It’s a common misconception that vegetable oil is inherently kosher and does not require reliable kosher supervision. In fact, the oil production industry is a complicated one, touching upon multiple halachic issues.

Nosein Ta’am Lifgam
Non-kosher items that were mixed into kosher food and affect the taste of
a mixture in a negative way are called “nosein ta’am lifgam”. This does not render the kosher food forbidden.

When non-kosher utensils are used for hot food preparation, these vessels
(metal, wood, or stone) should be properly cleaned and then kashered due to the absorption of non-kosher food. Even if it has been more than 24 hours since they were used to cook non-kosher food (after which the vessels become nosein ta’am lifgam), our Sages forbade cooking with these utensils because they might be confused with vessels which aren’t nosein ta’am lifgam.

Safeik S’feka (Double Doubt)
After the fact, if one cooked with a non-kosher vessel, even those used in a
heated process, the food is permissible because we assume that those vessels were not used within the past 24 hours. It is permissible because it is considered to be a double doubt; there is doubt whether the Gentile used this vessel within the last 24 hours, in which case all the taste that it has absorbed is considered foul and not a kosher issue. Even if it had been used
today, there is still a possibility that the Gentile used it for an item that might negatively affect the taste of the dish in question. For example: if the food in question is oil, if the Gentile previously cooked meat in that vessel, the taste of meat would negatively impact the taste of the oil.

From the outset, it is forbidden to cook with the vessels of a non-Jew by relying on the doubts, as mentioned above. If it is likely that a Gentile used these vessels within the last 24 hours, such as restaurant utensils that are constantly used (such as a fryer which is often used with animal fats), or an oil refinery that operates year-round, one cannot rely on any of the above-mentioned leniencies, even after the fact. If one does know that the vessel has not been used in the last 24 hours, but he also knows that the ingredients cooked in the vessels would not negatively impact the food in question, one of the doubts falls away and the food is forbidden.

The most common vegetable oils marketed to consumers are sunflower,
canola, rapeseed, and soy oils. Industrial vegetable oils include the aforementioned consumer oils, as well as palm, palm kernel, and coconut oils. Industrial oils often originate in the Far East. In addition to the unrefined vegetable oils, animal fats, such as fish and tallow, are processed in some refineries. The refining process addresses several components of the oil, including triglycerides, phosphates (gums), free fatty acids (FFA),
and wax, and enhancing the appearance and the smell. Several ingredients are used to achieve the desired refined oil. Some of these are antioxidants, beta carotene, rosemary extract, and anti-foam, in addition to the chemical auxiliary materials.

There are several steps during the refining process:
Pressing – The seeds are pressed with a mechanic pressor and then go through a second extraction with hexane. Then the oil is filtered to separate the waste and the hexane in a distillation process (steam which passes through the oil).

Degumming – Extracts the phosphates (gums) and lecithin. This process can be done in two ways:
Centrifugation with hot water – This separates the water from the oil and the phosphates are separated with the water because they dissolve in water.
Mix with phosphoric acid and citric acid – This is especially useful when the phosphates contain magnesium or calcium, which are difficult to remove with water alone.

Removing the fatty acids – The main components of the oil are triglycerides. All triglycerides are essentially a compound of glycerin and three fatty acids. As time passes, the oil naturally oxidizes, causing a separation between the acids and glycerin, and there are more other free fatty acids present in the oil. These FFA must be removed because it affects the taste of the oil and there are two ways to do this:
Chemical neutralization and centrifugation – This is done by mixing caustic soda with water. The FFA are dissolved in the water and then separated by centrifugation between the water and the oil.
Physically – by a deodorization facility. This is achieved by injecting steam into the oil under a vacuum (stripping) and the FFA evaporates out.
Bleaching – to improve the look and lighten the color. This is achieved by adding activated carbon and bleaching earth.

Winterization – extracting the wax by cooling, which causes the wax to crystallize, and then it is separated.

Fractionation (done in palm and palm kernel oil) – The oil undergoes a slow cooling process which causes the olein to separate and sink while the stearin remains at the top.

Hardening (for hardened oil production) – This is done with a nickel catalyst that has an oil coating. This ingredient needs to be kosher certified.

When setting up kosher supervision at an oil refinery, it is important that the refinery only processes vegetable oils. The heating system should not be shared with other factories in the area. If it is a shared system, the rabbi needs to find out what is produced in those factories, especially when the steam comes in direct contact with the oil. If the refinery supplements its production with refined oil purchased from other refineries, the oil must be kosher. Sometimes a company outsources part of the production (due to either technical or logistical reasons).

That refinery might be also producing non-kosher, so it is important to verify what happens in the co-manufacturer’s facility.

Some factories produce both kosher and non-kosher oils. Before certifying any facility, a formal binding contract that outlines the kosher requirements and obligations must be executed. This is in addition to appointing a mashgiach who understands the system well and is available for frequent inspections.

One should make sure that the kosher and non-kosher production lines are completely separated and physically divided. In addition, the steam system must be either separated, drained (not recycled), or pogum (bitter).

There is also the potential for issues in the way the oil is heated. To save energy, the incoming oil is often heated by the outgoing oil through a heat exchanger. The cooling water is often shared, as well.

If there is an identical kosher and a non-kosher product (such as glycerin), there has to be constant supervision (mashgiach temidi) for both production and transportation. This is necessary even if the systems are completely separate, for example, if one is done via ion exchange and one by distillation.

When transporting oil one has to make sure, as explained above, that the tankers and other reusable equipment were not used within the last 24 hours, because the previous cargo can be a potential kashrus problem according to the Torah if it is not pogum or if the kosher oil is not 60 times the volume of the non-kosher residue (which nullifies the non-kosher oil).
Based on the above considerations there is still a safeik d’oraisa, so measures must be taken to ensure that:

1. The vessels used for hauling the oil are either new or kosher for transporting the oil from its source to the refineries. This includes the large and small barges, including all of the storage cells. Kosher and non-kosher should not be transported at the same time, because the heating system can adversely affect the status of the kosher products.
2. The storage tanks located at the terminals in the ports, including the steam heating system, must be kosher.
3. The tanks used to transport the finished product from the refinery to the customers must also be new or kosher.

All of this requires special monitoring and complex data review to make sure all the equipment used is kosher by verifying that the last loads were acceptable and the storage vessels were thoroughly cleaned and koshered.
OK Kosher, under the leadership of Rabbi Berel Levy OB”M, was the first agency to set up this system for all kosher supervised oils. Rabbi Don Yoel Levy OB”M, who succeeded his father as the Kashrus Administrator of the OK, gave his body and soul to fortify kashrus around the world, especially for bulk oils. He was at the head of the campaign consistently and resolutely, until even in Europe, many tank cleaning stations include a cleaning and a kosherizing program which all hechsherim accept. Today the Vaad HaKashrus continues to uphold these high standards for all OK-certified bulk oils.

In 5767 (2007-2008), there were B’nei Torah in Lakewood who pointed out deficiencies in the kosher statuses of unmonitored transport ships, as mentioned in this article, and they turned to Rav Yosef Shalom Elyashiv ztz”l, who wrote a letter urging American rabbis to take care of this issue. As a result, Rav Dovid Feinstein ztz”l, called for a meeting of all of the Roshei Yeshivos and heads of kashrus agencies in the United States which took place at Yeshiva Tiferes Yerushalayim. I was privileged to attend this great assembly with my dear uncle, Rabbi Don Yoel Levy OB”M.

One of the Roshei Yeshivos suggested that there should be special productions of oil done at a high level of kosher supervision for B’nei Torah. It seemed to him that the general oil productions were too vast to be sufficiently monitored. I responded: “There are hundreds of kosher products containing oil that are sold in grocery stores; how can we make sure they are all up to our standard?”

When I was asked about the situation in Europe I explained, with G-d’s grace, clearly and at length the entire process and system used by OK Kosher. The rabbis and Roshei Yeshivos accepted our systems with great admiration and called upon all of the hechsherim to follow our example.
As one can see from the intricate process described in this article, there is certainly a major difference between a bottle of oil that is certified by an agency that monitors the entire refining process, from the source extraction through the bottling, and one that is not strictly monitored. Therefore, one should only purchase oil bearing a reliable kosher supervision.

This article is l’ilui nishmas my late wife, Bluma Chana bas Rav Chaim Aharon A”H, who passed away at a young age. She was always by my side, especially in my kashrus work and enabled me to teach, learn and serve Hashem according to His will. .ת.נ.צ.ב.