The little secret about "vegetable oil" that merchants won't tell you!

The production of most foods must comply with national standards.

The little secrets that merchants don’t want to tell you are clearly written in the standards!

Knowing what the standards say and understanding the little tricks behind them will help you choose high-quality food!

Let’s talk about “vegetable oil” today!

Vegetable oil refers to the national standard GB2716-Vegetable Oil. The standard stipulates that vegetable oil can be mainly divided into three categories: crude vegetable oil, edible vegetable oil, and edible vegetable blended oil.

Of course, crude vegetable oil is used to process vegetable oil and cannot be eaten directly, so vegetable oil is divided into only two categories. But when it comes to subcategories, there are so many varieties that it fills up a folder.

Palm oil, rice bran oil, peanut oil, soybean oil, rapeseed oil, sesame oil, linseed oil, sunflower seed oil, corn oil, walnut oil, grape seed oil, olive oil, tea seed oil, peony seed oil, and edible blending oil.

Tell us which one you care about in the comment section. We will explain them one by one later.

In order to ensure the quality of edible oil, the national standard stipulates a total of six dimensions to evaluate vegetable oil. Among them, four dimensions, namely raw material characteristics, pollutants and mycotoxins, pesticide residues, food additives and nutritional enhancers, are similar to other foods, while sensory quality and physical and chemical indicators have unique requirements. Let's talk about these two dimensions in detail.

1. Sensory quality

Edible oil products must have good appearance and flavor. The national standard states that qualified oils should be based on the following points:

①The color should not be abnormal

② No burnt, rancid or other odors

③ There is no foreign matter visible to the eyes in the oil body

If you do these things, the oil will look good!

Of course, sensory quality can only be evaluated from visible aspects, but in many cases it is invisible to the naked eye, so this has to be left to physical and chemical indicators!

2. Physical and chemical indicators

Physical and chemical indicators are mainly used to evaluate the deterioration or foreign matter in edible oil that is invisible to the naked eye, and mainly include: acid value, peroxide value, polar components, solvent residues, etc.

(1) Acid value

It is a measurement standard for the number of free carboxylic acid groups in vegetable oils, that is, it tests the content of free fatty acids.

In normal edible oils, fatty acids exist in a bound form. They combine with glycerol to form triglycerides, commonly known as "fats."

When cooking oil goes bad, although you may not see anything wrong on the outside, the fat in it will break down, releasing the bound fatty acids into free states, which can also be detected by acid value.

The higher the acid value, the higher the free fatty acids and the more severe the fat cracking, which means the oil is less fresh!

(2) Peroxide value

If the acid value is used to evaluate the degree to which the edible oil has deteriorated, then the peroxide value is used to look at the potential risk of deterioration of the oil.

If edible oil comes into contact with air during storage, the bad boy oxygen in it will enter the bodies of some fatty acids and plant small landmines. When certain conditions are met, these hidden dangers will explode and cause the edible oil to deteriorate.

Therefore, testing the peroxide value of edible oil is also an act of eliminating hidden dangers!

(3) Polar components

Under high temperature conditions such as frying, fat will break down to produce various substances that are harmful to health. These substances have one thing in common, which is that they have a stronger polarity than fat, collectively referred to as polar components (TPM).

Therefore, TPM is the standard for evaluating whether frying oil can continue to be used, and it is very critical for the oil in fried chicken shops!

In addition, for extracted oils, it is necessary to pay attention to the "solvent residue", and for vegetable oils containing cottonseed oil, it is also necessary to pay attention to the content of cottonpol, etc.

In short, physical and chemical testing is like a simple physical examination of edible oil, and those small problems that cannot be seen can be discovered!

Behind the vegetable oil standard, there is a description of the fatty acid composition. A similar table printed on the oil bottle packaging can also help us choose edible oil from the perspective of nutritional value.

Different edible oils contain different fatty acids. Some are mainly oleic acid (omega-9), while others are mainly linoleic acid (omega-6) or α-linolenic acid (omega-3). For convenience, we can simply call them No. 9 oil, No. 6 oil and No. 3 oil.

The following is a classification of common cooking oils:

Scientific oil usage recommends changing a model every 2-3 months, and don’t just focus on one type, so as to achieve a balanced requirement for fatty acid types!

The pictures in this article are authorized from the official gallery, please be careful when reprinting!