Beta-lactoglobulin (β-LG) is one of the most important allergens in whey protein. How to reduce the antigenicity of β-LG is a problem that needs to be solved. In this paper, alkaline proteinase, trypsin or their combination was used to hydrolyze whey protein, and samples were taken at different hydrolysis times. The degree of hydrolysis and molecular mass distribution of the hydrolysate with the lowest antigenicity of β-LG were analyzed, and its bitter taste was compared with that of two commercial hydrolyzed whey protein products. Overall, hydrolysis of bovine whey protein with a mixture of alkaline protease and trypsin (1:1, m/m) produced products with low bitterness and antigenicity (0.798 μg/mL). The process parameters were as follows: substrate concentration 15 g/100 mL, enzyme to substrate ratio 5 000 U/g (50% alkaline protease plus 50% trypsin), initial pH 8.0, and hydrolysis for 2.5 h at 48 ℃.

Streptococcus thermophilus phages pose a major threat to the production of many fermented dairy products. As new Streptococcus thermophilus phages have been continuously discovered and isolated during dairy fermentation, knowledge of the physiological characteristics and infection mechanism of Streptococcus thermophilus phages has gradually been improved. Understanding their biodiversity and determining their interaction with the host can provide a theoretical basis for the control of phages in the dairy industrial environment. This review summarizes the classification of Streptococcus thermophilus phages, the adsorption receptor and receptor binding protein of Streptococcus thermophiles and the molecular mechanisms of phage infection in order to provide useful information for the study and control of other Lactobacillus phages.

In this paper, we investigated the effect of test conditions such as probe diameter, compression distance, trigger force, container volume, pre-test speed, test speed, post-test speed on the textural properties of stirred yoghurt, and we also evaluated the effect of pre-test speed, test speed, post-test speed on the firmness, elasticity and viscosity of yoghurt with an orthogonal experimental design L9(34). In addition, the textural properties, viscosity and elastic modulus of 8 kinds of popular commercial yogurt were in situ determined without destroying the original packaging. The results showed that all test conditions affected the textural properties of stirred yoghurt. The appropriate test conditions were as follows: 1 mm/s of pre-test speed and test speed, 10 mm/s of post-test speed, 30 mm of compression distance, 35 mm of probe diameter, 5 g of trigger force, and 100 mL of container volume. At the confidence level of α = 0.05, test speed had a significant effect on the firmness and elasticity, while post-test speed was a significant factor influencing the adhesive force. Moreover, there existed obvious differences in the textural properties of different kinds of yoghurt. Elastic modulus was correlated with firmness, consistency, adhesiveness, adhesive force and elasticity, and viscosity was correlated with firmness, consistency, adhesiveness and adhesive force.

Propylene glycol alginate is widely used in dairy products or milk-based beverages as a thickener.The aim of the work was to study the influence of pH on the rheological properties of propylene glycol alginate solution.For this purpose,steady-state flow sweep,strain sweep,frequency sweep,dynamic viscoelasticity temperature sweep and dynamic viscosity temperature sweep experiments were carried out with an AR-G 2 rheometer.The experimental results showed that the viscosity,viscoelasticity,and complex viscosity of propylene glycol alginate solution decreased as pH increased,while the loss tangent increased.Meanwhile,at pH below 7 the degree of shear thinning decreased while it increased at pH above 7.In addition,pH influenced the effect of temperature on the viscosity and viscoelasticity of propylene glycol alginate solution.

The aim of this study was to explore the effects of parity and lactation stage on somatic cell counts in dairy herd improvement (DHI) milk samples and milk production loss in dairy cows. The results indicated that the somatic cell score (SCS) was increased with parity, and SCSs at different stages of lactation performance in different parities were different. SCS was increased with lactation time in first-parity dairy cows and SCS values were significantly different at three lactation stages (P < 0.05). The same trend was observed for SCS in second- and third-parity cows; SCS was higher at the early lactation stage than at the middle lactation stage, and its values at the two stages were significantly lower than that at the late lactation stage (P < 0.05). Milk production loss in dairy cows generally rose with parity and was higher at the early and late stages of lactation than at the middle stage.

The objective of this study was to determine the growth curves and antibacterial activity of two different strains of Lactobacillus salivarius. Streptococcus mutans, Porphyromonas gingivalis and Staphylococcus aureus were selected to perform antibacterial tests in vitro by the Oxford cup method. The results showed that the logarithmic growth phase of the two strains of Lactobacillus salivarius began respectively at 2 and 4 hours after inoculation and ended both at 8 hours, and the stationary phase began at 14 and 16 hours, respectively. It was proved that the bacteria cultures of both strains of Lactobacillus salivarius and their metabolites had antibacterial activity against Streptococcus mutans, Porphyromonas gingivalis and Staphylococcus aureus, and the antibacterial activity against Streptococcus mutans and Porphyromonas gingivalis was stronger than that against Staphylococcus aureus. Also, for both strains, neither bacterial sludge nor metabolite with an adjusted pH value (7.0) had antibacterial activity. Antibacterial activity of both strains of Lactobacillus salivarius came mainly from their metabolites, and it were acid or acid-dependent materials that play a key role in the antibacterial activity of metabolite.

Oat flour is widely used in beverage after being processed as a kind of grain. In this paper, pasting properties of starch from oat flour were studied using a rapid viscosity analyzer (RVA). Meanwhile, oat gluten was also characterized by measuring ethanol solubility index and the protein properties were determined using dilute lactic acid. The effects of different production processes for oat flour on pasting properties of starch and viscosity characteristics of gluten protein were discussed. We also determined the content of β-glucan in oat flour, which was found to have no obvious effect on the viscosity of gluten protein measured using dilute lactic acid. In addition, the peak viscosity and final viscosity measured using dilute lactic acid had obvious correlations with the final viscosity obtained from the method of ethanol solubility index showing correlation coefficients of 0.810 3 and 0.836 4, respectively, but no correlation with ethanol solubility index was observed.

This investigation determined the contents of the fat-soluble vitamins A, D and E in human milk samples collected from Hohhot, the capital of North China’s Inner Mongolia region, and analyzed the changing patterns of these vitamins during the lactation period. Nutritional evaluation of maternal breast milk with respect to these fat-soluble vitamins was conducted by the Chinese dietary reference intake (DRI) with the aim of guiding the development of milk powder products for infants. The results showed that the contents of VA and VE were 0.11 and 0.93 mg/100 mL in colostrum, and 0.05 and 0.29 mg/100 mL in mature milk, respectively, while VD content was too low to be detected in colostrum and mature milk. VA and VE contents tended to decline with prolonged lactation. Moreover, it was found that VA was relatively abundant in breast milk from Hohhot, which could meet infants’ nutritional requirements. However, breast milk could not meet VD and VE requirements for infants. As a result, dietary fortification and supplementation of VD and VE are needed for breastfed infants.

Objective: To develop a colloidal gold-based immunochromatographic assay for rapid detection of casein. Methods: We used casein and anti-casein polyclonal antibody as raw materials, nitrocellulose membrane and glass fiber paper as a carrier to prepare a rapid test strip. Results: The sensitivity of the test strip was 2.3 mg/mL, and the detection process required 10 min with good repeatability and stability. Conclusion: We have successfully developed a casein test strip.