NE41102-Topic 5

NE41102- Fats and Oil Technology

Semester 1 Session 2023/24

Fats Modification:

Hydrogenation

To know the principles and the application of
major technologies and processes in edible

fats and oils production.

Hydrogenation process..

•

During hydrogenation, vegetable oils are reacted
with hydrogen gas at about 60ºC.

•

A nickel catalyst is used to speed up the reaction.

•

The double bonds are converted to single bonds in
the reaction. In this way unsaturated fats can be
made into saturated fats – they are hardened.

Why Hydrogenation?

• Convert vegetable oils into plastic fat forms
• Two reasons:

1. Change into physical forms with consistency and

handling characteristics required

2. Increase oxidative stability

•

Depends on conditions used, the starting
oils, degree of saturation or isomerization!

Hydrogenation Process

• Hydrogenated products = very complex

mixture of simultaneous reactions occur:
– Saturation of double bonds
– cis-/trans-isomerization of double bonds

➢Changes from low-melting cis form to higher melting

trans form

– Shifts of double bond locations

➢Affects melting point

1. Iodine value – Wij Iodine reach with double bond

where there was direct relation with iodine value and
degree of saturation

2. Bromine water test. Unsaturated vegetable oils
contain double carbon-carbon bonds. These can be
detected using bromine water (just as alkenes can be
detected). Bromine water becomes colourless when
shaken with an unsaturated vegetable oil, but it stays
orange-brown when shaken with a saturated vegetable
fat

Testing of double bond

• 2 types of unsaturated fatty acid

– cis configuration — "on the same side" in Latin
– trans configuration — "across" in Latin

Substrate for Hydrogenation

Hydrogenation Process

Hydrogen Gas

+

Nickel Catalyst

160 - 200 0C

Unsaturated and cis-unsaturated

fatty acid

IV of RBD Soya Bean Oil = 125

Double bond

partial

Double bond

trans-unsaturated fatty acid

Single bond

full

Saturated

IV of Hydrogenated Soya Bean Oil = 70

Hydrogenation Process

• How?

Unsaturated fatty acids

contain one or more double bonds

[liquid, lower melting point]

Chemically react hydrogen gas with double bond

More saturated fatty acid

Shifting to new position / twisting to trans configuration

[increase melting point]

Hydrogenation Process

• How? Three Reactants:

1. Unsaturated oil
2. Catalyst
3. Hydrogen gas

–

Dissolved in liquid oil

Hydrogenation Process

• How?

Hydrogenation Process

• Operating variables

– Oil, hydrogen, catalyst
– sufficient supplied of

hydrogen will increase
reaction rate > trans-
isomer decrease, flatter
SFI curve

Hydrogenation Process

• Operating variables

– any condition affects the catalyst surface or

controls the supply of gas to catalyst surface ~

1. Temperature

•

Rate

•

Solubility of hydrogen gas

•

Selectivity

•

Fatty acid configuration

Hydrogenation Process

• Operating variables

2. Hydrogen Pressure

•

Availability of hydrogen gas

•

Selectivity

•

Fatty acid configuration

Hydrogenation Process

• Operating variables

3. Agitation

•

Solubility of hydrogen gas

•

Selectivity

•

Fatty acid configuration

Hydrogenation Process

• Operating variables

4. Catalyst

o

Level / concentration
➢

Rate

o

Type
➢

Nickel, sulfur-poisoned/treated catalyst, copper
chromite catalysts, precious metals (palladium)

o

Poisons (from refined oils and hydrogen gas)
➢

Sulfur, phosphorus, water, FFA

o

Reuse

How the catalyst work…

Hydrogenation Process

• Operating variables

5. Source oils

•

Type of unsaturated fatty acids

•

Number of unsaturated fatty acid per triacylglyceride

Fatty Acid

Relative Reactivity

C-18:3 Linolenic

40

C-18:2 Linoleic

20

C-18:1 Oleic

1

Hydrogenation Process

• Systems

– Batch (simplicity, flexibility)

• Two different designs

1.

Recirculation
»
Filled with hydrogen under pressure in
recirculation system

2.

Dead-end
»
Hydrogen is added and vented when endpoint
reached

»
Safer, more versatile, lesser oxidation and
hydrolysis

Recirculation System

The reaction mixture (oil, H2
and catalyst) is continuously
re-circulated by an external
pump through an external
heat exchanger and a venturi
jet that is located inside the
autoclave, where fresh H2 is
added (see figure 2). These
reactors are generally
referred to as ‘loop-reactors’

Dead-end System

Hydrogenation Process

• Systems

– Continuous

•

Limited, due to variety of products to be
hydrogenated

Hydrogenation Process

• Control / endpoint?

– SFI
– IV
– Refractive Index
– Melting point
– Quick titer (refractometer)

Hydrogenation

• Product modification

– Softness, plasticity, organoleptic

– More selective hydrogenation process with higher

temperature, lower hydrogen pressure, lower
hydrogen gas solubility, higher catalyst selectivity

➢Product with steeper SFI (more trans- formed)

Hydrogenation

• Product modification

– Less selective hydrogenation process with lower

temperature, higher pressure, lower catalyst
selectivity level

➢Product with flatter SFI (less trans- formed)

Source: http://blog.fooducate.com/tag/hydrogenation/

Hydrogenated Fats Consumption

Source: http://www.purplemedicalblog.com/2005/12/what-trans-fat-labels-meanread-them.html

Major Food Sources of Trans Fat for American Adults

(Average Daily Trans Fat Intake is 5.8 Grams or 2.6 Percent of Calories)

Hydrogenated Fats in Food Product

Thank You

To know the principles and the application of
major technologies and processes in edible

fats and oils production.

Hydrogenation process..

•

During hydrogenation, vegetable oils are reacted
with hydrogen gas at about 60ºC.

•

A nickel catalyst is used to speed up the reaction.

•

The double bonds are converted to single bonds in
the reaction. In this way unsaturated fats can be
made into saturated fats – they are hardened.

Why Hydrogenation?

• Convert vegetable oils into plastic fat forms
• Two reasons:

1. Change into physical forms with consistency and

handling characteristics required

2. Increase oxidative stability

•

Depends on conditions used, the starting
oils, degree of saturation or isomerization!

Hydrogenation Process

• Hydrogenated products = very complex

mixture of simultaneous reactions occur:
– Saturation of double bonds
– cis-/trans-isomerization of double bonds

➢Changes from low-melting cis form to higher melting

trans form

– Shifts of double bond locations

➢Affects melting point

1. Iodine value – Wij Iodine reach with double bond

where there was direct relation with iodine value and
degree of saturation

2. Bromine water test. Unsaturated vegetable oils
contain double carbon-carbon bonds. These can be
detected using bromine water (just as alkenes can be
detected). Bromine water becomes colourless when
shaken with an unsaturated vegetable oil, but it stays
orange-brown when shaken with a saturated vegetable
fat

Testing of double bond

• 2 types of unsaturated fatty acid

– cis configuration — "on the same side" in Latin
– trans configuration — "across" in Latin

Substrate for Hydrogenation

Hydrogenation Process

Hydrogen Gas

+

Nickel Catalyst

160 - 200 0C

Unsaturated and cis-unsaturated

fatty acid

IV of RBD Soya Bean Oil = 125

Double bond

partial

Double bond

trans-unsaturated fatty acid

Single bond

full

Saturated

IV of Hydrogenated Soya Bean Oil = 70

Hydrogenation Process

• How?

Unsaturated fatty acids

contain one or more double bonds

[liquid, lower melting point]

Chemically react hydrogen gas with double bond

More saturated fatty acid

Shifting to new position / twisting to trans configuration

[increase melting point]

Hydrogenation Process

• How? Three Reactants:

1. Unsaturated oil
2. Catalyst
3. Hydrogen gas

–

Dissolved in liquid oil

Hydrogenation Process

• How?

Hydrogenation Process

• Operating variables

– Oil, hydrogen, catalyst
– sufficient supplied of

hydrogen will increase
reaction rate > trans-
isomer decrease, flatter
SFI curve

Hydrogenation Process

• Operating variables

– any condition affects the catalyst surface or

controls the supply of gas to catalyst surface ~

1. Temperature

•

Rate

•

Solubility of hydrogen gas

•

Selectivity

•

Fatty acid configuration

Hydrogenation Process

• Operating variables

2. Hydrogen Pressure

•

Availability of hydrogen gas

•

Selectivity

•

Fatty acid configuration

Hydrogenation Process

• Operating variables

3. Agitation

•

Solubility of hydrogen gas

•

Selectivity

•

Fatty acid configuration

Hydrogenation Process

• Operating variables

4. Catalyst

o

Level / concentration
➢

Rate

o

Type
➢

Nickel, sulfur-poisoned/treated catalyst, copper
chromite catalysts, precious metals (palladium)

o

Poisons (from refined oils and hydrogen gas)
➢

Sulfur, phosphorus, water, FFA

o

Reuse

How the catalyst work…

Hydrogenation Process

• Operating variables

5. Source oils

•

Type of unsaturated fatty acids

•

Number of unsaturated fatty acid per triacylglyceride

Fatty Acid

Relative Reactivity

C-18:3 Linolenic

40

C-18:2 Linoleic

20

C-18:1 Oleic

1

Hydrogenation Process

• Systems

– Batch (simplicity, flexibility)

• Two different designs

1.

Recirculation
»
Filled with hydrogen under pressure in
recirculation system

2.

Dead-end
»
Hydrogen is added and vented when endpoint
reached

»
Safer, more versatile, lesser oxidation and
hydrolysis

Recirculation System

The reaction mixture (oil, H2
and catalyst) is continuously
re-circulated by an external
pump through an external
heat exchanger and a venturi
jet that is located inside the
autoclave, where fresh H2 is
added (see figure 2). These
reactors are generally
referred to as ‘loop-reactors’

Dead-end System

Hydrogenation Process

• Systems

– Continuous

•

Limited, due to variety of products to be
hydrogenated

Hydrogenation Process

• Control / endpoint?

– SFI
– IV
– Refractive Index
– Melting point
– Quick titer (refractometer)

Hydrogenation

• Product modification

– Softness, plasticity, organoleptic

– More selective hydrogenation process with higher

temperature, lower hydrogen pressure, lower
hydrogen gas solubility, higher catalyst selectivity

➢Product with steeper SFI (more trans- formed)

Hydrogenation

• Product modification

– Less selective hydrogenation process with lower

temperature, higher pressure, lower catalyst
selectivity level

➢Product with flatter SFI (less trans- formed)

Source: http://blog.fooducate.com/tag/hydrogenation/

Hydrogenated Fats Consumption

Source: http://www.purplemedicalblog.com/2005/12/what-trans-fat-labels-meanread-them.html

Major Food Sources of Trans Fat for American Adults

(Average Daily Trans Fat Intake is 5.8 Grams or 2.6 Percent of Calories)

Hydrogenated Fats in Food Product

Thank you