<P> A subset of food additives, micronutrients added in food fortification processes preserve nutrient value by providing vitamins and minerals to foods such as flour, cereal, margarine and milk which normally would not retain such high levels . Preservatives also reduce spoilage from sources such as air, bacteria, fungi, and yeast . </P> <P> ISO has published a series of standards regarding the topic and these standards are covered by ICS 67.220 . </P> <P> Many food additives absorb radiation in the ultraviolet or visible regions of the spectrum . This absorbance can be used to determine the concentration of an additive in a sample using external calibration . However, additives may occur together and the absorbance by one could interfere with the absorbance of another . A prior separation stage is necessary and the additives are first separated by high - performance liquid chromatography (HPLC) and then determined on - line using a UV and / or visible light detector . </P>

What is the difference between food additives and preservatives