antioxidant as antitoxic agents

1 | P a g e N a t u r a l A n t i o x i d a n t a s a n t i t o x i c a g e n t s
Aim
To realize and emphasize the importance
of our health.
To be aware of the causes and effects of
consumption of reheated oil on our health.
To make everyone in our country, safe
from harmful chemicals in their diet.
To give everyone, the privilege of healthy
and natural food habits.
H-highly
E-energetic
A-Ascent
L-living
t-towards

H-happiness
INTRODUCTION
Food becomes tastieron deep frying, and some of food items can
only be eaten, once they are deep fried. Reusing this deep fried oil
repeatedly for frying purposes is responsible for many health
hazards in human population. Increased viscosity and darkening
in colour are some of the physical changes which can alter the
fatty acid composition of the cooking oil on repeated frying.
Oxidation, hydrolysis and thermal polymerization are the
chemical reactions occurring as a result of repeated heating of
cooking oil for low and cheap food production. In this paper the
degradation of the quality of cooking oil on repeated frying, its
effects on human health and some ways to treat this cooking oil
so as to make it more cost effectiveand less dangerous for human
consumption are undertaken with special reference to Indore.

Types of Fats Found in Cooking Oils
While the oils lining your grocery storeshelves are typically
viewed as simply “vegetable fats”, there’s actually quitea bit
more involved. Every type of oil consists of different types of
fats that play a crucial role in whether they make a good
cooking oil or not.
All fats have a similarchemical structure consisting of carbon
atoms bonded to hydrogen atoms in a chain. The crucial
difference between each fat and how it stands up to cooking
with high heat depends upon the length and shape of the carbon
chain and the number of hydrogen atoms connected to the
carbon atoms.
Below we break down the three different fats found in oils for a
look at what’s really happening when you cook with them.

Monounsaturated Fats
Monounsaturated fats (MUFAs) contain a melting point
in between saturated and polyunsaturated fats, meaning
that they remain liquid at room temperature but begin to
solidify when chilled or refrigerated. This structure also
makes them slightly more stable than polyunsaturated fats
when exposed to heat.
MUFAs are the fats found in abundance in olive oils,
nuts, avocados, and other fatty plant foods. This is the
main fat that is mentioned when you hear people discuss
the benefits of the Mediterranean diet, which is rich in
olive oil and nuts.

Polyunsaturated Fats
The structure of Polyunsaturated fats (PUFAs) are makes
them less stable when exposed to heat because it contains
more than one double bond. And while a small amount of
PUFAs are necessary in our diets, too many of them
(especially after they’ve been heated) can cause
inflammation and set the stage for developing diseases like
cancer.
PUFAs also found in plant-based oils, but are found in a
higher concentration in oils like peanut, corn, soy,
sunflower, and canola oils.

Saturated Fats
Saturated fats are found in small concentrations in plant
oils (the exception being coconut, which is mostly
saturated fat).
Saturated fats are the number one choice for cooking due
to their ability to resist heat damage. While saturated fats
have been demonized in the past, modern research shows
they are actually an essential part of our diet and have a
multitude of benefits, such as increasing good cholesterol
and improving blood pressure.

Good vs. Bad Cooking Oil
Now, let’s dive a little deeper into the chemical bonds of what makes an oil a
good choice for cooking.
Number of factors play a role in how much heat is needed to make these oils
unstable:-
 Numberof double bonds- Ingeneral,the more No. of doublebonds a
fat contains,the less stableit willbe whenexposed to heat. This is
why polyunsaturatedfats, whichcontainat least two doublebonds,
are not great for cooking, whilesaturated andmonounsaturated
containzero or one.
 SmokePoint-Thesmoke point of an oil is the temperatureat which
an oil starts to break down and form compounds that can damage
your health. When it comes to high heat cooking, you want to choose
an oil with a higher smoke point.
 Name of the oil Smoke point
Corn, peanutand soy oil 320° F
Sunfloweroil 225° F

Coconutoil 350° F
Olive oil 405° F
Table showing smoke point of different oils.
 Oxidative Stability-Oxidativestabilityrefersto an oil’sabilityto
resist oxidation,whichis the process that causes fat moleculesin oil
to form free radicals.Free radicalscancause a whole host of health
problems, includingheartdisease, aging, cancer,Alzheimer’s,
Parkinson’s,andeveninflammatorydiseaselike arthritis. This is
mainlydue to their abilityto severelydamage your DNA.
This is why it’s extremely important to choose an oilwith a high oxidative
stability.This largelydepends on its chemicalmakeup, its smoke point (high
is better), and its antioxidantcontent,which can help protect it from
oxidation.
What is oil oxidation?
Oil oxidation is an undesirable series of chemical reactions involving
oxygen that degrades the quality of an oil. Oxidation eventually
produces rancidity in oil, with accompanying off flavours and smells.
The oil is in a state of oxidation - you cannot stop it completely - but
there are ways to reduce it. Attempts should therefore be made to
reduce oxidation at each stage of oil manufacture.
Oxidation is not one single reaction, but a complex series of reactions.
When oil oxidises it produces a series of breakdown products in
stages, starting with
 Primary oxidation products (peroxides, dienes, free fatty acids),
 Secondary products (carbonyls, aldehydes, trienes).
Oxidation progresses at different rates depending on factors such as
temperature, light, availability of oxygen, and the presence of
moisture and metals (such as iron). The type of oil also influences
the rate of oxidation. Marine oils (including fish oil) are highly

susceptible to oxidation due to the large number of
polyunsaturated fatty acids (PUFA) they contain.
Reaction involved in oxidation of oil
Oxidationis a slow, radical process which proceeds via a chain
reaction including induction, propagationand terminationsteps
that are shown below:-
Initiation
RH  R* + H*
Propagation
R* + O2  ROO*
ROO* + RH  ROOH +
R*
Termination
ROO* + R*  ROOR
R* + R*  R-R

10 | P a g e N a t u r a l A n t i o x i d a n t a s a n t i t o x i c
a g e n t s
Unsaturated fatty acids undergo oxidation by the above free-
radical chain reaction to form hydro peroxides. The hydro
peroxides are decomposed to form off-flavourcompounds, which
are called secondary oxidativeproducts.
Diseases caused by
consumption ofreheated
oil
 Atherosclerosis
 Alzheimer
 Parkinson’s
 Cancer
 Obesity
 High blood
pressure
 Bad cholesterol
 Heart diseases
 Arthritis

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 Diabetes,
 Accelerated aging
 Eyesight
deterioration
 Inflammation
Diseases caused by consumption of reheated oil

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Our survey
Cause of repeated heating of the cooking oil
Our Survey

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Indore is not only famous for sweets but also is well known for
fried Namkeen items. For cutting down the cost of fried food items
and to save money, many of the household ladies and maximum of
the Namkeen makers in Indore use the same cooking oil repeatedly
for frying different items. The oil is reused repeatedly and it is
discarded and replaced with fresh oil, only when it becomes foamy,
highly viscous, emits bad odour and become dark coloured and many
times it is never replaced at all, instead fresh oil is added to already
heated ,thick and highly viscous oil. A survey was conducted in this
regard clearly supports the above statement.20 different people
including household ladies and namkeen makers in the study area
were surveyed about the oil used in frying , number of times it is
reheated and ultimately its fate.

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The results of the survey were represented in the
form of graphs as given below:
19%
38%5%
38%
fate of discarded cooking oil
throw the oil
mix with new oil
give to soap makers
use it until it turn
black
8%
13%
17%
26%
36%
time of reheating the
oil(hours)
5
8
10
16
24
22%
28%
44%
6%
time period of oil changed(in
days)
1 day
2 days
3 days
5 days

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CHANGES DURING THE REHEATING OF THE OIL
Although eatinglimitedquantityof fried food items does not causeany kind
of healthprobleminnormalhumanbeing.Theproblembeginswhenthe same
oil is used again and again by repeated heating. During deep-frying of food
at temperatures between 170° – 200°C, the oil used undergo following
changes:
1. Hydrolysis– Moisturefrom the food beingfried vaporizesandhydrolyses
triglycerides(TGs) inthe frying oil to glycerol,free fatty acids (FFAs), mono
glycerides (MGs) and di glycerides (DGs).
2. Oxidation – Triglyceride molecules in the frying oil undergo primary
oxidation to unstable lipid species called ―hydro peroxides which cleave to
form secondary oxidationproducts whichcomprise non-volatileandvolatile
compounds. Some of these secondary products polymerize, increasing the oil
viscosity, cause browning on the surface, and darken the oil.
3. Thermal Polymerization– High temperatures of the frying operation
produce high molecularcyclicfatty acid (FA) monomers, and TG dimers and
oligomers. Fried food may absorb many oxidative products such as hydro
peroxide and aldehydes, which are produced during this process thus
affecting the quality of oil.
The qualityofoil deteriorateswith increasedlengthof fryingtime due to the
acceleratedformationof oxidizedand polymerized lipidspecies in the frying
medium. If the physio-chemical properties of cooking oil deteriorate, the oil
must bediscardedbecauseitcanprovetobeharmfulforhumanconsumption.
The rate of formation of cooking oil decomposition products depends on the
type of food beingfried, the type of oil used and the design of the fryer, etc.
The reactions in oil rich frying depend on factors such as replenishment of
fresh oil,frying conditions,originalquality offrying oil, food materials,type
of fryer, antioxidants, and oxygen concentration. Antioxidant decreases the
frying oiloxidation,but the effectivenessof antioxidantdecreaseswith high
frying temperature.

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Survey to rajeshwar sweets

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Our efforts
(Lab work)
To detect the presence of toxic aldehydes in oil
 Schiff’stest – we have taken sample of reheated oil in test tube
and added ethanol in it and Schiff’s reagent which is P-rosaniline
hydrochloridethe appearance of pink colour confirms the presence
of toxic aldehyde in reheated oil.
 Fehling’stest-We also performed Fehling test in whichwe have
taken reheated oil sample after addingFehling A and Fehling B
the appearance of red precipitate of copper oxide confirms the
presence of toxic aldehydein it.
These two test confirms the presence of toxic aldehyde in reheated oil

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Determination of peroxide value and viscosity
MATERIALS & METHODS
Coconut Oil, Sunflower Oil, and Soybean Oil, Potatoes.
PROCEDURE
One- fourthkg of potatowere taken, sliced, airdriedfor4-5hours
and then fried in app. 1 litre of each of the above mentioned
cooking oils separately, which were heated to 170-180⁰ C.
Frying was carried out in a stainless steel pan. After the frying
was completed, once heated oil was obtained. This sample was

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then cooled overnight and again fresh potatoes were taken,
sliced, air dried and then fried. The leftover oil was again cooled
overnight. The same process was repeated for 3times to get
reheated oil.Small amount of oileach timewas taken foranalysis
(viscosity and peroxide determination). The sample quantity was
proportionately adjusted with the amount of cooking oil left. No
fresh oil was added in between the frying processes to make up
for the loss due to uptake by the frying materials. A comparative
studyof thephysiochemicalchanges ofthedifferentoilsincluding
viscosity change and peroxide value was studied.
Viscosity is a fluid's resistance to flow. Fluids resist the motion
of layers with differing velocities within them. Viscosity can be
measured by using kinematics method in the lab.
 THE PEROXIDE VALUE
The peroxidevalueis defineas the amount of peroxide oxygen per 1kg of
fat or oil it is expressed in miliequivalents.
Peroxide values of the heated oils were determined. In this 5 g of the oil
sample was taken into a 250 mL conical flask then 30 mL of acetic acid-
chloroform (3:2) was added in it. The flask was swirled and then 0.5 mL of
saturated potassium iodide was added. Then, the solution was mixed again
for 1 minuteandfewdrops of starch solution(10%)wereadded.Thesolution
was titrated against previously standardized 0.01 N sodium thiosulphate
solution(Na2S2O3),untilthebluecolourdisappeared.Theperoxidevaluewas
expressed in miliequivalents of peroxide per kg of the sample calculated by
using formula:
Peroxide value (meq/kg) = [(Va-Vb) N × 1000]/W
Where;

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Va = volumeof sodium thiosulphate solution(mL)
Vb = volumeof sodium thiosulphatesolution(mL)
used for the blankN = normalityof sodium
thiosulphate
W = weight of the test portion (g)
Viscosity
We used a falling sphere viscometerto calculate viscositiesof
various products we used in our project. A falling sphere
viscometerutilizes stokes law to calculate viscosity. In the
experiment a series of steel ball bearings are utilized to fall
through a liquid.As the buoyant force, frictionalforce and
gravitationalforce are balanced on the ball, ball gains a
constant velocity called terminal velocity. The terminal
velocity is calculated and put in the formula:
Where V is Terminal Viscosity

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R is Radius of steel ball
µ is Dynamic Viscosity
D is Density
Result
The results are summarized in the table & chart given below:
Number of
frying
Sunflower oil Coconut oil Soyabean oil
0
0.5
1
1.5
2
2.5
3
1st fryig 2nd frying 3rd frying
sunflower oil coconut oil soybean oil

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Peroxide value Peroxide value Peroxide value
1st
frying 0.40 0.34 0.70
2nd
frying 1.05 1.10 1.15
3rd
frying 4.90 3.98 5.01
Calculated peroxide values
Number of frying Sunflower oil Coconut oil Soyabean oil
Viscosity Viscosity Viscosity
1st
frying 182 175 274
2nd
frying 232 216 321
3rd
frying 261 238 412
Calculated viscosity of
oil
EFFECT ON HUMAN HEALTH
Frying makes the eatables tasty. Frying of edible items includes
the usage of large amount of oil. Increased oil consumption is
not considered to be good for human health. Even though a
certain amount of potentially toxic products are produced
during frying (such as polar compoundsor polymers),fried foods
are generally considered safe. It is only when frying oil is used
repeatedly that it becomes toxic for human consumption.
Repeated heating of theoil accelerates oxidativedegradationof
sunflower oil
coconut oil
soybean oil
0
100
200
300
400
500
1st frying 2nd
frying
3rd frying
sunflower oil coconut oil soybean oil

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lipids, forming hazardous reactive oxygen species and
depleting the natural antioxidant contents of the cooking oil.
Long-term ingestion of food prepared using reheated oil could
severely compromiseone’s antioxidantdefence network, leading
to pathologies such as hypertension, diabetes and vascular
inflammation. Lipid oxidation causes a high risk for the
development of coronary heart diseases. The human body is
constantly subjected to a significant oxidativestress as a result
of themisbalance between ant oxidativeprotectivesystems and
the formation of strong oxidizing substances, including free
radicals. This stress can damage DNA, proteins, lipids and
carbohydrates and could cause negative effect to intracellular
signal transmission.
Innovative solution
Role of antioxidant in stability of edible oil
Like human being, food also needs to protect itself by oxidation.
Antioxidants are kind of additives that are essentialin oils to
avoid the process of lipid oxidationthat results in off flavour
development. As oxidationin food is a chain process, trace
amount of antioxidant is required to retard the process of

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oxidation.Plant extracts were found as source of antioxidant
due to their high contents of phenolic compounds; hence these
are widely used to retard lipid oxidationin foods. Antioxidants
prevent such changes by retarding or slowing down the process
of oxidationor rancidity.
Mechanism of antioxidant
Oxidationcan be induced catalytically by light, temperature,
enzymes, metals, and microorganismswith the reaction
involving free radicals or active oxygen species. In case of
unsaturated fatty acid, formationof free radical takes place by
abstractionof allylic hydrogen. The resultant radical becomes
very susceptible to attack by oxygen to form peroxide free
radicals. These free radicals serve as strong initiators and
promoters of oxidationby extracting hydrogen from another
fatty acid molecule which triggers propagationin the final stage
of fatty acid oxidation,the primary oxidationproducts of
rancidity formed are hydro peroxides. These hydro peroxides are
quite unstable and subsequently degrade into smaller chain
organic compounds such as aldehydes, ketones, alcohols and
acids, the secondary oxidationproducts of rancidity. It is the
latter compounds which actually render fats and oils rancid and
unacceptable and unsuitable for food purposes.
Natural extracts as antioxidants for stability of edible oils
Syntheticantioxidants,such as Butylated hydroxyl toluene
(BHT), Tertiary butyl hydroquinone (TBHQ) are widely used in
edible vegetable oil to prevent rancidification, due to their high
Performance and lower cost. These antioxidants are used as
preservativein the food industry; however, some reports suggest

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that, these may be responsible for liver damage and
carcinogenesis. Hence, interest in the use natural antioxidants
in the food industry has been increased when compared to
syntheticantioxidants, natural antioxidants have the following
advantages,
They are readily acceptable by the consumers.
They are considered to be safe.
These natural antioxidants are identical to the food in
which people ate for hundreds of years or mixed with their
food.
List of natural antioxidant
 Rosemary extract.
 Garlic extract.
 Pomegranate peel extracts.
 Turmeric extract.
 Sugar beet pulp extract.
 Drumstick leaves extract.

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Turmeric extract
In lab we prepared turmeric extract we have taken 20 gm of fine
turmeric powder and mix it with80% ethanol solution to make it
100ml solutionafter shaking the solution filter it and then dried the
residue turmeric extract was obtained. We have taken this extract in
With respect to soya bean oil because soya bean oil is very common oil
used in householdas well as commercial places. During frying at
different temp withthis turmeric extract we obtain the following
results from this results we can see that on the additionof turmeric
extract the viscosityand peroxide value of repeatedly heated oil
gradually decreases as compare to the frying withoutturmeric extract.
Soybean oil Frying Without
turmeric extract
Frying With
turmeric extract
Peroxidevalue 5.01 3.61
viscosity 412 375
Graph for viscosity
Graph for peroxide value
0
1
2
3
4
5
6
without
turmeric
with turmeric
peroxide value
350
360
370
380
390
400
410
420
without
turmeric
with turmeric
viscosity

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Here turmeric acts as a natural anti-oxidant which
reduce the harmful effect of oil deterioration product.
This is because of the presence of curcuminpigment
present in turmeric curcumin is effective to be used as
antioxidant because it can scavenge free radical by
donating Hydrogen atom from phenolic as its active
group.
The antioxidant free radical does not initiate another free
radical due to stabilisation of free electron. Hydrogen
donation to free radical by antioxidant and formation of
a complex between the lipid radical and the antioxidant
radicals stabilise it.

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Other carcinogenic substance
Apart from reheated vegetable oil some other food component
became toxic and releases carcinogenic properties during
reheating-
Spinach
Any green vegetable like
spinach like coriander leaves
contains high amount of iron
and on reheating spinach
oxidation of iron generates
dangerous free radicals which
are known to cause many
diseases including infertilityand cancer.
Rice

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Rice contain spores of
bacillus cereus bacteria which
multiple on heating causing
food poisoning.
Egg
Protein rich foodlike egg
chicken contains lot of
nitrogen which get oxidised
due to reheating and there
protein compositioncompletely
changes further causing
cancer.
Potatoes

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If they are reheated
again and again they
produce clostridium
botulinum even if you
leave the cooked
potatoesout in room
temperature, the
productionof bacteria
will only increase. So if
you want to avoid the
growthof bacteria, best
is to keep them refrigerated
or throw them away if not being consumed within 1-2 days.
Survey to a nutritionist
We visited nutritionist Mr. Rahul Kumavat who told us some
preventive measures and some tips to live a healthy life.

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He said “Make sure you are careful about how much oil is being
used in the first place, so there isn't too much left over anyway.
We often pour in a few extra ladles knowing that it could be
used 'next time'.”
There is no set number to how many times one can reuse the oil as it
depends on factors like which oil is used, how long the oil was
heated, was it used for deep frying or shallow frying, what type of
food was cooked in it etc…
Though using a fresh batch every time is good, it is not really
practical. But if done correctly, one can reduce the risk of negative
effects that reused oil may pose.
Preventive measures
 Make sure the leftover oil from cooking or frying is cooled
down and then transferred into an airtight container
through a strainer/cheesecloth. This will remove any food
particles in the oil as they spoil the oil much sooner than
expected.
 Make sure you check the oil each time before reusing for the
colour and thickness. If it’s dark in colour and is
greasy/sticky than usual it is time to change the oil.
 Also, if the oil is smoky on heating much before than
expected, you need to discard this batch.
 Another thing to remember is that not all oils are same.
Some of them have a high smoke point i.e. they can be used
for frying, deep frying. Basically they do not break down at
high temperatures such as olive oil coconut oil. Which do
not have a high smoke point such as sunflower, safflower,

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soybean, rice bran, peanut, sesame, mustard and canola
oil should only be used for sautéing, nothing which will
involve high temperatures. So make sure you do not use
the wrong oil for cooking and definitely don’t reuse it for
frying, etc.
 Antioxidants reduces the oxidationof oil so natural
antioxidants such as sugarcane bagasse , rosemary extract,
ginger extract ,garlic extract, pomegranate peel extracts,
sugar beet pulp extract drumsticks leaves extracts and other
spices like clove oil and pepper oil can also be used to reduce
the formationof harmful products on reheating.
Conclusion
Above studies clearly indicatethat edible oil becomes
highly viscous and presence of harmful products increases
when oil is heated repeatedly. This oil now becomes
dangerous for human consumption. Thereforeoil should
not be heated again and again and the formationof
harmful products can be minimised by discarding it or
using it with certain antioxidants.
“Our own health lies in our hands
only.”

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“Health is everything, but
everything is nothing without
health”
References
 www.plantandfood.com
 www.acedemicgenerals.org
References
 www.jakraya.com
 www.wikipedia.com
 Healthy cooking oils
 Www.abouttoxicoil.com
 www.heathlyliving.com
It’snot ashorttermdiet
It’sa longtermlife stylechange

a g e n t s

antioxidant as antitoxic agents

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