Whey protein is an important component of milk, but heat treatment during sterilization has a certain impact on the structure and properties of whey protein. Therefore, this study investigated the effect of different heat treatments on the denaturation degree, physicochemical properties and functionality of camel whey protein, which was separated from camel milk heat-treated under different conditions, 65 ℃/30 min, 85 ℃/15 s, 125 ℃/4 s and 135 ℃/4 s, after milk fat and casein precipitation. The results showed that whey protein treated at 65 ℃ for 30 min had the highest turbidity (0.14), particle size (0.24 μm), zeta potential (?9.54 mV), solubility (24.57 mg/mL), and relative content of α-helix (31%) as well as the lowest relative contents of β-turn (13%) and random coil (19%); the water-holding capacity (WHC), foaming capacity and emulsifying capacity were significantly increased by the heat treatment, which indicated that 65 ℃/30 min treatment resulted in the smallest denaturation degree of whey protein and improvements in its functional properties such as emulsifying capacity, foaming capacity, WHC and oil-holding capacity (OHC) without significantly changing its physicochemical properties. With an increase in the heating temperature, the particle size of whey protein under 85 ℃/15 s treatment was increased to 0.32 μm, and the solubility was reduced to 22.34 mg/mL, but its functionality was improved compared with that of raw milk whey protein. Treatment at 125 ℃ for 4 s or 135 ℃for 4 s led to a large number of whey protein denaturation, destroyed the secondary structure, increased the particle size and turbidity, decreased the solubility, and worsened the functional properties.

The optimization of culture temperature, initial medium pH, and carbon and nitrogen sources for improved production of extracellular polysaccharides by Lactobacillus plantarum XN1904E was carried out using one-factor-at-a-time (OFAT) and orthogonal array design methods. The results showed that the optimal culture conditions were determined as follows: initial pH 6.5, temperature 37 ℃, galactose as the best carbon source, and fish peptone as the best nitrogen source. Under these conditions, the production of extracellular polysaccharide was 235.41 mg/L. The polysaccharide at 0.2 mg/mL had antioxidant activity in terms of scavenging rate (27.54%) against 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical.

Lactobacillus acidophilus LA-G80, isolated from the human intestinal flora, has probiotic functions. In this study, the medium composition and culture conditions for this strain were optimized. The results obtained showed that the optimal medium consisted of glucose 41.5 g/L, maltose 20 g/L, soybean oligosaccharide 10 g/L, beef extract powder 18.64 g/L, tryptone 10 g/L, yeast peptone 15 g/L, Tween-80 1 mL/L, K2HPO4·7H2O 2 g/L, NaAc·3H2O 5 g/L, triammonium citrate 2 g/L, MgSO4·7H2O 0.25 g/L, MnSO4·4H2O 0.05 g/L, aspartic acid 0.16 g/L, alanine 0.16 g/L, serine 0.16 g/L, peanut protein powder 5 425 g/L, and soybean cake powder 7 425.48 g/L. The optimal culture conditions were as follows: inoculum size 2%, initial pH 6.0, constant pH 5.5, and constant temperature 37 ℃. Experiments carried out in a 5 L fermenter gave a viable cell count of 42.2 × 108 CFU/mL, which was about 10 times higher than that of observed with MRS medium.

DNA was extracted from milk by collecting exfoliative cytology samples from dairy cows. A set of specific primers (α-La-F/R) was designed based on the α-Lactalbumin-encoding gene. A PCR method to detect milk allergens were established by screening the optimum experimental conditions. The results showed that the optimum PCR conditions were 56.5 ℃, 0.15 μmol/L and 35 for annealing temperature, primer concentration and number of cycles, respectively. The PCR method was highly specific and its sensitivity was 0.04 ng DNA. The PCR results of 10 types of commercial dairy products were identical to those described in the product label, suggesting this method to be accurate, reliable and thus applicable in practice.