BREAD

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

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

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

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  1780steam power  1870use of steel rollers

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

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

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

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

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

CakeAll-purposeStrong bread

Alternative leavening agents  Baking powder  Acid + alkali mix  Cream of tartar & baking soda  Produces CO 2 when heated  Mechanical  Beating or creaming to whip in air  Steam generation  Whipped egg white

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

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

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

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

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

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

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