Food Analysis: Analysis of Lipids & Proteins

What are the general steps in the Kjeldahl method?

• Distillation - Digestion - Titration

• Digestion - Distillation - Titration

• Titration - Digestion - Distillation

• Titration - Distillation - Digestion

Answer explanation

The correct steps in the Kjeldahl method are Digestion, Distillation, and Titration, making the correct order Digestion - Distillation - Titration.

What is the difference between Dumas method and Kjeldahl method?

• Dumas method is Time consuming

• Dumas method has affordable equipment

• Dumas method uses hazardous chemicals

• Dumas method can analyze many samples

Answer explanation

The correct choice highlights that the Dumas method can analyze many samples, distinguishing it from the Kjeldahl method.

The end point color of biuret method is...

• Green

• Red

• Blue

• Purple

Answer explanation

The correct end point color of the biuret method is purple, indicating the presence of proteins.

In Lowry Method, what kind of special reagent is added to the samples?

• Tyrosine and Tryptophan residues

• Folin Ciocalteau phenol

• Biuret reagent

• Lowry reagent

Answer explanation

In the Lowry Method, Folin Ciocalteau phenol is added as a special reagent to the samples for protein quantification.

What is the most distinguishing element present in proteins?

• Nitrogen

• Sulfur

• Carbon

• Hydrogen

Answer explanation

The most distinguishing element present in proteins is Nitrogen.

Proteins have ___ levels of structure.

• 1

• 2

• 3

• 4

Answer explanation

Proteins have 4 levels of structure: primary, secondary, tertiary, and quaternary structures, each contributing to the overall function and shape of the protein.

When a protein loses its shape it's called: _______________ .

• denaturation

• degradation

• decomposing

• determent

Answer explanation

When a protein loses its shape, it is called denaturation. Denaturation involves the disruption of the protein's structure without breaking its peptide bonds.

Which of the following will cause proteins to lose their shape?

• heat

• enzyme

• salt

• all of these

Answer explanation

Proteins lose their shape due to heat, enzymes, and salt. Therefore, all of these factors will cause proteins to lose their shape.

Which method measures total nitrogen?

• Kjeldahl

• Dye-binding

• Lowry

• Biuret

Answer explanation

The method that measures total nitrogen is Kjeldahl. It is a widely used method for determining the nitrogen content in organic compounds.

_________ method quantifies total protein by complex formation of cupric ions with proteins.

• Lowry

• Kjeldahl

• Biuret

• Dye-binding

Answer explanation

The correct method that quantifies total protein by complex formation of cupric ions with proteins is the Biuret method.