not ash) for it’s potassium carbonate. have ability to hold gas bubbles for long • When reacted with lactic acid produce carbon • Yeast production takes too long dioxide gas • Quick breads – use a chemical means to Baking Soda– sodium bicarbonate produce gas in a short time • When reacted in water with an acid Most chemical leavening agents produce CO2 will produce CO2 gas gas bubbles from one source or another 4 Baking Powder – a double agent! Preparing the Dough Baking Powders – dried forms of acids and Mixing – add all ingredients together bicarbonate • Starch will swell when wet • Goal is to produce the gas when chemicals are • Enzymes from flour will digest some of the dissolved in water or other liquid sugars reducing yeast growth • Mixed with starch to keep dry • Initial mixing of gluten draws proteins together • Acids vary from tartaric acid (cream of tartar) to but as air oxidizes sulfur ends, the glutens form phosphate acids (which take longer to produce end to end bonds creating long chains acid and work when heated) Autolysis – mix water and flour first to let Double acting powders – create two sets of gluten and starch absorb water before reactions – one set when wet, the other during baking adding rest of components Kneading Rising Kneading stretches and compresses proteins Rising is fermentation (quick breads don’t rise) over and over to strengthen the gluten • Low to mid temps avoid unpleasent yeast network products • Aligns proteins on long strands • When dough doubles in size, bread has finished • Encourages links between strands fermenting/rising • Also creates pockets of air to expand when • High protein flours may need a second rise to heated fully develop gluten – these breads are knocked down or kneaded again and allowed to rise • Low kneaded breads will result in large air during baking pockets with less developed gluten Baking Baking Ovens – see book chapter on types of ovens Late baking – as the temp approaches boiling and processes point: Early Baking – Steam of water in bread or • the starch turns into a gel oven creates further expansion of gasses • and the crust browns • The dough rises from steam and heating of • Finished bread will be fully set and detected by gluten-trapped gas bubbles indirect tapping on the bottom of the loaf • Alcohol from yeast evaporates and brings small • Uncooked bread will be wet with gluten gel and aromatic molecules with it some caramelization – should sound heavy and dense the smell of baked bread! • Cooked bread will be an open sponge and sound hollow 5 Special Breads Biscuits Sourdough Bread – Acid flavor French for twice cooked – originally baked until which enhance gluten formation dry and hard (biscotti cookies are twice • Acid comes from bacterial culture in dough baked) • Maintaining cultured dough with lactic acid • Leavened with carbon dioxide producing agents producing bacteria and specific strains of yeast– not yeast can be used over and over • Early and European biscuits are more like • Cultures are fed flour and water over time. cookies than what we think of biscuits • Other forms of acid used are buttermilk or yogurt • US biscuits – no sugar and sometimes no eggs – instead have moist loose dough with baking soda Pancakes Cakes More flour and thick batter than crepes or Web of flour eggs sugar and fat (shortening) to popovers (more fats and water) produce mostly thin cages of protein around • Folding batter with low water, a bit more salt and the gas bubbles. cooking slow create softer thicker pancakes (less • The more bubbles the more “light” the cake glutten and bigger gas bubbles) • Sugar, butter or fat and low protein cake flour • High mixing, more water, higher heat (quick (about half of all purpose flour) create poorly cooking time) and low salt will produce thinner connected and low amounts of gluten. but more dense pancakes • Too much inhibition of gluten will collapse the cages around the bubbles and a thick cake results Cake Baking Secrets Mixing and baking Cake shortening – hydrogenated vegetable Mixing is critical – introduces bubbles to expand oil with nitrogen gas bubbles works at room during heating temp to mix will.