CORN OILAn emerging industrial

product

Ambika Rajendran. R, Nirupma SinghVinay Mahajan, D.P. Chaudhary

Sapna, R. Sai Kumar

DIRECTORATE OF MAIZE RESEARCHNew Delhi – 110 012 (India)

Correct citation:Ambika Rajendran. R, Nirupma Singh, Vinay Mahajan, D.P. Chaudhary,Sapna & R. Sai Kumar. Corn Oil: An emerging industrial product.2012. Directorate of Maize Research, New Delhi, Technical Bulletin,No. 8: 36 p.

© Directorate of Maize Research, New Delhi

Printed:2012

Published by:Director,Directorate of Maize ResearchPusa Campus, New Delhi-110 012 (India)Ph: 91-11-25841805, 25842372, 25849725FAX: 91-11-25848195Email: pdmaize@gmail.com

Printed by:Alpha Printographics (India)Mobile : 9811199620, 9999039940

Preface

Maize is an abundant food and feed crop.Diversied use of crop adds higher value to itscultivation and production. Maize is one suchcrop which yields several useful products. Henceit remains one of the favourite crops in industrialsector. Among several corn related products,corn oil is an emerging one. The recent surge ofurbanisation, health consiouness and improvedlife style of masses demands quality productsfor consumption. Corn oil is becoming popularamong edible oils owing to its unique healthrelated benefits. Corn oil extraction also opensup new avenues of enterprenuership to corngrowers and processsors. This booklet providestechnical as well as scientific information forharnessing the oil value of corn.

Authors

CONTENTS

PARTICULARS PAGE No.

1. INTRODUCTION 1Corn Oil Value 2

2. CORN OIL IN EDIBLE OIL INDUSTRY 10Extraction of Corn Oil 11

3. PRODUCTION TECHNOLOGY 13Xenia effect and High Oil Corn production 15

4. HIGH OIL CORN IMPROVEMENT 17

5. PROSPECTS, STRATEGIES AND GOALS 19

5. SIGNIFICANT REFERENCES 23

1

INTRODUCTION

Corn is one of the most successful food, feed and industrialcereal. Industries consume 12-15% of corn production in India.Corn flour, corn oil, cornflake, corn syrup, popcorn, rice cornand corn soap are some popular corn products. Corn oil is apale yellow oil procured from the kernel of corn. The firstcommercial production of corn oil took place in 1889. Refinedcorn oil is tasteless and odorless oil. Corn oil is used as acooking medium and for manufacturing hydrogenated oil.

Figure 1. a. Parts of corn kernel, b. Nutrient composition of corn kernels

Corn having oil content of more than 6% is called high oilcorn. The parts of corn seed/kernel are endosperm (82%), germ(embryo and scutellum) (12%) (Figure 1 a & b). 80 to 84% oftotal kernel oil is present in the germ region followed by 12% inaleurone and 5% in endosperm.

b

a

2

Corn Oil Value

Among the grain crops, the oilis highest in oats (Figure 2).Unsaturated fats are found inproducts derived from plantsources, such as vegetableoils, nuts, and seeds. There aretwo main fatty acids:polyunsaturated (PUFA) (highconcentrations in sunflower,corn, and soybean oils) andmonounsaturated fatty acid(MUFA) (high concentrations incanola, peanut, and olive oils).The high PUFA content meets the essential fatty acidrequirements in human nutrition. In corn oil, the total percentageof PUFA constituted by linoleic acid (18:2) alone is about 60%

Good cooking oil

1. Canola oil

2. Flax seed oil

3. Groundnut oil

4. Olive oil

5. Non-hydrogenatedsoft margarine

6. Safflower oil

7. Sunflower oil

8. Corn oil

Figure 2. Percentage distribution of total oil, PUFA, MUFA andSFA content in cereals (Dunford, 2005)

3

and MUFA (oleic acid; 18:1) is about 24%. Among saturatedfatty acids (SFA), palmitic acid (16:0) is almost 13% and stearicacid (18:0) is 1%. The percentage of PUFA is high in corn amongcereals (Figure 2). Figure 3 shows the percentage of fatty acidsin common edible oils in total fat percent. SFA is highest inpalm kernel and coconut oil. Corn oil ranks fourth in PUFAcontent. Olive and canola oil are highest for MUFA.

Corn oil is a rich source of linoleic acid (essential fattyacid), which is one of two essential acids necessary for theintegrity of the skin, cell membranes and the immune systemand for synthesis of eicosanoids necessary for reproductive,cardiovascular, renal, gastrointestinal functions and resistanceto disease and it is highly effective for lowering serumcholesterol, primarily low-density-lipoprotein cholesterol.Omega-6 fatty acid is rich in corn, safflower, sunflower, soybean,and cottonseed oil. Oil has good stability in cooking and storagebecause of low proportion of linolenic acid, a fatty acid prone tooxidation.

Utilisation of high oil corn in livestock feed increases energydensity, allows a higher gain: feed consumption ratio, improvesamino acid balance and reduces the need for expensive dietarysupplements. High oil corn has higher total protein containinghigher levels of essential amino acids like lysine, threonine andmethionine. High oil corn is better in all nutrients except starchcontent of normal corn. High oil corn has larger embryo whereamino acids are well balanced. It is also recognized as anexcellent source of antioxidants (tocopherol) and Vitamin E.Antioxidants are important health wise and helps retards oilrancidity. Corn oil contains 968 milligrams of phytosterols per100 gram of oil. It has one of the highest phytosterol levelsamong the refined vegetable oils. Phytosterols reduce bloodcholesterol by inhibiting its absorption from the intestines. Cornoil is the only product containing a natural mixture of freephytosterol, phytosterol esters and phytostanol esters. Table 1summarises the features of important edible oils including cornoil.

4

Figure 3. Percentage of fatty acids in edible oils in totalpercent of fat

5

Tota

l oi

lco

nten

t

Tem

pera

ture

Vit

amin

s/M

iner

als

(*pp

m.

stan

ds f

orpa

rts

per

mil

lion

)

Fats

MU

FA /

Ole

ic

Cor

n O

il

3-4

%

Med

ium

Tem

p.45

7°F

(Hig

h)

Om

ega-

6 &

3, V

itam

inC

, H

ighe

stam

ount

of

antio

xida

nts

amon

g al

loi

ls

25%

Can

ola

43 %

450°

F(m

ediu

mte

mpe

ratu

re)

Not

to

beus

ed a

t hi

ghte

mpe

ratu

re

Vita

min

A,D

,E,K

;O

meg

a-3,

beta

-ca

rote

ne

61%

Sunf

low

er

45%

Hig

h 47

5°F

Vita

min

E(h

ighe

st),

Om

ega-

6

20%

Oli

ve

30%

375-

468°

F(d

epen

ding

on t

he t

ype)

Not

to

beus

ed a

t hi

ghte

mp

Ant

ioxi

dant

s

77%

Saff

low

er

30-4

0%

Hig

h 50

9°F

Vita

min

E,

Om

ega-

6Cis

-lin

olei

c

13%

Soya

bean

20%

Hig

h 44

0°F

Om

ega-

3Vita

min

E

24%

Ric

e B

ran

3% 490°

F(H

igh)

Vita

min

E,

Squa

lenc

e,N

eutr

aceu

ti-ca

l,G

amm

a-or

yzan

ol

47%

Mus

tard

Oil

34%

489

°F

Ant

ioxi

dant

sEs

sent

ial

Vita

min

s

60%

Tabl

e 1.

Sum

mar

y of

feat

ures

of i

mpo

rtan

t edi

ble

oils

6

SFA

:M

UFA

:PU

FA

Dig

estib

ility

PUFA

/Li

nole

icac

id

Satu

rate

dfa

ts

62%

13%

13:

25:

62(H

igh

PUFA

)

Hig

h

33%

7% 6: 6

2: 3

2(L

owes

tSF

A)

Slow

sdi

gest

ion

69%

11%

9: 8

2: 9

(hig

hol

eic)

,9:

65:

26 (reg

ular

)11:

20:

69(l

inol

eic)

Impr

oves

appa

rent

dige

stib

ility

of S

FA,

MU

FA a

ndPU

FA b

utre

duce

s th

ere

tent

ion

ofM

UFA

and

PUFA

9% 14%

14:7

7:8,

1- O

meg

a-3

(Hig

hest

MU

FA)

Goo

d ev

enat

hig

hte

mpe

ratu

re

77%

10%

9: 1

3: 7

8(H

igh

PUFA

)

Goo

d

61%

15%

15:

24:

58,

3-O

meg

a-3

Low

Dig

estib

ility

33%

20%

22:4

3:35

(Hig

hM

UFA

)

Easi

lydi

gest

ed

21%

13%

3:65

:25,

7-O

meg

a-3

Stim

ulat

esdi

gest

ion

7

Col

our

Tast

e/A

rom

a

Vis

cosi

ty /

Oil

den

sity

Use

s

Gol

den

Yel

low

Red

dish

shad

e

Tas

tele

ss

Low

visc

osit

y

Fry

ing,

baki

ng,

sala

d

Ligh

t ye

llow

Mild

fla

vour

Slig

htly

thic

ker

invi

scos

ity

Fryi

ng,

baki

ng, s

alad

dres

sing

Pale

Tra

nspa

rent

Yel

low

Yes

(Hig

hO

leic

),N

o(R

egul

ar)

Low

visc

osity

Coo

king

,sa

lad

dres

sing

s,

Yello

wis

h to

gree

n(G

reen

er i

tis

, pur

er i

tis

)

Stro

ngfl

avou

r

Saut

ee,

stir

fryi

ng,

cook

ing,

Pale

Yel

low

No

flav

our

Odo

urle

ss

Coo

king

,sa

lad

Cle

ar,

tran

spar

ent,

wat

er l

ike

colo

urLi

ght

Yel

low

No/

Bol

dta

steB

land

(Non

Spi

ced)

Med

ium

Odo

ur

Slig

htly

thic

ker

invi

scos

ity

Coo

king

,sa

lad

dres

sings

,ve

geta

ble

Ligh

tgo

lden

colo

ur

Plea

sant

nutt

y &

butt

ery

tast

e

Ligh

tvi

scos

itym

akin

g it

non-

stic

kyan

d ea

sily

emul

sifie

s in

dres

sing

san

d sa

uces

Coo

king

,fr

ying

, de

epfr

ying

,

Yel

low

Pung

ent

tast

eSpi

cyod

our

Coo

king

,fr

ying

, de

epfr

ying

,

8

dres

sing

s,m

arga

rine

,sh

orte

ning

1. E

asy

toD

iges

t2.

Ben

efi-

cial

to

hea

lth

hear

t3.

Red

uce

risk

of

Ch

ron

icd

isea

ses

1. L

ower

risk

of

hear

tdi

seas

e2.

Low

erra

tes

ofca

ncer

mar

gari

ne,

shor

teni

ng

1. L

ower

the

leve

l of

bad

chol

este

rol

wit

hout

low

erin

gle

vel

ofgo

odch

oles

tero

l

sala

d oi

ls,

mar

gari

ne

1. R

educ

ehe

art

dise

ase,

ris

kof

som

eca

ncer

,di

abet

es2.

Infl

uenc

ebo

dy f

atdi

stri

butio

n

dres

sing

s,m

arga

rine

1. H

elps

in

losi

ngw

eigh

t2.

Red

uce

leve

l of

chol

este

rol

3. S

tren

gth-

en i

mm

unity

4. H

elps

in

trea

tmen

t of

diab

etes

5. P

rom

otes

hair

gro

wth

and

ahe

alth

y sk

in

oil,

mar

gari

ne,

1. R

educ

eca

ncer

cel

lac

tivi

ty2.

Low

erch

oles

tero

l3.

Hel

ps i

nco

ntro

lling

oste

opor

osis

4. C

ontr

olbl

ood

suga

rle

vel

5. C

heap

sala

ds,

dres

sing

s.Ve

ry c

lean

flav

oure

d &

pala

tabl

e.

1. N

och

oles

tero

l&

No

tran

sfa

tty a

cids

.N

atur

ally

low

in

satu

rate

dfa

t.2.

Ric

h in

olei

c an

dlin

olei

cfa

tty a

cids

.3.

Nat

ural

lyfr

ee o

f tr

ans

fatty

aci

ds(T

FA’s

)

sala

ds,

dres

sing

s.Ve

ry c

lean

flav

oure

d &

pala

tabl

e

1. I

t ca

n be

used

as

antib

acte

rial

oil

2. P

rote

cts

teet

h fr

omge

rms

ifru

bbed

on

gum

s an

dm

ake

gum

sst

rong

3. O

rgan

icm

usta

rd o

ilhe

lps

prev

enti

ngca

ncer

and

is

also

hel

pful

for

slow

ing

dow

n th

e

Ben

efit

s

9

Rec

omm

end-

ed b

yA

mer

ican

Hea

lth

Com

mis

sion

(AH

C)

2. R

etai

ns10

0% f

ood

tast

e

App

rove

d as

heal

thie

stoi

l by

man

yas

soci

atio

ns(A

mer

ican

Dia

betic

Ass

ocia

tion,

and

Am

eric

anH

eart

Ass

ocia

tion)

Ret

ain

moi

stur

e in

skin

& r

esis

tin

fect

ion

inin

fant

s

1. L

onge

rst

orag

eli

fe2.

Hea

lthie

stw

hen

cons

umed

unco

oked

.

In s

alad

beca

use

does

n’t

get

solid

ify

whe

nch

illed

, us

edin

bot

h

Add

itio

nal

Soyb

ean

oil

cont

ains

natu

ral

antio

xida

nts

whi

chre

mai

n in

the

oil

even

afte

r

Reco

mm

ende

dby

The

Am

eric

anH

eart

Ass

ocia

tion

agei

ngpr

oces

s

Hel

psin

win

ter

for

mak

ing

body

war

m a

ndge

nera

ting

mild

irri

tatin

gef

fect

thro

ugh

mas

sage

on

body

It c

anbe

use

d as

an

irri

tant

for

stim

ulat

ing

sens

atio

n in

sens

eles

sor

gans

and

mus

cles

.Ir

rita

nts

are

also

use

ful

for

driv

ing

up m

uscl

es

10

CORN OIL IN EDIBLE OIL INDUSTRYIndia is a leading player in edible oils, being the world’s

largest importer and the world’s third-largest consumer. Theprimary sources of oil are soybeans, rapeseed, sunflower,groundnut, cottonseed, coconut, palm and olive. In terms ofvolumes, palm oil, soybean oil and mustard oil are the threelargest consumed edible oils in India (Figure 4). Among thenon-conventional oils, rice bran oil and cotton seed oil are themost important. The corn oil emerged in USA. The large scaleproduction of the corn oil began in the 1910s. Since 1950s,developed countries have taken up corn oil. Presently, corn oilmakes a meagre proportion in the edible oil consumption. Cornoil is used in margarine, soup, soap, paint, as rust preventativeand many more products.

In India, most of the corn is used for feed industry and starchextraction. Germ used to be a waste product obtained afterstarch extraction from seed. Currently, germ is in demandbecause of its high oil content and utilisation as byproduct.Refined corn oil is considered to be the best edible oil usedinternationally. Considering the large planting area under cornand high unit production there is present commercial interest incorn oil production. Cost benefit ratio in maize is highest due toits high productivity. Through good cultivars, processing andcomprehensive utilization, the value of high-oil corn can beimproved considerably.

Figure 4. Percentage share of edible oil consumption in India(Source: www.icra.in)

11

Corn Oil ExtractionThe oil is typically extracted from the germ by a combination ofmechanical expression and hexane extraction. During starchextraction process the germ is seperated from kernel aftercleaning and steeping. The oil is seperated from germ throughsteps given in Figure 5. Refining involves several steps: (i)formation of sodium soaps of the free fatty acids, (ii) removal ofthe emulsion containing the soaps and phospholipids bycentrifugation, (iii) removal of waxes by chilling, (iv) removal ofpigments by contact with bleaching clays, (iv) removal of odoursby high-vacuum distillation at 225°C to 260°C. The fatty acidfraction is recovered by heating the emulsion in the presence ofsulphuric acid and is sold as an ingredient for use in feed rations.The germ residue is saved and used as a component of animalfeeds. The starch component of the grain is further processedto give a number of products. The wet corn milling operationrecovers 50-60% of germ oil. With right oil extraction machinery,a number of useful products such as corn oil and corn mealscan be extracted.

12

Figure 5. Schematic diagram of corn oil extraction

13

PRODUCTION TECHNOLOGY

Production technology of high-oil corn is same as normal corn.

Seasons Kharif, rabi and zaid

Land Selection From hilly regions up to an elevationof 2700m

All types of soils from sandy to heavyclay

5-6 irrigations

Avoid water stress at the time ofanthesis

Land Preparation Disc ploughing followed by landlevelling

FYM @5-6 tonnes/ha during lastploughing.

Inter row distance of 60-75cm; Intrarow spacing 15-30cm

Date of Sowing 10-15 days before onset of rain inirrigated areas

Best planting time is June-July inkharif (rainy) and September-Octoberin rabi (winter) season

Seed Rate 10-11 Kg seeds ha-1

Plant population for optimum yield is55000-60000 plants per hectare

Method of Sowing Two seeds per hil l are dibbledmanually or mechanically one thirdfrom the top on the side of the ridge.

Planting dept - 3-4 cm

Plants are thinned to one plant perhill 10-12 days after emergence

14

Nutrient 110-130 Kg of nitrogen, 60-80 Kg

Management of phosphate (P2O5) and 55-65 Kgpotash (K2O) ha-1

Fertilizer should be applied in 1 or 2bands approximately 7-8 cm to theside and 5-7 cm below the seed.

Weed Management Weed-free during the early stages ofplant growth

Efficient weed control is achieved for30-35 days through a spray of theherbicide Atrazine @ 1 Kg ai/ha for1-2 days after initial irrigation

Water Management 4-5 irrigations in heavy soils and 7-8irrigations in light soils

Irrigate at least 2.5-4.0 cm a week inorder to obtain high yield

Critical time periods are tassellingand silking

Intercultivation Top dressing of Urea is done 25 daysafter emergence after running acultivator in between the rows that willhelp weed control and better rootaerat ion apart f rom soi l waterconservation

Pest and Disease Endosulfan 35EC @ 2ml/l of waterManagement is given to 10-14 days old plants to

take care of stalk borers Chilopartellus in kharif and Sesamiainferens in rabi

Crop rotation and sequential planting

Spray with Bavistin @ 1 g/litre takescare of most of the foliar diseases

15

XENIA EFFECT AND HIGH OIL CORN PRODUCTION

Pollen parent also influences the oil content of the seed parentcalled as xenia effect. Male gametophyte of the high oilpopulation has additive or dominant gene action causing thegerm size of the normal oil hybrid to increase slightly andincrease the concentration of oil in the germ with small changein grain yield.

Recently, there has been much interest in producing high-oilcorn from hybrids using the topcross system. The systeminvolves planting two types of corn. One type, representing 90to 92% of the seed, is an elite hybrid taken as the “grain parent.”remaining is elite high oil inbred as “pollinator.” The grain parentis an elite commercial hybrid detasselled during pollination. Thepollen shed from these pollinator plants contain genes that causea kernel to produce a much larger than average germ or embryoutilising xenia effect). As most of the oil and essential aminoacids are in the germ, the oil and protein quality of the grainproduced by fertilization with these pollinators is enhanced.Pollinator plants contribute very little to overall grain yield.

Figure 6. Mature corn cobs of top cross hybrids of high oil lines

16

Thomison et al. (2002) used this system to produce high oilgrain and designated it as TC Blend®. High oil trait would notbe expressed if pollen from normal or low oil corn hybridspollinates male sterile hybrids in the blend. In our experimentsalso topcrosses were found to be better in terms of seed settingand seed production compared to single crosses (Figure 6).

17

HIGH OIL CORN IMPROVEMENT

To increase the oil content, efficient corn breeding programshas to be developed, which requires the knowledge of inheritanceof oil related traits.

A high-oil corn hybrid is the result of long term conventionalselection and breeding for the trait. The first high-oil corn varietieswere selected in 1896 at the University of Illinois. High oil inbredsshow high rate of oil accumulation from 15-45 days afterpollination as compared to normal inbreds. Germ weight andkernel weight increased linearly until the seventh week of kerneldevelopment. The third and fourth week of kernel developmentis the time of rapid metabolism in producing oil. It reachesmaximum by 45 to 48 days after pollination. Oil production iscompleted when seed is physiologically fully mature. Increasedkernel oil concentration has been attributed to increased embryo:kernel ratio and increased embryo oil concentration. Oil contentseems to be less influenced by the effects of environment andgenotype x environment interaction. The additive genetic varianceseems to be the main component in the control of this trait.Most literature illustrates influence of the male parent genotypethrough xenia effect in the determination of oil content in cornkernels. Corn fatty acid composition is variable and heritable.In India under National Agricultural Technology Project two highoil populations, HOP-I and HOP-II have been developed withseven per cent oil content. Sowing these two populations in 6:1ratio with promising hybrids improves oil content withoutcompromising yield. Hybrids are detassled at flowering. AtDirectorate of Maize Research, New Delhi, corn inbreds exhibitedhigh variability for oil content, which varied from 7.37 % in Tempx Trop (HO) QPM-B-B-B-60-B-B to 2.86 % in EC646025. Thebest high oil corn inbreds found were Temp x Trop(HO)QPM-B-B-B-60-B-B, Temp x Trop (HO)QPM-B-B-B-100-B-B, DMHOC4,HKI Talar, Temp x Trop (HO)QPM-B-B-B-57-B-B, HKITall-8-1-1and AF-04-B-5796-A-7-1-1 (Figure 7). These inbreds can be used

18

in further breeding programme for developing hybrids with highoil content. NIRA (Near Infra red analyser) and NIRS (Near Infrared Spectrophotometer) are non-destructive laboratoryinstruments to estimate oil content in a given sample of seedsin lot or singly on dry weight basis. Soxhlet apparatus is fordestructive oil estimation method

Generally, high oil hybrids have high oil kernels but withreduced starch levels, smaller endosperm and kernel size. Suchseeds have shorter longevity and greater deterioration. Synthesisof oil is physiologically independent in the interval from 4 to 7%oil. The fatty acid composition of corn oil is affected by positionof kernels on the ear. Palmitic and linoleic acid content of theoil increases for kernels from the base to the tip of the ear. Onthe other hand, oleic fatty acid content of the kernels decreasesfrom base to tip. Sampling of kernels in the central portion ofthe ear is recommended for samples to be analyzed for fattyacid composition. With each one per cent oil increase, starchin kernel would decrease by 1.48% to 1.83%. The average grainyield of the high oil hybrids is reduced by 5% compared to normalhybrids. Grain yield of high oil hybrids reduces as oil increasesgreater than eight per cent.

Figure 7. Mature corn cobs of high oil lines

19

PROSPECTS, STRATEGIES AND GOALS

The spotlight towards quality food products has initiatedresearch and development activities to develop and promotehealthy food. Quality products are becoming increasinglyimportant in agriculture. Corn oil is gaining importance due toits health benefits. Subsequently, non-traditional oils such ascorn oil are entering market. Development of high oil corn haspicked up recently in India.

Conventional selection breeding can increase oil in kernel.Selection for high oil increases the proportion of germ and furthercontent of germ oil. The problems that overshadow successfulproduction of high oil corn are low grain yield potential,physiological cost of oil synthesis, low seed vigour, low kernelweight, shorter seed longevity and poor germination of high oilcorn lines. Study of seed related traits at advanced level onseed germinability, setting, maturation and mobilisation ofoleosomes and oleosins can be done to overcome thesedemerits. The amenable proportion of embryo and endospermin oily kernel can increase nutrients present especially inembryo without reducing starch in endosperm. A breedingprogram to increase oil content in the kernels should beconsidered to avoid grain yield reduction by accumulatingpositive alleles distributed among genotypes. Gathering ofpositive alleles from different genotypes can provide transgressivesegregants with higher oil content.

Corn oil is an important value added product from leftover embryo/germ in addition to starch extraction from endospermof kernel. The commercial and economic value of discardedembryo is enhanced when corn oil is extracted from it. Increasingthe proportion of germ and oil content in germ will be the foremostobjective of breeding for oil in corn. Exploitation of xenia effectis a well established fact for breeding of oil in corn. It impartsincreased oil in germ as well as germ size without affecting

20

yield. The pollinators need to be high in oil with good amount ofpollen and increased duration of pollen shedding. Hence,prospecting germplasm for good pollinators is essential. Femaleline can be good normal corn inbred, or elite single cross hybridgiving good seed production. Elite single cross hybrid can beused as female after detasseling. Higher doses of N, P and Kinfluence grain yield and oil production per hectare.

At present, the availability of molecular tools has widenedthe knowledge of genetics of oil and oil related traits in corn.QTL analysis has given information of several QTL regionsgoverning quality and quantity of oil. In good quality oil there isincrease of oleic acid and reduction of saturated fatty acid i.e.,palmitic acid. Metabolism/pathways/enzymes involved inaccumulation of oil, starch and protein in kernel can be utilisedfor studying beneficial correlation between fatty acids, carbonflow for oil, starch and protein synthesis and to improve thevalue and amount of oil. Abundant information is availabledescribing the synthesis of fatty acid and triglycerol. Regulatoryrole of over expression of DGAT allele in determining seed oilcontent during seed maturation is well noted. Geneticengineering and ‘omics’ approaches can give betterunderstanding of plant metabolism mechanism. Marker assistedselection could allow more efficient breeding program for thistrait using QTLs with no or lower pleiotropic effects on grainyield, favourable QTLs from elite and non-elite lines for high oilcontent identif iable before flowering, marker-assistedbackcrossing of QTLs with larger phenotypic variation. Cost-effective marker-assisted selection can be successful in plantbreeding programs.

Germ derived from different conventional wet mill processappeared to have a slightly increased amount of oil contentrelative to the other processes. There is a strong correlationbetween the market value of germ and its extractable oil content.

Processors carry out blending of oil such as corn oil witholive oil and rice bran oil etc. Blending with corn oil results in

21

recommended ideal levels of monounsaturated andpolyunsaturated fatty acids. This ensures excellent flavourstability as well as the taste of food. Annexure I gives in detailthe Agricultural Produce (Grading and Marking) (AGMARK)specifications regarding corn oil grade and quality for duepurposes. Contract production of high oil grain may offer corngrowers higher profits through premiums. In this context conceptof seed village for production of high oil corn linked with suitablemarket outlets is to be encouraged with buy back guarantee isto be encouraged. An assured market of high oil corn is to becreated so that farmers receive good premium of their produce.Higher corn oil content is a desirable trait for corn starchindustries, especially starch. It is observed that majority of thecorn based starch factories are located in the states of Gujarat,Maharashtra, Andhra Pradesh, Karnataka, Haryana and Punjab(Figure 8). Eastern India states like Bihar and Uttar Pradeshlacks such factories.

22

Figure 8. Relative distribution of corn starch, oil and oil caketraders in India

Tapping these corn producing areas for corn based industriesespecially for starch can supplement corn oil industry. Extractionof corn oil is a latest area of entrepreneurship. In the comingyears, emphasis will be to support corn oil to catch a formidableposition in edible oil market. High oil is a useful, unique andspecialty trait for plant breeders.

23

SIGNIFICANT READINGS

• Alrefai, R., Berke, T.G. and Rocheford, T. R. Quantitative traitlocus analysis of fatty acid concentrations in corn. Genome,1995, 38, 894–901

• Berke, T.G. and Rocheford, T. R. Quantitative trait loci forflowering, plant and ear height, and kernel traits in corn. CropSci, 1995, 35, 1542–1549.

• Bouchez, A., Hospital, F., Causse, M., Gallais, A. andCharcosset, A., Marker-assisted introgression of favorablealelles at quantitative trait loci between corn elite lines.Genetics, 2002, 162, 1945–1959.

• Cedomila, M., D. Robert, T. Marin, G. Jasminka, C. Mira, R.Biserka and C. Zlatko, 2001. Effect of olive oil- and corn oil-enriched diets on the tissue mineral content in mice. Biol.Trace Elem. Res., 82: 201-210.

• Dunford, N. T. 2005. Germ Oils from Different Sources Bailey’sIndustrial Oil and Fat Products, Sixth Edition, SixVolume Set.Edited by Fereidoon Shahidi. Copyright # 2005 John Wiley &Sons, Inc

• Goldman, I. L., Rocheford, T.R. and Dudley, J.W. Molecularmarkers associated with corn kernel oil concentration in anIllinois high protein x Illinois low protein cross. Crop Sci., 1994,34, 908–915.

• Harwood, J. L., Fatty acid biosynthesis. In Plant lipids: biology,util ization and manipulation (ed Murphy, D. J.). Oxford,Blackwell Publishing, 2005. pp. 27–66.

• Hospital, F., Moreau, L., Charcosset, A. and Gallais, A., Moreon the efficiency of marker assisted selection. Theor. Appl.Genet., 1997, 95, 1181–1189

• Laurie, C. C., Chasalow, S. D., LeDeaux, J. R., McCarroll, R.,Bush, D., Hauge, B., Lai, C., Clark, D., Rocheford, T. R. andDudley, J. W., The genetic architecture of response to long-

24

term artiûcial selection for oil concentration in the corn kernel.Genetics, 2004, 168, 2141–2155.

• Li., Y. L., Li ., X. H., Li., J. Z., Fu., J. F., Wang., Y. Z. and Wei, M.G., Dent corn genetic background influences QTL detection forgrain yield and yield components in high-oil corn. Euphytica,2009, 169, 273–284.

• Lung, S.C. and Weselake, R.J., Diacylglycerol acyltransferase:A key mediator of plant triacylglycerol synthesis. Lipids, 2006,41, 1073–88.

• Mangolin, C. A., de Souza Jr., C. L., Garcia, A. A. F., Garcia, A. F.,Sibov, S. T. and de Souza, A. P., Mapping QTLs for kernel oilcontent in a tropical corn population. Euphytica, 2004, 137,251–259

• Mihaljevic, R., Utz, H.F. and Melchinger, A. E., Congruency ofquant i tat ive trai t loci detected for agronomic trai ts intestcrosses of five populations of European corn. Crop Sci.,2004, 44, 114–124

• Mikkilineni, V. and Rocheford, T. R., Sequence variation andgenomic organization of fatty acid desaturase-2 (fad2) and fattyacid desaturase-6 (fad6) cDNAs in Corn. Theor. Appl. Genet.,2003, 106, 1326–1332

• Ohlrogge, J. B., Browse J. Lipid biosynthesis. Plant Cell, 1995,7, 957–70.

• Rakshit, S., Venkatesh, S. and Sekhar, J. C. High oil corn. InSpeciality Corn Technical Bulletin Series 4, Directorate of CornResearch, New Delhi, India, 2003, 16p.

• Snyder, C.L., Yurchenko, O.P, Siloto, R.M.P., Chen, X., Liu, Q.,Mietkiewska, E., Acyltransferase action in the modification ofseed oil biosynthesis. New Biotech., 2009 published online.doi:10.106/j.nbt.2009.05.005.

• Song, X. F., Song, T. M., Dai, J. R., Rocheford, T., and Li, J. S.,QTL mapping of kernel oil concentration with high-oil corn bySSR markers. Maydica, 2004, 49, 41-48.

• Stuber, C.W and Sisco, P., Marker-facilitated transfer of QTLalelles between elite inbred lines and responses in hybrids.

25

In 46th Annual Corn and Shorghum Research. Conference,Am. Seed Trade Assoc.,Washington, DC, USA, 1992, pp.104-113

• Stymne, S. and Stobart, A. K., Triacylglycerol biosynthesis. InThe biochemistry of plants, Vol. 9, lipids: structure and function(ed. Stumpf, P.K.), New York, New York: Academic Press; 1987,pp. 175–214

• Thomison, P.R. Kernel composition affects seed vigour of corn.In Proceedings International Seed Seminar: Trade, Productionand Technology (eds. McDonald, M.B. and Contreras, S.). 15-16 October, Santiago, Chile, 2002, pp.150-152

• Weselake, R. J., Taylor, D. C., Habibur Rahman, M., Shah, S.,Laroche, A., McVetty, P. B. E. and Harwood, J. L., Increasing theFlow of Carbon into Seed Oil. Biotechnol. Adv., 2009, 27, 866-878

• Weselake, R.J., Storage lipids. In Plant l ipids: biology,utilization and manipulation. (ed. Murphy, D.J.), Oxford:Blackwell Publishing; 2005, pp.162–221.

• Willmot, D. B., Dudley, J. W., Rocheford, T. R. and Bari, A., Effectof random mating on marker-QTL associations for grain qualitytraits in the cross of Illinois High Oil ? Illinois Low Oil, Maydica, 2006, 51, 187–199.

• Yang, X., Guo, Y., Yan, J., Zhang, J., Song, T., Rocheford, T. andJian-Sheng Li., Major and minor QTL and epistasis contributeto fatty acid compositions and oil concentration in high-oil corn.Theor. Appl. Genet., 2010, 120, 665–678.

• Zhang., J., Lu, X. Q., Song, X. F., Yan, J. B., Song, T. M., Dai, J.R., Rocheford, T. and Li, J. S., Mapping quantitative trait locifor oil, starch, and protein concentrations in grain with high-oilcorn by SSR markers. Euphytica, 2008, 162, 335–344

• Zheng, P., Allen, W. B., Roesler, K., Williams, M. E., Zhang, S., Li,J., Glassman, K., Ranch, J., Nubel, D. and Solawetz, W., Aphenylalanine in DGAT is a key determinant of oil content andcomposition in corn. Nat. Genet., 2008, 40, 367-372.

Annexure I

Agmark grade designation and definition of quality forMaize (Corn) Oil

1 Grade Designation Refined

2 Moisture and impurities 0.10percent by weight(not more than)

3 Colour on Lovibond scale* 10in 1/2" cell expressed asY + 5R (not deeper than)

4 Specific gravity at 300/300C 0.913 to 0.920

5 Refractive Index at 400C 1.4645 to 1.4675

6 Saponification value 187 to 195

7 Iodine value (Wij’s method) 103 to 128

8 Unsaponifiable matter 1.5percent by weight (notmore than)

9 Acid value (not more than) 0.5

10 Description Maize (corn) oil shall beobtained by a process ofexpression from the germsof clean and sound seedsof the plant Zea maysLinn. fam. Gramineaewhich are separated fromthe remainder of the kernelby the wet or dry millingprocess in themanufacture of starch orglucose. The oil shall berefined by neutralization

with bleaching earth and/or activated carbon anddeionised with steam. Noother chemical agent shallbe used.

11 General Requirements The oil shall be clear andfree from turbidity when afiltered sample of oil iskept at 300C for 24 hours.The oil shall be free fromrancidity, adulterants,sediments, suspended andforeign matters, other oilsand substances, mineraloil, separated water andadded colour andflavouring substance andobnoxious odour. The oilmay contain permittedanti-oxidants not excedingin concentration asspecified under Preventionof Food AdulterationRules 1955.

NOTE : *In the absence of Lovibond Tintometer, the colour of the oilshall be matched against standard colour comparators.

28

NOTES

29

NOTES