The influence of temperature and pressure factors in supercritical fluid extraction for optimizing nonpolar lipid extraction from buttermilk powder

Fat reduction (%) in supercritical fluid extraction-treated buttermilk powder for 3 different pressures (15, 25, and 35MPa) and temperatures (40, 50, and 60°C). Bars with different letters denote significant difference (P<0.05).

Lipid solubility properties in supercritical CO₂ for pressure (15, 25, and 35MPa) and temperature values: 40°C (▴), 50°C (■), and 60°C (●). The top set of values (left y-axis) is for the theoretical solubility parameter and the lower set of values (right y-axis) is experimental solubility.

An interaction plot for percentage fat reduced shows that at the lowest pressure setting (15MPa), lipid extraction efficiency is somewhat limiting to the other 2 settings, regardless of temperature. Temperature values: 40°C (−1), 50°C (0), and 60°C (+1); pressure values: 15MPa (●), 25MPa (■), and 35MPa (♦).

Main effects plot for pressure and temperature on percentage fat reduction in supercritical fluid extraction-treated buttermilk powder. The values shown (−1, 0, and +1) indicate the 3 levels for pressure (15, 25, and 35MPa, respectively) and temperature (40, 50, and 60°C, respectively).

Thin layer chromatograph showing nonpolar lipid profiles from 9 supercritical fluid extraction experimental settings with buttermilk powder (BMP) using the petroleum ether:ethyl ether:acetic acid (85:15:2, vol:vol:vol) solvent system. Lane 1 = phospholipid standard mix; lane 2 = original BMP; lanes 3 to 11, defatted samples A to I; lanes 12 to 19 = removed fat from experimental settings (A-ext to H-ext). PL = phospholipids; MAG = monoacylglycerides; DAG = diacylglycerides; Chol = cholesterol; FFA = free fatty acids; TAG = triacylglycerides; and CholEster = cholesterol esters.

Reducing SDS-PAGE (12%) stained with Coomassie Blue and silver stain, on supercritical fluid extraction-treated buttermilk powders (BMP) from the first trial. Lanes: 1) 35 MPa/50°C; 2) original BMP; 3) molecular weight marker; 4) 35 MPa/60°C; 5) 15 MPa/40°C; 6) 15 MPa/50°C; 7) 15 MPa/60°C; 8) 25 MPa/40°C; 9) 25 MPa/50°C; 10) 25 MPa/60°C; 11) 35 MPa/40°C. MFGM = milk fat globule membrane.

A) Reducing SDS-PAGE (12%) stained with Coomassie Blue on untreated buttermilk powder (BMP) and supercritical fluid extraction (SFE)-treated powder under extreme conditions (37.5 MPa/77°C). Lanes: 1) molecular weight marker; 2) original BMP; 3) BMP treated under extreme conditions. B) Microfluidic–laser-induced fluorescence (in relative fluorescence units) virtual electrophoretogram of reducing proteins on untreated BMP (- - -) and SFE-treated BMP (—) under extreme conditions (37.5 MPa/77°C). MFGM = milk fat globule membrane.

Protein solubility determined in a 5% protein solution for supercritical fluid extraction-treated buttermilk powders. Treatment of powders indicated by pressure (15, 25, and 35MPa) and temperature (40, 50, and 60°C).^a,bBars with different letters denote significant difference (P<0.05); error bars indicate SD.