Manipulating and combining food materials and components and the application of this in food processing and product development

  • Created by: AbbieKP56
  • Created on: 06-06-17 10:20

Modified starch

  • Modified by cross linking and stabilising.
  • Cross linking improves process tolerance meaning that the starch can withstand heating, stirring, acids, pumping and packaging.
  • Stabilising helps resist retrogradation.
  • The starch has freeze and thaw stability.
  • Also a 'novel food'.
  • It is classified as a smart food and is used by manufacturers in a variety of products.
  • Pizza toppings - topping thickens when heated in the oven and will not run off the pizza.
  • Sauce/gravy granules - boiling water can be added to thicken without the sauce going lumpy.
  • Modified starch is used as a fat replacer in low-fat meals.
  • The noodles in 'pot snacks' are pre-gelatinised; so boiled water will reheat and 'cook' them.
  • Modified starch is used in 'cup-a-soups' to improve mouth-feel, thicken then drink/soup when the boiled water is added, and blend uniformly without lumps.
  • Modified starches allow sauces to be reheated by syneresis.
  • This is useful in dishes that are cooked from frozen, e.g. Lasagne
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Factors affecting consistency of gels

  • The presence of acid, e.g. lemon juice hydrolyses stach and reduced gel strength forming a viscous plate.
  • An example of this is the lemon sauce in a lemon meringue pie.
  • The presence of sugar reduced gel strength because sugar competes with starch for water, thus reducing the viscosity of the gel.
  • The proportion of amylose in the starch affects the gel because amylose aids gelling and therefore high amylose starches are used where a rigid gel is needed. More likely to retrograde.
  • If there is too much present, the starch may only partially gelatinize and the sauce may go lumpy, due to lack of available moisture.
  • Insufficient amylose present and the sauce may not gel.
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Interaction of foods in sauces

  • Essential ingredients are starch and liquid. Fat is added to enrich and to give a glossy apperance.
  • Blended method - starch blended with some liquid to seperate the starch. Liquid is heated to almost boiling, before the blended starch is added. The mixture is stirred until gelatinisation occurs.
  • Roux method - fat is melted and flour is stirred in. The starch is coated with fat and cooked over a low heat. Remove from the heat and add liquid. Starch forms suspension in cold liquid. Return to heat and gelarinises.
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Interaction of foods in pastries

  • Short crust - popular for pies, flans, tarts. Short, crisps, light. Flour, fat and water are used. Fat is rubbed into the flour, liquid hydrates the flour particles, forming gulten. When baked the fat melts and is absorbed by the flour. The starch gelatinises. Gulten coagulates.
  • Flaky/rough - flour, fat and liquid used. Fat coats some of the flour particles. Water hydrates the flour particles, forming gluten strands. The dough is rolled out and fat spread over the dough. When baked the fat melts, water evaporates, lets off steam and the dough rises in layers.
  • Puff - flour, fat and liquid used. Fat coats some of the flour particles. Water hydrates the flour particles, forming gluten strands. The dough is rolled out and folded nine times, with fat added to each layer.
  • Choux - melted fat and hot water. Eggs are beaten in. The melted fat is absorbed by the flour, starch gelatinised, liquids releases steam and egg and flour proteins coagulate.
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Interaction of foods in cakes and biscuits

  • Flour - forms framework of cake. Low gluten soft flours are used.
  • Raising agent - enables the cake to rise, e.g. baking powder
  • Fat - entangles and holds air in the mixture.
  • Sugar - sweetens, entangles air, increases volume
  • Eggs - enrich the colour and flavour
  • Liquid - enable the gelatinisation of starch and hydration of gluten
  • Whisking method - eggs, sugar, flour, high quantities of air are incorporated. Air and steam act as raising agents.
  • Creaming method - the butter and sugar are creamed together, liquid added, flour added.
  • Melting method - used for biscuits such as gingerbread. The ingredients of syrup, sugar and fat are melted. Egg, flour, raising agents and flavourings are added. Fat and sugar are absorbed by the flour. Carbon dioxide and steam expand the product.
  • Rubbing in method - fat is rubbed into flour. Egg and milk are added, with gluten strands forming. When heated the gluten strands coagulate, fat is absorbed by the flour, starch gelatinises, egg and flour proteins coagulate and air and carbon dioxide expand the mixture.
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Interaction of foods in bread

  • Flour - strong flour is required. High proportion of gluten. When hydrates, forms very elastic gluten.
  • Liquid - too much weakens the gluten and too little produces a stiff dough with little gluten development. Temperature should be 25 - 27 degrees so it does not kill the yeast.
  • Yeast - acts as a raising agent as ferments to produce carbon dioxide. Provided with sugar to help development.
  • Salt - gives flavour to the dough, strengthens the gluten and slows the action of yeast
  • Fat - enriches the dough and improves softness and colour. Delays staling
  • Kneading - traps air in the dough, develops the gluten, breaks the chains of yeast so an even texture is obtained.
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