Question

Comparison of Fresh and Sour Milk

pH of fresh milk:

pH of sour milk:

Which type of milk has the lower pH?

The greater acidity?

The greater H+ concentration. What organic (carboxylic) acid produces the H+ in sour milk? What is its source?

Answer 1

1) soured milk is food product produced from acidification of milk it is not same as the spoiled milk.fresh milk is some time refered to as a sweet milk.

2) P^H of fresh cow milk in between 6.5 and 6.7

3) P^H of Sour milk is not more than 7 but its P^H = 4.4 it comes under the catagory of acids.

4) soured milk has the lower P^H because it is in acid category i.e P^H = 4.4 but fresh milk P^H=6.6

the pH 6 of milk is due to the casein (milk protein) which is a phosphoprotein and therefore milk is slightly acidic.

during curdling, the lactobacillus keeps growing and it breaks down the lactose (the natural sugar in milk) into lactic acid which acidifies the milk even further.

therefore, the pH of the milk will drop (decrease) (as the more acidic the substance the lower the pH) as it gets converted into curd.

5) the four most abundant fatty acids in milk are myristic,palmitic, stearic, and oleic acids. Myristic, palmitic, and stearic acids are solids at room temperature and oleic acid is a liquid at room temperature.

Lactic acid (2-hydroxypropanoic acid) produces H⁺ in sour milk

Yoghurt is produced by the controlled fermentation of milk by two species of lactic acid bacteria (Lactobacillus sp. and Streptococcus sp.). The acid they produce causes the milk to form a characteristic curd and flavour.