Week4-Course1 Flashcards
The inclusion of inferior substances having properties similar to the foods in which they are added is ______
Intentional food adulteration
Define food adulteration
Food adulteration can be defined as lowering the quality of food by intentional or unintentional substitution of food with some inferior foreign particle or by removal of some value added food substitute from main food item
The simplest strategy to prove adulteration is to demonstrate the presence of a …….
Foreign substance
What are the three basic strategies that can be followed to demonstrate adulteration?
Demonstrating : 1. Foreign substance
- a component is deviated from nomal level
- that a profil is unlikely to occur
Electronic microscopy is a _____ method
physical
Added water to milk can be detected by measuring milk’s specific gravity. This method is classified as a …… technique for adulteration detection.
Physical
Witch method can you use to detect the adulteration of olive oil with hazelnut oil?
HPLC
What is the most used technique in the analytical techniques of adulterant
HPLC
What is the difference between HPLC and gas chromatography
HPLC is used for non-volatile compounds while gas chromatography is used for volatile compounds
Witch of the techniques can be used as a quality control tool because it can separate various chemical constituents from mixtures and that is also used for characterizing food products
HPLC
Gas chromatography (GC) is a chemical method that can detect ……… to discriminate among different varieties of the same food product, such as wine.
Volatile organic compounds
Name the three techniques that are non-destructives techniques with respect to the sample
- GC
- HPLC
- FTIR
…… is a chemical method that can detect milk adulterants.
FTIR
…… is a chemical method that can detect an adulterant and it can provide structural identification of the adulterant.
NMR (nuclear magnetic resonance)
…… is a molecular method that is used to detect interspecies and varietal adulteration in coffee.
real time PCR
Why is RAPD considered unreliable ?
Because of the lack of reproducibility
What is the structure level that remains intact throughout denaturation
primary structure
Name the phenomena that occurs when proteins form solids or semisoft cloths. Is it reversible?
Coagulation. No it is permanent.
Solidification of eggs is due to ___
thermally induced denaturation of proteins
Production of foam in beaten egg white is due to _____
surface-denatured protein molecules
Production of foam in beaten egg white is due to _____
surface-denatured protein molecules. They encapsulate air bubbles
What does the coagulation change in the case of proteins?
1- changes its physical characteristics
2-alters the ability to bind water (solubility)
3. interferes with biological interactions of enzymes
T or F : some denaturated proteins can return to their original states
T, example of beaten eggs
Name 5 factors that can lead to denaturation
- temperature change
- Mechanical actions
- Sound waves and irradiations
- pH
- exposure to salts, metals or minerals
what is the cause of curdling?
cold temperatures
Why is pH so important in the case of denaturation?
Because changes in pH affects the charge the proteins, it may neutralize the charge and proteins will coagulate
Among the most important physicochemical properties of proteins in relation to their functional properties are their ____
interactions and solubility in water
____ charges between two proteins make the coagulation more difficult because of ____
similar
electrostatic repulsion
Amino acids that are _____ are hydrophilic
polar
What can be the functional groups in the proteins that are hydrophilic and polar
hydroxyl (OH) sulfhydryl (SH) amide (o=c-NH2) carboxyl (COOH_ amino (NH2)
What groups in the proteins are the major contributor of the hydrogen bonds that makes the protein more soluble in water
NH (amine) and COOH (carboxyl)
Hydrophobic amino acids have ____ or ____ side chains
aliphatic
aromatic
What is the most important factor determining the functionality of proteins?
The solubility in water.
What are the three broad classes of proteins
- Globular (soluble)
- Fibrous (insoluble)
- Membrane (insoluble)
Protein denaturation resulting in exposure of the hydrophobic core decreases solubility and may result in _____
protein aggregation (coagulation)
The tertiary structure of ___ proteins is fairly spherical
globular
Name two things that can result in coagulation
1- change in net charge (ph)
2- Denaturation that expose the hydrophobic core outside the protein
What are the two structure coagulated protein can form
1- curds (coagulated mass)
2- gel (entrapping of water in the protein aggregate)
A protein molecule that has significant number of amino acids with carboxylic functional groups in their side chains will be:
hydrophilic
Carboxyl group containing amino acids are more soluble at a pH under ___ because ___
4, because the COOH is ionized to COO- and can make a bond with the H in water
amine group containing amino acids are more soluble at a pH over ___ because ___
10, because NH2 is ionized to NH3+
What are the 4 factors you need to analyse in order to know if a specific protein would be of good use in a product
- degree of water absorption
- solubility
- viscosity
- stability in acids an alkalis (basic) sln
What are the functional properties of proteins in food (7)
- Emulsifying
- Meat analog formation
- Viscoelasticity
- Agents for profuction of flavor/color
- thickening agents
- Gelling agents
- Curd forming
What protein gives pigment in muscle (meat)
myoglobin
What responsible of the brown color in meat
prolonged exposure of myoglobin to oxygen
Why is the maillard rxn unfavorable from a nutritional perspective in the case of lysine
Lysine side chain is NH2, so when it participate in the maillard reaction, the essential amino acid becomes unusable.
Does only amino acids that contain an amine side chain like lysine participate in maillard rxn?
no, every free amine group can take part in maillard rxn.
Does the amine group of attached to the alpha carbon (not of the side chain) can participate in maillard rxn
no, because the peptide bonds transform the amino groups into amide groups for all amino acids in the chain expept the last a.a of the chain
What are the nutritional contributions of proteins in the human body (6)
1-support growth and repair 2-fight disease 3-maintain fluid and mineral balance 4-maintain pH balance 5-control bodily functions 6-provide energy
Why does protein is not a good source of energy other than as last resort
because of the breakdown causing ammonia and ketones, strainning the kidneys
Name example of the function of enzymes in the processing of food and give the enzyme that is associated with the function? (4)
1- HFS (amylase and isomerase)
2-meat tenderization (papain: protease)
3-removal of headspace oxygen from food (glucose oxidase)
4-curd formation (rennet)
