REAKSI MINYAK/LEMAK Dr.Ir. Susinggih Wijana, MS.

Jurusan Teknologi Industri Pertanian

FAKULTAS TEKNOLOGI PERTANIAN

UNIVERSITAS BRAWIJAYA

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Pohon Industri

Kelapa sawit

Pohon Industri

Kelapa

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Flowchart Proses

Minyak Sawit

Tandan sawit

segar

Minyak sawit kasar Inti sawit kering Cairan limbah

DIAGRAM PROSES PEMURNIAN MINYAK SAWIT 1

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Crude Palm Oil

(minyak kasar)

Neutralized, Bleached and

Deodorized Palm Oil

(minyak murni)

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REAKSI PADA SENYAWA MINYAK

A. Reaksi selama prosesing ekstraksi

dan pemurnian

B. Reaksi penyabunan

C. Reaksi hidrogenasi

D. Reaksi trans-esterifikasi

E. Reaksi akibat proses penggorengan

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A. REAKSI PADA PROSES EKSTRAKSI DAN

PEMURNIAN

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Perlakuan fisis :

Degumming,

penghilangan gum

dengan steam.

Bleaching, penghilangan

warna dengan adsorben.

Deodorising, pengilang-

an bau dengan panas

dan tekanan vakum.

Reaksi khemis :

Oksidasi

Penyabunan

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Oksidasi .

Terjadi akibat adanya

panas dan oksigen udara.

Panas proses pengolahan

memacu peristiwa oksi-

dasi, yaitu terbentuk-nya

senyawa radikal bebas.

Radikal bebas dipacu

juga oleh penggunaan

alat dari logam berat (Fe

dan Cu).

Hasil oksidasi lanjut

adalah terbentuk

senyawa malonaldehid

yang berbau tengik

Penyabunan/

netralisasi

Reaksi ini digunakan

untuk menghilangkan

asam lemak bebas

minyak (bau tengik).

Dilakukan dengan

mereaksikan minyak

dengan NaOH

B. REAKSI PENYABUNAN

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Reaksi antara Asam Lemak Bebas dengan basa NaOH (sabun keras) atau KOH (sabun lunak)

Juga merupakan salah satu bagian proses pemurnian minyak (degumming, netralisasi/ penyabunan, deodorizing)

Dalam industri pembuatan sabun dibuat dengan mencampur minyak (TG) dengan NaOH/KOH.

Reaksi :

R-COOH + NaOH R-COO-Na +

HOH

C. REAKSI HIDROGENASI 1

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Tejadi pada minyak yang dijenuhkan

menjadi margarine dan shortening

Menggunakan katalis Pt atau Ni

Jumlah ikatan rangkap mempengaruhi

kebutuhan H2

Terdapat penambahan garam dan vit A

Reaksi :

PROSES PENAMBAHAN HIDROGEN PADA IKATAN RANGKAP ASAM LEMAK

TIDAK JENUH DENGAN BANTUAN KATALISATOR Ni/Pt H2

CH3 - (CH2)7 - CH = CH - (CH2)7 - COOH CH3 - (CH2)16

COOH

Ni/Pt

Tujuan:

1. Menurunkan ketidak jenuhan minyak dengan penambahan H2

Linolenat lenoleat oleat stearat

2. Merobah bentuk fisik Trigliserida dari cair menjadi semi padat

atau padat, tergantung tingkat kejenuhan

3. Menaikkan titik cair

4. Meningkatkan daya tahan trigliserida dari proses oksidasi

TEMPERATUR, TEKANAN, KONSENTRASI KATALIS, KONSENTRASi

HIDROGEN , TINGKAT PENGADUKAN.

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D. TRANS-ESTERIFIKASI

Reaksi Ester Asam Lemak dengan

Alkohol (Alcoholysis)

Reaksi dipercepat dengan

menggunakan katalis basa NaOH

atau KOH

Kecepatan reaksi tergantung dari

suhu, jumlah KOH, jumlah alkohol ,

Digunakan dalam industri bio-

diesel dari berbagai jenis minyak

pangan (goreng) dan non-pangan

(jarak pagar dll.)

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CH2 O COR1 CH2OH

CH O COR2 + 3 (CH3OH) CHOH + 3 (R-COOCH3)

CH2 O COR3 CH2OH

trigliserida metil alkohol gliserol ester asamlemak dg alkohol

(BIODISEL)

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Reaksi Tranesterifikasi

E. REAKSI PADA PROSES PENGGORENGAN 1

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Deep-fat Frying is a process of immersing food in hot oil.

A process of cooking and drying produces unique fried foods by simultaneous heat and mass transfer.

Flavor compounds are formed and retained in a crisp crust of food

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Physical and Chemical Reactions during

Deep-Fat Frying

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Physical Changes of Deep-Fat Frying

Viscosity Increase

Thickening of oil

Decrease of interfacial tension

Increase of density

Increase of the specific heat

OIL CONTENTS IN DEEP-FAT FRIED FOODS 10

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Products Oil Contents (%)

Potato chips 33-38

Corn chips 30-38

Tortilla chips 23-30

Doughnuts 20-25

Frozen food 10-15

French fries 10-15

CHEMICAL CHANGES OF DEEP-FAT FRYING 10/23

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Formation of flavor

Flavor stability and quality changes

Color and texture of the fried foods

changes

Nutritional changes

CHEMICAL REACTIONS IN FRYING OIL

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1. Hydrolysis

2. Oxidation

3. Polymerization

4. Pyrolysis

1. HIDROLISIS MINYAK

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Proses hidrolisis terjadi semakin cepat dengan

semakin tingginya kadar air dari minyak/

lemak maupun dari produk yang digoreng

2. REAKSI OKSIDASI 1

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1. Inisisasi

2. Propagasi

3. Terminasi

Tahapan Oksidasi 1. Tahap Inisisasi

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R + O2 ROO

ROO + RH R + ROOH

ROOH + Fe2+ OH- +

RO + Fe3+

R + R RR

R + O2 ROO

ROO + ROO ROOR

+ O2

Salah satu bentuk ROOR

adalah asam malonal-dehida

(MDA) yang beraroma tengik

2. Tahap Propagasi 3. Tahap Terminasi

CHEMICAL REACTIONS IN DEEP-FAT FRYING

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Volatile Flavor Compounds:

220 volatile compounds have been identified.

DEEP-FAT FRIED FLAVOR 1

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4-hydroxy-2-nonenoic acid, lactone

4- hydroxy-3-nonenoic acid

2,4-decadienal

nutty, fried fat notes plus a butter-like note

Some of volatile compounds formed in deep-fat

frying condition are known as TOXIC COMPOUNDS.

Example:

1,4- Dioxane

Benzene

Toluene

Hexyl-benzene

VOLATILE PRODUCTS FROM DEEP-FAT FRYING

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Acids -- > - Saturated Acids

- Unsaturated acids (cis, trans)

- Hydroxy acids

Hydrocarbons - Saturated hydrocarbons

- Unsaturated hydrocarbons

Alcohols/

Aldehydes - Saturated

- Unsaturated

Ketones

Esters

Aromatic Compounds

Lactones

Miscellaneous: 2-Pentyl furan

1,4-Dioxane

AROMATIC COMPOUND FORMATION

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C H 3 ( C H 2 ) 3 C H 2 C H C H C H 2 C H C H ( C H 2 ) 7 C O O R

O 2

C H 2

C ( C H 2 ) 7 C O O R

O

C H 2 ( C H 2 ) 2 C H 3

C H 2

C H 2

( C H 2 ) 6 C O O R

( C H 2 ) 2

C H 3

D - H O 2

EFFECT OF METHIONINE ANALOGS ON POTATO CHIP-

FLAVOR IN DEEP-FAT FRYING.

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Compounds

Structures

Flavor Characteristics

D-Methionine

L-Methionine

DL-Methionine

CH3-S-CH2-CH2-CH(NH2)COOH

Good potato chip-like

S-Methyl-L-Cysteine

CH3-S-CH2-CH(NH2)COOH

Good potato chip-like

Methionine Hydroxy

Analog

CH3-S-CH2-CH2-CH(OH)COOH

Obnoxious

(cooked turnip)

S-Carboxymethyl-L-

Cysteine

HOOC-CH2-S-CH2-CH(NH2)COOH

Obnoxious

(cooked turnip)

3. POLYMER FORMATION

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Carbon-Carbon Bond: A. Vinyl Type

C

C C

C

C

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B. Diels Alder Type

C C

H

C C C

H H H H

- .H

C

H

H

H H H H

C C C C

C C

H H

C

H

H H

H C C

C

H

C

H C C

Intermolecularly or Intramolecularly

Carbon-Carbon Bond:

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Carbon-Oxygen Bond

Through peroxide group formed by autoxidation.

This can be formed intermolecularly or intramolecularly.

Through ether linkage formed at high temperature.

O

O

O

O

POLYMERS FORMED DURING DEEP-FAT FRYING

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The 74 hrs. deep-fat frying conditions

Trilinolenin 26.3%

Trilinolein 10.0%

Triolein 10.8%

Tristearin 4.2%

TYPES OF POLYMERS

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Trilinolein Monocyclic, Nonpolar C-C Dimer 4.9%

Noncyclic, Polar C-C Dimer 2.8%

Trimers - C-C, 8.4%

Trimers - 2 C-O, or 1 C-C, 1 C-O 4.9%

C O O R

C O O R

COOR

COOR

OH

OH

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C H 2

C H

C H 2

C H 2

C H

C H 2

Dimerization Between Two Acyl Groups in the Same Triglyceride or

Dimerization Between Two Acyl Groups in Two Triglycerides

Dimerization

COMPOSITION OF OXIDIZED AND POLYMERIZED MATERIALS

FORMED DURING SIMULATED DEEP-FAT FRYING AT 185C

FOR 74 HRS.

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TRILINOLEIN

TRIOLEIN

TRISTEARIN

Cyclic Dimers

Carbon-to-Carbon

Linkages

4.9

0.0

0.0

Noncyclic Dimer

Carbon-to-Carbon

Linkages

2.8

3.4

0.7

Trimers

Two Carbon-to-

Carbon Linkages

8.4

0.3

0.4

4.9

1.2

Dimers and Trimers

Carbon-to-Carbon or

Oxygen Linkages

6.2

4. PIROLISIS

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Terjadi akibat

penggorengan

dengan suhu terlalu

tinggi.

Minyak terbakar

menjadi asap CO2

dan H2O

Kehilangan kualitatif

dan kuantitatif.

Aroma dan rasa residu

minyak menjadi pahit

BIOLOGICAL EFFECTS OF USED FRYING OIL

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A slight depression in growth to very poor growth

Diminished feed efficiency

Increased liver, kidney and heart sizes

Fatty tissues of liver, kidney and heart organs

Liver enzymes such as thiokinase and succinyldehydro-

genase had lower activity

The evidence of carcinogenicity (in highly abused

frying oil)

SAFETY 10/23

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Under Good Practice of Deep-Fat Frying:

Fats are not nutritionally damaged

THERMAL OXIDATION EFFECT ON LINOLEIC ACID

CONCENTRATION

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Levels of Linoleic Acid a

FAT FRESH OXIDIZED

Corn oil 61.0 1.1

Olive oil 7.7 Trace

Lear b

21.7 1.1

Lard 10.7 1.4

a

Expressed as % of total fatty acids. b

Lear = Low erucic acid rapeseed oil.

TOXICITY SYMPTOMS OF HIGHLY HEAT-ABUSED OILS TO

LABORATORY ANIMALS

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Irritation of the digestive tract

Organ enlargement (kidney & liver)

Growth depression

Carcinogenic properties

Good Practice of Deep-Fat Frying

Fats are not nutritionally damaged.

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