Solubility of lactose‐free milk powders: Influence of protein content, incorporation of UF permeate and maltodextrin

Rationale Enzymatic hydrolysis and ultrafiltration (UF), when used independently, pose distinct challenges in manufacturing lactose‐free milk powder. Combining these approaches produces high protein lactose‐free milk, which, on spray drying, results in a powder that suffers from poor solubility and Maillard browning, restricting its use. Aim Study was conducted to address the challenges of poor solubility and Maillard browning associated with spray drying of lactose‐free milk prepared using UF coupled with enzymatic hydrolysis. Methods Lactose‐free concentrated milk was prepared using ultrafiltration (UF) followed by enzymatic hydrolysis. Further, lactose‐free milk powder (LFMP) was prepared by spray drying of lactose‐free concentrated milk with and without the addition of maltodextrin and permeate (UF/DF). Five types of LFMP were produced: LFMP‐1 (control) UF retentate, LFMP‐2 UF retentate and maltodextrin, LFMP‐3 DF permeate and maltodextrin, LFMP‐4 UF permeate and maltodextrin, and LFMP‐5 UF retentate and permeate. Major Findings All LFMPs possessed higher protein content (55.1–68.80%) but were less soluble than skim milk powder (SMP), which has about 33% protein. LFMP‐4 showed significantly lower protein and calcium content but higher sodium and potassium levels ( P < 0.05) compared to other LFMPs. This led to significantly higher solubility (98.54%) than the control LFMP‐1 (67.96%) and other formulations. Improved solubility of LFMP‐4 correlated with higher potassium (980 mg/100 g) and sodium (890 mg/100 g) but lower calcium (620 mg/100 g) and surface hydrophobicity (4746.46), which contributed to better particle dispersion and rehydration behaviour. Zeta potential also indicated greater electrostatic repulsion (−31.47 mV), further supporting the superior reconstitution properties of LFMP‐4. Raman spectroscopy also confirmed the complete absence of lactose in all formulations. The BI was also significantly lower in LFMP‐4. Industrial Implications UF permeate‐maltodextrin formulation (LFMP‐4) offers excellent potential as a high‐protein, highly soluble, lactose‐free milk powder suitable for lactose‐intolerant consumers.