Food additives refer to artificially synthesized or natural substances added to food to improve the variety, color, aroma, and taste of food, as well as for preservation and processing needs such as preservatives. China strictly regulates the types, usage scope, and usage amounts of food additives, which must comply with the provisions of GB2760. Otherwise, excessive amounts of food additives in food can easily threaten consumers' health and even cause food poisoning.

Food additives in China are mainly divided into 22 categories, among which commonly used food additives include sweeteners, colorants, color protectors, preservatives, bleaching agents, antioxidants, thickeners, and stabilizers.

Currently, China's laws and regulations regarding food additives are not yet perfect, and there are significant safety and quality risks in the use of food additives in the food industry. Food manufacturers often add various food additives to make products more colorful, have longer shelf life, and taste better, sometimes even using additives excessively or beyond the permitted scope. Especially in some small food processing factories, there are many problems with food additives, seriously endangering consumers' health. Excessive use of food additives not only harms human health but also disrupts market order and is detrimental to the development of the industry economy.

Due to the increasingly prominent issues with food additives in the current food industry, safety testing of additives in food is extremely necessary. Testing food additives mainly includes testing the quality of food and the residue levels of additives in food. By strictly following the national or industry standards for food additive residue determination in China, the residue levels of related food additives in food are strictly tested to control food safety and quality. The following is an analysis of common detection methods for food additives.

1. Detection Methods for Food Sweeteners:

According to the relevant provisions in the "Hygienic Standard for the Use of Food Additives," sweeteners include natural sweeteners and artificial synthetic sweeteners. Among them, 15 types are synthetic sweeteners, such as sodium saccharin, aspartame, acesulfame potassium, alitame, and cyclamate sodium.

Current methods for detecting sweeteners mainly include gas chromatography, liquid chromatography, ion chromatography, ultraviolet spectrophotometry, thin-layer chromatography, and liquid chromatography-mass spectrometry. Among these, high-performance liquid chromatography can analyze most sweeteners and separate multiple sweeteners simultaneously, facilitating detection work.

2. Detection Methods for Colorants:

Colorants generally include natural pigments and synthetic food colorants. The commonly used synthetic food colorants include amaranth, cochineal red, lemon yellow, sunset yellow, indigo, and erythrosine.

Currently, China mainly uses high-performance liquid chromatography to detect synthetic colorants. This method has high sensitivity and accuracy. According to the "Determination of Synthetic Colorants in Food" GB/T5009.35-2003, liquid chromatography is first used to measure synthetic colorants. Using high-performance liquid chromatography can effectively detect synthetic colorant components in food.

Additionally, techniques such as paper chromatography, polarography, high-performance liquid chromatography-mass spectrometry, ultra-high-performance liquid chromatography, capillary electrophoresis, and test kits can be used to detect the content of synthetic colorants.

3. Detection Methods for Color Protectors

Color protectors in the food industry mainly include additives such as nitrites and nitrates. Unscrupulous vendors add color protectors to ham, bacon, sausages, and other foods to enhance the appearance of meat products and stimulate consumers' desire to purchase, thereby making profits. China's "Hygienic Standard for the Use of Food Additives" GB2760-2011 specifies the latest detection standards for nitrites and nitrates. Relevant detection methods are used to test the residue levels and usage scope of color protectors to ensure products meet food safety and hygiene quality requirements.

For nitrite and nitrate color protectors, China mainly uses ion chromatography for detection. Additionally, spectrophotometry, polarography, capillary electrophoresis, and high-performance liquid chromatography can also be used to detect the residue levels of these color protectors, effectively monitoring the types and amounts of additives in food and protecting consumers' interests.

4. Detection Methods for Preservatives

Currently, unscrupulous vendors in China's food industry add various preservatives to prevent food spoilage. Common preservatives include sorbic acid and its salts, benzoic acid and its salts, methylparaben, propylparaben, nitrites and nitrates, sulfites, sodium diacetate, and other additives.

China mainly uses spectrophotometry, gas chromatography, ion chromatography, capillary electrophoresis, and high-performance liquid chromatography to detect preservatives. The commonly used methods are gas chromatography and high-performance liquid chromatography, which can simultaneously measure multiple preservatives, are simple and fast, and provide relatively accurate results.

As more foods use mixed preservatives, overly single detection methods can no longer accurately detect the types and residue levels of preservatives in food. High-performance liquid chromatography can effectively, accurately, and quickly detect the types of preservatives in food.

5. Detection Methods for Bleaching Agents

Currently, many unscrupulous vendors use bleaching agents to soak food, such as soaking bean sprouts and mushrooms in bleaching agents and preservatives to make wild mushrooms appear fresher and more tender, attracting consumers. Even in making marinated foods, harmful substances like hydrogen peroxide are added to make the appearance bright and appetizing; or lotus roots are soaked in oxalic acid to whiten them, seriously endangering consumers' health.

Sulfites are the most commonly used food bleaching agents in China. Currently, China's "Hygienic Standard for the Use of Food Additives" GB/T2760-2014 clearly stipulates the usage amount and scope of nitrites and prohibits the use of sulfur for bleaching or preservation except for fumigation. However, sulfur fumigation easily produces sulfur dioxide, which seriously harms consumers' health.

(1) Hydrochloric acid p-rosaniline method. Currently in China, the main method for detecting free sulfites and total sulfites in food is the hydrochloric acid p-rosaniline method, which is based on a complexometric colorimetric principle. This detection method is widely used, but it involves the use of the highly toxic reagent sodium tetrachloromercurate, which poses significant risks to humans and the environment. Additionally, the sulfur dioxide standard solution used during detection is unstable, with its concentration gradually decreasing over time.

Therefore, to reduce the error margin in detection results, the reagents must be freshly prepared and used immediately during the detection process to avoid affecting accuracy, sensitivity, and uncertainty, ensuring highly accurate results. Moreover, some foods may contain interfering substances that disrupt the complexation reaction, leading to false positives.

(2) Besides the hydrochloric acid p-rosaniline method, total sulfite content can also be detected by methods such as distillation-iodometry, gravimetric method, ion chromatography, high-performance liquid chromatography, electrochemical chromatography methods, enzyme catalysis, and others for total sulfite detection.