Question

1 Provide a term that matches each description below. a Mixture of liquids that are usually immiscible b Reagent used to test for the presence of starches c The pH at which the net charge of a protein is zero d Chemical test for the presence of simple carbohydrates such as lactose e Major class of proteins found in milk f Chemical test for the presence of proteins .. g Solid mixture of protein and fat formed by adding acid to milk h Aqueous liquid formed by removing proteins and fat from milk 2 Complete each sentence below. a The first step in the separation scheme for milk involves removing the curds by treating the milk with and b The curds are removed from the aqueous portion (whey) by ......... filtration. is removed from the curds by mixing the solids with ethyl acetate, leaving behind a relatively pure protein called d Water-soluble are precipitated by heating the whey, leaving an aqueous mixture primarily composed of ..... and 3 Explain why ethyl acetate, a nonpolar solvent, can be used to separate the nonpolar fats from the casein protein.

Answer 1

1 (a) emulsion

Explanation:-2 liquids are said to be immisible if they are insoluble in each other.

(b)Iodine

Explanation:iodine turns blue or black in the presence of starch di to the formation of an intermolecular charge-transfer complex.

(c)Isoelectric point

Explanation:- As pH value increases most of the protein gains negative charge. When the pH is equal to the isoelectric value (pl) the protein has zero net charge

(d)Benedict's reagent

Explanation:- A positive test is shown by color change from clear blue to brick red precipitate.

(e)Casein

Explanation:-In cow's milk approximately 92% of milk protein is casein and remaining 18%is serum,or whey protein

(f)Biuret solution test

Explanation:-Blue coloured biuret solution in presence of protein changes to pink purple color .

(g)curd

Explanation:when milk is acidified they transform into a solid component, called curd.

(h)Milk serum

Explanation:-milk serum is milk minus fat globules and casein micelles

2(a) acetic acid; heat

(b)vacuum

(c)milk fats; casein

(d)whey protein;simple carbohydrate; soluble ions

3. A non polar solvent can separate a non polar fat because like dissolves in like.