Introduction proteins Flashcards
Measuring protein content (how much protein)
Dumas or Kjeldahl
Protein composition (Which proteins are present)
SDS-PAGE
FUNCTION OF THE PROTEIN: Solubility: Emulsification/foaming: Gelation: Viscosity: Water binding: Fat and flavour:
FOOD:
Solubility: beverages
Emulsification/foaming: soups, salad dressing, whipped toppings, ice cream
Gelation: meat products, candy, pasta
Viscosity: soups, salad dressings
Water binding: meat products, cakes, breads
Fat and flavour: drinks, bakery products
DRIVERS PROTEINS:
- *Varability between variants/batches of the same ingredient.
- *Increase flexibility in applications of the ingredient.
The different steps in the production process of protein (figure 4)ingredients lead to 2 important consequences on their functionality (figure 5):
1- There can be a large varation in functionality within a set of similar protein ingredients ( milk, whey protein).
2- The difference in functionality between proteins from different sources (whey , soy) can be similar or smaller than the range of varation within a set of samples for each source separately.
SOURCES (4) AND VARATION IN PROTEIN(functional properties 2) SAY THE STEPS
*Source :Plant / Animal
*Isolation :Purity / composition
*Modification (optional) :Maillard/ hydrolysis
*Heating / processing: Unfolding / Aggregation
**Powder properties: Particle size / wettability/colour
Dispersability / Solubility.
**Molecular properties: Solubility (pH / I),mHeat stability.
**–> functional properties
TYPE OF FUNCTIONALITY
- Nutritional. (essential amino acids –> primary structure)
- Phisiologycal. (bio- active peptides, anti nutritional factors, e.g gluten )
- Physical/ technological. (texture in bread, beer foam –> primary and tertiary)
Proteins do not always denature when heated (TRUE/FALSE)
TRUE: During spray drying Evaporation of water (takes energy) - Cools down product - Decreased water content - Increased denaturation temperature, Temperature of the protein/droplet is always below of the Td.
Higher Td in dry conditions, so more protein unfolding during heating in solution (pasteurisation) than during spray drying.
Protein concentrates and isolates heterogeneous or homogeneous?
heterogeneous
Protein concentrates and isolates… they contain…. and can be present in different forms
*They contain non protein compounds
*The ‘main’ protein can be present in different forms
-glycated (coupling to reducing)
-denatured
-aggregated
**Sources contain different classes of proteins
**The classes consist of different types of proteins
**Each type of protein can be present in different
states
Solubility of hydrolysates affected by: and give a reason of the decrease of solubility at higher pH (when hydrolyzes)
Solubility of hydrolysates affected by:
(1) Exposure hydrophobic groups and
(2) Loss of single pI (different pI).
EXPLANATION:
Increase of the solubility when we hydrolize, At high pH typically we see a decrease in the solubility when we hydrolize ( intact protein has a folder structure where all the hydrophobic groups are in the inside, hydrophilic outside, when i hydrolizes the structure is lose and the hydrophobic aminoacids are expose like to interact and make agreggation, the other point native protein at pH 8 is negative charge, easy to be desolved, electrostatic repulsion but when i hydrolizated i lose the repulsion energy, there is going to be positive and negative peptides and maybe can interact together).
Native protein only one isoelectric point, low solubility at pI.
What can you say about the solubility of proteins from the different sources below ? Milk, Meat and Egss
The natural state of the proteins in milk and eggs, is that they are in a solution. Therefore, these proteins will have a good solubility (in water). Proteins in muscle tissue should not dissolve in water, and therefore are typically poorly soluble.
