One-step method for the isolation of α-lactalbumin and β-lactoglobulin from cow’s milk while preserving their antigenicity

Figures & data

Figure 1. SDS-PAGE analysis of whey protein supernatant and whey protein precipitate using 10–90% ammonium sulfate 1: Marker (10–170 kDa); 2–9: Supernatant of whey protein and whey protein precipitate using 10–90% ammonium sulfate. (a) Supernatant of whey protein (b) Precipitated whey protein.

Figure 2. Chromatogram of whey protein separation using anion exchange chromatography and SDS-PAGE analysis of the peaks collected during anion exchange chromatography 1: F1; 2: F2; 3: F3; 4: α-LA standard; 5: β-LG standard; 6: Marker (10–170 kDa).

Table 1. Linear equation and coefficient correlation of two standard samples.

Whey	Linear range (mg/mL)	Linear equation	Coefficient correlation
α-LA	0.016–1.000	y = 7144.21x + 174.8203	R^2 = 0.9989
β-LG	0.031–2.000	y = 5192.15x + 68.9273	R^2 = 0.9995

Figure 3. RP-HPLC Chromatogram of α-lactalbumin and β-lactoglobulin (a) Chromatographic pattern for an α-LA standard (b) Chromatographic pattern for a β-LG standard (c) Chromatographic pattern for α-lactalbumin (F2) from isolating the protein is shown in Fig. 2 (d) Chromatographic pattern for β-lactoglobulin (F3) from isolating the protein is shown in Fig. 2.

Figure 4. Indirect competitive ELISA assays for the antigenicity of α-lactalbumin and β-lactoglobulin (a) α-LA (b) β-LG.

Table 2. Linear equation and coefficient correlation of indirect competitive ELISA.

Protein	Linear range (ng/mL)	Linear equation	Coefficient correlation
Standard α-LA	0.5–500	y = –22.152x + 88.963	R^2 = 0.9984
Purified α-LA	1–500	y = –26.231x + 97.034	R^2 = 0.9951
Standard β-LG	1–1000	y = –25.738x + 97.954	R^2 = 0.9940
Purified β-LG	5–500	y = –33.25x + 112.5	R^2 = 0.9959