Food additives are chemically synthesized or natural substances added to food to improve the quality and color, aroma, taste, shape, and functions of preservatives, freshness and processing technology. As long as the food additives are used in a reasonable manner and in a reasonable dose, they will not cause Food safety issues. According to the above definitions, Which of the following are food additives:. ['Pigments, leavening agents, protein extracts, preservatives.', 'Sweetener, moisture, emulsifier, sodium sulfide.', 'MSG, native sugar alcohols, vitamins, minerals.', 'Colorants, poppy shells, flour treatment agents.']