food commodities Flashcards
choux pastry, bread making, emulsions, milk, eggs, fats, cheese, yoghurt, fruit and veg
what is the ratio of choux pastry?
3:1flour to fat
why should you cool the choux paste before adding the eggs?
so they don’t denature and cook
what are some examples of choux?
chocolate eclairs, profiteroles, gougers, churros
what is the scientific process of browning in choux pastry?
the dry heat from the oven breaks down the carbohydrates into dextrins, dextrinisation occurs creating a brown surface, which is called the maillard reaction, the sugar caramelises and the pastry turns golden
how to cook choux pastry:
use a high temperature and DO NOT open the oven door, as this raises the liquid rapidly to boiling point, helps to produce steam and acts as raising agent, cold air will be introduced to the oven and the pastries will sink
what is the function of flour in choux
oo/ plain flour forms the bulk/ structure, acts as a thickening agent, gluten strands stretch to allow the gas bubbles to expand
what is the function of butter in choux
enriches the dough
what is the function of water in choux
binds the dry ingredients together to produce a dropping consistency, converts to steam during cooking and acts as a raising agent
what is the function of eggs in choux
the protein in egg dentures on heating and coagulates- which sets the mixture, adds colour, flavour and HBV protein
what is the purpose of a choux paste?
removes lumps, develops gluten strands when you beat it (which helps the pastry stretch when it rises), traps air (which acts as a raising agent)
what are the sensory qualities of choux
well risen- does not collapse, crisp texture, golden brown colour, hollow centre which is not soggy or doughy, light and airy
reasons for why the choux mixture is too thin to pipe:
too much water used, water not at boiling point or was allowed to cool when flour was added, too much egg, incorrect proportions/ ratio of ingredients, not enough flour
reasons for why the choux pastry has a dense and heavy texture when cooked:
too much flour used, not enough water, incorrect oven temperature, incorrect proportions, opened the door during cooking
what are the main ingredients used to make bread, and why are they used?
strong plain flour- high gluten content which gives a strong elastic dough
yeast- to make the bread rise
salt/sugar- to add flavour and control action of the yeast
fat- to extend shelf life
water- to activate gluten formation
define the term ‘leavened’ in bread making
a substance has been added to the dough to start fermentation and make it rise
what is yeast, and how is it used in bread making to make the dough rise?
microorganism that produces gas to make the dough rise (multiplies and turns starches and sugars into alcohol and produces carbon dioxide gas)
why is yeast mixed with warm water before adding it the flour? what would happen if it was mixed with hot or cold water?
so that it can multiply
cold water- wont multiply
hot water- kills the yeast
what is the name the proteins found in flour
gliadin and glutenin
why are gliadin and glutenin important in bread making?
because when water is added, the 2 proteins join together to form gluten. gluten gives the dough softness and elasticity (so it can expand when the gas bubbles produced by yeast form)
gluten also sets when the bread is baked (forms the structure of bread)
what are the main stages of bread making?
mixing, kneading, proving, knocking back, shaping, baking
define ‘kneading’ and why it is important in bread making
working/mixing the ingredients together
helps gluten formation which softens and strengthens the dough
define ‘proving’ and why it is important in bread making
leaving the dough to rise
this helps the yeast cells multiply and produce carbon dioxide gas
define ‘knocking back’ and why it is important in bread making
removing large gas bubbles
which ensures a more even texture and better rise
what is unleavened bread
bread made without yeast or other raising agents
extended question: describe the function of strong plain flour, yeast and water when making bread and explain how they work together to produce a quality product (8 marks)
strong plain flour
-provides gluten
-forms an elastic stretchy dough- when mixed with a liquid
-gluten stretches to hold the co2 bubbles produced by yeast
-provides structure- coagulates when cooked at high temp
-enables dextrinisation of starch- brown colour
yeast
-uses both respiration and fermentation to develop
-produces gas bubbles which is trapped by the dough and makes the bread rise
-uses available sugar for growth
water
-binds dry ingredients together
-if warm, provides suitable condition for yeast to activate
-provides moist conditions for the yeast
what is the yeast used by bakers called?
saccharymosa cereviserae
what is a colloidal structure?
more than one ingredient mixed together
fill in the blank:
colloidal structures give _______ to many products
texture
how are colloids formed
when one substance is dispersed (mixed) through another
give an example of a liquid colloid
vinegar, oil, water, milk
give an example of a gas colloid
air, carbon dioxide
give an example of a solid colloid
starch granules e.g. corn flour, arrowroot, wheat flour
what are the 5 colloidal structures
emulsions, foam, solid foam, gel, suspension
what 2 parts make up an emulsion
give an example
liquid + liquid
e.g. olive oil + vinegar
-mayonnaise
what 2 parts make up a foam
give an example
gas + liquid
e.g. air bubbles + egg white
-beaten egg white
what 2 parts make up a solid foam
give an example
gas + solid
e.g. air bubbles + baked egg white
-meringue, cakes, bread
what 2 parts make up a gel
give an example
liquid + solid
e.g. water, juice + fruit
-jams, jellies, cheesecake, pana cotta
what 2 parts make up a suspension
give an example
solid + liquid
e.g. starch grains + milk
-white sauce, blended sauce
define the term immiscible
give an example of 2 immiscible ingredients
substances that cant mix or dissolve in each other to form a homogenous mixture as they separate
e.g. water and oil
what emulsifier does egg yolk contain
lecithin
what is an emulsifier
give examples of some
‘match maker’- helps to bring 2 immiscible parts together
-lecithin in egg yolk (natural)
-lecithin in soya beans (synthetic and cheaper)
-glycerol monostearate/ GMS (made from glycerol and stearic acid, used in margarine)
what is a temporary emulsion? give an example
blending of ingredients that eventually separates
e.g. simple vinaigrette
what is a permanent emulsion? give an example
mixing of ingredients that come together and do not separate
e.g. mayonnaise
how is an emulsion made
when 2 equal parts of liquid are mixed together with a match maker (emulsifier)
define hydrophilic
water loving (e.g. water)
define hydrophobic
water hating (e.g. oil)
describe the steps you would take if mayonnaise curdles
pour out the curdled mixture into a measuring jug, put another egg yolk in the processor and gradually pour in the curdled mixture, then the remaining oil
what should you do if a cake mixture curdles?
add a tbsp of flour to the mixture
what is it meant by the plasticity of fats and explain why margarine has more plasticity than lard
plasticity= the ability of fat to soften over a range of temperatures and be shaped and spread with light pressure
margarine has more plasticity because it contains more unsaturated fats
name all the nutritional values of milk?
good source of HBV protein-3.5%
calcium
contains 55% water
3-5% fat
what does calcium need to be paired with to be absorbed?
vitamin D- complementary
how is milk treated??
via heat
what is the first step of the milk process and how does it work?
pasteurisation- heat raw milk to 75* for 25 seconds then rapidly cool to 5*- to kill any unwanted bacteria
what is the second step of the milk process and how does it work?
homogenisation- breaks up fat globules so they can be evenly distributed through the milk, creating a emulsion
what is the third step of the milk process and how does it work?
skimming- separate the cream (fat) from the milk, to produce semi and fully skimmed milk
what is the fourth step of the milk process and how does it work?
sterilising- place milk into sealed bottles and heat to 110-130* for 30 minutes
what is the last step of the milk process and how does it work?
Ultra-heat treating (UHT)- where milk is heated to 135* for 1 second, sealing it into storage packs that can be stored for up to 6 months
how should fresh milk be stored?
in a fridge (1-4C). must be sealed (lid) to prevent it from absorbing any strong smells such as garlic.
out of sunlight
when milk is heated it often forms a skin on the surface. why?
as the proteins denature
what are the main uses of milk in cooking?
sauces, batters, custards- gives nutrients and adds a creamy texture
what are the main substitutes for cows milk?
almond, oat, soy, rice and coconut milk
what are the main groups of people that won’t consume cows milk?
vegans, lacto-vegetarians, lactose intolerant
name all the classes of eggs?
battery, barn, free-range, organic
what information has to be printed on every egg?
the lion mark- food safety such as being vaccinated against salmonella, passport system (code), best before date, method of production, strict food safety controls
what are the 4 different sizes of eggs and name all their weights?
small- under 53g
medium- 53-63g
large- 64-73g
v large- 73g +