Emulsi Pada Produk Susu

Chocolate milk and infant formulae

Complete nutritional formula

Kasein Misel

Mengapa susu segar berwarna putih ?

Jawab : • Susu tersusun dari berbagai nutrien yang terlarut

dalam air atau terdispersi sebagai koloid

• Susu segar bukan hanya merupakan larutan dan dispersi koloid, namun juga merupakan emulsi

• Warna putih pada susu segar disebabkan oleh koloid dan emulsi komponen susu (lemak dan protein) dalam fase air.

Mengapa susu segar berwarna putih ?

1. Protein susu - casein micelles

2. Bentuk, ukuran dan kenampakan misel kasein memberikan warna putih pada susu

3. Perbesaran 37,500x (garis: 1.2 µm).

Koagulasi Susu Segar

The coagulation of milk by chymosin includes two separate steps: proteolysis and aggregation

Aggregation behavior of emulsifier molecules(a) Head group larger than the tail: micelle formation in water(b) Cylinder-shaped molecule: formation of parallel bilayers(c) Head group smaller than the tail: formation of inverted micelles, enclosing water.

A schematic drawing of a lamellar phase. The emulsifier molecules are arranged in parallel sheets in such way that the hydrophilic head groups of the molecules are in contact with water and that the hydrophobic chains are in contact with each other

and excluded from water.

Misel Kasein

Caseins exist in large spherical collodial micells with calcium phosphate. These micelles comprises 93% (w/w) caseins and range in size from 500 to 3000 A in diameter. The calcium and phosphate play a very important role in maintaining the integrity of the casein mucelles, and are commonly referred to as colloid calcium phosphate.

Emulsion formation, structure and stability

• During homogenisation, fat globules with sub-micron size are formed

• Milk proteins migrate to the newly formed fat globule surfaces

• Capability to form a stable emulsion is determined by the ability of the protein to unfold at the fat-water interface

• Protein load affects the stability of emulsion towards heating and storage

Fat globules in recombined milk

Natural milk

10 mm

Fat globules in recombined milk

Natural milkRecombined

(homogenized milk)

10 mm 10 mm

Fat Globule Stabilization by Milk Proteins

Protein at fat/aqueous interface

Emulsion destabilisation in recombined milk

• Thermodynamically unstable

• Mechanisms of destabilisation: aggregation, flocculation, coalescence and creaming

Flocculation and coalescence

Aqueous phase

Whey proteins

Oil droplet

Casein micelle

Flocculation and coalescence

Aqueous phase

Flocculation

Whey proteins

Oil droplet

Casein micelle

Flocculation and coalescence

Aqueous phase

Flocculation Coalescence

Whey proteins

Oil droplet

Casein micelle

Consequences of coalescence

Coalescence leads to an increase in the rate of separation

Oil

Water

Particle size distribution – A stable recombined milk

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Freq

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0.01 0.1 1 10 100

Particle size (um)

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0.01 0.1 1 10 100

Particle size (µm)

Particle size distribution – unstablerecombined milks