the simplest form of mixture.
it is when ingredients dissolve into a liquid, becoming homogeneous (as one).
oil and water mixed together.
an emulsifier is needed to keep them mixed togetjer, egg yolk contains an emulsifier called Lecithin. amufacturers use emulsifiers in cake mix, butter, margarine, cho, mayonnaise, salad crea, etc.
in a suspension, a solid won't dissolve in a liquid and will sink if not stirred.
starchy suspensions can be prevented by heating, which causes gelatinisation.
a gel is a thick solution, and is when a small amount of solid sets a lot of liquid.
pectin helps jams and jellies set when mixed with acid from the fruit and sugar.
foam is when air is mixed with a liquid, for example in meringues air is whipped into egg whites.
sugar can stabilise the foam, and stop it changing and separating.
heating coagulates (semi-solidifies) the protein, and sets the foam in meringues.
types of production
developed to see if the product would sell.
jobbing/ one-off production
one product is made, and every item is unique and made to specific requirements.
it needs specialised workersand takes more time, so the product is more expensive, but is high quality.
this is used when making specific quantities of a product, and batches can be repeated as many times as required.
the machinery and labout used is flexible so the manufacturers can alternate between batched of similar products, however there needs to be time between batches for cleaning called down time, which is unproductive and can cause the manufacturer to lose money.
the product is made 24/7, so is used for products that are sold regularly in large numbers such as baked beans.
the specialised equiptment required is expensive, so it is expensive to set up, and the costs too much to turn off, so has to be kept running continuously. if anything goes wrong, it takes time to get the process re-started, which loses money.
computer aided manufacturer includes using bread makers and electronic scales.
it makes manufacturing products quicker and reduces the number of workers needed, so reduces cost. it alsi improves the quality and consistency of the product.
it is hygenic because food is not handled by people, and the machines do the work, so it is often safer for the workers.
bacteria are microscopic, single-celled organisms found everywhere, and are the main cause of food poisoning.
in the right conditions (warm and moist with a food source), they multiply rapidly. food symptoms include sickness, diarrhoea, stomach cramps, fever and in extreme cases death.
high risk foods
bacteria prefer moist foods that are high in protein. these are high risk foods:
- meat, fish and poultry can contain salmonella, and raw meat can contain E-coli.
- dairy products and eggs can contain Listeria, a bacteria that causes food poisoning, if unpasteurised. raw eggs contain salmonella.
- gravies, stocks and sauces sometimes contain the bacteria clostridium perfringens, which causes…