How to identify whether soybean oil is adulterated, and how to identify the authenticity of edible s

The first thing to know about is soybean oil.

The normal quality characteristics of soybean oil have changed, indicating that the quality of soybean oil has changed. When buying oil at the market, it is most likely that the oil is adulterated, and rice soup is usually added. The method of identifying adulteration is as follows:

1) Look at the brightness: *** soybean oil, the texture is clear and transparent, and there is no turbidity. If the oil is cloudy, it means that it is adulterated.

2) Smell the smell: soybean oil has a beany smell, and the oil without the smell of beany indicates that it is adulterated.

3) Look at the precipitation: the soybean oil, after multiple procedures processing, the impurities have been separated, there will be no impurities at the bottom of the bottle, if there is precipitation, it means that the soybean oil is rough or mixed with starch.

4) Test the moisture: pour a little oil into the pot, when heating, if there is a horn sound in the oil, it means that there is water in the oil. When buying oil in the market, you can also drop a few drops of oil on the waste paper, and if there is a horn sound when igniting and burning, it means that the oil is mixed with water.

In order to accurately identify the presence of other oils in vegetable oils, chemical tests can be used.

Take 5 ml of oil sample and add 2 ml of methane and 2% potassium nitrate to the test tube.

3 ml of solution, shake the tube vigorously so that the solution becomes milky.

Today, I took out several oil samples that had been frozen overnight in the freezer area of the refrigerator and found some abnormalities!

1. Soybean oil. Freeze into milky white lumps and thaw after about 1 minute.

2.A well-known brand blended oil, slightly opaque, liquid.

What's going on? The main ingredient of both oils is soybean oil, why do they behave differently after freezing?

This kind of test has also been done in different batches of soybean oil before, but it will not freeze into lumps, does it indicate that this soybean oil is adulterated, mixed with 44% palm oil?

1) Refrigeration identification. Put the soybean oil in the refrigerator, zero or 4, take it out after 30 minutes, the pure soybean oil is still clear and transparent, and the impure soybean oil will appear white flocculent or sediment.

2) Observe the transparency of the oil. The vegetable oil has high transparency, less water and impurities. After standing for 24 hours, it is clear and transparent, no turbidity, no precipitation, and no suspended solids. Otherwise, it is inferior oil.

3) Look at the color of the oil. The soybean oil is dark yellow and sometimes pale yellow.

4) Smell the aroma of the oil. Dip your fingers in a little oil, rub it in the palm of your hand and smell it. In addition to the smell of soybeans, soybean oil generally has no other peculiar smell. If there is a peculiar smell, it means that the quality of the oil is not good or it has deteriorated.

5) Tasting. Use chopsticks to dip a little oil and rub it on the tongue to identify its taste, and the normal quality of the pants has no peculiar smell. If the oil has bitter, spicy, sour, numb and other tastes, it means that the oil has deteriorated, and the quality of the oil with a burnt smell is not good.

6) Heating identification. Vegetable oils with a high moisture content foam and squeak when heated. The oil smoke has a choking bitter and spicy taste, indicating that the oil is rancid. The oil should foam less and disappear quickly.

Soybean oil contains VE, which has the effect of beauty and beauty, and soybean oil is relatively cost-effective, and it is the most commonly used edible oil in life. Hope mine is helpful to you!

Taste: soybean oil has a strong beany smell, rapeseed oil has a light rapeseed fragrance, cottonseed oil has a cottonseed flavor mixed with caustic alkali smell, and sesame oil has a fishy smell. When the oil is heated to 45 50, the smell is easier to distinguish.

If there is a hala smell or foul smell in the cooking oil, it means that the oil has been rancid and deteriorated, and it is inedible. You can also use your fingers to dip a little oil and apply it to your tongue to discern the taste. Generally, there should be no peculiar smell, such as sour, bitter and spicy, numb, etc., indicating that the oil has deteriorated and has a burnt smell'The oil quality is not good either.

Look at the color: A good cooking oil should be light yellow, yellow or brown and should be completely transparent. For example, the oil is mixed with starchy oils such as rice soup, sweet potato soup, and radish soup, and the oil color is blue; The oil sample is heated to 150 degrees and then cooled and poured out, and the bottom of the oil pan is cohesed or agglomerate.

Heating: Some rural soil pressed oil has a higher water content and less water content for spiral oil pressing. The moisture content of the oil is not enough.

If it is exceeded, it is called water heavy grease. Heavy water oils and fats are prone to hydrolysis, rancidity and bitterness, and even odor and deterioration. If the water weight is measured, a small amount of oil can be poured into the hot pan, and the foaming oil surface is the water heavy oil.

If heated to 150-180, the oil with high water content will make a squeaky sound; If there is a choking spicy smell in the oil smoke, it means that the protein in the oil is rancid and cannot be eaten. The oil should be less foamy and disappear quickly.

Now, the fakers are too powerful. Let's not try to discern. It's as simple as going to the big supermarket to buy something.

1. Color identification.

Pure grease is a colorless, transparent, slightly viscous liquid.

For sensory identification of the color of soybean oil, the sample is mixed and filtered, and then poured into a beaker with a diameter of 50 mm and a height of 100 mm, with an oil layer height of not less than 5 mm. Observe at room temperature in natural light.

It is then placed in front of a white background and observed by its reflected light. When the oil thickens or solidifies in winter, take about 250 grams of oil sample, heat it to 35 40 to make it present, and cool it to about 20 to identify it according to the above method.

Good quality soybean oil – yellow to orange-yellow in color.

Minor soybean oil – the oil color is brown to tan.

2. Identification of transparency.

For sensory identification of the transparency of soybean oil, a well-mixed 100 ml sample is placed in a cuvette and then placed in front of a white background to observe it with reflected light.

Good quality soybean oil – completely clear and transparent.

Inferior soybean oil – slightly cloudy with a small amount of suspended solids.

Inferior soybean oil – the oil is cloudy and has a large amount of suspended solids and sediment.

3. Odor identification.

Sensory identification of the smell of soybean oil can be carried out in the following 3 ways:

First, when the container containing grease is opened, put your nose close to the mouth of the container and smell its smell.

The second is to take 1 2 drops of oil sample and put it on the palm and back of the hand, close the hands together and rub it quickly until it is hot, and smell the smell. The third is to take about 25 grams of oil samples with a steel spoon. Heat to about 50 °C, approach the oil surface with your nose and smell it.

Good quality soybean oil – has the inherent odor of soybean oil.

Inferior soybean oil - the inherent smell of soybean oil is bland and slightly peculiar, such as grass.

Inferior soybean oil – has undesirable odors such as musty, burnt, hala, etc.

Basic concept of soybean oil.

Soybean oil is derived from soybean seeds, and soybean oil is the most produced oil in the world.

There are many types of soybean oil, which can be divided into pressed soybean oil and leached soybean oil according to the processing method; According to the type of soybean, it can be divided into soybean**, genetically modified soybean oil.

Soybean oil has a dark color and a special beany smell; The thermal stability is poor, and more foam will be produced when heated.

Soybean oil contains more linolenic acid, which is more susceptible to oxidation and deterioration and produces "bean odor".

From the perspective of edible quality, soybean oil is not as good as sesame oil, sunflower oil, and peanut oil.

First, look at the color and transparency. High-quality soybean oil is yellow or orange-yellow, with high transparency, almost completely clear and transparent; The inferior soybean oil is dark in color and brown or tan, and the oil is slightly turbid due to more impurities.

Second, smell the smell of soybean oil. I believe everyone knows the smell of soybean oil, and high-quality soybean oil has the inherent smell of soybean oil; Inferior odors are lighter, and even have peculiar smells such as musty odors.

Third, the quality of soybean oil depends on the taste of the oil. High-quality soybean oil has the inherent aroma of soybean oil and has no peculiar smell; Inferior soybean oil, on the other hand, will taste bitter or sour.

Generally speaking, soybean oil can be distinguished by looking, smelling and trying. soybean oil, in terms of color, should be the color of vegetable oil with a little golden yellow, not dark color, and there are not many impurity particles in it (after all, it is a filtration method, and it is still a little impurity, but it is not easy to see with the naked eye); The second is to smell, the soybean oil should smell a little fragrant, and if the soybean oil is stored for too long, it will have an unpleasant taste; Thirdly, the oil of soybean oil can be twisted by hand, if it is a normal oil, it is a little sticky, and conversely, if it is mixed with other things, the viscosity will decrease or become more sticky.