16 kievit concentrate properties

8/2/2019 16 Kievit Concentrate Properties

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Kievit Indonesia March 2008

1998-05-1109-186pc

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Concentrate Properties


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Objective

To understand the different properties of the concentrate.

To understand how the properties interact with each other.


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Concentrate Properties

Main subjects:

Viscosity.

Composition.

Content of dry matter.

Temperature.

Homogenisation.

Pasteurisation.

Density.

Age-thickening. De-aeration.

Agitation.

Crystals.


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the tendency of the liquid to resist flow.

Viscosity

Definition:

The internal friction of a liquid or

The strategy is to maximise the total solids and at the same time

keep an atomizable concentrate.

The usual understanding is thickness of a fluid.


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Evaluation of Atomizability

The concentrate can be atomized if the

concentrate is able to drip from the tip.


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Composition

Viscosity

Content of Dry Matter

Temperature

Homogenisation

Pasteurisation

Viscosity

Viscosity

Factors affecting the viscosity:


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Composition

Increasing ViscosityProtein Increases.

Fat Decreases.

A protein concentrate solution may contain 20% TS and a

carbohydrate solution 70% TS and have the same viscosity.

Keeping the total solids constant and changing

the ratio between ingredients:

Carbohydrate

(excl. of hydrocolloids) Decreases.

Hydrocolloids Increases.

Minerals and Vitamins Decreases.


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Content of Dry Matter

Dry matter is also often called total solids (TS).

Viscosity increases when the dry matter content increases.


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Temperature

Viscosity decreases when the temperature increases.

The upper temperature limit is determined by:

The higher the temperature of the concentrate the closer it is

to its evaporation point.

This means that high concentrate temperature provides

higher capacity than low concentrate temperature.

Denaturation considerations. Preservations of crystals.


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Homogenisation

If using the same total pressure e.g. 200 bar:

Homogenisation increases the viscosity.

This phenomenon is caused by cluster-formation.

One-stage homogenisation e.g. 200 bar will increase the viscosity

more compared with a two-stage homogenisation, e.g. 150/50 bar.

Homogenisation is usually necessary to reduce free fat.


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Pasteurization

Pasteurization increases the viscosity due to

denaturation of proteins.

The degree of denaturation is indicated by thewhey protein nitrogen index (WPNI).

Low heat powder (WPNI > 6 mg/g) agglomerates more easily

compared with medium and high heat powder (WPNI < 1.5 mg/g).

The more intense the heat treatment the lower the WPNI.

The WPNI is the ratio of whey proteins that are soluble.


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Pasteurization

Pasteurization temperature and time influence on the

whey protein nitrogen index (WPNI).


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Pasteurization

S SSH

Hydrophilic

surface

Hydrophobic

centre

Native proteins.

Temperature

stretches protein

and puts strain

on bonds.

Bonds startbreaking at 70C

S SH S

S SH S

SS

H

SH

S

S

S SSH

Hydrophobicsurface

Free bonds find

pairs in other chain


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Density

There is a linear relation between the density and total solidsat constant temperature.

Density (V) is used in the evaporator to control total solids because

it is possible to measure the density very precisely.

NB! The higher the fat content the smaller absolute changes in

density will cause relatively large changes in total solids.

Example cream 53% and skim milk concentrate at 60C:

Skim milk concentrate Cream 53% concentrate

V = 1.2018 g/ml 50% TS V = 1.0492 g/ml 55%

TS.

An absolute reduction 0.0106 in density gives:

V = 1.1912 g/ml

48 % TS. V = 1.0386 g/ml

47 % TS.


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Relation between Density and Total Solids

TS of Milk Concentrate with 26,5 % fat

40

41

42

43

44

45

46

47

48

49

50

51

52

53

54

55

1,1000 1,1025 1,1050 1,1075 1,1100 1,1125 1,1150 1,1175 1,1200

Density, g/ml

TS,

40C

45C

50C

55C

60C

65C


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Age Thickening

high dry matter content

without agitation/movement

for a period of time

is left at high temperature

age thickening can be observed.

When a feed with


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Age Thickening

Viscosity as function of time at

different solids contents (T = 55C)

Viscosity.

Time, h.

Total

solids, %


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Age Thickening

Viscosity.

Temperatures.

Time, h.

Viscosity as function of time at different

temperatures (SM-concentrate 48.5% TS)


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Other Issues

De-aeration and agitation.

De-aeration is usually performed in the evaporator and subsequent

handling should minimise incorporation of air in the concentrate.

Air bubbles in the concentrate will become occluded air

in the powder and reduce bulk density.

If an evaporator is not part of the process,

mixing should be performed under vacuum.

For some products air addition is desirable from

either a drying or product point of view.

The amount of occluded air in the powder can

be determined using a laboratory analysis.


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Particle Density, Interstitial and Occluded Air

Particle density.

Often, particle density should be as high as possible, indicating a

minimum of interstitial air and occluded air.

Interstitial air

Occluded air

Particle density.

Occluded air

forms vacuoles.

Particle

density is the

mass of the

box

divided by its

volume.


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Particle Density, Interstitial and Occluded Air

Occluded air

Interstitial air


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Gas Injected Particle


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Crystals

Crystals in the concentrate.

Crystals are hard to process-equipment and will gradually grind.

Drying may require crystallisation to avoid stickiness.

Atomization should be done with an abrasive resistant

rotary atomizer.

Crystallization will promote the free fat content by destroying

the protective fat globule membrane.


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Evaluation of Drying Behaviour

Look at:

- Film formation

- Stickiness

- Binding strength


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Summary

Milk Composition

Protein content

Fat content

Carboh. content

Mineral content

Milk Composition

Protein content

Fat content

Carboh. content

Mineral content

Heat Treatment

Past. system

Indirect

Direct

Past. temperature

Holding time

Heat Treatment

Past. system

Indirect

Direct

Past. temperature

Holding time

Evaporation

Concentrate TS

Concentrate density

Conc. temperature

De-aeration

(Fouling in evaporator)

Evaporation

Concentrate TS

Concentrate density

Conc. temperature

De-aeration

(Fouling in evaporator)

Homogenisation

Pressure

One or two stage

Homogenisation

Pressure

One or two stage

Concentrate

Viscosity

Concentrate

Viscosity

Spray

Drying

Spray

Drying

Age-thickening

Agitation

Age-thickening

Agitation

Milk Quality

Acidity

pH

Milk Quality

Acidity

pH

CrystalsCrystals

16 kievit concentrate properties

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