Effect of preheating and other process parameters on whey protein reactions during skim milk powder manufacture

• Published in: International dairy journal 2005-05, Vol.15 (5), p.501-511
• Main Authors: Oldfield, D.J., Taylor, M.W., Singh, H.
• Format: Article
• Language: English
• Subjects: Aggregation; beta-lactoglobulin; Biological and medical sciences; bovine serum albumin; casein; casein micelle; Denaturation; dried skim milk; Evaporation; Food industries; food processing; Fundamental and applied biological sciences. Psychology; heat treatment; immunoglobulin G; lactalbumin; lactoglobulins; Milk and cheese industries. Ice creams; preheating; protein aggregates; Skim milk powder; Spray drying; temperature; Whey protein
• ISSN: 0958-6946; 1879-0143
• DOI: 10.1016/j.idairyj.2004.09.004

Skim milk powder was manufactured in a milk powder plant using different preheating temperatures, concentrate heating temperatures and spray drying temperatures. Varying the preheating conditions from 70 °C for 52 s to 120 °C for 52 s had a marked effect on the denaturation of β -lactoglobulin A, β -lactoglobulin B, α -lactalbumin, bovine serum albumin (BSA), and immunoglobulin G. In contrast, varying concentrate heating temperature (65–74 °C) and inlet/outlet air dryer temperature (200/101 °C–160/89 °C) had a minimal effect on whey protein denaturation. Most of the whey protein denaturation and association with the casein micelle occurred in the preheating section of the powder plant. Aggregation of β-lactoglobulin ( β-lg) and BSA predominantly involved disulphide bonds. Although, greater than 90% of the β-lg and BSA was denatured after preheating at 120 °C for 52 s, the extent of association with the casein micelle was lower, 50% for β-lg and 75% for BSA.