A. Fatty Acid Composition

Each oil comes from a different source. In the case of vegetable oils, it comes from different fruits, seeds, nuts, etc. In the case of animal oils (in our case, ghee) it might be coming from dairy products having fats of their own.

1. Unsaturated Fatty Acids
   1. Monounsaturated Fatty Acid (MUFA)
   2. Polyunsaturated Fatty Acid (PUFA)
2. Saturated Fatty Acids
3. Trans Fatty Acids
4. Free Fatty Acids

B. Smoke Point

Smoke point is the temperature at which oil starts burning and degrades itself. Oil continuously heated at temperatures above smoke point is not safe to consume and may also lead to the development of carcinogenic elements.
This also considers suitability at deep-frying. Some oils because of their intrinsic properties are more stable when deep-frying either because of chemical composition or the presence of antioxidants.

C. Health benefits and side-effects

Since each oil is coming from a different source, it also packs unique inherent properties which have their own benefits as well as side effects (probably on over-consumption)

D. Vitamin composition

Each source of Oils also contains different levels of Vitamins. Vitamin E and Vitamin K are vitamins that are mostly found in oils but their quantity might be different.

E. Cholesterol levels and calories

Most of the oils provide similar energy on consumption (calorific value). While we talk about cholesterol, there are two types of cholesterol: HDL and LDL, the former regarded as the good one.

F. Unrefined or refined

Oil is extracted from the base (fruits, nuts, seeds, dairy) in multiple ways. These processes could produce unrefined or refined oil.

G. Physical attributes of the oil

The oil has multiple physical characteristics like color, flavor, aroma, stickiness, etc. We use this comparison factor for oil since this is the first impression of the oil.

H. Reusability of the Oil

While it's no surprise that the oil is reused in households and even in commercial setups. One has to be smart about how to select the oil that has a higher reusability factor as well as how to enhance the same.

A. Fatty Acid Composition

Dietary fat despite having a bad reputation is vital for health since the body requires fat for energy and absorption of certain vitamins and minerals and many other critical processes.

1. Unsaturated Fatty Acids

Unsaturated fatty acid is one in which there is one or more double bond in the fatty acid chain

1. Monounsaturated Fatty Acid (MUFA)

• One double bond
• MUFA may help lower LDL (bad cholesterol) and maintain a high level of HDL (good cholesterol)
• It may help lower the risk for cardiovascular disease and overall mortality
• Anti-inflammatory properties

2. Polyunsaturated Fatty Acid (PUFA)

• More than one double bond
• May lower LDL cholesterol
• Helps with muscle movement and blood clotting
• Since the human body doesn’t make PUFA, one has to get it through dietary intake
• Omega-3s are important for the fetal development of the brain
• Omega-6s support the cardiovascular, immune, and reproductive system

The greater the degree of unsaturation, in fatty acid (ie more double bonds), the more it is vulnerable to rancidity (ie oxidation of oils resulting in a bad taste and smell).

When double bonds are formed, hydrogen atoms are eliminated.

2. Saturated Fatty Acids

Saturated fat is "saturated" with hydrogen atoms and contains no double bonds. SFA is solid at room temperature and hence also called “solid fat”. Research studies often suggest the impact of saturated fat on heart health, leaving this confusing for consumers. SFA raises LDL (bad cholesterol) levels and certain other heart disease risk factors, such as inflammation. Though it is not clear if it certainly poses risk for heart diseases. Since SFA doesn't have any double bonds, it is the most stable at high temperatures and doesn't break down easily.

3. Trans Fatty Acids

This fatty acid is changed by a process called hydrogenation. This process aims to increase the shelf life of the fat making it harder at room temperature thus making crispier and flakier crusts. TFA can raise cholesterol levels and hence is advised to be consumed as little as possible. These can be found in processed foods, snack foods, such as chips and crackers, cookies, etc. TFA adds no nutritional value to the diet and may also harm health.

4. Free Fatty Acids

Free Fatty acids (FFA) are produced by the hydrolysis of oils and fats. Since FFA are less stable than neutral oil, they are more prone to oxidation and to turning rancid.

One should try to consume more unsaturated fat instead of saturated fat and trans fat which may help improve cholesterol levels. The proportion of MUFA:PUFA:SFA for maintaining the ideal ratio of HDL/LDL is 40:30:30. The below table contains our ranking for the selected oils.

Rank	Oil	MUFA	PUFA	SFA	Offset Angle
1	Rice bran Oil	34%	33%	33%	0.13
2	Groundnut Oil	50%	30%	20%	0.23
3	Sesame Oil	41%	44%	15%	0.34
4	Pistachio Oil	54%	34%	12%	0.36
5	Canola Oil	58%	32%	10%	0.41
6	Palm Oil	40%	11%	50%	0.45
7	Mustard Oil	60%	21%	12%	0.45
8	Olive Oil	70%	15%	15%	0.52
9	Soybean Oil	23%	58%	19%	0.56
10	Avocado Oil	76%	12%	12%	0.60
11	Safflower Oil	79%	12%	9%	0.63
12	Sunflower Oil	82%	9%	9%	0.66
13	Ghee	30%	4%	66%	0.68
14	Coconut Oil	7%	2%	91%	0.96

From the above ranking, one might be surprised to see the likes of coconut, sunflower, olive, avocado oil, and ghee not making it to the top. However, it's been established that a high-mono diet inferior to a diet with a balanced MUFA:PUFA:SFA ratio.

B. Smoke Point

When we talk about smoke point, there are few things to consider:

• Smoke point of the refined oil
• Smoke point of the unrefined oil
• Threshold of Oil temperature

Before we move further, it is important to understand the difference between unrefined and refined oil.

Factors		Unrefined	Refined
Extraction Process	Heat Exposure	Minimal exposure to the heat during extraction	Exposed extensively to the heat
	Toxic Elements	Natural resins and other beneficial particles burn easily while cooking	Toxic and harmful ingredients are eliminated after clarifying and sifting the raw crude oil
	Chemical Methods	No chemical methods	Chemical methods but without harsh or damaging chemicals
	Bleach/ Wash/ Deodorize	Not at all bleached or washed out and deodorized	Washed out or decolorized and deodorized
	Natural Smell	They contain the natural smell of the seed	The unwanted smell from the oil is removed
Suitability for deep-frying		- Best used unheated in dressings or with low heat sauteing or baking - Natural resins and other beneficial particles burn easily and develop unpleasant flavors and unhealthful properties if overheated	- More resistant to smoking, high-heat cooking, and deep-frying
Nutrition		More nutritious	Refining reduces the nutrient level
Storage		Short storage life	Particles and resins removed making it more stable for longer storage
Appearance		May appear cloudy or have visible sediment (does not compromise quality)	More thoroughly filtered and strained than unrefined
Flavor/Aroma		Authentic in their color, taste, smell, and flavor	Refining reduces the flavor (free from any bad odor)

Video for reference: Click here

For our usage of deep-frying, we are not supposed to exceed 180*C and have to choose an oil that has a smoke point above this temperature. This also helps us reuse the oil conservatively and more safely since oil that reaches smoke point is deemed unfit for reuse.

Further, let's get into the smoke points of different oils and find which one matches our requirements.

Deep-frying Threshold: 180*C		Smoke Point (*C)
Ranks	Oil	Unrefined	Refined
1	Avocado Oil	250	271
2	Pistachio Oil	190	266
3	Rice bran Oil	180	254
4	Mustard Oil	180	250
5	Soybean Oil	190	230
6	Palm Oil	170	240
9	Safflower Oil	107	266
7	Sesame Oil	176	232
8	Olive Oil	190	215
10	Ghee	160	233
11	Sunflower Oil	160	232
12	Groundnut Oil	160	230
13	Canola Oil	160	229
14	Coconut Oil	177	204

C. Health benefits and side-effects

Each oil as mentioned earlier comes from a different source that could be a nut, seed, vegetable, or dairy. Inherent to the source, each oil will have different components and will impact the consumers’ health in different ways.

The study will not be able to highlight all the positive and negative impacts here as it is a comprehensive list, but let's try to cover up major points which will help us become more aware consumers.

Avocado Oil

Benefits

• Inhibits the growth of prostate cancer, breast cancer, oral cancer
• Benefits heart health
• High in antioxidants and neutralizes free radicals
• Enhances the Absorption of Important Nutrients
• Removes toxic elements from the body

Side-effects

• Not good for pregnant and lactating mothers
• Causes skin allergies in some people
• Excess consumption damages liver

Canola Oil

Benefits

• Anticancer Potential
• Reduce the risk of heart disease
• Prevents Inflammation
• inhibit cholesterol absorption
• Improves Glycemic Control

Side-effects

• Erucic acid causes damage to the Heart, Kidney, Liver

Coconut Oil

Benefits

• Boost heart health
• MCTs help increase HDL (good cholesterol)
• Used in keto diet since MCTs are harder for the body to convert into stored fat and easier to burn off
• MCTs are also helpful for kidney disorder people and Alzheimer’s disease
• Help reduce harmful abdominal fat

Side-effects

• Not good for diabetic or liver disease patients

Ghee

Benefits

• Butyric acid act as an anti-cancer agent
• Improves heart health
• Antioxidants presence make ghee as anti-inflammatory, neuroprotective
• CLA in the ghee helps in reducing body weight
• Balance the hormones especially the thyroid

Side-effects

• Ghee may contain COPs (Cholesterol Oxidation Compounds) which is carcinogenic

Groundnut Oil

Benefits

• Resveratrol found in groundnut protects our cells from cancer
• Improves cardiovascular health and reduces chances of heart diseases
• Protects blood vessels from plaque deposits and toxins
• Phytochemicals (natural antioxidants) in the oil reduce inflammation
• Lowers cholesterol and reduces the risk of weight gain and prevents obesity
• Regulates blood sugar and increase insulin sensitivity

Side-effects

• Excess consumption may cause allergies

Mustard Oil

Benefits

• Allyl isothiocyanate acts as a cancer chemo-preventive and slows cancer growth
• Improves cardiovascular health
• Allyl isothiocyanate and selenium has anti-inflammatory potential
• Lowers blood sugar and blood pressure

Side-effects

• Erucic acid is toxic and kills myocardial cells hence FDA 2016 banned mustard oil
• Tendency to irritate lungs

Olive Oil

Benefits

• Protects the body against breast cancer
• Reduces cardiovascular diseases and chances of stroke
• Full of antioxidants like tocopherols, β-carotene, lutein, squalene, lipophilic and hydrophilic phenols
• Oleocanthal (found in Olive Oil) may affect several inflammatory diseases
• Reduces hyperlipidemia (high blood cholesterol and triglyceride levels) and hypertension (high blood pressure)
• Reduced the risk of type 2 diabetes

Side-effects

• Excessive consumption may cause stroke, massive fall in blood pressure, kidney failure, and gallstones

Palm Oil

Benefits

• Helps in reducing the risk of cancer
• Helps in preventing cardiovascular issues
• It boosts bone health
• It acts as a blood coagulant

Side-effects

• Forms potentially carcinogenic substances on overheating
• Excess consumption causes a yellowing skin

Pistachio Oil

Benefits

• Prevents Heart Attack
• increases HDL lowers LDL
• Stimulates insulin production, reduces blood sugar, and hence prevents diabetes
• Improves immune system

Side-effects

• It's not good for pregnant women
• High doses or overconsumption may cause allergies

Rice Bran Oil

Benefits

• Tocotrienols (group of antioxidants) may have anticancer effects
• Has antioxidant and anti-inflammatory effects
• Oryzanol (found in rice bran oil) is good for cholesterol
• Support healthy blood sugar levels by improving insulin resistance, a risk factor for type 2 diabetes

Side-effects

• Lowers blood calcium in a pregnant woman
• Not good for people having digestive disorders

Safflower Oil

Benefits

• It may have Anti-inflammatory properties
• Reduces cholesterol level
• The compounds in safflower oil thin the blood and promote the smooth flow of blood
• Helps in muscle growth

Side-effects

• It's not good for pregnant women
• Potentially severe side effects include cardiovascular disease, diabetes, obesity, hyperlipidemia, hyperthermia, and thrombocytopenia

Sesame Oil

Benefits

• Suppresses growth of colon cancer cells
• Good for heart health
• Copper in the oil has anti-inflammatory properties
• May help - Control blood sugar, lowers the glucose levels in blood
• High iron content reduces Anemia

Side-effects

• It's not good for pregnant women
• Appendix infection, hair loss, skin rashes, and diarrhea

Soybean Oil

Benefits

• Maintains brain function
• Reduces pain and stiffness
• Strengthens body tissues
• Prevents anemia

Side-effects

• Studies found high consumption led to adverse metabolic changes
• Overconsumption may cause high blood sugar levels and fatty liver

Sunflower Oil

Benefits

• Selenium reduces the risk of cardiac problems
• Phytochemicals like choline and phenolic acid are beneficial for the heart
• Brings down inflammation
• Rich in antioxidants which increase immunity
• Promotes digestion and gut health
• Selenium reduces the risk of Liver degradation

Side-effects

• Excess consumption increases fasting insulin, blood sugar levels and may cause allergies

Based on these benefits and side-effects and their severity, we have tried to rank them as below. The above-mentioned points may be sufficient to help consumers decide for themselves

Ranks	Oil
1	Olive Oil
2	Groundnut Oil
3	Avocado Oil
4	Sunflower Oil
5	Sesame Oil
6	Mustard Oil
7	Coconut Oil
8	Ghee
9	Pistachio Oil
10	Rice bran Oil
11	Canola Oil
12	Palm Oil
13	Soybean Oil
14	Safflower Oil

Vitamin composition

Inherent to the source of oil, the vitamin composition of these oils also differs. Mostly Vitamin E and Vitamin K are found in oils and they also have their own benefits.

Vitamin E

• Prevents cancer

  • Promotes healthy heart and reduces the risk of heart disease
  • Improves hair growth and skin health
  • Prevents cataract formation
  • Boosts immune system
  • Fights Osteoarthritis Inflammation

Vitamin K

• Anticancer potential

  • Prevents blood clots
  • Improves heart health
  • Reduces excessive menstrual flow
  • Prevents osteoporosis
  • Prevents internal bleeding
  • Improves cognitive health
  • Prevents hemorrhaging in babies
  • Protects the immune system

To be able to decide which oil is better in terms of these vitamins, we should look at the quantities each oil has to offer.

Rank	Oil	per 100 gm Oil
		Vit. E (mg)	Vit. K (µg)
1	Pistachio Oil	226	0
2	Soybean Oil	8.1	183.9
3	Canola Oil	27.34	71.3
4	Olive Oil	14.39	60.2
5	Sunflower Oil	41.08	11.8
6	Rice bran Oil	32.3	24.7
7	Safflower Oil	34.1	7.1
8	Mustard Oil	34	0
9	Palm Oil	15.94	8
10	Groundnut Oil	15.7	0.7
11	Ghee	15.7	0
12	Avocado Oil	12	0
13	Sesame Oil	0.2	1.8
14	Coconut Oil	0.2	0.5

Cholesterol levels and calories

• The cholesterol level in each oil is near 0 and there is no additional cholesterol that these oils pump into the body. Although the fatty acids in these oils can impact in maintaining HDL and LDL in the body
• Ghee packs 256 mg cholesterol in 100 gm serving
• Each oil provides similar calories on intake ie 884 calories in 100 gm serving

Physical attributes of the oil

The physical attributes of these oils that we are going to cover here play certain importance in the perception of these oils and they also add to the flavor/aroma or the usage of the oil. From the presentation point of view, below is the data and our rankings.

Reusability of the Oil

Reusability of oil is a topic where one feels like reusing the oil without understanding the fundamentals behind its suitability to be reused.

1. What happens when you use fresh oil?

The oil has natural components which get heated along with the oil during cooking. These components may add additional flavor, the aroma when heated.

2. What happens when you heat oil at the smoke point?

Smoke point is essentially the temperature at which the oil (or the components) start burning.

Like any other substance, when these components are heated to a high temperature (say smoke point or above), they may burn, leaving them unsuitable for consumption.

Heating at smoke point (or above) oxidizes oil, creates free radicals, and also causes the unpleasant odors and flavor that is associated with rancidity.

3. What are free radicals and are they harmful?

While cooking, these components get oxidized and generate free radicals which contribute to the etiology of many chronic health problems such as cardiovascular and inflammatory disease, cataracts, and cancer.

4. What role do Natural(or synthetic) antioxidants play?

Antioxidants prevent the oxidation of oil and hence the generation of free radicals. They also reduce induced tissue damage by preventing the formation of radicals, scavenging them, or by promoting their decomposition.

Some oils have naturally abundant oxidants like avocado, groundnut, olive, sunflower, etc. Also, there are some naturally occurring antioxidants coming from phytochemicals that inhibit oxidation if added to the oil. Then, there are some synthetic antioxidants like BHT, BHA, TBHQ, and propyl gallate which are added in oils while deep-frying to artificially inhibit oxidation while cooking. Synthetic oils may have certain side effects.

As part of traditional methods, in some parts of India, adding alum to the oil is a common practice while deep-frying. As a surprise, alum is a mild anti-oxidant.

5. How is the reusability of the oil decided?

Now that it is clear what makes oil unusable for reuse, we are in a better position to decide how to evaluate the oil on its reusability factor.

• Most of the oils can be reused once
• Certain oils which have the presence of antioxidants in their composition can be reused twice
• Olive oil has an abundance of natural antioxidants that can be reused thrice
• Oils not touching the smoke point in their usage are more reusable than oils heated to smoke point. Hence, it is advisable to select the oil which has a high smoke point which delays the burning process and generation of free-radicals
• Once the oil starts generating foam while using, it is past its point of reuse

6. What to do with the used oil?

• Once the oil starts generating foam while using, it is past its point of reuse
• The oil that was deemed unfit for high heating can be used for low-heating purposes like shallow frying or tossing, etc.
• The oil that is unfit for any consumption at all should be properly discarded.
• Biodiesel can be generated from waste edible oils and can be sourced to the appropriate vendors. Video for reference