1. The recent application trend and development direction of acidifier, probiotics, enzyme preparations, oligosaccharide and natural extract etc. were overviewed.

2. It was concluded that the study of acidifier formula with the uniform design method was feasible and the test efficiency of formula of acidifier study was improved with the uniform design method.

3. In conclusion, the addition of acidifier, probiotics and oligosaccharides alone or combined in the diet improved microbial population status and immune function of weaning piglets.

4. This paper analyzed the Structure-Activity Relationship of some kinds of food additives, such as preservative, antioxidant, thickener, emulsifying agent, sweetener and acidifier, etc.

5. The kelp drink was prepared by mixing the diluted hydrolysate sweetener, acidifier and stabilizer.

6. Therefore, the two experiments were hereby to set up to investigate the formulation of complex acidifier and its mechanism in weaned pigs.

7. Acidifiers are widely used in feed, especially in feed of weaned pigs. However, there are still disputes on effect and mechanism of acidifier.

8. Accuracy of analysis results was improved by buffer solution as the acidifier.