Nutrient Loss And Microbial Changes In The Processing Of Children’s Milk Powder

Childhood is the golden period of intellectual and physical development,and the demand for nutrients has changed significantly compared with the infant period,so the requirements of children’s milk powder are very different from those of ordinary formula milk powder.This study designed a formula of children’s milk powder by measuring the macronutrient and micronutrient contents of raw and auxiliary materials,calculating the amino acid pattern of raw and auxiliary materials,referring to children’s nutritional needs and national standards,and verified the formula by the nutrient loss during milk powder processing.In addition,to further verify the formula,this study studies the loss of nutrients in the processing of children’s milk powder.Finally,this study monitored the microbial changes in the processing of children’s milk powder which provide a basis for the microbial research of milk powder.The following are the key research results of this study:（1）The amino acid patterns of valine and sulfur-containing amino acids in raw milk are lower than that in children’s requirement pattern,and the amino acid patterns of sulfur-containing amino acids and aromatic amino acids in desalted whey powder are lower than that in children’s requirement pattern.The proportion of whey protein powder is adjusted to increase the amino acid content of milk powder on the basis of macronutrients of raw and auxiliary materials.The types and contents of nutrients that need to be fortified are determined by the content of micronutrients in raw and auxiliary materials,and the basic formula of children’s formula milk powder is determined with reference to children’s dietary nutrient requirements and national standards:Raw milk（dry matter）about 20%,desalted whey powder（type of D90）about 12%,whey protein powder（type of WPC70）about 2.5%,edible vegetable blend oil（containing1,3-dioleate-2-palmitic triglyceride）about 12%.Five vitamins（A,D,E,C,K₂）,three minerals（calcium,iron,zinc）,one protein amino acid（histidine）,and two fatty acids（DHA,OPO）are required to be fortified.（2）In order to further verify whether the nutrient content in the formula of milk powder can meet the national requirements,this study studies the loss of vitamin C,iron and sodium is the most in the process section of ingredient standardization,with the loss rates of 20.7%,12.3%and 23.3%,respectively.The losses of vitamin A,vitamin D and vitamin C in the sterilization and concentration process section were the most,with loss rates of 7.1%,7.3%and 20.7 respectively.The loss rate of vitamin A,vitamin E and vitamin C in the spray drying process was 7.4%,19.1%and 34.9%respectively.At the end of the wet processing,vitamin C,vitamin D,vitamin E,iron and sodium lost the most,with loss rates of 59%,12.7%,7.1%,25.2%and 13.1%respectively.There is basically no loss of macronutrients,so only micronutrients and amino acids are verified in this study.The results showed that the nutrient content of finished milk powder met the requirements of national standards,and the amino acid pattern of finished milk powder met the amino acid demand pattern of children.（3）Microbiological analysis was carried out on the samples from eight stages of children’s milk powder processing.The results showed that the relative abundance of Streptococcus was significantly increased in premixed,dry mixed and packaged sections（p<0.05）.The relative abundance of Pseudomonas was significantly increased from raw milk to pasteurization stage（p<0.05）,and significantly decreased from pasteurization stage（p<0.05）.The bacteria was not detected in the spray drying stage and the subsequent process stage.Camobacterium and Serratia were only found in raw milk and were not identified in pasteurization and subsequent stages.Thermus and Anoxybacillus only existed in the process of standardization of ingredients,concentration and spray drying.Staphylococcus and Enterococcus mainly existed in the ingredients,standardization,concentration and spray drying stages,and were not detected in the process stages after the spray drying process stage.Pasteurization,concentration of ingredients and spray drying were the process stages of microbial changes in the process of milk powder processing.This study determines the formula of a child’s milk powder and is verified by the loss of nutrients in the process,and the formula of the children’s formula meets the requirements of the state,and the study of the microbial changes in the processing process is studied,and the production practice of the child milk powder is provided.