FOOD PRESERVATIVE TEST

FOOD PRESERVATIVE TEST

Food additives (food additives) are used so that food looks more attractive and durable; these ingredients can be preservatives, colorings, flavorings and aromas, anti-oxidants, and others. So the ingredient is not nutritionally valuable, but is added to food in the manufacture or transportation to influence or maintain the special characteristics of the food.

Some food additives have a bad influence on human health; therefore the Ministry of Health has regulated / stipulated the types of food additives that may and may not be used in food processing. Additional ingredients that are prohibited from being used in food are formalin (formaldehyde) and boric acid (the salt is sodium tetraborate / borax).

BORAX

Borax is a sodium salt Na₂B₄O₇.10H₂O which is widely used in various non-food industries, especially paper, glass, solder, cleaning materials, wood preservatives, antiseptics, cockroach controls and ceramics. The famous pyrex glass is made with a mixture of borax.

Borax is used as a solder, cleaning agent, wood preservative, antiseptic and cockroach control. Borax is a poisonous and dangerous material for humans, because it can cause toxic effects, but the mechanism of toxicity is different from formaldehyde.

What is dangerous, borax can be absorbed by the body and stored cumulatively in the liver, brain, intestines or testicles so that the dose in the body becomes high. If consumed yearly can cause cancer. Borax is also often misused in food. Usually added to crackers, meatballs, rice cake and others. Laymen know borax by the name of Bleng (Indonesian) or Cetitet.

Symptoms can include nausea, vomiting, diarrhea, decreased body temperature, weakness, headaches, erythermatous rash, and can even cause shock. Death in adults can occur in doses of 15-25 grams, whereas in children in 5-6 grams doses. The danger of Borax on health is absorbed through the intestines, damaged skin and mucous membranes.

Following are some of the characteristics of foods containing borax. Although it is not too typical but can help distinguish it from food without borax.

a.      Wet noodles containing borax: The texture is very chewy, usually more shiny, not sticky and does not break quickly.

b.      Meatballs contain borax: The texture is very chewy, the color is not brown like the use of meat but is more likely to whitish

c.      The characteristics of crackers contain borax: The texture is very crispy, can give a bitter taste

WHAT IS FORMALDEHYDE

Another name for formalin is Formaldehyde or Metanal with the general formula HCHO. Formalin is a colorless and pungent solution, at room temperature in the form of a gas that can dissolve in alcohol, acetone or water.

In the chemical industry, it is very important as a disinfectant, fungicide, bactericide, basic material for making resins, preservatives of human beings / animals. Formaldehyde is a toxic in humans that can cause: Abdominal pain, skin irritation, Lack of protein (proteinuria), Excess acid (acidosis), Headaches to death, and Carcinogens / causes of cancer.

BORAX TEST

Tests on borax containing samples were carried out by adding 10 drops of conc. H₂SO₄ and 2 ml of methanol. Let stand for a while and then burned. This test produces the same yellowish green color as the flame test of pure borax compounds. This proves that the sample does indeed contain borax.

For test samples that do not contain borask the procedure is carried out the same as in test samples containing borax. But the results obtained do not cause a yellowish green flame.

The other ways to test for the presence of preservatives, especially borax, are:

To 0.5 ml the sample solution is added:

a.      Silver nitrate, white sediment will occur from metaborac silver. In heating, black Ag2O deposits will occur

b.      Saturated barium chloride, white barium metaborate will occur

FORMALIN TEST

A. Fehling Test

Take 10 grams of sample (tofu / wet noodles / meatballs) then puree using a mortar. Add 10 ml of water, stir until smooth. Then strain. Take ± 2ml of the filtered result, put it into a test tube. Add 3 ml of Fehling's solution. Heat 5-10 minutes. Observe and record the changes that occur. Solution contains formaldehyde if the initially blue solution turns green and yellow or red precipitate is formed.

B. Potassium permanganate test

               Test tube containing 10 ml of milk spiked with 1 drop of 1N KMnO₄ solution. The white milk solution will turn pink. The length of time the pink color is lost from a drop of a potassium permanganate solution into a test tube containing a sample of fresh milk is an indicator of possible formalin content in the milk.

               If 1 hour there is no change in color (stable pink) it means that the milk does not contain formaldehyde (or rather say it does not use formaldehyde as a preservative), and is followed by another series of tests before being declared acceptable as raw material. If the pink color of the potassium permanganate solution immediately fades / disappears to become colorless, it means there is a possibility in milk samples containing formalin which is reacting to eliminate the color (reducing) potassium permanganate.

               False positive (false results) can occur if the food contains other reducing agents that react with potassium permanganate such as oxalic acid, etc. But most of the preserved foods are plant / animal foods (wet fish, meatballs, tofu) that have high protein content are very unlikely to contain oxalic acid naturally.