Electrostatic Spray Drying of a Milk Protein Matrix-Impact on Maillard Reactions

Area of Science:

• Food Science and Technology
• Dairy Processing
• Drying Technologies

Background:

• Milk protein powders (whey protein isolate, skim milk powder, lactose) are susceptible to degradation during drying.
• Maillard reaction and lactose crystallization are key quality concerns affecting milk powders.
• Conventional spray drying (CSD) can induce thermal degradation, impacting powder quality.

Purpose of the Study:

• To compare electrostatic spray drying (ESD) with conventional spray drying (CSD) and freeze-drying (FD) for milk protein matrices.
• To evaluate the impact of drying methods on Maillard reaction indicators (free -NH2 groups, HMF) and lactose crystallization.
• To assess the stability of milk powders during storage under various temperature conditions.

Main Methods:

• Production of milk protein powders using ESD, CSD, and FD at different water activities (a_w).
• Quantification of free amino groups (available lysine) and 5-hydroxymethylfurfural (HMF) post-drying and during storage (28 days at 20, 40, 60 °C).
• Analysis of lactose crystallization in powders under different storage conditions.

Main Results:

• ESD and FD powders retained higher levels of free amino groups (~15% more) compared to CSD powders.
• CSD powders exhibited higher HMF concentrations (~14% more) than ESD and FD powders.
• All powders showed decreased free amino groups and increased HMF with higher storage temperatures; lactose crystallization occurred earlier in CSD and ESD powders at elevated temperatures.

Conclusions:

• Electrostatic spray drying (ESD) is a gentle drying technology for milk protein matrices.
• ESD effectively minimizes Maillard reaction markers, preserving lysine and reducing HMF formation compared to CSD.
• ESD offers a promising alternative for producing high-quality milk protein powders with improved stability.