NFS 53 1st Edition Lecture 15Outline of Last Lecture I. Grains/ Cereal reviewII. Whole Grains vs. Grain FloursIII. Flour and Baked GoodsIV. Flours Classed by UseV. Flour-Water MixturesVI. What is Gluten?VII. Gluten DevelopmentVIII. Gluten and FoodsIX. Working with GlutenX. Breada. Role of ingredientsb. Leavening agentsc. Leavening= GasOutline of Current Lecture I. Characteristics of GlutenII. Gluten: Limit or develop?III. Control of GlutenIV. Starch and GasV. Yeast BreadsThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.VI. Yeast as Leavening AgentsVII. Chemical Reactions in Bread DoughVIII. Types of YeastIX. Basic Methods of making Yeast BreadsX. Principles of Making Breada. Mixing and Kneadingb. FermentationXI. Steps in Making BreadCurrent LectureI. Characteristics of Glutena. Plastic: change its shape under pressureb. Elastic: resists this pressure and wants to move back to original shape.Elasticity relaxes over time.c. Strong elastic gluten works for yeasted breads and puff pastry. Does not work well for cakes, cookies and such.II. Gluten: Limit or develop?a. Develop for breads and chewy preparation.b. Limit for cakes, cookies and tender preparations.III. Control of Glutena. Type of Flouri. high protein = strong glutenii. low protein = weak glutenb. Amount of wateri. more water, less concentrated gluten, moister doughc. Amount of salt – more salt effects protein bondsd. Sugar – limits gluten developmente. Fat – weakens gluten bondsf. Acid – weakens gluten bondsg. Gluten is thus a complex of stretchy, spring-like glutenins lubricated by a bunch of ball-bearing-like little gliadins IV. Starch and Gasa. For palatability, baked products must be porous and light. Thus, the goal is to create leavening through the process of making and baking breads.b. Starch accounts for 70% of weight of flour, tenderize gluten, helps water vapor topop.c. Gas bubbles weakens gluten and starch granules, creating aeration. (80% of volume is empty space!)V. Yeast Breadsa. Flour - high protein content for good gluten development. Flours may be mixed to make breads-oats, rye, soyb. Liquid - dissolution, hydration, and gelatinization.c. Salt - flavor, also favors amylase action and inhibits protein splitting enzymes. Canalso inhibit yeast growthd. Sugar - fermentable sugar for yeast.VI. Yeast as Leavening Agentsa. Yeasts have been used to encourage leavening in wheat dough for thousands of years.b. The leavening process identified by Louis Pasteur in the 1800s.c. Yeasts are microscopic single-celled fungi.d. Yeast - Saccharomyces cerevisiae, cells metabolize sugar (fructose, glucose, sucrose, maltose) and release CO2. e. C6H12O6 --> 2 C2H5OH + 2 CO2 glucose ethyl alcohol carbon dioxide f. Yeast also effects elasticity, stickiness, and flow properties of dough.VII. Chemical Reactions in Bread DoughVIII. Types of Yeasta. Dry (Active) – available in small packages which will leaven 4-6 cups of flour. Needs to by hydrated in 115oF (46oC) liquidb. Fresh – compressed or cake yeast, highly perishable because of high moisture content. Hydrated in 85oF (29oC) liquidc. Instant, Quick-Rising, or Fast-Acting – rises in ½ the time, hydrated between 125-130oF (52-54oC), less time for flavor developmentIX. Basic Methods of making Yeast Breadsa. Straight dough - liquid warmed with sugar, salt and fat. Cooled, yeast is added to mixture. Flour added, beaten, more flour, kneaded, then raised.b. Batter or No Knead - more liquid, gluten develops in bowl as batter is beaten.c. Sponge - liquid, sugar, yeast, and part of the flour are mixed. Allowed to become light and fluffy in bowl, remainder of flour, fat, and salt are added. Kneaded and raised.X. Principles of Making Breada. Mixing and Kneading - allows development of strong elastic gluten. i. Starch meets Water1. Starch granules absorb water2. Enzymes create sugars3. Yeast Cells feed on sugars and create carbon dioxide and alcoholii. Gluten is formed1. Long chains are formed2. Gluten network is strengthened3. Dough is aeratedb. Fermentation - period where dough is allowed to rise in bowl and yeast producesleavening gas.i. Fermentation has become a more general term for the mass growth of bacterial and fungal cultures.ii. Best temperature for fermentation of bread dough is 80’F/35’Ciii. Fermentation is complete when the volume of the dough doublesiv. Types of Fermentations1. Lactic acid fermentationa. Conversion of pyruvate to lactic acidb. Common to many bacteria speciesc. Very important for preserving foodstuffs2. Ethanolic fermentationa. Conversion of pyruvate to ethanol and carbon dioxideb. Common to yeastsc. Very important for bread-baking and for alcohol productionc. Punching - light kneading after fermentation prior to shaping.d. Proofing - final rising in the pan after dough is shaped.e. Oven spring - rapid increase in loaf volume when first put into the over for baking.XI. Steps in Making Breada. “There are four basic steps in making bread. We mix together the flour, water, yeast and salt; we knead the mixture to develop the gluten network; we give the yeast time to produce carbon dioxide and fill the dough with gas cells; and we bake the dough to set its structure and generate flavor.” Harold McGee, page 534b. Choices made in every step along the way determines final qualities in the