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BREAD. C ereals provide Bread. Cereals are the World’s staple Provide the majority of carbohydrates as starch for the world’s population Members of the grass family Wheat Rice Maize Oat, Rye Barley, Sorghum. How are they used ?. Direct consumption Rice, Maize, Oats

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BREAD


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    Presentation Transcript
    1. BREAD

    2. Cereals provide Bread • Cereals are the World’s staple • Provide the majority of carbohydrates as starch for the world’s population • Members of the grass family • Wheat • Rice • Maize • Oat, Rye Barley, Sorghum

    3. How are they used? • Direct consumption • Rice, Maize, Oats • Milled for flour • Wheat, Rice, Maize, Rye • Milled for starch • Maize, wheat, rice • Fermentation substrate • Barley, Wheat, Rye, Rice, Maize

    4. Milling • Grains crushed by a series of rollers • Remove hull and bran • Remove germ (embryo) • Pulverise endosperm • Wholemeal flour • Contains bran & embryo • Higher lipid content, rancidity problem

    5. Mills • 8,000 BC first grain crops, hand crushing • 1,500 BC Millstones • 1,000 BC animal powered mills • 400 BC watermills • 1,000 windmills • 1780 steam power • 1870 use of steel rollers

    6. Flour • Carbohydrate • Bulk of endosperm, in intact starch granules • Protein • Endosperm storage proteins • Wheat 13% protein • Glutenin & Gliadin • Lipid • Mostly removed with embryo

    7. Types of Flour • Strong flour • From hard wheat • High protein content • For bread • Soft flour • From soft wheats • Lower protein content • For cakes & biscuits

    8. Bread • Dough formation • Mixture of flour & water • Water uptake depends on protein content • Kneading • Developing gluten • Leavening • Generation of gas to expand dough • Baking

    9. Straight Dough • Flour & water mixture • Yeast, leavening agent • Sugar for yeast growth • Salt for yeast metabolism • Fat to soften texture, reduce staling. • Saturated fats better • 5% in bread 30-50% in cakes • Milk to improve crumb texture • Kneading to mix thoroughly • Develop elastic gluten network

    10. Proofing • Incubate 30°C 1 to 2h • Yeast fermentation • Production of ethanol & CO2 • Gas expands dough • Elastic dough will stretch • Punching, allows some CO2 to escape • Moulding & shaping

    11. Cake All-purpose Strong bread

    12. Alternative leavening agents • Baking powder • Acid + alkali mix • Cream of tartar & baking soda • Produces CO2 when heated • Mechanical • Beating or creaming to whip in air • Steam generation • Whipped egg white

    13. Baking • 250 – 300°C, 30 – 60 min • Further gas generation • Dough rises to final shape • Yeast killed off • Starch gelatinises • Gluten coagulates • Bread becomes hard • Crust develops and browns

    14. Sponge Dough • Moderately stiff dough • Only 50 % of the flour + yeast & sugar • Fermented 3 –4 hours • Remaining flour, fats & water added • Finer texture, smaller gas holes

    15. Batter whipped process • Chorleywood Process • Continuous production • Liquid fermentation with little flour • Remaining flour added • Agitated to incorporate air • Extruded into baking pans • Fine uniform texture

    16. Starch • Starch, main polysaccharide in flour • Present in starch granules • Contains 2 polysaccarides • Amylose & amylopectin • As heat increases • Starch granules absorb water & swell • Release amylose from granule • On cooling • Amylose molecules combine to form gel

    17. Starch Retrogradation • Realignment of amylose chains • Stick to each other more strongly • Forms more rigid crystalline structure • Slow process so takes time • Inhibited by fats that can interact with amylose • Starch becomes harder

    18. Staling • Stale bread = old bread • Harder texture • Crumb more brittle • Dryer, poor release of flavour • Promoted by low temperature • Regeneration possible by wet heat

    19. Bread deterioration • Prone to fungal contamination • Fungal growth normally prevented in foods by low humidity and temperature • Dry storage at low temp. promotes staling • Added mould inhibitors common • Eg. Calcium propionate