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

Abstract

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.

Comparison of nanofiltration and evaporation technologies on the storage stability of milk protein concentrates

“…MPC rehydrated suspensions (20 mL) were immediately transferred to the sample cup of the viscometer. Data was recorded in 30 s after starting the instrument (Liu et al 2012). …”

“…2.2) were measured by the same particle analyzer, with a presentation code that assumed the following optical parameters: a relative refractive index between the dispersed and continuous phases of 1.57, a particle absorbance of 0.00, and a continuous phase refractive index of 1.33. The results of particle size were presented by d 50 (Liu et al 2012). …”

“…The protein bands were stained using a solution of Coomassie Blue R-250. After staining and destaining of the gels, the protein bands were digitally scanned using Kodak Gel Logic 212 Imaging System (Eastman Kodak Company, Rochester, NY) (Liu et al 2012). Each sample was analyzed at 0-, 4-, 12-, and 24-week storage.…”

Qualitative and quantitative identification of adulteration of milk powder using DNA extracted with a novel method

“…Adulteration is economically viable because cow milk powder costs less and is more available than goat milk in many countries (Zachar et al, 2011). Each year in China, 16 to 18 million babies are born and 300,000 t of milk powder is consumed (Liu et al, 2012); thus, the authenticity of milk powder is a major issue in China and has been a concern of government authorities for decades. To avoid the possible fraudulent substitution of goat milk powder with cow milk, it is necessary to develop analytical procedures able to detect such fraud and protect consumers from misleading labels.…”

Changes in physicochemical properties and DNA quality of milk as affected by different heat treatments

“…However, heat treatments also have an adverse effect on the nutritional quality of milk, as many reactions occur during the sterilisation process, such as protein denaturation and the Maillard reaction (Van Boekel 1998;Corredig and Dalgleish 1999). Several studies have evaluated the effects of heat treatments on the nutritional quality and physical properties of milk (Cook et al 1951;Efigênia et al 1997;Liu et al 2012), studies into the effects of heat treatment on the DNA quality of milk are rare.…”