After summer or rainy season, I bought foods with high oil content such as melon seeds, peanuts, biscuits, etc. for a long time. When I opened the packaging and ate it, I often had a pungent, unpleasant, bitter and numb smell, commonly known as "Ha" smell.
How does the "Ha" smell come about? What impact does it have on health? How does
"Ha" smell come about?
"Ha" smell is an odor caused by oxidation and rancidity of oil under the action of oxygen, sunlight, moisture and temperature. The oils in food will be decomposed into free fatty acids , peroxide , aldehydes, ketones and other substances under the action of oxygen, light, heat in the air, as well as their own moisture, microorganisms, lipase , etc. This change is called the rancidity of oils, and the odor produced is what we commonly call "ha" smell.
How to measure the degree of fat rancidness in food?
fat rancidity is divided into hydrolytic rancidity and oxidative rancidity, which correspond to two important indicators for measuring the freshness of oils in food: acid value and peroxide value. Acid value is an indicator used to detect the content of free fatty acids produced during the hydrolytic rancidity of oil and fat and to measure the degree of oil and fat hydrolysis. Peroxide value is an indicator used to detect the peroxide content generated during the oxidative rancidity of oil and fat and to measure the degree of oxidation of oil and fat.
National food safety standards stipulate the limits of acid value and peroxide value in foods such as edible oils and oil content, such as nuts, biscuits, pastries, breads, puffed foods, etc. The maximum limit value of acid price is between 1.0 mg/g-5.0 mg/g (calculating in potassium hydroxide ), and the maximum limit value of peroxide value is between 0.10 g/100g-4.0 g/100g. Generally speaking, the smaller the acid value and peroxide value, the better the quality, freshness and refinement of the oil.
(Regulations on acid value and peroxide value in some foods)
What are the dangers of oil rancidity in foods? If the acid value and peroxide value exceed the standard, it will affect the flavor and nutritional value of the food. Within the national standard limit, it will generally not endanger human health. However, if you eat too much food that has been rancid, it may irritate the digestive tract and cause discomfort such as nausea, vomiting, abdominal pain, diarrhea, etc. Long-term consumption can also damage the liver and increase the risk of cardiovascular and tumors.
What should be paid attention to when purchasing and edible foods? . Purchase foods with high oil content. Pay attention to checking the production date and shelf life to avoid buying expired foods. It is recommended to buy independent small packaged foods to avoid wasting waste if they cannot be eaten at one time. Stored foods should be in accordance with the requirements of food labels, such as keeping them in a cool and dry place, etc.; foods after opening should be sealed and stored and eaten as soon as possible. If foods are found to have "slow" smells, they should be avoided.
Source: Kaifeng Quality and Technical Supervision and Inspection Center Wang Wenjie
Edited by: Henan Provincial Institute of Standardization and Quality Tian Xin
