Heat stability improvement of antimicrobial whey proteins from yak milk and colostrum at various acidic conditions

The aim of this study was to characterize the effect of heat denaturation on Immunoglobulin G (IgG) and Lactoferrin (LF) inyak milk and colostralliquidwheyat mediumacidicconditionsinpresenceofprotectants(CaCl₂;Glyceroland Sodium Dodecyl Sulphate - SDS). Results indicated significant (P < 0.05) heat stability improvement of IgG and LF in liquid whey samples at medium acidic and temperature (72 - 90°C) with less precipitates formation regardless of type of protectants added especially at pH 3.5 and 4.6. The mean concentration values for IgG percentage reduction (72 – 90°C; pH 3.5 – 5.5; protectants) ranged from 6 to 26% and 15 to 31% in yak milk and colostral liquid whey, respectively. The percentage of heat denaturation effect for LF ranged from 11 to 32% and 14 to 38% in yak milk and colostral liquid whey, respectively. Application of glycerol in both environmental processing conditions was the most effective in heat stability improvement followed by SDS and CaCl₂.