NFS 53 1st Edition Lecture 15 Outline of Last Lecture I Grains Cereal review II Whole Grains vs Grain Flours III Flour and Baked Goods IV Flours Classed by Use V Flour Water Mixtures VI What is Gluten VII Gluten Development VIII Gluten and Foods IX Working with Gluten X Bread a Role of ingredients b Leavening agents c Leavening Gas Outline of Current Lecture I Characteristics of Gluten II Gluten Limit or develop III Control of Gluten IV Starch and Gas V Yeast Breads These 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 Agents VII Chemical Reactions in Bread Dough VIII Types of Yeast IX Basic Methods of making Yeast Breads X Principles of Making Bread a Mixing and Kneading b Fermentation XI Steps in Making Bread Current Lecture I Characteristics of Gluten a Plastic change its shape under pressure b 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 Gluten a Type of Flour i high protein strong gluten ii low protein weak gluten b Amount of water i more water less concentrated gluten moister dough c Amount of salt more salt effects protein bonds d Sugar limits gluten development e Fat weakens gluten bonds f Acid weakens gluten bonds g Gluten is thus a complex of stretchy spring like glutenins lubricated by a bunch of ball bearing like little gliadins IV Starch and Gas a 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 to pop c Gas bubbles weakens gluten and starch granules creating aeration 80 of volume is empty space V Yeast Breads a Flour high protein content for good gluten development Flours may be mixed to make breads oats rye soy b Liquid dissolution hydration and gelatinization c Salt flavor also favors amylase action and inhibits protein splitting enzymes Can also inhibit yeast growth d Sugar fermentable sugar for yeast VI Yeast as Leavening Agents a 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 f ethyl alcohol carbon dioxide Yeast also effects elasticity stickiness and flow properties of dough VII Chemical Reactions in Bread Dough VIII Types of Yeast a Dry Active available in small packages which will leaven 4 6 cups of flour Needs to by hydrated in 115oF 46oC liquid b Fresh compressed or cake yeast highly perishable because of high moisture content Hydrated in 85oF 29oC liquid c Instant Quick Rising or Fast Acting rises in the time hydrated between 125130oF 52 54oC less time for flavor development IX Basic Methods of making Yeast Breads a 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 Bread a Mixing and Kneading allows development of strong elastic gluten i Starch meets Water 1 Starch granules absorb water 2 Enzymes create sugars 3 Yeast Cells feed on sugars and create carbon dioxide and alcohol ii Gluten is formed 1 Long chains are formed 2 Gluten network is strengthened 3 Dough is aerated b Fermentation period where dough is allowed to rise in bowl and yeast produces leavening 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 C iii Fermentation is complete when the volume of the dough doubles iv Types of Fermentations 1 Lactic acid fermentation a Conversion of pyruvate to lactic acid b Common to many bacteria species c Very important for preserving foodstuffs 2 Ethanolic fermentation a Conversion of pyruvate to ethanol and carbon dioxide b Common to yeasts c Very important for bread baking and for alcohol production c 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 Bread a 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 534 b Choices made in every step along the way determines final qualities in the loaf