Wang Xingguo: The culprit of the "rancid smell" - excessive peroxide value

Professor Wang Xingguo

Professor of School of Food Science and Engineering, Jiangnan University

Director of the International Joint Laboratory of Lipid Nutrition and Safety

Expert opinion 1: Peroxide value is one of the important indicators reflecting the degree of fat oxidation in food

The peroxide value reflects the content of hydroperoxide, the primary oxidation product of fats and oils in food, and is one of the important indicators for measuring the degree of oxidation of unsaturated fatty acids in fats and oils. The national food safety standard stipulates the limit values ​​of peroxide values ​​for edible oils and various oil-containing foods. For example, the National Food Safety Standard for Vegetable Oils (GB 2716-2018) stipulates that the peroxide value of crude vegetable oil and edible vegetable oil should be less than or equal to 0.25 g/100 g. Generally speaking, the higher the peroxide value, the higher the degree of oxidation of the fat.

Expert opinion 2: The peroxide value of food is easily affected by the external environment and increases

Biscuits, cakes, cooking oils, melon seeds, nuts and other foods all contain oils, and the oxidation of oils will cause the peroxide value to exceed the standard. In addition to the characteristics of the food itself, the factors that affect the oxidation rate of oils are also related to external environmental factors such as temperature, oxygen content and light. Generally speaking, the higher the storage temperature, the faster the oxidation rate; the higher the oxygen content, the faster the oxidation rate; light will also accelerate the oxidation rate of oils. Therefore, if the company is not careful in the raw material processing, production process, storage, transportation and other links, it will cause the peroxide value to exceed the standard, thereby affecting product quality.

Expert opinion 3: Foods with excessive peroxide values ​​pose potential risks to human health

If the peroxide value of food exceeds the standard, it means that the food has been oxidized and deteriorated, which may have adverse effects on the human body. The hazards are mainly manifested in three aspects: first, changes in taste and smell and loss of nutrients; second, aldehydes, ketones, acids, etc. produced when food is severely oxidized and deteriorated will destroy the absorption of fat-soluble vitamins, causing gastrointestinal discomfort, diarrhea, and even liver damage; third, long-term consumption of food with excessive peroxide value will aggravate chronic diseases such as cardiovascular diseases.

Picture丨TuChong Creative

Expert suggestion 1: Food production companies should strengthen process control according to the characteristics of different foods

Food production companies should select high-quality raw materials and optimize process parameters according to the characteristics and production goals of different foods. For foods rich in fat, strict measures such as oxygen isolation, deoxygenation and adding antioxidants should be adopted to delay fat oxidation. At the same time, the shelf life of the product should be reasonably evaluated to ensure the stability of the circulation link.

Expert advice 2: Pay attention to product label information and make reasonable purchases

When buying food, consumers should first check the outer packaging information, focusing on the production date, shelf life and storage conditions. From the perspective of a balanced diet, fat-rich foods should be consumed in moderation and in a reasonable manner, not too much or too little. The Dietary Guidelines for Chinese Residents recommends that the daily fat energy supply ratio for the general population should be controlled below 30%, and the intake of vegetable oil should be around 25 grams.

Expert advice three: Store cooking oil and oil-rich foods at low temperatures, away from light and oxygen

After purchasing edible oil and foods rich in fat, they should be stored in a low-temperature, light-proof, oxygen-proof environment. At the same time, small-packaged foods should be selected as much as possible, or large-packaged products with separate small packages. Food that is not finished after opening at one time should be sealed, packaged, and placed in a dark, cool place.

The "Scientific Interpretation of Food Safety and Health Hot Topics Media Communication Conference" has been held for 10 consecutive years since 2012. Every year, authoritative experts are invited to provide scientific interpretations of the annual food safety and health hot topics. In the form of "consensus in the scientific and technological community", it is widely disseminated through mainstream media and new media, such as television, newspapers, the Internet, Weibo, WeChat, etc. With scientific truth and fair suggestions, we will guide the public opinion on food safety in my country to gradually change in a scientific, objective and rigorous direction, and convey the positive energy of China's food safety.