Food Proteins - Soy Flashcards
What food properties are organoleptic?
Colour
Odour
Flavour
Texture
What food properties are hydration?
Water holding capacity
Solubility
What food properties are rheological?
Aggregation
Elasticity
Viscosity
What food properties are surface?
Emulsification
Foaming
What is soya?
A hairy stemmed plant of the legume family
Give two examples of non-fermented soy.
Tofu
Soy milk
Given an example of fermented soy.
Soy sauce
How is tofu produced?
- Soak soy beans overnight in water
- Grind soy beans
- Cook soy beans with added fresh water (produces soy milk)
- Coagulation with calcium and magnesium salts (produces curds and whey)
- Whey is drained off
- Curds are pressed in a cheesecloth
How is soy sauce produced?
Production of a fermented paste from soy beans, brine and roasted grain
Pressing of the paste produces a liquid which is soy sauce
What is the fermented paste produced in soy sauce production fermented by?
Aspergillus
What types of molecules do soy beans contain?
Protein Oil Insoluble and soluble carbohydrates Vitamins B and E Phytochemicals Phosphorous Potassium Zinc Iron
What other proteins are soy proteins similar to in terms of protein value?
Eggs proteins
Milk proteins
Meat proteins
Soy = a cheap replacement
What amino acids do soy proteins contain?
A complete range of essential amino acids
What are the two main soy proteins?
Beta-conglycinin and glycinin
What is beta-conglycinin and what is its structure?
Glycoprotein 3 subunits - Alpha ' - Alpha - Beta
What is the structure of glycinin?
Hexamer = 6 subunits - 1a - 1b - 2 - 3 - 4 - 5 All linked by disulphide bonds
How do beta-conglycinin and glycinin differ?
In their gel formation
Beta-conglycinin = soft, transparent, elastic gels
Glycinin = turbid, hard gels
How are soy concentrates produced?
- Clean, crack and hull soy beans
- Heat and flake
- Hexane extraction
- Vapour desolventise
- Remove sugars
- Grind
- Moisten
- Dry
How is soy flour produced?
- Clean, crack and hull soy beans
- Heat and flake
- Hexane extraction
- Vapour desolventise
- Grind
- Moisten
- Dry
How are soy isolates produced?
- Clean, crack and hull soy beans
- Heat and flake
- Hexane extraction
- Vapour desolventise
- Protein solubilizing
- Precipitation with acid at isoelectric point
- Separation of protein flakes
- Spray drying
What are the uses of soy proteins?
Soy flour = bakery
Soy concentrates = bakery, dairy products, meat products
Soy isolates = products used to replace or reinforce (meat substitutes, improve nutritional quality)
What are the functional properties of soy proteins?
- High water holding capacity
- Pasty gel formation
- Fat binding emulsifiers
- Extrusion under high pressure produces pieces resembling dry meat
