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36 Valorization of By-Products of Milk Fat Processing

36.2

Processing of Milk Fat and Its By-Products

Raw milk received in the dairy plant is often standardized in terms of its fat and

solids not fat (SnF) content, to meet statutory guidelines. This requires the separa-

tion of cream from the received milk, and recombining the cream and skim milk in

pre-calculated proportions, resulting in a stock of cream with the dairy. The cream

is either directly or after a period under cold storage channeled to the process line

of other value-added products such as ice cream, butter, butter oil, ghee, etc. In pro-

cess of conversion of cream to butter or ghee, two major and potentially valuable

by-products, namely butter milk and ghee residue, respectively, are generated.

36.3

Valorization of Buttermilk

The churning of cream (oil-in-water emulsion) leads to formation of butter

(water-in-oil emulsion) through a process of controlled phase reversal. The aqueous

solution that is removed amid the process of cream churning (destabilization) dur-

ing butter preparation is referred to as butter milk. This aqueous solution is known

to contain the components of the cream, which majorly include water-soluble

components such as minerals, milk proteins and lactose and are more importantly

fragments of milk fat globule membrane (MFGM).

It is well established that the MFGM is a thin (∼15 nm) layer and is built of a

complex mixture of polar lipids (constituting 90% of dry weight) and proteins [1].

The polar lipids present in MFGM are primarily glycerophospholipids consisting

of phosphatidylserine (PS), phosphatidylethanolamine (PE), phosphatidylcholine

(PC), phosphatidylinositol (PI), etc. A second group is composed of sphingolipids;

among which sphingomyelin (SM) is the most abundant.

The composition of sweet (from fresh cream), sour (from aged cream)

dried buttermilk, in terms of moisture, fat, proteins, lactose, total minerals,

respectively, are 2.8% and 4.8%, 5.3% and 5.7%, 34.3% and 37.6%, 50.0% and

38.8%, and 7.6% and 5.7% [2]. Since buttermilk contains nutritive elements such as

proteins, minerals, phospholipids, etc., this by-product is a valuable commodity in

terms of its nutritional and functional attributes. Buttermilk, being a by-product of

fat processing, is low in fat and calories and hence an ideal beverage for persons

having obesity-related disorders. It is also a good source of vitamin B12, thereby

helping in cell repair due to an active functional role in the synthesis of amino

acids and fatty acids. Regular consumption of buttermilk is known to protect

against ailments such as heart diseases, cancer, diabetes, etc. [3]. It also alleviates

stress and anemia and plays an important role in promoting nerve cell growth [4].

The addition of buttermilk, both in its fluid and powdered form, to foods with

special function, offers benefits such as improved antioxidant potential and notable

buffering effect.

Buttermilk is known to help to prevent colon cancer and helps in reduction of

cholesterol levels [5]. Even at minute amounts, sphingolipids are highly bioactive

compounds making it beneficial. Regular consumption of buttermilk could provide