Changes of microbiological and physicochemical properties in Chinese infant formula caused by high heat treatment applied on concentrated milk

In 2010, China published highly strict food safety standard for infant formula (GB 10765 2010 ). However, many manufacturers in China found it difficult to meet the new microbiological standard. The aim of this study was to find the appropriate processing conditions for producing Chinese infant milk with reduced microbial load. Concentrated milk was heated at 95 °C for 15 s (LHT) and 110 °C for 4 s (HHT), and their effects on the microbiological quality and physicochemical properties of the infant formula milk powder were investigated. Compared to LHT, HHT made significant effects on the bacterial, thermophilic, and aerobic spore counts. In addition, the total bacterial count of the infant formula milk powder after HHT met the requirements of the safety standard (GB 10765 2010 ). In terms of nutritional content, both powders met the requirement (GB 10765 2010 ) with no significant differences observed. There were also no significant differences observed between the two powders in terms of particle morphology, wettability, free fat content, thermal characteristics of fat, or milk fat globule membrane permeability. Although some slight differences ( P ≤ 0.05) were found in solubility, dispersibility, viscosity, particle size of the reconstituted powder, and protein characteristics, the acceptability of the product under both heat treatments was found to be similar. The knowledge derived from this work can potentially provide an effective method for processing infant formula milk powder in China.