Corn cooking oil

What is Corn Oil or Corn germ oil?

Corn oil popularly known as Corn germ oil or Maize oil is a cooking oil that is extracted from the inner part of the corn kernel. Due to its high smoke point properties and relatively cheaper than other cooking oil it is widely used in cooking.  The smoking point of corn oil is approx 450°F or 232°C making it suitable for frying , sauteing & Baking. It is extensively used in salad dressing & marinades due to its mild flavor. 

pic source-https://www.amazon.in/Eywa-Seeds-Exports-Pvt-Ltd/dp/B0BP2QJMFY

• Generally speaking, corn oil is less expensive than most of the vegetable oils. Corn oil is usually refined to remove impurities, which gives it a lighter color and neutral taste. Unrefined corn oil retains more nutrients and flavor but has a lower smoke point.

Charastristic of corn cooking oil:-

Corn cooking oil has many characteristice making it suitable for cooking purpose. Example of main characteristic of corn cooking oil are:-

• Corn kernel consisit of 81% endosperm, 11.5% corn germ, and 7.5% bran make up a corn kernel. In general, corn kernels make up 4-6% of the oil by weight. 80–85% of the total oil in maize comes from the germ, 12% from the corn protein aleurone, and the remaining 5% comes from the endosperm.

• Flavor:- Corn cooking oil has neutral & mild flavor that does not overpower the flavor of food items. 

• Smoke point:- It has high smoke point usually around 450°F (232°C) making itsuitable for frying, sauteing & grilling.

• Appearance:- Corn oil has light yellow in color with clear appearance .

• Corn oil is rich in polyunsaturated fatty acids, particularly linoleic acid (omega-6), along with monounsaturated fats and a smaller proportion of saturated fats.

• Corn oil is very versatile and can be used in vide range of cooking starting from frying to baking to salad dressing & marinades. 

• Shelf life:- Corn oil has relatively long shelf life due to its processing.

pic source-https://www.healthline.com/nutrition/corn-oil

Processing of corn cooking oil from corn kernel 

Corn kernels are made up of 7.5% bran, 11.5% corn germ, and 81% endosperm. Typically, 4-6% of the weight is made up of corn kernels. Corn germ contains 80–85% of the total oil in corn, while aleurone, a corn protein, contains 12% and the remaining 5% is found in the endosperm.

• Corn Kernel Preparation:- The corn kernels are first cleaned to remove dust, dirt, and other impurities.

• After being cleaned, the corn kernels are ground or milled into tiny pieces so that the oil may be extracted more easily. The oil-rich germ is separated from the remaining kernel by the milling process.

• Mechanical Pressing:- The corn is mechanically pressed to extract the  oil.

• Refining:- The crude corn oil is then treated with water or an acid to remove gums & other impurities. The oil is then bleached to remove pigments and other impurities that affect its color and clarity.

• After refining, the oil is filtered again to ensure purity and is then packaged in bottles or containers for distribution.

Brief history of production of corn oil:-

The first manufacturing of corn oil was done in USA in the year 1889 and after few year the large scale production of corn oil began in the year 1910 in USA.

After 1950, several developed countries also have taken up manufacturing of the corn oil. Initially majority of the corn oil production is used in the manufacturing of margarine, soap, paints etc whereas a very minimal amount of corn oil was used in cooking purpose.

With the advancement of the refining technique make it feasible for crude corn oil to refined it for cooking purpose. In USA corn oil constitutes around 4.5% of vegetable oil production and around 7.5% of total domestic oil utilization.

In India, Corn oil is not very popular till date for domestic use and even there is a very lack of public awareness in our country regarding the health benefit associated with use of Corn oil. Corn oil also does not constitute a part of conventional food receive in our countries.

In recent year, there are few companies which has started producing of corn oil in India. Some of the popular corn oil brands are- Korn drop refined corn oil, Vimal corn life etc.

Characteristic of Corn oil:-

• Corn oil is basically a by-product of corn meal and all the corn oil is refined for used in cooking purpose. Corn oil is an excellent source of essential fatty acids as it is high in poly unsaturated fatty acid (linoleic acid) accounting for approx 60% which is a heart-healthy fat and the 2^nd major fatty acid is Mono unsaturated fat (Oleic acid) accounting for approx.25% and rest are saturated fat (Linolenic acid) account for approx 15%.
• Corn oil having low melting points due to its low content of glycerides containing more than one solid fatty acid per molecule. It is therefore a natural salad oil that is it does not require the removal of stearin
• Refined Corn oil is a pale yellow in color, tasteless & odourless. Refined corn oil is considered to be the best edible oil used internationally.
• Corn oil has high stability, high smoke point, pleasant taste, light color & texture. Corn oil is an ideal for salad & cooking purpose as it tends to have good flavour stability and high smoke point and a good choice for deep fat frying.
• Mayonnaise sauce made of corn oil with stands freezing without breakup the emulsion better than that made with most to other salad oils.
• Corn oil is also used in the manufacturing of margarine by process of hydrogenation in which hydrogen gas is passed at high temperature and pressure in the presence of catalyst in the corn oil making it more saturated to convert into margarine.

Extraction process of corn oil:-

Step-1:- Cleaning of corn germ:-

After separation of corn germs from the corn kernel, the corn germs are thoroughly cleaned to remove any impurities. It is passed on the magnetic separator to detect any metal impurities.

Step-2:- Cracking the cleaned corn germs

The purpose of cracking the cleaned corn germs is to corn germ with smaller size prior to softening & flaking in order to improve the quality and capacity of corn germ flakes. Horizontal drum rotary cooker is used to adjust the temperature and moisture of corn germ prior to flaking. This helps to improve the yield of the corn oil.

Step-3: Flaking of corn germs:- After softening the corn germ, it is then flakes into thin flakes usually 0.3 mm in size, this helps to extract the corn oil easily from corn germ.

Step-4: Mechanical pressing of softened corn germ flakes:- Traditionally mechanical screw pressing machine or hydraulic press are used to squeeze the crude corn oil from the softened corn germ flakes. After 1^st press and 2^nd press almost 80% of corn oil are extracted from the corn germs where are approx 20% of corn oil still remains in the corn germs cakes which can also be extracted using chemical extraction solvent using hexane.

Step-5:-Filtering of crude corn oil:- The crude corn oil which is directly obtain from 1^st and 2^nd press from corn germs are then filtered to remove all the undesirable impurities. After filtering the crude corn oil it is still not ready for culinary use, therefore it is chemically refined to make it useful for culinary purpose.

Step-6:- Chemical refining of crude corn oil & oil obtain from the corn germ flakes by process of solvent extraction:-

All the filtered crude oil & corn oil obtain from the process of solvent extraction from corn germ flakes are then chemically refined by de-gumming, de-odoring, de-coloring, bleaching, winterization etc.

Pic source-seed oil press

Culinary use of Corn oil:-

• Corn oil has variety of uses from cooking to Non cooking applications. It has high smoke point similar to the peanut oil (450°F (232°C) making it ideal for deep fat frying, sautéing, baking products such as biscuits & cookies, pastries etc.
• Refined Corn oil is edible oil which has mild, medium-yellow color and neutral in taste as refining removes free fatty acids and phospholipids from corn oil resulting making the corn oil ideal for frying, grilling, baking, sautéing etc. Corn oil also have high smoke point and pleasant taste and less expensive as compare to the other vegetable oil.
• Corn oil is also used in the manufacturing of margarine by process of hydrogenation in which hydrogen gas is passed at high temperature and pressure in the presence of catalyst in the corn oil making it more saturated to convert into margarine.
• Corn oil is also extensively used in the manufacturing of salad dressing as well as in the cold sauces such as mayonnaise.
• Note:- Refined Corn oil & canola oil are similar in color and can be used interchangeably

Health benefit of corn oil & its Nutritional value-

Corn oil contains heart healthy compound such as linoleic acid, phytosterols & Vitamin –E which helps to lower the risk of heart disease. It also helps in reducing cholesterol especially LDL i.e bad cholesterol as it is high in anti-inflammatory phytosterol & other compound.

Corn oil is high in Omega-6 fatty acid(Linoleic acid) which is known to boost our immunity and also for some of the essential immune system functions.

Corn oil is highly refined oil. Corn oil contains Poly unsaturated fatty acid- 55, Mono unsaturated fatty acid- 30% and 15% of saturated fatty acid.

Corn oil contains Vitamin E which acts as an antioxidant and is required for the body. This too is one of the major health benefits of corn germ oil.

Just like olive oil, corn germ oil has the ability to reduce the blood pressure after consumption, especially in the case of hypertensive patients.

Nutritional value of corn oil (100gms)

• Energy:- 884 kcal
• Poly unsaturated fat-55gms
• Mono unsaturated fat- 30gms
• Saturated fat- 15gms
• Vitamin E & K
• Cholesterol- NIL
• Trans fat- 1.9gms

Shelf life of Corn oil:-

Corn oil should be stored in cool and dark location away from direct sunlight to protect it from getting rancid. In normal conditions, the shelf life of refined corn oil is around 12 to 18 months.

Ref:-

Indian council for agricultural research (ICAR), Directorate of maize research

Report on corn oil by Corn refineries association, Washington DC, USA

Feasibility report on corn oil by engineers India research institute.